MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Current Opinion in Microbiology' source. Thu, 09 Feb 2012 21:34:57 +0100 http://www.medworm.com/index.php?rid=5658029&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22280885%26dopt%3DAbstract Authors: Sham LT, Tsui HC, Land AD, Barendt SM, Winkler ME Abstract Streptococcus pneumoniae is a serious human respiratory pathogen that has the capacity to evade capsule-based vaccines and to develop multidrug antibiotic resistance. This review summarizes recent advances in understanding the mechanisms and regulation of peptidoglycan (PG) biosynthesis that result in ellipsoid-shaped, ovococcus Streptococcus cells. New results support a two-state model for septal and peripheral PG synthesis at mid-cell, involvement of essential cell division proteins in PG remodeling, and mid-cell localization of proteins that organize PG biosynthesis and that form the protein translocation apparatus. PG biosynthesis proteins have already turned up as promising vaccine candidates and targets of an... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5658029 Tue, 24 Jan 2012 05:00:00 +0100 5658029 http://www.medworm.com/index.php?rid=5658030&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22265250%26dopt%3DAbstract Authors: Ali SS, Xia B, Liu J, Navarre WW Abstract Xenogeneic silencing proteins facilitate horizontal gene transfer by silencing expression of AT-rich sequences. By virtue of their activity these proteins serve as master regulators of a variety of important functions including motility, drug resistance, and virulence. Three families of silencers have been identified to date: the H-NS like proteins of Gram-negative bacteria, the MvaT like proteins of Pseudomonacae, and the Lsr2 proteins of Actinobacteria. Structural and biochemical characterization of these proteins have revealed that they share surprising commonalities in mechanism and function despite extensive divergence in both sequence and structure. Here we discuss the mechanisms that underlie the ability of these proteins to... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5658030 Thu, 19 Jan 2012 05:00:00 +0100 5658030 http://www.medworm.com/index.php?rid=5620184&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245564%26dopt%3DAbstract Authors: Fang W, Azimzadeh P, St Leger RJ Abstract Insect pathogenic fungi play an important natural role in controlling insect pests. However, few have been successfully commercialized due to low virulence and sensitivity to abiotic stresses that produce inconsistent results in field applications. These limitations are inherent in most naturally occurring biological control agents but development of recombinant DNA techniques has made it possible to significantly improve the insecticidal efficacy of fungi and their tolerance to adverse conditions, including UV. These advances have been achieved by combining new knowledge derived from basic studies of the molecular biology of these pathogens, technical developments that enable very precise regulation of gene expression, and genes e... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5620184 Fri, 13 Jan 2012 05:00:00 +0100 5620184 http://www.medworm.com/index.php?rid=5620185&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22236805%26dopt%3DAbstract Authors: Hanson BR, Neely MN Abstract The cell surface of Gram-positive pathogens represents a complex association of glycopolymers that control cell division, homeostasis, immune evasion, tissue invasion, and resistance to antimicrobials. These glycopolymers include the peptidoglycan cell wall, wall-teichoic acids, lipoteichoic acids, and capsular polysaccharide. Disruption of individual factors often results in pleiotropic effects, making it difficult to discern regulation and function. In this review we collate recent work describing these pleiotropic phenotypes, and propose that this is due to coordinated regulation of biosynthesis or modification of these cell surface components. A better understanding of the regulatory networks that control the relative prevalence of each fac... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5620185 Mon, 09 Jan 2012 05:00:00 +0100 5620185 http://www.medworm.com/index.php?rid=5577859&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226607%26dopt%3DAbstract Authors: Sondermann H, Shikuma NJ, Yildiz FH Abstract Cyclic dimeric guanosine monophosphate (c-di-GMP) is a common, bacterial second messenger that regulates diverse cellular processes in bacteria. Opposing activities of diguanylate cyclases (DGCs) and phosphodiesterases (PDEs) control c-di-GMP homeostasis in the cell. Many microbes have a large number of genes encoding DGCs and PDEs that are predicted to be part of c-di-GMP signaling networks. Other building blocks of these networks are c-di-GMP receptors which sense the cellular levels of the dinucleotide. C-di-GMP receptors form a more diverse family, including various transcription factors, PilZ domains, degenerate DGCs or PDEs, and riboswitches. Recent studies revealing the molecular basis of c-di-GMP signaling mechanisms enh... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5577859 Thu, 05 Jan 2012 05:00:00 +0100 5577859 http://www.medworm.com/index.php?rid=5577862&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221896%26dopt%3DAbstract Authors: Burnside K, Rajagopal L Abstract A growing body of evidence indicates that serine/threonine kinases (STKs) and phosphatases (STPs) regulate gene expression in prokaryotic organisms. As prokaryotic STKs and STPs are not DNA binding proteins, regulation of gene expression is accomplished through post-translational modification of their targets. These include two-component response regulators, DNA binding proteins and proteins that mediate transcription and translation. This review summarizes our current understanding of how STKs and STPs mediate gene expression in prokaryotes. Further studies to identify environmental signals that trigger the signaling cascade and elucidation of mechanisms that regulate crosstalk between eukaryotic-like signaling enzymes, two-component syste... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5577862 Tue, 03 Jan 2012 05:00:00 +0100 5577862 http://www.medworm.com/index.php?rid=5577861&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221897%26dopt%3DAbstract Authors: Sadykov MR, Bayles KW Abstract The processes involved in the development of complex multicellular communities, including the programmed elimination of individual cells during the formation of specialized structures, exhibit fundamental similarities between prokaryotic and eukaryotic organisms. Mechanistic similarities may also exist at the molecular level, as bacterial proteins hypothesized to be related to the apoptosis regulator Bax/Bcl-2 family have been identified, fueling speculation about the existence of bacterial PCD. Here we review the regulatory networks controlling cell death and lysis in Staphylococcus aureus and examine the environmental parameters that might influence them during the development of a biofilm. We hypothesize that the heterogeneous environmenta... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5577861 Tue, 03 Jan 2012 05:00:00 +0100 5577861 http://www.medworm.com/index.php?rid=5577860&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221898%26dopt%3DAbstract Authors: Rigel NW, Silhavy TJ Abstract The outer membrane (OM) of Gram-negative bacteria is an essential organelle that serves as a selective permeability barrier by keeping toxic compounds out of the cell while allowing vital nutrients in. How the OM and its constituent lipid and protein components are assembled remains an area of active research. In this review, we describe our current understanding of how outer membrane proteins (OMPs) are delivered to and then assembled in the OM of the model Gram-negative organism Escherichia coli. PMID: 22221898 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5577860 Tue, 03 Jan 2012 05:00:00 +0100 5577860 http://www.medworm.com/index.php?rid=5559501&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209085%26dopt%3DAbstract Authors: Rath CM, Dorrestein PC Abstract Microbial communities in the gut have been hypothesized to play key roles in the health of the host organism. Exploring the relationship between these populations and disease states has been a focus of the human microbiome project. However, the biological roles of the compounds produced by the gut bacteria are largely unknown. We hypothesize that these compounds act as metabolic exchange factors-mediating inter-species and intra-species interactions in the microbiome. This view is supported through this review of known bacterial metabolic exchange factors and evidence for uncharacterized metabolic exchange factors in the gut. The impact of model systems and technological developments in exploring this hypothesis are also discussed. Together,... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5559501 Fri, 30 Dec 2011 05:00:00 +0100 5559501 http://www.medworm.com/index.php?rid=5559500&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209485%26dopt%3DAbstract Authors: Richter-Dahlfors A, Duménil G PMID: 22209485 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5559500 Thu, 29 Dec 2011 05:00:00 +0100 5559500 http://www.medworm.com/index.php?rid=5559502&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22206860%26dopt%3DAbstract Authors: Tazi A, Bellais S, Tardieux I, Dramsi S, Trieu-Cuot P, Poyart C Abstract Streptococcus agalactiae (group B Streptococcus, GBS), a normal constituent of the intestinal microbiota is the major cause of human neonatal infections and a worldwide spread 'hypervirulent' clone, GBS ST-17, is strongly associated with neonatal meningitis. Adhesion to epithelial and endothelial cells constitutes a key step of the infectious process. Therefore GBS surface-anchored proteins are obvious potential adhesion mediators of barrier crossing and determinant of hypervirulence. This review addresses the most recent molecular insights gained from studies on GBS surface proteins proven to be involved in the crossing of the brain-blood barrier and emphasizes on the specificity of a hypervirulent c... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5559502 Tue, 27 Dec 2011 05:00:00 +0100 5559502 http://www.medworm.com/index.php?rid=5559504&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22204808%26dopt%3DAbstract Authors: Alteri CJ, Mobley HL Abstract Bacterial growth in the host is required for pathogenesis. To successfully grow in vivo, pathogens have adapted their metabolism to replicate in specific host microenvironments. These adaptations reflect the nutritional composition of their host niches, inter-bacterial competition for carbon and energy sources, and survival in the face of bactericidal defense mechanisms. A subgroup of Escherichia coli, which cause urinary tract infection, bacteremia, sepsis, and meningitis, have adapted to grow as a harmless commensal in the nutrient-replete, carbon-rich human intestine but rapidly transition to pathogenic lifestyle in the nutritionally poorer, nitrogen-rich urinary tract. We discuss bacterial adaptations that allow extraintestinal pathogenic ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5559504 Mon, 26 Dec 2011 05:00:00 +0100 5559504 http://www.medworm.com/index.php?rid=5559503&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22204809%26dopt%3DAbstract Authors: Rumbaugh KP, Kaufmann GF Abstract Environmental and commensal microbes that live within, on and around us have an enormous impact on human health. Recent progress in studies of prokaryotic interplay as well as host-bacteria interactions suggests that secreted microbial products, including quorum sensing signals (QSS), are important mediators of these intrakingdom and interkingdom relations. Reports have assigned QSS diverse and sometimes seemingly contradictory effects on mammalian cell physiology ranging from either blunting of the immune response or exerting pro-inflammatory activities to inducing cellular stress pathways and ultimately apoptosis. Thus, it is still unclear whether microbes utilize QSS to establish and maintain infections via modulation of host signaling ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5559503 Mon, 26 Dec 2011 05:00:00 +0100 5559503 http://www.medworm.com/index.php?rid=5548436&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22197250%26dopt%3DAbstract Authors: Göpel Y, Görke B Abstract Bacterial two-component systems (TCSs) and small regulatory RNAs (sRNAs) form densely interconnected networks that integrate and transduce information from the environment into fine-tuned changes of gene expression. Many TCSs control target genes indirectly through regulation of sRNAs, which in turn regulate gene expression by base-pairing with mRNAs or targeting a protein. Conversely, sRNAs may control TCS synthesis, thereby recruiting the TCS regulon to other regulatory networks. Several TCSs control expression of multiple homologous sRNAs providing the regulatory networks with further flexibility. These sRNAs act redundantly, additively or hierarchically on targets. The regulatory speed of sRNAs and their unique features in gene regulation ma... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5548436 Fri, 23 Dec 2011 05:00:00 +0100 5548436 http://www.medworm.com/index.php?rid=5548437&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22189442%26dopt%3DAbstract Authors: Harding M, Kubes P Abstract The development of intravital imaging techniques to visualize cellular behaviour in vivo has enhanced our understanding of the diverse cell types involved in vascular anti-bacterial immunity. Once considered simply a site of leukocyte adherence, we now know that endothelial cells play an active role in the host response, mediating detection of infectious pathogens and facilitating the access of leukocytes to sites of infection. Once recruited, cells such as neutrophils clear pathogens through a number of mechanisms which ensnare and kill bacteria. For example, neutrophils collaborate with platelets to produce neutrophil extracellular traps that play an active role in trapping and eradicating bacteria. It is well known that Kupffer cells in the v... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5548437 Mon, 19 Dec 2011 05:00:00 +0100 5548437 http://www.medworm.com/index.php?rid=5532937&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22185907%26dopt%3DAbstract Authors: Melican K, Dumenil G Abstract Bacterial infection of human vasculature can lead to unregulated systemic activation of coagulation and innate immunity and rapidly becomes life threatening. Neisseria meningitidis is a vascular pathogen that causes fatal sepsis and meningitis. Post-mortem histological analysis of tissues from individuals infected with N. meningitidis show large bacterial aggregates in close association with the vascular wall of small vessels. The ability of this bacterium to colonize blood vessel endothelium is likely to impact its capacity to both multiply in the blood stream and reach the brain. This process will be referred to as vascular colonization. Recent work has described a number of early steps in N. meningitidis vascular colonization, from attachme... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532937 Sun, 18 Dec 2011 05:00:00 +0100 5532937 http://www.medworm.com/index.php?rid=5532928&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22185908%26dopt%3DAbstract Authors: Stacy AR, Diggle SP, Whiteley M Abstract Microbiologists often describe communication as occurring within and between bacterial species and even across the prokaryote-eukaryote divide. In a strictly evolutionary sense, however, communication should occur only rarely between unrelated organisms. Clearly, the microbiological and evolutionary definitions and standards for what qualifies as communication widely differ. In microbiology, the term "communication" is often used to denote any interaction between two organisms. Advancement in knowledge hinges on precise language and conceptual distinctions when introducing new scientific ideas. While terminology exists for describing interactions which are not true communication, excessive preoccupation with semantics may impede pro... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532928 Sun, 18 Dec 2011 05:00:00 +0100 5532928 http://www.medworm.com/index.php?rid=5532938&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22177113%26dopt%3DAbstract Authors: Hansson GC Abstract The intestinal mucus is an efficient system for protecting the epithelium from bacteria by promoting their clearance and separating them from the epithelial cells, thereby inhibiting inflammation and infection. The function of the colon inner mucus layer is especially important as this explains how we can harbor the large number of bacteria in our gut. The major component of this mucus system is the MUC2 mucin which organizes the mucus by its enormously large net-like polymers. Pathogenic microorganisms, in turn, have developed mechanisms for circumventing this well-organized mucus protective system. PMID: 22177113 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532938 Wed, 14 Dec 2011 05:00:00 +0100 5532938 http://www.medworm.com/index.php?rid=5532939&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22172627%26dopt%3DAbstract Authors: Jung K, Fried L, Behr S, Heermann R Abstract Two-component systems, composed of a histidine kinase (HK) and a response regulator (RR), are the major signal transduction devices in bacteria. Originally it was thought that these two components function as linear, phosphorylation-driven stimulus-response system. Here, we will review how accessory proteins are employed by HKs and RRs to mediate signal integration, scaffolding, interconnection and allosteric regulation, and how these two components are embedded in regulatory networks. PMID: 22172627 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532939 Tue, 13 Dec 2011 05:00:00 +0100 5532939 http://www.medworm.com/index.php?rid=5532940&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22169833%26dopt%3DAbstract Authors: Robbins JR, Bakardjiev AI Abstract Placental infections are major causes of maternal and fetal disease. This review introduces a new paradigm for placental infections based on current knowledge of placental defenses and how this barrier can be breached. Transmission of pathogens from mother to fetus can occur at two sites of direct contact between maternal cells and specialized fetal cells (trophoblasts) in the human placenta: firstly, maternal immune and endothelial cells juxtaposed to extravillous trophoblasts in the uterine implantation site and secondly, maternal blood surrounding the syncytiotrophoblast (SYN). Recent findings suggest that the primary vulnerability is in the implantation site. We explore evidence that the placental SYN evolved as a defense against path... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532940 Mon, 12 Dec 2011 05:00:00 +0100 5532940 http://www.medworm.com/index.php?rid=5532941&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22155062%26dopt%3DAbstract Authors: Wakeman CA, Skaar EP Abstract Owing to the unique redox potential of transition metals, many of these elements serve important roles as cofactors in numerous enzymes. However, the reactive nature of metal becomes an intracellular threat when these ions are present in excess. Therefore, all organisms require mechanisms for sensing small fluctuations in metal levels to maintain a controlled balance of uptake, efflux, and sequestration. The ability to sense metal ion concentration is especially important for the survival of pathogenic bacteria because host organisms can both restrict access to essential metals from invading pathogens and utilize the innate toxicity of certain metals for bacterial killing. Host-induced metal ion fluctuations must be rapidly sensed by pathogeni... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532941 Fri, 09 Dec 2011 05:00:00 +0100 5532941 http://www.medworm.com/index.php?rid=5532942&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22153710%26dopt%3DAbstract Authors: Hammer ND, Skaar EP Abstract The Gram-positive pathogen Staphylococcus aureus poses a serious risk to public health due to its prevalence as a commensal organism, its ability to cause a multitude of diseases, and the increasing incidence of antibiotic resistant strains. S. aureus infects diverse niches within vertebrates despite being challenged by a robust immune response. The host-pathogen confrontation occurs in an environment nearly devoid of metals that are essential for bacterial proliferation. S. aureus is able to flourish in these conditions and often causes significant morbidity and mortality. This review highlights current themes pertaining to the process of host-mediated metal sequestration known as 'nutritional immunity', S. aureus metal acquisition strategies,... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532942 Mon, 05 Dec 2011 05:00:00 +0100 5532942 http://www.medworm.com/index.php?rid=5532943&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22143042%26dopt%3DAbstract Authors: Crimmins GT, Isberg RR Abstract The study of bacterial pathogens has historically been viewed with a wide lens, providing a picture of how bacterial populations act as groups, but with insufficient resolution to see how microorganisms act as individuals. For most bacterial pathogens, we do not know the minimal number of microbes that initiate infection in a particular organ site, the number that spread outside the site of initial colonization, and how many persist over time. Recent studies have begun to shed light on these points, and the development of new techniques has dramatically increased the ability of researchers to interrogate these problems. With new approaches, the field of bacterial pathogenesis is on the verge of understanding the role and fate of individual b... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532943 Sat, 03 Dec 2011 05:00:00 +0100 5532943 http://www.medworm.com/index.php?rid=5532945&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137884%26dopt%3DAbstract Authors: Callaghan M, McClean S Abstract Chronic infection is a hallmark of cystic fibrosis (CF) and the main contributor to morbidity. Microbial infection in CF is complex, due to the number of different species that colonise the CF lung. Their colonisation is facilitated by a host response that is impaired or compromised by highly viscous mucous, zones of hypoxia and the lack of the cystic fibrosis transmembrane regulator (CFTR). Successful dominant CF pathogens combine an effective arsenal to establish infection and counter-attack the host response, together with an ability to adapt readily to an unfavourable environment. Hypermutability is common among CF pathogens facilitating adaptation and as the host response persists, progressive destruction of the normal architecture of l... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532945 Thu, 01 Dec 2011 05:00:00 +0100 5532945 http://www.medworm.com/index.php?rid=5532944&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137885%26dopt%3DAbstract Authors: Krishna S, Miller LS Abstract Staphylococcus aureus is responsible for the vast majority of bacterial skin infections in humans. The propensity for S. aureus to infect skin involves a balance between cutaneous immune defense mechanisms and virulence factors of the pathogen. The tissue architecture of the skin is different from other epithelia especially since it possesses a corneal layer, which is an important barrier that protects against the pathogenic microorganisms in the environment. The skin surface, epidermis, and dermis all contribute to host defense against S. aureus. Conversely, S. aureus utilizes various mechanisms to evade these host defenses to promote colonization and infection of the skin. This review will focus on host-pathogen interactions at the skin inte... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532944 Thu, 01 Dec 2011 05:00:00 +0100 5532944 http://www.medworm.com/index.php?rid=5532946&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137596%26dopt%3DAbstract Authors: Monack DM Abstract Host-adapted strains of Salmonella enterica cause systemic infections and have the ability to persist systemically for long periods of time and pose significant public-health problems. Multidrug-resistant Salmonella enteric serovar Typhi (S. Typhi) and non-Typhoidal Salmonella (NTS) are on the increase, and are often associated with HIV infection. Chronically infected hosts are often asymptomatic and transmit disease to naïve hosts via fecal shedding of bacteria, thereby serving as a critical reservoir for disease. Salmonella utilizes multiple strategies to evade and modulate host innate and adaptive immune responses in order to persist in the presence of a robust immune response. In addition, the intestinal microbiota plays a critical role in controlli... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5532946 Wed, 30 Nov 2011 05:00:00 +0100 5532946 http://www.medworm.com/index.php?rid=5439086&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088393%26dopt%3DAbstract Authors: Kim HK, Thammavongsa V, Schneewind O, Missiakas D Abstract Staphylococcus aureus causes purulent skin and soft tissue infections (SSTIs) that frequently reoccur. Staphylococal SSTIs can lead to invasive disease and sepsis, which are among the most significant causes of infectious disease mortality in both developed and developing countries. Human or animal infections with S. aureus do not elicit protective immunity against staphylococcal diseases. Here we review what is known about the immune evasive strategies of S. aureus that enable the pathogen's escape from protective immune responses. Three secreted products are discussed in detail, staphylococcal protein A (SpA), staphylococcal binder of immunoglobulin (Sbi) and adenosine synthase A (AdsA). By forming a complex with... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5439086 Mon, 14 Nov 2011 05:00:00 +0100 5439086 http://www.medworm.com/index.php?rid=5439085&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088394%26dopt%3DAbstract Authors: Thanbichler M PMID: 22088394 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5439085 Mon, 14 Nov 2011 05:00:00 +0100 5439085 http://www.medworm.com/index.php?rid=5418743&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22074861%26dopt%3DAbstract Authors: Reece ST, Kaufmann SH Abstract The granuloma in tuberculosis (TB), referred to as the tubercle, is a lesion containing multiple cell types and is the one definite hallmark of this disease. A number of tubercle phenotypes are seen during infection yet how these contribute to development of TB remains unclear. Here we highlight recent results using diverse models of tubercle development as well as recent findings from studies of human TB in an attempt to illustrate the plasticity of the tubercle and to place it between the poles of pathology and protection. Such insights could lead to future interventions to address TB as a global health issue. PMID: 22074861 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5418743 Tue, 08 Nov 2011 05:00:00 +0100 5418743 http://www.medworm.com/index.php?rid=5418742&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22074862%26dopt%3DAbstract Authors: Heitman J PMID: 22074862 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5418742 Tue, 08 Nov 2011 05:00:00 +0100 5418742 http://www.medworm.com/index.php?rid=5418744&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22070968%26dopt%3DAbstract Authors: Richter-Dahlfors A, Rhen M, Udekwu K Abstract The vertebrate host represents an extraordinarily complex and heterogenous environment which pathogenic bacteria of different types able to colonize and infect. This implies that all contributory elements of an infected tissue type or intact host are pre-requisites for full understanding of bacterial pathogenesis. Within this context, intravital techniques allow such studies of infection under realistic conditions within the live host, and with improved detection methods another level of understanding is attained. Here we define this field as tissue microbiology, with its focus placed on monitoring and mimicking host-pathogen interaction within the dynamic micro-ecology significant for infectious niches in the live host. Such a... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5418744 Mon, 07 Nov 2011 05:00:00 +0100 5418744 http://www.medworm.com/index.php?rid=5418745&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22055570%26dopt%3DAbstract Authors: Chan CY, St John AL, Abraham SN Abstract Mast cells (MCs) have been implicated in orchestrating the host's early innate immune and adaptive immune responses in several models of acute bacterial infections. Most of this activity results in early clearance of the bacteria and timely resolution of infection. However, during chronic infections because of the prolonged nature of MC-bacterial interactions, the role of the MC in determining the fate of infection is markedly more complex. Depending on the nature of the pathogen, severity of infection, and its association with a preexisting inflammatory disease, MCs may promote rather than contain chronic infections and exacerbate their pathological sequellae. PMID: 22055570 [PubMed - as supplied by publisher] (Source: Current ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5418745 Thu, 03 Nov 2011 04:00:00 +0100 5418745 http://www.medworm.com/index.php?rid=5418746&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22055466%26dopt%3DAbstract Authors: Uehara T, Bernhardt TG Abstract Enzymes that degrade the peptidoglycan (PG) cell wall layer called PG hydrolases or autolysins are often thought of as destructive forces. Phages employ them to lyse their host for the release of virion particles and some bacteria secrete them to eliminate (lyse) their competition. However, bacteria also harness the activity of PG hydrolases for important aspects of growth, division, and development. Of course, using PG hydrolases in this capacity requires that they be tightly regulated. While this has been appreciated for some time, we are only just beginning to understand the mechanisms governing the activities of these 'tailoring' enzymes. This review will focus on recent advances in this area with an emphasis on the regulation of PG hydr... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5418746 Wed, 02 Nov 2011 04:00:00 +0100 5418746 http://www.medworm.com/index.php?rid=5379169&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22047950%26dopt%3DAbstract Authors: Kaimer C, Graumann PL Abstract DNA translocases play important roles during the bacterial cell cycle and in cell differentiation. Escherichia coli cells contain a multifunctional translocase, FtsK, which is involved in cell division, late steps of chromosome segregation and dimer resolution. In Gram-positive bacteria, the latter two processes are achieved by two translocases, SftA and SpoIIIE. These two translocases operate in a two step fashion, before and after closure of the division septum. DNA translocases have the remarkable ability to translocate DNA in a vectorial manner, orienting themselves according to polar sequences present in bacterial genomes, and perform various additional roles during the cell cycle. DNA translocases genetically interact with Structural Ma... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379169 Mon, 31 Oct 2011 04:00:00 +0100 5379169 http://www.medworm.com/index.php?rid=5379170&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22035946%26dopt%3DAbstract Authors: Umen JG Abstract Sexual reproduction in Volvocine algae coevolved with the acquisition of multicellularity. Unicellular genera such as Chlamydomonas and small colonial genera from this group have classical mating types with equal-sized gametes, while larger multicellular genera such as Volvox have differentiated males and females that produce sperm and eggs respectively. Newly available sequence from the Volvox and Chlamydomonas genomes and mating loci open up the potential to investigate how sex-determining regions co-evolve with major changes in development and sexual reproduction. The expanded size and sequence divergence between the male and female haplotypes of the Volvox mating locus (MT) not only provide insights into how the colonial Volvocine algae might have evol... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379170 Thu, 27 Oct 2011 04:00:00 +0100 5379170 http://www.medworm.com/index.php?rid=5379171&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22032932%26dopt%3DAbstract Authors: Dyer PS, O'Gorman CM Abstract Fungi have some of the most diverse sex lives in nature, ranging from self-fertility to obligate outcrossing systems with several thousand different sexes, although at least 20% of fungal species have no known sexual stage. However, recent evidence suggests that many supposed 'asexual' species do indeed have the potential to undergo sexual reproduction. Using experimental and genomic findings from Aspergillus and Penicillium species as examples, it is argued that evidence such as the presence and expression of apparently functional sex-related genes, the distribution of mating-type genes, detection of recombination from population genetic analyses, and the discovery of extant sexual cycles reveal an on-going revolution in the understanding of ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379171 Tue, 25 Oct 2011 04:00:00 +0100 5379171 http://www.medworm.com/index.php?rid=5379173&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22030446%26dopt%3DAbstract Authors: Steinberg G Abstract Fungal tip growth underlies substrate invasion and is essential for fungal virulence. It requires the activity of molecular motors that deliver secretory vesicles to the growth region or which mediate bi-directional motility of early endosomes. Visualizing motors and their cargo in living fungal cells revealed unexpected cooperation between motors in membrane trafficking: (1) Class V chitin synthase, which has a class 17 myosin motor domain, moves bi-directionally, with myosin-5 and kinesin-1 cooperating in delivery to the growth region, and dynein taking it back to the cell centre. The myosin-17 motor domain competes with dynein by tethering the chitin synthase to the plasma membrane before exocytosis; (2) Long-range endosome motility is based on a co... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379173 Mon, 24 Oct 2011 04:00:00 +0100 5379173 http://www.medworm.com/index.php?rid=5379172&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22030447%26dopt%3DAbstract Authors: Thiennimitr P, Winter SE, Bäumler AJ Abstract The intestine is host to a diverse bacterial community whose structure, at the phylum level, is maintained through unknown mechanisms. Acute inflammation triggered by enteric pathogens, such as Salmonella enterica serotype Typhimurium (S. Typhimurium), is accompanied by changes in the bacterial community structure marked by an outgrowth of the pathogen. Recent studies show that S. Typhimurium can harness benefit from the host response to edge out the beneficial bacterial species that dominate in the healthy gut. The elucidation of how S. Typhimurium alters the bacterial community structure during gastroenteritis is beginning to provide insights into mechanisms that dictate the balance between the host and its microbiota. P... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379172 Mon, 24 Oct 2011 04:00:00 +0100 5379172 http://www.medworm.com/index.php?rid=5379174&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22024380%26dopt%3DAbstract Authors: Shank EA, Kolter R Abstract Bacillus subtilis regulates its ability to differentiate into distinct, co-existing cell types in response to extracellular signaling molecules produced either by itself, or present in its environment. The production of molecules by B. subtilis cells, as well as their response to these signals, is not uniform across the population. There is specificity and heterogeneity both within genetically identical populations as well as at the strain-level and species-level. This review will discuss how extracellular signaling compounds influence B. subtilis multicellularity with regard to matrix-producing cannibal differentiation, germination, and swarming behavior, as well as the specificity of the quorum-sensing peptides ComX and CSF. It will also highl... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379174 Sat, 22 Oct 2011 04:00:00 +0100 5379174 http://www.medworm.com/index.php?rid=5379175&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22020108%26dopt%3DAbstract Authors: Lopez MA, Nguyen HT, Oberholzer M, Hill KL Abstract Protozoan parasites cause tremendous human suffering worldwide, but strategies for therapeutic intervention are limited. Recent studies illustrate that the paradigm of microbes as social organisms can be brought to bear on questions about parasite biology, transmission and pathogenesis. This review discusses recent work demonstrating adaptation of social behaviors by parasitic protozoa that cause African sleeping sickness and malaria. The recognition of social behavior and cell-cell communication as a ubiquitous property of bacteria has transformed our view of microbiology, but protozoan parasites have not generally been considered in this context. Works discussed illustrate the potential for concepts of sociomicrobiology... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5379175 Fri, 21 Oct 2011 04:00:00 +0100 5379175 http://www.medworm.com/index.php?rid=5344230&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22014508%26dopt%3DAbstract Authors: Barry RM, Gitai Z Abstract The bacterial cytoskeleton is composed of a complex and diverse group of proteins that self-assemble into linear filaments. These filaments support and organize cellular architecture and provide a dynamic network controlling transport and localization within the cell. Here, we review recent discoveries related to a newly appreciated class of self-assembling proteins that expand our view of the bacterial cytoskeleton and provide potential explanations for its evolutionary origins. Specifically, several types of metabolic enzymes can form structures similar to established cytoskeletal filaments and, in some cases, these structures have been repurposed for structural uses independent of their normal roles. The behaviors of these enzymes suggest that... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5344230 Tue, 18 Oct 2011 04:00:00 +0100 5344230 http://www.medworm.com/index.php?rid=5344229&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22014725%26dopt%3DAbstract Authors: Hogan DA, Muhlschlegel FA Abstract In the healthy individual, Candida albicans is frequently found as a harmless commensal residing in the gastrointestinal tract. However, in the compromised patient, C. albicans may invade the body and cause disease that is associated with poor prognosis and high mortality. The C. albicans adenylyl cyclase, Cyr1, which is required for virulence in animal models, regulates three developmental programs, including invasive filamentous growth, phenotypic switching to a mating-competent cell type, and biofilm formation. Evidence suggests that Cyr1 controls these phenotypes in response to various environmental cues that are present within microbial populations. Additionally, C. albicans secretes an autoregulatory molecule, farnesol, which was re... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5344229 Mon, 17 Oct 2011 04:00:00 +0100 5344229 http://www.medworm.com/index.php?rid=5344231&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21981908%26dopt%3DAbstract Authors: Kirkpatrick CL, Viollier PH Abstract Cytokinesis in bacteria is mediated by a macromolecular machine known as the divisome, consisting of an assembly of FtsZ polymers around the cylindrical axis of the cell and the downstream regulators of division that are subsequently recruited to it. FtsZ polymerizes into filaments in a GTP-dependent manner, similarly to its eukaryotic structural homolog tubulin. The initial placement of the FtsZ polymerization site is tightly regulated by multiple mechanisms, as are the subsequent polymer reshaping and force generation that separate the two daughter cells from each other. New factors have been recently discovered that contribute to this regulation, notably affecting FtsZ polymer shaping, and modulating FtsZ polymerization in response t... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5344231 Wed, 05 Oct 2011 04:00:00 +0100 5344231 http://www.medworm.com/index.php?rid=5296179&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963111%26dopt%3DAbstract Authors: Chen HM, Neiman AM Abstract A significant fraction of the eukaryotic genome is transcribed into RNAs that do not encode proteins, termed non-coding RNA (ncRNA). One class of ncRNA that is of particular interest is antisense RNAs, which are complementary to protein coding transcripts (mRNAs). In this article, we summarize recent studies using different yeasts that reveal a conserved pattern in which meiotically expressed genes have antisense transcripts in vegetative cells. These antisense transcripts repress the basal transcription of the mRNA during vegetative growth and are diminished as cells enter meiosis. While the mechanism(s) by which these antisense RNAs interfere with production of sense transcripts is not yet understood, the effects appear to be independent of th... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5296179 Thu, 29 Sep 2011 04:00:00 +0100 5296179 http://www.medworm.com/index.php?rid=5296178&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963112%26dopt%3DAbstract Authors: Szardenings F, Guymer D, Gerdes K Abstract Prokaryotic chromosomes and plasmids can be actively segregated by partitioning (par) loci. The common ParA-encoding par loci segregate plasmids by arranging them in regular arrays over the nucleoid by an unknown mechanism. Recent observations indicate that ParA moves plasmids and chromosomes by a pulling mechanism. Even though ParAs form filaments in vitro it is not known whether similar structures are present in vivo. ParA of P1 forms filaments in vitro at very high concentrations only and filament-like structures have not been observed in vivo. Consequently, a 'diffusion-ratchet' mechanism was suggested to explain plasmid movement by ParA of P1. We compare this mechanism with our previously proposed filament model for plasmid m... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5296178 Thu, 29 Sep 2011 04:00:00 +0100 5296178 http://www.medworm.com/index.php?rid=5296180&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21962291%26dopt%3DAbstract Authors: Granek JA, Kayıkçı O, Magwene PM Abstract Developmental phenotypes in Saccharomyces cerevisiae and related yeasts include responses such as filamentous growth, sporulation, and the formation of biofilms and complex colonies. These developmental phenotypes are regulated by evolutionarily conserved, nutrient-responsive signaling networks. The signaling mechanisms that control development in yeast are highly pleiotropic - all the known pathways contribute to the regulation of multiple developmental outcomes. This degree of pleiotropy implies that perturbations of these signaling pathways, whether genetic, biochemical, or environmentally induced, can manifest in multiple (and sometimes unexpected) ways. We summarize the current state of knowledge of developmental pleiotropy... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5296180 Wed, 28 Sep 2011 04:00:00 +0100 5296180 http://www.medworm.com/index.php?rid=5276577&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21958462%26dopt%3DAbstract Authors: Sorek R, Serrano L PMID: 21958462 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276577 Tue, 27 Sep 2011 04:00:00 +0100 5276577 http://www.medworm.com/index.php?rid=5276580&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21955886%26dopt%3DAbstract Authors: Bulyha I, Hot E, Huntley S, Søgaard-Andersen L Abstract In bacteria, large G domain GTPases have well-established functions in translation, protein translocation, tRNA modification and ribosome assembly. In addition, bacteria also contain small Ras-like GTPases consisting of stand-alone G domains. Recent data have revealed that small Ras-like GTPases as well as large G domain GTPases in bacteria function in the regulation of cell polarity, signal transduction and possibly also in cell division. The small Ras-like GTPase MglA together with its cognate GAP MglB regulates cell polarity in Myxococcus xanthus, and the small Ras-like GTPase CvnD9 in Streptomyces coelicolor is involved in signal transduction. Similarly, the large GTPase FlhF together with the ATPase FlhG regulat... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276580 Mon, 26 Sep 2011 04:00:00 +0100 5276580 http://www.medworm.com/index.php?rid=5276579&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21955887%26dopt%3DAbstract Authors: Collette JR, Lorenz MC Abstract The incidence of life-threatening fungal infections has continued to increase in recent years, predominantly in patients debilitated by iatrogenic interventions or immunological dysfunctions. While the picture of the immunology of fungal infections grows increasingly complex, it is clear that the phagocyte-pathogen interaction is a critical determinant of establishing an infection. About 10 years ago, genome-scale approaches began to elucidate the intricate and extensive fungal response to phagocytosis and in the last few years it has become clear that some of this response actively modulates immune cell function. Fungal pathogens avoid detection by masking pathogen-associated molecular patterns, such as cell wall carbohydrates, and by downr... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276579 Mon, 26 Sep 2011 04:00:00 +0100 5276579 http://www.medworm.com/index.php?rid=5276578&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21955888%26dopt%3DAbstract Authors: Brown MT, Delalez NJ, Armitage JP Abstract The proteins that make up the bacterial flagellar rotary motor have recently been shown to be more dynamic than previously thought, with some key proteins exchanging with pools of proteins in the membrane/cytoplasm. It has also become clear that in addition to simply switching in response to chemosensory signals, the rotation of the bacterial flagellar motor can be slowed or stopped, using a clutch or a brake, by signals from metabolism and growth state. PMID: 21955888 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276578 Mon, 26 Sep 2011 04:00:00 +0100 5276578 http://www.medworm.com/index.php?rid=5276582&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945217%26dopt%3DAbstract Authors: Evguenieva-Hackenberg E, Klug G Abstract The pivotal role of posttranscriptional gene regulation is strongly underlined by genome-wide analyses showing strikingly low correlation between mRNA and protein levels in bacterial and archaeal cells. The stability of an mRNA and its availability for translation contribute to posttranscriptional gene regulation, and are determined by the following factors: i) the cell-specific set of ribonucleases and related proteins, ii) regulatory RNAs, and iii) the sequence and structural features of the RNA molecule itself. High-resolution analyses of whole prokaryotic transcriptomes allow comprehensive mapping of processed transcripts, detection of essentially all expressed regulatory RNAs, and monitoring of the global impact of ribonuclease... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276582 Thu, 22 Sep 2011 04:00:00 +0100 5276582 http://www.medworm.com/index.php?rid=5276581&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945218%26dopt%3DAbstract Authors: Collins JJ, Donadio S PMID: 21945218 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276581 Thu, 22 Sep 2011 04:00:00 +0100 5276581 http://www.medworm.com/index.php?rid=5276583&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21943683%26dopt%3DAbstract Authors: Cloots L, Marchal K Abstract Molecular entities present in a cell (mRNA, proteins, metabolites,…) do not act in isolation, but rather in cooperation with each other to define an organisms form and function. Their concerted action can be viewed as networks of interacting entities that are active under certain conditions within the cell or upon certain environmental signals. A main challenge in systems biology is to model these networks, or in other words studying which entities interact to form cellular systems or accomplish similar functions. On the contrary, viewing a single entity or an experimental dataset in the light of an interaction network can reveal previous unknown insights in biological processes. In this review we give an overview of how integrated networks c... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5276583 Wed, 21 Sep 2011 04:00:00 +0100 5276583 http://www.medworm.com/index.php?rid=5259528&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21937262%26dopt%3DAbstract Authors: Allison KR, Brynildsen MP, Collins JJ Abstract Bacterial persistence is a state in which a subpopulation of cells (persisters) survives antibiotic treatment, and has been implicated in the tolerance of clinical infections and the recalcitrance of biofilms. There has been a renewed interest in the role of bacterial persisters in treatment failure in light of a wealth of recent findings. Here we review recent laboratory studies of bacterial persistence. Further, we pose the hypothesis that each bacterial population may contain a diverse collection of persisters and discuss engineering strategies for persister eradication. PMID: 21937262 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5259528 Mon, 19 Sep 2011 04:00:00 +0100 5259528 http://www.medworm.com/index.php?rid=5218300&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21900036%26dopt%3DAbstract Authors: Fischbach MA Abstract New drug development strategies are needed to combat antimicrobial resistance. The object of this perspective is to highlight one such strategy: treating infections with sets of drugs rather than individual drugs. We will highlight three categories of combination therapy: those that inhibit targets in different pathways; those that inhibit distinct nodes in the same pathway; and those that inhibit the very same target in different ways. We will then consider examples of naturally occurring combination therapies produced by micro-organisms, and conclude by discussing key opportunities and challenges for making more widespread use of drug combinations. PMID: 21900036 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5218300 Mon, 05 Sep 2011 04:00:00 +0100 5218300 http://www.medworm.com/index.php?rid=5218301&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21873107%26dopt%3DAbstract Authors: Jabes D Abstract There is an urgent need for new antibacterials to target emerging multidrug-resistant bacteria. The need for such agents is rising while the efforts in antibacterial research have declined dramatically in the past few decades with the result of only four compounds belonging to new chemical classes being approved for clinical use. The main reasons that led to this critical situation are shortly described. A renewed interest in the research of new effective antimicrobials is nonetheless delivering compounds deriving mainly from modification of existing drugs, yet new chemical classes are appearing. Because many of these activities have started relatively recently, we should expect a long period before new antibiotics are added to the medical armamentarium. ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5218301 Fri, 26 Aug 2011 04:00:00 +0100 5218301 http://www.medworm.com/index.php?rid=5174931&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21868281%26dopt%3DAbstract Authors: Lu TK, Koeris MS Abstract Bacteriophage therapy for bacterial infections is a concept with an extensive but controversial history. There has been a recent resurgence of interest into bacteriophages owing to the increasing incidence of antibiotic resistance and virulent bacterial pathogens. Despite these efforts, bacteriophage therapy remains an underutilized option in Western medicine due to challenges such as regulation, limited host range, bacterial resistance to phages, manufacturing, side effects of bacterial lysis, and delivery. Recent advances in biotechnology, bacterial diagnostics, macromolecule delivery, and synthetic biology may help to overcome these technical hurdles. These research efforts must be coupled with practical and rigorous approaches at academic, com... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5174931 Mon, 22 Aug 2011 23:00:00 +0100 5174931 http://www.medworm.com/index.php?rid=5174932&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21865081%26dopt%3DAbstract Authors: Cambray G, Mutalik VK, Arkin AP Abstract The advent of genetic engineering-the ability to edit and insert DNA into living organisms-in the latter half of the 20th century created visions of a new era of synthetic biology, where novel biological functions could be designed and implemented for useful purposes. We are witnessing an exciting revolution of scale, wherein technical progresses allow for the manipulation of genetic material at the whole genome level. This will enable the manufacture of increasingly complex genetic designs to solve pressing challenges in health, energy and the environment-if and when such designs can be specified. We argue that the organized development of key common application organisms, engineered for engineerability, and attendant libraries of ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5174932 Sun, 21 Aug 2011 23:00:00 +0100 5174932 http://www.medworm.com/index.php?rid=5174934&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21862391%26dopt%3DAbstract Authors: Parsons JB, Rock CO Abstract The emergence of resistance against most current drugs emphasizes the need to develop new approaches to control bacterial pathogens, particularly Staphylococcus aureus. Bacterial fatty acid synthesis is one such target that is being actively pursued by several research groups to develop anti-Staphylococcal agents. Recently, the wisdom of this approach has been challenged based on the ability of a Gram-positive bacterium to incorporate extracellular fatty acids and thus circumvent the inhibition of de novo fatty acid synthesis. The generality of this conclusion has been challenged, and there is enough diversity in the enzymes and regulation of fatty acid synthesis in bacteria to conclude that there is not a single organism that can be considered... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5174934 Fri, 19 Aug 2011 23:00:00 +0100 5174934 http://www.medworm.com/index.php?rid=5174933&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21862392%26dopt%3DAbstract Authors: Srivastava A, Talaue M, Liu S, Degen D, Ebright RY, Sineva E, Chakraborty A, Druzhinin SY, Chatterjee S, Mukhopadhyay J, Ebright YW, Zozula A, Shen J, Sengupta S, Niedfeldt RR, Xin C, Kaneko T, Irschik H, Jansen R, Donadio S, Connell N, Ebright RH Abstract A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the ne... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5174933 Thu, 18 Aug 2011 23:00:00 +0100 5174933 http://www.medworm.com/index.php?rid=5174935&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21856213%26dopt%3DAbstract Authors: Popa O, Dagan T Abstract Gene acquisition by lateral gene transfer (LGT) is an important mechanism for natural variation among prokaryotes. Laboratory experiments show that protein-coding genes can be laterally transferred extremely fast among microbial cells, inherited to most of their descendants, and adapt to a new regulatory regime within a short time. Recent advance in the phylogenetic analysis of microbial genomes using networks approach reveals a substantial impact of LGT during microbial genome evolution. Phylogenomic networks of LGT among prokaryotes reconstructed from completely sequenced genomes uncover barriers to LGT in multiple levels. Here we discuss the kinds of barriers to gene acquisition in nature including physical barriers for gene transfer between cel... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5174935 Tue, 16 Aug 2011 23:00:00 +0100 5174935 http://www.medworm.com/index.php?rid=5141063&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21840247%26dopt%3DAbstract Authors: Hess WR Abstract Cyanobacteria are the only prokaryotes that directly convert solar energy and CO(2) into organic matter by oxygenic photosynthesis, explaining their relevance for primary production in many ecosystems and the increasing interest for biotechnology. At present, there are more than 60 cyanobacteria for which a total genome sequence is publicly available. These cyanobacteria belong to different lifestyles and origins, coming from marine and freshwater aquatic environments, as well as terrestrial and symbiotic habitats. Genome sizes vary by a factor of six, from 1.44Mb to 9.05Mb, with the number of reported genes ranging from 1241 to 8462. Several studies have demonstrated how these sequences could be used to successfully infer important ecological, physiologic... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141063 Wed, 10 Aug 2011 23:00:00 +0100 5141063 http://www.medworm.com/index.php?rid=5141062&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21840248%26dopt%3DAbstract Authors: Coleman K Abstract The β-lactams have been among the most successful classes of antibacterial agents for the past half century. However, a disturbing increase in resistance to β-lactams has been noted among Gram-negative bacteria, which is attributable to β-lactamase enzymes not within the spectrum of currently marketed β-lactams or β-lactam/β-lactamase inhibitor combinations. Diazabicyclooctanes (DBOs) were first investigated as β-lactam mimics in the mid-1990s by chemists at Hoechst Marion Roussel (now part of Sanofi-Aventis) and proved to be a rich source of β-lactamase inhibitors (BLI). Two members of this novel series of highly potent, broad spectrum BLIs are now in clinical development and their properties are reviewed here. PMID: 21840248 [PubMed - as su... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141062 Wed, 10 Aug 2011 23:00:00 +0100 5141062 http://www.medworm.com/index.php?rid=5141064&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21839669%26dopt%3DAbstract Authors: Filiatrault MJ Abstract Genome-wide expression studies transformed the field of transcriptomics and made it feasible to study global gene expression in extraordinary detail. These new methods have revealed an enhanced view of the transcriptional landscape and have yielded many biological insights. It is increasingly clear that the prokaryotic transcriptome is much more complex than once thought. Recent advances in microbial transcriptome analyses are highlighted in this review. Areas of progress include the development of optimized techniques that minimize the abundance of ribosomal RNAs in RNA samples as well as the development of novel methods to create transcriptome libraries. Advances such as these have led to a new emphasis in areas such as metatranscriptomics and sin... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141064 Tue, 09 Aug 2011 23:00:00 +0100 5141064 http://www.medworm.com/index.php?rid=5141066&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21835684%26dopt%3DAbstract Authors: Rey FA PMID: 21835684 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141066 Mon, 08 Aug 2011 23:00:00 +0100 5141066 http://www.medworm.com/index.php?rid=5141065&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21835685%26dopt%3DAbstract Authors: Tardieux I PMID: 21835685 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141065 Mon, 08 Aug 2011 23:00:00 +0100 5141065 http://www.medworm.com/index.php?rid=5141068&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21824805%26dopt%3DAbstract Authors: Lazarow PB Abstract Viruses that are of great importance for global public health, including HIV, influenza and rotavirus, appear to exploit a remarkable organelle, the peroxisome, during intracellular replication in human cells. Peroxisomes are sites of lipid biosynthesis and catabolism, reactive oxygen metabolism, and other metabolic pathways. Viral proteins are targeted to peroxisomes (the spike protein of rotavirus) or interact with peroxisomal proteins (HIV's Nef and influenza's NS1) or use the peroxisomal membrane for RNA replication. The Nef interaction correlates strongly with the crucial Nef function of CD4 downregulation. Viral exploitation of peroxisomal lipid metabolism appears likely. Mostly, functional significance and mechanisms remain to be elucidated. Rece... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141068 Fri, 05 Aug 2011 23:00:00 +0100 5141068 http://www.medworm.com/index.php?rid=5141067&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21824806%26dopt%3DAbstract Authors: Ruigrok RW, Crépin T, Kolakofsky D Abstract A hallmark of negative-strand RNA viruses (NSVs) is that their genomes never exist as free RNA, but instead are always assembled with many copies of a single nucleoprotein (N) to form highly stable nucleocapsids. Moreover, viral genomes are the only RNAs in infected cells that are assembled with N. The mechanism by which this specific association occurs, for both the segmented (s) and non-segmented (ns) viruses, has recently become clearer due to our expanding knowledge of N protein and nucleocapsid structures. PMID: 21824806 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141067 Fri, 05 Aug 2011 23:00:00 +0100 5141067 http://www.medworm.com/index.php?rid=5141070&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21821465%26dopt%3DAbstract Authors: Snyder JC, Young MJ Abstract Our understanding of host-virus interactions in archaeal systems generally lags behind our knowledge of host-virus interactions in bacterial and eukaryotic systems. This is due to the limited number of archaeal host-virus systems available for study under laboratory conditions, as well as the absence of diseases known to be caused by archaea. However, in recent years there has been a rapid expansion of our understanding of archaeal host-virus interactions combining traditional genetic and biochemical approaches with 'omics' based approaches in both laboratory and natural environmental studies. We highlight here the emerging features of host-virus interactions in archaea with a particular emphasis on host-virus interactions gathered from the stu... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141070 Thu, 04 Aug 2011 23:00:00 +0100 5141070 http://www.medworm.com/index.php?rid=5141069&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21821466%26dopt%3DAbstract Authors: Cole ST, Riccardi G Abstract Tuberculosis (TB) remains a major global health concern whose control has been exacerbated by HIV and the emergence of multidrug-resistant (MDR-TB) and extensively drug-resistant (XDR-TB) strains of Mycobacterium tuberculosis. The demand for new and faster acting TB drugs is thus greater than ever. In the past decade intensive efforts have been made to discover new leads for TB drug development using both target-based and cell-based approaches. Here, we describe the most promising anti-tubercular drug candidates that are in clinical development and introduce some nitro-aromatic compounds that inhibit a new target, DprE1, an essential enzyme involved in a crucial step in mycobacterial cell wall biosynthesis. PMID: 21821466 [PubMed - as suppl... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141069 Thu, 04 Aug 2011 23:00:00 +0100 5141069 http://www.medworm.com/index.php?rid=5141073&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21816663%26dopt%3DAbstract Authors: Amini S, Tavazoie S Abstract The emergence of pathogenic bacteria resistant to multiple antimicrobial agents is turning into a major crisis in human and veterinary medicine. This necessitates a serious re-evaluation of our approaches toward antibacterial drug discovery and use. Concurrent advances in genomics including whole-genome sequencing, genotyping, and gene expression profiling have the potential to transform our basic understanding of antimicrobial pathways and lead to the discovery of novel targets and therapeutics. PMID: 21816663 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141073 Mon, 01 Aug 2011 23:00:00 +0100 5141073 http://www.medworm.com/index.php?rid=5141072&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21816664%26dopt%3DAbstract Authors: Filler SG PMID: 21816664 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141072 Mon, 01 Aug 2011 23:00:00 +0100 5141072 http://www.medworm.com/index.php?rid=5141071&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21816665%26dopt%3DAbstract Authors: Bidle KD, Vardi A Abstract Despite the critical importance of viruses in shaping marine microbial ecosystems and lubricating upper ocean biogeochemical cycles, relatively little is known about the molecular mechanisms mediating phytoplankton host-virus interactions. Recent work in algal host-virus systems has begun to shed novel insight into the elegant strategies of viral infection and subcellular regulation of cell fate, which not only reveal tantalizing aspects of viral replication and host resistance strategies but also provide new diagnostic tools toward elucidating the impact of virus-mediated processes in the ocean. Widespread lateral gene transfer between viruses and their hosts plays a prominent role in host-virus diversification and in the regulation of host-viru... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5141071 Mon, 01 Aug 2011 23:00:00 +0100 5141071 http://www.medworm.com/index.php?rid=5097571&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807554%26dopt%3DAbstract Authors: Ibrahim AS Clinical hallmarks of mucormycosis infections include the unique susceptibility of patients with increased available serum iron, the propensity of the organism to invade blood vessels, and defective phagocytic function. These hallmarks underscore the crucial roles of iron metabolism, phagocyte function, and interactions with endothelial cells lining blood vessels, in the organism's virulence strategy. In an attempt to understand how Mucorales invade the host, we will review the current knowledge about interactions between Mucorales and the host while evading phagocyte-mediated killing. Additionally, since iron is an important determinant of the disease, we will focus on the role of iron on these interactions. Ultimately, a superior understanding of the pathogenesis ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5097571 Fri, 29 Jul 2011 23:00:00 +0100 5097571 http://www.medworm.com/index.php?rid=5097553&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807555%26dopt%3DAbstract Authors: Choe H, Jemielity S, Abraham J, Radoshitzky SR, Farzan M At least five New World arenaviruses cause severe human hemorrhagic fevers. These viruses are transmitted to humans through contact with their respective South American rodent hosts. Each uses human transferrin receptor 1 (TfR1) as its obligate receptor. Accidental similarities between human TfR1 and TfR1 orthologs of arenaviral host species enable zoonoses, whereas mice and rats are not infectable because they lack these TfR1 determinants of infection. All pathogenic New World arenaviruses bind to a common region of the apical domain of TfR1. The ability of a New World arenavirus to use human TfR1 is absolutely predictive of its ability to cause hemorrhagic fevers in humans. Nonpathogenic arenaviruses, closely related t... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5097553 Fri, 29 Jul 2011 23:00:00 +0100 5097553 http://www.medworm.com/index.php?rid=5097603&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21803640%26dopt%3DAbstract Authors: Drummond RA, Brown GD Dectin-1 is an innate immune pattern recognition receptor (PRR) that, through its ability to bind β-glucans, is involved in the recognition of several pathogenic fungi. Dectin-1 can stimulate a variety of cellular responses via the Syk/CARD9 signalling pathway, including phagocytosis, cytokine production and the respiratory burst. Several advances in our understanding of Dectin-1 immunobiology have been made in recent years, including characterisation of additional signalling pathways and demonstration of its ability to directly induce the development of adaptive immunity. However, the physiological role of many of the functions of this receptor is still unclear. This review aims to provide an update on Dectin-1 and its role within antifungal immune resp... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5097603 Thu, 28 Jul 2011 23:00:00 +0100 5097603 http://www.medworm.com/index.php?rid=5097593&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21803641%26dopt%3DAbstract Authors: Gaur D, Chitnis CE Invasion of erythrocytes by Plasmodium merozoites is a complex process that is mediated by specific molecular interactions. Here, we review recent studies on interactions between erythrocyte binding antigens (EBA) and PfRH proteins from the parasite and erythrocyte receptors involved in invasion. The timely release of these parasite ligands from internal organelles such as micronemes and rhoptries to the merozoite surface is critical for receptor-engagement leading to successful invasion. We review information on signaling mechanisms that control the regulated secretion of parasite proteins during invasion. Erythrocyte invasion involves the formation and movement of a junction between the invading merozoite and host erythrocyte. We review recent studies on t... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5097593 Thu, 28 Jul 2011 23:00:00 +0100 5097593 http://www.medworm.com/index.php?rid=5097623&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21802979%26dopt%3DAbstract Authors: Kumamoto CA Candida organisms commonly colonize the human gastrointestinal tract as a component of the resident microbiota. Their presence is generally benign. Recent studies, however, show that high level Candida colonization is associated with several diseases of the gastrointestinal tract. Further, results from animal models argue that Candida colonization delays healing of inflammatory lesions and that inflammation promotes colonization. These effects may create a vicious cycle in which low-level inflammation promotes fungal colonization and fungal colonization promotes further inflammation. Both inflammatory bowel disease and gastrointestinal Candida colonization are associated with elevated levels of the pro-inflammatory cytokine IL-17. Therefore, effects on IL-17 levels... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5097623 Wed, 27 Jul 2011 23:00:00 +0100 5097623 http://www.medworm.com/index.php?rid=5051457&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21741878%26dopt%3DAbstract Authors: Ganguly S, Mitchell AP Biofilms are microbial communities that form on surfaces and are embedded in an extracellular matrix. C. albicans forms pathogenic mucosal biofilms that are evoked by changes in host immunity or mucosal ecology. Mucosal surfaces are inhabited by many microbial species; hence these biofilms are polymicrobial. Several recent studies have applied paradigms of biofilm analysis to study mucosal C. albicans infections. These studies reveal that the Bcr1 transcription factor is a master regulator of C. albicans biofilm formation under diverse conditions, though the most relevant Bcr1 target genes can vary with the biofilm niche. An important determinant of mucosal biofilm formation is the interaction with host defenses. Finally, studies of interactions between ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5051457 Wed, 06 Jul 2011 23:00:00 +0100 5051457 http://www.medworm.com/index.php?rid=5000932&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21724450%26dopt%3DAbstract Authors: Schrettl M, Haas H The opportunistic fungal pathogen Aspergillus fumigatus adapts to iron limitation by upregulation of iron uptake mechanisms including siderophore biosynthesis and downregulation of iron-consuming pathways to spare iron. These metabolic changes depend mainly on the transcription factor HapX. Consistent with the crucial role of iron in pathophysiology, genetic inactivation of either HapX or the siderophore system attenuates virulence of A. fumigatus in a murine model of aspergillosis. The differences in iron handling between mammals and fungi might serve to improve therapy and diagnosis of fungal infections. PMID: 21724450 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=5000932 Thu, 30 Jun 2011 23:00:00 +0100 5000932 http://www.medworm.com/index.php?rid=4906182&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21632276%26dopt%3DAbstract Authors: Brochier-Armanet C, Forterre P, Gribaldo S Little more than 30 years since the discovery of the Archaea, over one hundred archaeal genome sequences are now publicly available, of which ∼40% have been released in the last two years. Their analysis provides an increasingly complex picture of archaeal phylogeny and evolution with the proposal of new major phyla, such as the Thaumarchaeota, and important information on the evolution of key central cellular features such as cell division. Insights have been gained into the events and processes in archaeal evolution, with a number of additional and unexpected links to the Eukaryotes revealed. Taken together, these results predict that many more surprises will be found as new archaeal genomes are sequenced. PMID: 21632276 [PubM... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4906182 Mon, 30 May 2011 23:00:00 +0100 4906182 http://www.medworm.com/index.php?rid=4906183&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21621451%26dopt%3DAbstract Authors: Davis MF, Price LB, Liu CM, Silbergeld EK The industrialization of food animal production, specifically the widespread use of antimicrobials, not only increased pressure on microbial populations, but also changed the ecosystems in which antimicrobials and bacteria interact. In this review, we argue that industrial food animal production (IFAP) is appropriately defined as an anthropogenic ecosystem. This paper uses an ecosystem perspective to frame an examination of these changes in the context of U.S. broiler chicken production. This perspective emphasizes multiple modes by which IFAP has altered microbiomes and also suggests a means of generating hypotheses for understanding and predicting the ecological impacts of IFAP in terms of the resistome and the flow of resistance wit... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4906183 Wed, 25 May 2011 23:00:00 +0100 4906183 http://www.medworm.com/index.php?rid=4906184&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21612976%26dopt%3DAbstract Authors: Sato T, Atomi H The Archaea harbor many metabolic pathways that differ to previously recognized classical pathways. Glycolysis is carried out by modified versions of the Embden-Meyerhof and Entner-Doudoroff pathways. Thermophilic archaea have recently been found to harbor a bi-functional fructose-1,6-bisphosphate aldolase/phosphatase for gluconeogenesis. A number of novel pentose-degrading pathways have also been recently identified. In terms of anabolic metabolism, a pathway for acetate assimilation, the methylaspartate cycle, and two CO(2)-fixing pathways, the 3-hydroxypropionate/4-hydroxybutyrate cycle and the dicarboxylate/4-hydroxybutyrate cycle, have been elucidated. As for biosynthetic pathways, recent studies have clarified the enzymes responsible for several steps inv... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4906184 Sun, 22 May 2011 23:00:00 +0100 4906184 http://www.medworm.com/index.php?rid=4855983&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21602097%26dopt%3DAbstract Authors: Takai K, Nakamura K Over the past 35 years, researchers have explored deep-sea hydrothermal vent environments around the globe and studied a number of archaea, their unique metabolic and physiological properties, and their vast phylogenetic diversity. Although the pace of discovery of new archaeal taxa, phylotypes and phenotypes in deep-sea hydrothermal vents has slowed recently, bioinformatics and interdisciplinary geochemistry-microbiology approaches are providing new information on the diversity and community composition of archaea living in deep-sea vents. Recent investigations have revealed that archaea could have originated and dispersed from ancestral communities endemic to hydrothermal vents into other biomes on Earth, and the community structure and productivity of ch... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4855983 Thu, 19 May 2011 23:00:00 +0100 4855983 http://www.medworm.com/index.php?rid=4855984&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21601510%26dopt%3DAbstract Authors: Monier JM, Demanèche S, Delmont TO, Mathieu A, Vogel TM, Simonet P The ongoing development of metagenomic approaches is providing the means to explore antibiotic resistance in nature and address questions that could not be answered previously with conventional culture-based strategies. The number of available environmental metagenomic sequence datasets is rapidly expanding and henceforth offer the ability to gain a more comprehensive understanding of antibiotic resistance at the global scale. Although there is now evidence that the environment constitutes a vast reservoir of antibiotic resistance gene determinants (ARGDs) and that the majority of ARGDs acquired by human pathogens may have an environmental origin, a better understanding of their diversity, prevalence and ecolo... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4855984 Wed, 18 May 2011 23:00:00 +0100 4855984 http://www.medworm.com/index.php?rid=4855985&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21596617%26dopt%3DAbstract Authors: Grohmann D, Werner F RNA polymerases (RNAPs) make repeatedly use of their templates by cycling through initiation, elongation and termination phases of transcription; during each step RNAP is interacting with and regulated by distinct transcription factors. The dynamic interplay between nucleic acid sequences, transcription factors and RNAP affects the activity and distribution of transcription complexes across the genome, and ultimately executes the genetic programme of the organism. This review covers recent discoveries about the mechanisms of archaeal transcription obtained by a combination of in vivo and in vitro approaches, from the molecular to the global level. PMID: 21596617 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4855985 Mon, 16 May 2011 23:00:00 +0100 4855985 http://www.medworm.com/index.php?rid=4855986&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21571580%26dopt%3DAbstract Authors: Moissl-Eichinger C, Huber H Several species of Archaea are involved in symbiotic or parasitic associations with representatives of Eukarya, Bacteria and other Archaea. Eukaryal interactions include different members of methanogens, found in the gut of arthropods, in the rumen of cattle, and in the human intestine, while Cenarchaeum symbiosum is a partner of a marine sponge. Examples for bacterial-archaeal associations are the anaerobic methane oxidation consortia and the SM1 Euryarchaeon with its highly unusual 'hami' as extracellular appendages. The so far only known and cultivated association between two Archaea is composed of Nanoarchaeum equitans and its obligate host Ignicoccus hospitalis. All these consortia can often not be assigned to the 'classical' concepts of mutali... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4855986 Thu, 12 May 2011 23:00:00 +0100 4855986 http://www.medworm.com/index.php?rid=4855987&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21570338%26dopt%3DAbstract Authors: Top EM, Wilson DB PMID: 21570338 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4855987 Tue, 10 May 2011 23:00:00 +0100 4855987 http://www.medworm.com/index.php?rid=4804092&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21550839%26dopt%3DAbstract Authors: Reeve JN, Schleper C PMID: 21550839 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804092 Thu, 05 May 2011 23:00:00 +0100 4804092 http://www.medworm.com/index.php?rid=4804093&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21550296%26dopt%3DAbstract Authors: Gaston MA, Jiang R, Krzycki JA In Methanosarcina spp., amber codons in methylamine methyltransferase genes are translated as the 22nd amino acid, pyrrolysine. The responsible pyl genes plus amber-codon containing methyltransferase genes have been identified in four archaeal and five bacterial genera, including one human pathogen. In Escherichia coli, the recombinant pylBCD gene products biosynthesize pyrrolysine from two molecules of lysine and the pylTS gene products direct pyrrolysine incorporation into protein. In the proposed biosynthetic pathway, PylB forms methylornithine from lysine, which is joined to another lysine by PylC, and oxidized to pyrrolysine by PylD. Structures of the catalytic domain of pyrrolysyl-tRNA synthetase (archaeal PylS or bacterial PylSc) revealed ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804093 Wed, 04 May 2011 23:00:00 +0100 4804093 http://www.medworm.com/index.php?rid=4804095&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21546306%26dopt%3DAbstract Authors: Pester M, Schleper C, Wagner M Thaumarchaeota range among the most abundant archaea on Earth. Initially classified as 'mesophilic Crenarchaeota', comparative genomics has recently revealed that they form a separate and deep-branching phylum within the Archaea. This novel phylum comprises in 16S rRNA gene trees not only all known archaeal ammonia oxidizers but also several clusters of environmental sequences representing microorganisms with unknown energy metabolism. Ecophysiological studies of ammonia-oxidizing Thaumarchaeota suggest adaptation to low ammonia concentrations and an autotrophic or possibly mixotrophic lifestyle. Extrapolating from the wide substrate range of copper-containing membrane-bound monooxygenases, to which the thaumarchaeal ammonia monooxygenases belong... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804095 Tue, 03 May 2011 23:00:00 +0100 4804095 http://www.medworm.com/index.php?rid=4804094&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21546307%26dopt%3DAbstract Authors: Heuer H, Schmitt H, Smalla K The usage of antibiotics in animal husbandry has promoted the development and abundance of antibiotic resistance in farm environments. Manure has become a reservoir of resistant bacteria and antibiotic compounds, and its application to agricultural soils is assumed to significantly increase antibiotic resistance genes and selection of resistant bacterial populations in soil. The genome location of resistance genes is likely to shift towards mobile genetic elements such as broad-host-range plasmids, integrons, and transposable elements. Horizontal transfer of these elements to bacteria adapted to soil or other habitats supports their environmental transmission independent of the original host. The human exposure to soil-borne resistance has yet to b... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804094 Mon, 02 May 2011 23:00:00 +0100 4804094 http://www.medworm.com/index.php?rid=4804096&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21543251%26dopt%3DAbstract Authors: Samson RY, Bell SD Until recently little was known about the cell cycle parameters and division mechanisms of archaeal organisms. Although this is still the case for the majority of archaea, significant advances have been made in some model species. The information that has been gleaned thus far points to a remarkable degree of diversity within the archaeal domain of life. More specifically, members of distinct phyla have very different chromosome copy numbers, replication control systems and even employ distinct machineries for cell division. PMID: 21543251 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804096 Sun, 01 May 2011 23:00:00 +0100 4804096 http://www.medworm.com/index.php?rid=4804097&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21536481%26dopt%3DAbstract Authors: Gibson DM, King BC, Hayes ML, Bergstrom GC The plant cell wall is a major barrier that many plant pathogens must surmount for successful invasion of their plant hosts. Full genome sequencing of a number of plant pathogens has revealed often large, complex, and redundant enzyme systems for degradation of plant cell walls. Recent surveys have noted that plant pathogenic fungi are highly competent producers of lignocellulolytic enzymes, and their enzyme activity patterns reflect host specificity. We propose that plant pathogens may contribute to biofuel production as diverse sources of accessory enzymes for more efficient conversion of lignocellulose into fermentable sugars. PMID: 21536481 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804097 Fri, 29 Apr 2011 23:00:00 +0100 4804097 http://www.medworm.com/index.php?rid=4804100&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21531607%26dopt%3DAbstract Authors: Terns MP, Terns RM CRISPR-Cas systems are recently discovered, RNA-based immune systems that control invasions of viruses and plasmids in archaea and bacteria. Prokaryotes with CRISPR-Cas immune systems capture short invader sequences within the CRISPR loci in their genomes, and small RNAs produced from the CRISPR loci (CRISPR (cr)RNAs) guide Cas proteins to recognize and degrade (or otherwise silence) the invading nucleic acids. There are multiple variations of the pathway found among prokaryotes, each mediated by largely distinct components and mechanisms that we are only beginning to delineate. Here we will review our current understanding of the remarkable CRISPR-Cas pathways with particular attention to studies relevant to systems found in the archaea. PMID: 21531607 ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804100 Thu, 28 Apr 2011 23:00:00 +0100 4804100 http://www.medworm.com/index.php?rid=4804099&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21531608%26dopt%3DAbstract Authors: Prangishvili D, Quax TE Virion release from the host cell is the final and essential step for completion of the viral life cycle and spread of virions in the environment. Although for eukaryotic and bacterial viruses the egress mechanisms are reasonably well understood, this subject has not been studied in detail for archaeal viruses until recently. Here we summarize available data on the extraordinary egress mechanism exploited by the Sulfolobus islandicus rod-shaped virus SIRV2 and the Sulfolobus turreted icosahedral virus STIV. In addition, we describe features of the virus-induced pyramidal formation, VAP, involved in this process. Being an autonomous structure different from the capsid, the VAP can be considered as a representative of a specific class of virus-coded struc... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804099 Thu, 28 Apr 2011 23:00:00 +0100 4804099 http://www.medworm.com/index.php?rid=4804098&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21531609%26dopt%3DAbstract Authors: Wilson DB Enzymatic hydrolysis of cellulose by microorganisms is a key step in the global carbon cycle. Despite its abundance only a small percentage of microorganisms can degrade cellulose, probably because it is present in recalcitrant cell walls. There are at least five distinct mechanisms used by different microorganisms to degrade cellulose all of which involve cellulases. Cellulolytic organisms and cellulases are extremely diverse possibly because their natural substrates, plant cell walls, are very diverse. At this time the microbial ecology of cellulose degradation in any environment is still not clearly understood even though there is a great deal of information available about the bovine rumen. Two major problems that limit our understanding of this area are the vast... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804098 Thu, 28 Apr 2011 23:00:00 +0100 4804098 http://www.medworm.com/index.php?rid=4804102&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21489863%26dopt%3DAbstract Authors: Thauer RK Anaerobic oxidation of methane (AOM) with sulfate is apparently catalyzed by an association of methanotrophic archaea (ANME) and sulfate-reducing bacteria. In many habitats, the free energy change (ΔG) available through this process is only -20kJ/mol and therefore AOM with sulfate reduction generating life-supporting ATP is predicted to operate near thermodynamic equilibrium (ΔG=0kJ/mol). On the basis of meta-genome sequencing and enzyme studies, it has been proposed that AOM in ANME is catalyzed by the same enzymes that catalyze CO(2) reduction to CH(4) in methanogenic archaea. Here, this proposal is reviewed and evaluated in terms of the process thermodynamics, kinetics, and enzyme reversibilities. Currently, there is no evidence for the presence of the gene that... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804102 Sun, 10 Apr 2011 23:00:00 +0100 4804102 http://www.medworm.com/index.php?rid=4804101&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21489864%26dopt%3DAbstract Authors: Defoirdt T, Sorgeloos P, Bossier P The wide and frequent use of antibiotics in aquaculture has resulted in the development and spread of antibiotic resistance. Because of the health risks associated with the use of antibiotics in animal production, there is a growing awareness that antibiotics should be used with more care. This is reflected in the recent implementation of more strict regulations on the prophylactic use of antibiotics and the presence of antibiotic residues in aquaculture products. For a sustainable further development of the aquaculture industry, novel strategies to control bacterial infections are needed. This review evaluates several alternative biocontrol measures that have emerged recently. Most of these methods are still in research phase; few have been ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804101 Sun, 10 Apr 2011 23:00:00 +0100 4804101 http://www.medworm.com/index.php?rid=4804103&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21482178%26dopt%3DAbstract Authors: Pohlschroder M, Ghosh A, Tripepi M, Albers SV In both bacteria and Archaea, the biosynthesis of type IV pilus-related structures involves a set of core components, including a prepilin peptidase that specifically processes precursors of pilin-like proteins. Although in silico analyses showed that most sequenced archaeal genomes encode predicted pilins and conserved pilus biosynthesis components, recent in vivo analyses of archaeal pili in genetically tractable crenarchaea and euryarchaea revealed Archaea-specific type IV pilus functions and biosynthesis components. Studies in a variety of archaeal species will reveal which type IV pilus-like structures are common in Archaea and which are limited to certain species within this domain. The insights gleaned from these studies may... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4804103 Wed, 06 Apr 2011 23:00:00 +0100 4804103 http://www.medworm.com/index.php?rid=4697465&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21470902%26dopt%3DAbstract Authors: Phillips G, de Crécy-Lagard V tRNA modifications are important for decoding, translation accuracy, and structural integrity of tRNAs. Archaeal tRNAs contain at least 47 different tRNA modifications, some of them, including archaeosine, agmatidine, and mimG, are specific to the archaeal domain. The biosynthetic pathways for these complex signature modifications have recently been elucidated and are extensively described in this review. Archaeal organisms still lag Escherichia coli and Saccharomyces cerevisiae in terms of genetic characterization and in vivo function of tRNA modifications. However, recent advances in the model Haloferax volcanii, described here, should allow closing this gap soon. Consequently, an update on experimental characterizations of archaeal tRNA modifi... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4697465 Sun, 03 Apr 2011 23:00:00 +0100 4697465 http://www.medworm.com/index.php?rid=4578817&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21388862%26dopt%3DAbstract Authors: de Las Heras A, Cain RJ, Bielecka MK, Vázquez-Boland JA Listeria monocytogenes is the causative agent of listeriosis, a severe foodborne infection. These bacteria live as soil saprotrophs on decaying plant matter but also as intracellular parasites, using the cell cytosol as a replication niche. PrfA, a regulatory protein, integrates a number of environmental cues that signal the transition between these two contrasting lifestyles, activating a set of key virulence factors during host infection. While a number of details concerning the general mode of action of this virulence master switch have been elucidated, others remain unsolved. Recent work has revealed additional mechanisms that contribute to L. monocytogenes virulence modulation, often via cross-talk with PrfA, or by ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578817 Mon, 07 Mar 2011 00:00:00 +0100 4578817 http://www.medworm.com/index.php?rid=4578818&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21382741%26dopt%3DAbstract Authors: Henkin TM, Casadesús J PMID: 21382741 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578818 Sat, 05 Mar 2011 00:00:00 +0100 4578818 http://www.medworm.com/index.php?rid=4578822&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353625%26dopt%3DAbstract Authors: Soares JA, Ahmer BM Escherichia and Salmonella do not synthesize quorum-sensing signaling molecules of the N-acyl-l-homoserine lactone (AHL) type but they can detect AHLs produced by other species of bacteria. AHLs are present in the bovine rumen but not in the remainder of the gastrointestinal tract. Enterohemorrhagic E. coli (EHEC) responds to AHLs extracted from the bovine rumen. Salmonella fails to detect AHLs in the gastrointestinal tracts of pathogen-free mice or pigs, suggesting that AHLs are not present. However, Salmonella does detect the AHL production of Yersinia enterocolitica in mouse Peyer's patches. In response to AHLs, EHEC represses flagellar genes and the LEE pathogenicity island while it activates the acid fitness island, whereas Salmonella activates the rck... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578822 Thu, 24 Feb 2011 00:00:00 +0100 4578822 http://www.medworm.com/index.php?rid=4578821&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353626%26dopt%3DAbstract Authors: Meyer AS, Baker TA Proteolysis is a fundamental process used by all forms of life to maintain homeostasis, as well as to remodel the proteome following environmental changes. Here, we explore recent advances in understanding the role of proteolysis during the heat shock response of Escherichia coli. Proteolysis both regulates and contributes directly to and the heat shock response at multiple different levels, from adjusting the levels of the master heat shock response regulator (σ(32)), to eliminating damaged cellular proteins, to altering the activity of chaperones that refold heat-denatured proteins. Recent results illustrate the complexity of the heat shock response and the pervasive role that proteolysis plays in both the cellular response to heat shock and the subsequen... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578821 Thu, 24 Feb 2011 00:00:00 +0100 4578821 http://www.medworm.com/index.php?rid=4578820&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353627%26dopt%3DAbstract Authors: Dunny GM, Johnson CM The regulatory system controlling pheromone-induced plasmid transfer in Enterococcus faecalis is the most thoroughly studied genetic system of this species. Transcription initiation from the target promoter is controlled by a pheromone receptor/repressor protein whose activity is determined by its interaction with two peptide signaling molecules that compete for the same binding site, but have opposing effects on the activity of the receptor protein. For the system to function as a sensitive and robust biological switch, several additional levels of post-transcriptional regulation are also required. Expression of important functions encoded within the enterococcal core genome may also be controlled by multilayered regulatory circuitry. The pheromone system... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578820 Thu, 24 Feb 2011 00:00:00 +0100 4578820 http://www.medworm.com/index.php?rid=4578819&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21354362%26dopt%3DAbstract Authors: Keiler KC Bacteria localize proteins and DNA regions to specific subcellular sites, and several recent publications show that RNAs are localized within the cell as well. Localization of tmRNA and some mRNAs indicates that RNAs can be sequestered at specific sites by RNA binding proteins, or can be trapped at the location where they are transcribed. Although the functions of RNA localization are not yet completely understood, it appears that one function of RNA localization is to regulate RNA abundance by controlling access to nucleases. New techniques for visualizing RNAs will likely lead to increased examination of spatial control of RNAs and the role this control plays in the regulation of gene expression and bacterial physiology. PMID: 21354362 [PubMed - as supplied by ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4578819 Thu, 24 Feb 2011 00:00:00 +0100 4578819 http://www.medworm.com/index.php?rid=4525338&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21342782%26dopt%3DAbstract Authors: Cruz-Vera LR, Sachs MS, Squires CL, Yanofsky C Ribosomes catalyze protein synthesis using transfer RNAs and auxiliary proteins. Historically, ribosomes have been considered nonspecific translational machines, having no regulatory functions. However, a new class of regulatory mechanisms has been discovered that is based on interactions occurring within the ribosomal peptide exit tunnel that result in ribosome stalling during translation of an appropriate mRNA segment. These discoveries reveal an unexpectedly dynamic role ribosomes play in regulating their own activity. By using nascent leader peptides in combination with bound specific amino acids or antibiotics, ribosome functions can be altered significantly resulting in regulated expression of downstream coding regions. This... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4525338 Sun, 20 Feb 2011 00:00:00 +0100 4525338 http://www.medworm.com/index.php?rid=4525337&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21342783%26dopt%3DAbstract Authors: Hobbs EC, Fontaine F, Yin X, Storz G Historically, small proteins (sproteins) of less than 50 amino acids, in their final processed forms or genetically encoded as such, have been understudied. However, both serendipity and more recent focused efforts have led to the identification of a number of new sproteins in both Gram-negative and Gram-positive bacteria. Increasing evidence demonstrates that sproteins participate in a wide array of cellular processes and exhibit great diversity in their mechanisms of action, yet general principles of sprotein function are emerging. This review highlights examples of sproteins that participate in cell signaling, act as antibiotics and toxins, and serve as structural proteins. We also describe roles for sproteins in detecting and altering m... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4525337 Sun, 20 Feb 2011 00:00:00 +0100 4525337 http://www.medworm.com/index.php?rid=4525340&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21334965%26dopt%3DAbstract Authors: Condon C, Bechhofer DH Regulation of bacterial gene expression at the post-transcriptional level has emerged as a major control mechanism, although not yet as well recognized as the mechanisms of control at the transcriptional level. In this article, we focus on regulated RNA decay in the control of gene expression in Gram-positive organisms, with an emphasis on Bacillus subtilis. Discovery of new ribonuclease activities in B. subtilis and other Gram-positive species, especially the dual-functioning RNase J1, which specifies both an endonuclease activity and the long-sought bacterial 5'-to-3' exoribonuclease activity, has led to the recognition of intriguing mechanisms of gene regulation at the level of RNA decay. PMID: 21334965 [PubMed - as supplied by publisher] (Source:... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4525340 Fri, 18 Feb 2011 00:00:00 +0100 4525340 http://www.medworm.com/index.php?rid=4525339&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21334966%26dopt%3DAbstract Authors: Turnbough CL Gene regulation involves many different types of transcription control mechanisms, including mechanisms based on reiterative transcription in which nucleotides are repetitively added to the 3' end of a nascent transcript due to upstream transcript slippage. In these mechanisms, reiterative transcription is typically modulated by interactions between RNA polymerase and its nucleoside triphosphate substrates without the involvement of regulatory proteins. This review describes the current state of knowledge of gene regulation involving reiterative transcription. It focuses on the methods by which reiterative transcription is controlled and emphasizes the different fates of transcripts produced by this reaction. The review also includes a discussion of possible new a... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4525339 Fri, 18 Feb 2011 00:00:00 +0100 4525339 http://www.medworm.com/index.php?rid=4470717&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21292543%26dopt%3DAbstract Authors: van der Woude MW Phase variation yields phenotypic heterogeneity in a clonal population as the result of one of a limited number of known molecular mechanisms. These include slipped strand mispairing, site-specific recombination and epigenetic regulation mediated by DNA methylation. Recently new regulatory variants utilizing these mechanisms have been identified, which is facilitating the identification of additional phase variation events solely from genome sequence analysis. Furthermore, it is becoming increasingly clear that in many cases phase variation control is integrated with regulatory networks and with cellular processes of a growing cell. This review focuses specifically on these recent advances in the understanding of the regulation of phase variation. PMID: 21... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4470717 Tue, 01 Feb 2011 00:00:00 +0100 4470717 http://www.medworm.com/index.php?rid=4470719&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21288763%26dopt%3DAbstract Authors: Rimsky S, Travers A Bacterial DNA is organised in a compact nucleoid body that is tightly associated with the coupled transcription and translation of mRNAs. This structure contains abundant DNA-binding proteins which perform both structural and regulatory roles, and, in Escherichia coli, serve to buffer and organise pervasive DNA superhelicity. We argue that NAPs coordinate regulation of gene expression and superhelicity at the global (or chromosomal) and at local (corresponding to promoter activity and genetic recombination) levels. PMID: 21288763 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4470719 Mon, 31 Jan 2011 00:00:00 +0100 4470719 http://www.medworm.com/index.php?rid=4470718&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21288764%26dopt%3DAbstract Authors: Py B, Moreau PL, Barras F Iron-sulfur (Fe-S) clusters are ubiquitous cofactors present in a myriad of proteins controlling processes as diverse as DNA replication, photosynthesis, respiration and gene regulation. Their assembly and delivery into apo-proteins are catalysed by different multi-protein systems conserved throughout prokaryotes and eukaryotes. Because so many cellular processes are dependent upon Fe-S proteins, alteration of the Fe-S clusters or of the systems that make them has profound impact on cellular physiology. The present review aims at covering and discussing those situations wherein these highly efficient redox sensitive cofactors turn from faithful sentinels into enfeebled assistants or, worse, into dangerous insiders. PMID: 21288764 [PubMed - as supp... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4470718 Mon, 31 Jan 2011 00:00:00 +0100 4470718 http://www.medworm.com/index.php?rid=4400278&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21239213%26dopt%3DAbstract Authors: Thao S, Escalante-Semerena JC Recently published work indicates that reversible N(ɛ)-lysine (N(ɛ)-Lys) acetylation of proteins in bacteria may be as diverse, and as important for cellular function, as it has been reported in eukaryotes for the last five decades. In addition to biochemical and genetic approaches, proteomic studies have identified N(ɛ)-Lys acetylation of proteins and enzymes involved in diverse cellular activities such as transcription, translation, stress response, detoxification, and especially carbohydrate and energy metabolism. These findings provide a platform for elucidating the molecular mechanisms behind modulation of enzyme activity by N(ɛ)-Lys acetylation, as well as for understanding how the prokaryotic cell maintains homeostasis in a changing env... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400278 Fri, 14 Jan 2011 00:00:00 +0100 4400278 http://www.medworm.com/index.php?rid=4400277&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21239214%26dopt%3DAbstract Authors: Elías-Arnanz M, Padmanabhan S, Murillo FJ Bacteria sense and respond to light, a fundamental environmental factor, by employing highly evolved machineries and mechanisms. Cellular systems exist to harness light energy usefully as in phototrophic bacteria, to combat photo-oxidative damage stemming from the highly reactive species generated on absorption of light energy, and to link the light stimulus to DNA repair, taxis, development, and virulence. Recent findings on the genetic response to light in nonphototrophic bacteria highlight the ingenious transcriptional regulatory mechanisms and the panoply of factors that have evolved to perceive and transmit the signal, and to bring about finely tuned gene expression. PMID: 21239214 [PubMed - as supplied by publisher] (Source:... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400277 Fri, 14 Jan 2011 00:00:00 +0100 4400277 http://www.medworm.com/index.php?rid=4400276&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21239215%26dopt%3DAbstract Authors: Finlay BB, Bonas U PMID: 21239215 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400276 Fri, 14 Jan 2011 00:00:00 +0100 4400276 http://www.medworm.com/index.php?rid=4400281&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21236723%26dopt%3DAbstract Authors: Rico A, McCraw SL, Preston GM The bacterial plant pathogen Pseudomonas syringae causes economically important diseases of a wide variety of plant species and is used as a model organism to understand the molecular basis of plant disease. Much existing research into P. syringae-plant interactions has focused on the molecular basis of plant disease resistance and the role of secreted effector proteins in the suppression of plant defences. However, researchers have speculated that the diverse array of effectors, toxins and hormones produced by this pathogen also play an important role in manipulating plant metabolism to promote infection. Recent advances in metabolomics, genomics, transcriptomics and metabolic modelling offer new opportunities to address this question and generat... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400281 Wed, 12 Jan 2011 00:00:00 +0100 4400281 http://www.medworm.com/index.php?rid=4400280&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21236724%26dopt%3DAbstract Authors: Batut J, Mergaert P, Masson-Boivin C For two decades, signalling research in the rhizobium-legume symbiosis field has been dominated by oligosaccharide signals (mainly Nod factors and, to a lesser extent, surface polysaccharides made by the microsymbionts) and phytohormones. Recently, plant peptides have emerged as another major class of signalling molecules in the rhizobium-legume symbioses contributing to the control of nodulation, infection and bacteroid differentiation. Here we focus on three examples of symbiotically relevant peptides, namely Enod40, CLE and NCR peptides. The number of genes encoding these peptides, as well as the recent discovery of additional peptide players in the context of symbiosis, suggests that we might be seeing only the tip of the peptide iceber... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400280 Wed, 12 Jan 2011 00:00:00 +0100 4400280 http://www.medworm.com/index.php?rid=4400279&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21236725%26dopt%3DAbstract Authors: Han SW, Lee SW, Ronald PC Innate immunity provides a first line of defense against pathogen attack and is activated rapidly following infection. Although it is now widely appreciated that host receptors of conserved microbial signatures play a key role in innate immunity in plants and animals, very little is known about the biological function of the microbially derived molecules recognized by such receptors. We have recently demonstrated that the rice XA21 receptor binds the AxY(S)22 peptide corresponding to the N-terminal region of Ax21, a type I-secreted protein that is highly conserved in all Xanthomonas species as well as in Xylella fastidiosa and the human pathogen, Stenotrophomonas maltophilia. We hypothesize that post-translational modification of Ax21 is carried out b... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400279 Wed, 12 Jan 2011 00:00:00 +0100 4400279 http://www.medworm.com/index.php?rid=4400282&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21233007%26dopt%3DAbstract Authors: O'Brien HE, Desveaux D, Guttman DS The first wave of Pseudomonas syringae next-generation genomic studies has revealed insights into host-specific virulence and immunity, genome dynamics and evolution, and genetic and metabolic specialization. These studies have further enhanced our understanding of type III effector diversity, identified an atypical type III secretion system (T3SS) in a new clade of nonpathogenic P. syringae, identified metabolic pathways common to pathogens of woody hosts and revealed extensive genomic diversity among strains that infect common hosts. In general, these discoveries have illustrated the utility of draft genome sequencing for quickly and economically identifying candidate loci for more refined genetic and functional analyses. PMID: 21233007... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400282 Tue, 11 Jan 2011 00:00:00 +0100 4400282 http://www.medworm.com/index.php?rid=4400283&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21227738%26dopt%3DAbstract Authors: Block A, Alfano JR The phytopathogenic bacterium Pseudomonas syringae can suppress both pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) by the injection of type III effector (T3E) proteins into host cells. T3Es achieve immune suppression using a variety of strategies including interference with immune receptor signaling, blocking RNA pathways and vesicle trafficking, and altering organelle function. T3Es can be recognized indirectly by resistance proteins monitoring specific T3E targets resulting in ETI. It is presently unclear whether the monitored targets represent bona fide virulence targets or guarded decoys. Extensive overlap between PTI and ETI signaling suggests that T3Es may suppress both pathways through comm... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4400283 Mon, 10 Jan 2011 00:00:00 +0100 4400283 http://www.medworm.com/index.php?rid=4336117&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215681%26dopt%3DAbstract Authors: Keeney KM, Finlay BB Residing within the intestine is a large community of commensal organisms collectively termed the microbiota. This community generates a complex nutrient environment by breaking down indigestible food products into metabolites that are used by both the host and the microbiota. Both the invading intestinal pathogen and the microbiota compete for these metabolites, which can shape both the composition of the flora, as well as susceptibility to infection. After infection is established, pathogen mediated inflammation alters the composition of the microbiota, which further shifts the makeup of metabolites in the gastrointestinal tract. A greater understanding of the interplay between the microbiota, the metabolites they generate, and susceptibility to enteric ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4336117 Wed, 05 Jan 2011 00:00:00 +0100 4336117 http://www.medworm.com/index.php?rid=4336116&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215682%26dopt%3DAbstract Authors: Kereszt A, Mergaert P, Maróti G, Kondorosi E Rhizobium-legume symbiosis has been considered as a mutually favorable relationship for both partners. However, in certain phylogenetic groups of legumes, the plant directs the bacterial symbiont into an irreversible terminal differentiation. This is mediated by the actions of hundreds of symbiosis-specific plant peptides resembling antimicrobial peptides, the effectors of innate immunity. The bacterial BacA protein, associated in animal pathogenic bacteria with the maintenance of chronic intracellular infections, is also required for terminal differentiation of rhizobia. Thus, a virulence factor of pathogenesis and effectors of the innate immunity were adapted in symbiosis for the benefit of the plant partner. PMID: 21215682 [... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4336116 Wed, 05 Jan 2011 00:00:00 +0100 4336116 http://www.medworm.com/index.php?rid=4336115&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215683%26dopt%3DAbstract Authors: Segonzac C, Zipfel C The first active layer of plant innate immunity relies on the recognition by surface receptors of molecules indicative of non-self or modified-self. The activation of pattern-recognition receptors (PRRs) by pathogen-associated molecular patterns (PAMPs) is in essence sufficient to stop pathogen invasion through transcriptional reprogramming and production of anti-microbials. The few PRR/PAMP pairs that are characterised provide useful models to study the specificity of ligand-binding and likely activation mechanisms. Both classical and new approaches are still required to identify new bacterial PAMPs. Current genetic screens, functional genomics and biochemical analyses have identified the regulation mechanisms of PRR transcription and biogenesis, provided... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4336115 Wed, 05 Jan 2011 00:00:00 +0100 4336115 http://www.medworm.com/index.php?rid=4336114&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215684%26dopt%3DAbstract Authors: Ivanov II, Littman DR Intestinal bacteria form a resident community that has co-evolved with the mammalian host. In addition to playing important roles in digestion and harvesting energy, commensal bacteria are crucial for the proper functioning of mucosal immune defenses. Most of these functions have been attributed to the presence of large numbers of 'innocuous' resident bacteria that dilute or occupy niches for intestinal pathogens or induce innate immune responses that sequester bacteria in the lumen, thus quenching excessive activation of the mucosal immune system. However it has recently become obvious that commensal bacteria are not simply beneficial bystanders, but are important modulators of intestinal immune homeostasis and that the composition of the microbiota is a... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4336114 Wed, 05 Jan 2011 00:00:00 +0100 4336114 http://www.medworm.com/index.php?rid=4336113&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215685%26dopt%3DAbstract Authors: Scholze H, Boch J TAL (transcription activator-like) effectors constitute a novel class of DNA-binding proteins with predictable specificity. They are employed by Gram-negative plant-pathogenic bacteria of the genus Xanthomonas which translocate a cocktail of different effector proteins via a type III secretion system (T3SS) into plant cells where they serve as virulence determinants. Inside the plant cell, TALs localize to the nucleus, bind to target promoters, and induce expression of plant genes. DNA-binding specificity of TALs is determined by a central domain of tandem repeats. Each repeat confers recognition of one base pair (bp) in the DNA. Rearrangement of repeat modules allows design of proteins with desired DNA-binding specificities. Here, we summarize how TAL specif... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4336113 Wed, 05 Jan 2011 00:00:00 +0100 4336113 http://www.medworm.com/index.php?rid=4218001&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21112809%26dopt%3DAbstract Authors: Shahnazari S, Brumell JH Autophagy is a key component of our immune response to invading pathogens. Autophagic targeting of intracellular bacteria within vacuolar compartments or the cytosol helps to control bacterial replication in the host cell. The mechanism by which these invading pathogens are selectively targeted for degradation is of particular interest. Recently, several signaling factors have been shown to play roles in the specific targeting of bacteria by the autophagy pathway including: pattern recognition receptors, reactive oxygen species, ubiquitin and diacylglycerol. Here, we discuss these signaling factors and the consequences of bacterial targeting by autophagy during infection of host cells. PMID: 21112809 [PubMed - as supplied by publisher] (Source: Cur... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4218001 Fri, 26 Nov 2010 00:00:00 +0100 4218001 http://www.medworm.com/index.php?rid=4218002&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21112241%26dopt%3DAbstract Authors: Worrall LJ, Lameignere E, Strynadka NC The bacterial injectisome is a specialized protein-export system utilized by many pathogenic Gram-negative bacteria for the delivery of virulence proteins into the hosts they infect. This needle-like molecular nanomachine comprises >20 proteins creating a continuous passage from bacterial to host cytoplasm. The last few years have witnessed significant progress in our understanding of the structure of the injectisome with important contributions from X-ray crystallography, NMR and EM. This review will present the current state of the structure of the injectisome with particular focus on the molecular structures of individual components and how these assemble together in a functioning T3SS. PMID: 21112241 [PubMed - as supplied by pu... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4218002 Thu, 25 Nov 2010 00:00:00 +0100 4218002 http://www.medworm.com/index.php?rid=4185011&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21074484%26dopt%3DAbstract Authors: Lutkenhaus J PMID: 21074484 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4185011 Wed, 10 Nov 2010 00:00:00 +0100 4185011 http://www.medworm.com/index.php?rid=4166120&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21071265%26dopt%3DAbstract Authors: Pérez-Martín J PMID: 21071265 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4166120 Tue, 09 Nov 2010 00:00:00 +0100 4166120 http://www.medworm.com/index.php?rid=4139544&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21050804%26dopt%3DAbstract Authors: Bernander R, Ettema TJ A dedicated cell division machinery is needed for efficient proliferation of an organism. The eukaryotic actin-myosin based mechanism and the bacterial FtsZ-dependent machinery have both been characterized in detail, and a third division mechanism, the Cdv system, was recently discovered in archaea from the Crenarchaeota phylum. Despite these findings, division mechanisms remain to be identified in, for example, organisms belonging to the bacterial PVC superphylum, bacteria with extremely reduced genomes, wall-less archaea and bacteria, and in archaea that carry out the division process without cell constriction. Cytokinesis mechanisms in these clades and individual taxa are likely to include adaptation of host functions to division of bacterial symbiont... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139544 Mon, 01 Nov 2010 00:00:00 +0100 4139544 http://www.medworm.com/index.php?rid=4139546&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21041110%26dopt%3DAbstract Authors: Van Melderen L Toxin-antitoxin (TA) systems are small genetic modules that are abundant in bacterial genomes. Three types have been described so far, depending on the nature and mode of action of the antitoxin component. While type II systems are surprisingly highly represented because of their capacity to move by horizontal gene transfer, type I systems appear to have evolved by gene duplication and are more constrained. Type III is represented by a unique example located on a plasmid. Type II systems promote stability of mobile genetic elements and might act at the selfish level. Conflicting hypotheses about chromosomally encoded systems, from programmed cell death and starvation-induced stasis to protection against invading DNA and stabilization of large genomic fragments h... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139546 Sat, 30 Oct 2010 00:00:00 +0100 4139546 http://www.medworm.com/index.php?rid=4139545&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21041111%26dopt%3DAbstract Authors: Miyagishima SY, Kabeya Y Chloroplasts have evolved from a cyanobacterial endosymbiont and have been retained in eukaryotic cells for more than one billion years via chloroplast division and inheritance by daughter cells during cell division. Recent studies revealed that chloroplast division is performed by a large protein complex at the division site, encompassing both the inside and the outside of the two envelope membranes. The division complex has retained a few components of the cyanobacterial division complex to go along with other components supplied by the host cell. On the basis of the information about the division complex, we are beginning to understand how the division complex evolved, and how eukaryotic host cells regulate chloroplast division during proliferation ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139545 Sat, 30 Oct 2010 00:00:00 +0100 4139545 http://www.medworm.com/index.php?rid=4139547&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21036658%26dopt%3DAbstract Authors: Flärdh K Streptomyces cells grow by building cell wall at one pole-the hyphal tip. Although analogous to hyphal growth in fungi, this is achieved in a prokaryote, without any of the well-known eukaryotic cell polarity proteins, and it is also unique among bacterial cases of cell polarity. Further, polar growth of Streptomyces and the related mycobacteria and corynebacteria is independent of the MreB cytoskeleton and involves a number of coiled-coil proteins, including the polarity determinant DivIVA. Recent progress sheds light on targeting of DivIVA to hyphal tips and highlight protein phosphorylation in the regulation of actinobacterial growth. Furthermore, cell polarity affects not only cell envelope biogenesis in Streptomyces, but apparently also assembly of fimbriae, con... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139547 Fri, 29 Oct 2010 00:00:00 +0100 4139547 http://www.medworm.com/index.php?rid=4139549&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21036098%26dopt%3DAbstract Authors: Stecher B, Hardt WD The intestinal microbiota can protect efficiently against colonization by many enteric pathogens ('colonization resistance', CR). This phenomenon has been known for decades, but the mechanistic basis of CR is incompletely defined. At least three mechanisms seem to contribute, that is direct inhibition of pathogen growth by microbiota-derived substances, nutrient depletion by microbiota growth and microbiota-induced stimulation of innate and adaptive immune responses. In spite of CR, intestinal infections are well known to occur. In these cases, the multi-faceted interactions between the microbiota, the host and the pathogen are shifted in favor of the pathogen. We are discussing recent progress in deciphering the underlying molecular mechanisms in health an... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139549 Thu, 28 Oct 2010 00:00:00 +0100 4139549 http://www.medworm.com/index.php?rid=4139548&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21036099%26dopt%3DAbstract Authors: Kruzel EK, Hull CM The dikaryons of basidiomycete fungi represent an unusual cell type required for complete sexual development. Dikaryon formation occurs via the activities of cell type-specific homeodomain transcription factors, which form regulatory complexes to establish the dikaryotic state. Decades of classical genetic and cell biological studies in mushrooms have provided a foundation for more recent molecular studies in the pathogenic species Ustilago maydis and Cryptococcus neoformans. Studies in these systems have revealed novel mechanisms of regulation that function downstream of classic homeodomain complexes to ensure that dikaryons are established and propagated. Comparisons of these dikaryon-specific networks promise to reveal the nature of regulatory network evo... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139548 Thu, 28 Oct 2010 00:00:00 +0100 4139548 http://www.medworm.com/index.php?rid=4139550&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21035377%26dopt%3DAbstract Authors: Leonard AC, Grimwade JE New rounds of bacterial chromosome replication are triggered during each cell division cycle by the initiator protein, DnaA. For precise timing, interactions of DnaA-ATP monomers with the replication origin, oriC, must be carefully regulated during formation of complexes that unwind origin DNA and load replicative helicase. Recent studies in Escherichia coli suggest that high and low affinity DnaA recognition sites are positioned within oriC to direct staged assembly of bacterial pre-replication complexes, with DnaA contacting low affinity sites as it oligomerizes to 'fill the gaps' between high affinity sites. The wide variability of oriC DnaA recognition site patterns seen in nature may reflect myriad gap-filling strategies needed to couple oriC funct... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4139550 Wed, 27 Oct 2010 00:00:00 +0100 4139550 http://www.medworm.com/index.php?rid=4107878&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20971679%26dopt%3DAbstract Authors: Leung KY, Siame BA, Snowball H, Mok YK Pathogens use type VI secretion systems (T6SSs) to transport proteins into the environment or host cells in response to external stimuli. T6SSs are tightly regulated together with other virulence determinants such as type III secretion systems, quorum sensing (QS), and flagella synthesis. Five pathogens (Salmonella enterica, Edwardsiella tarda, Aeromonas hydrophila, Vibrio cholerae, and Pseudomonas aeruginosa) are examined for crosstalk proteins (global regulators) that connect T6SSs to other virulence determinants. Common transcriptional regulators (TRs) include two component systems (i.e. PhoPQ), σ(54) and σ(54)-dependent TRs (i.e. VasH), and QS regulators. Greater understanding of this integral communication network will define what ... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4107878 Thu, 21 Oct 2010 23:00:00 +0100 4107878 http://www.medworm.com/index.php?rid=4107879&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20971034%26dopt%3DAbstract Authors: Salzman NH An estimated 100 trillion microbes colonize human beings, with the majority of organisms residing in the intestines. This microbiota impacts host nutrition, protection, and gut development. Alterations in microbiota composition are associated with susceptibility to various infectious and inflammatory gut diseases. The mucosal surface is not a static barrier that simply prevents microbial invasion but a critical interface for microbiota-immune system interactions. Recent work suggests that dynamic interactions between microbes and the host immune system at the mucosal surface inform immune responses both locally and systemically. This review focuses on intestinal microbiota-immune interactions leading to intestinal homeostasis, and show that these interactions at the... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4107879 Wed, 20 Oct 2010 23:00:00 +0100 4107879 http://www.medworm.com/index.php?rid=4088280&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20951078%26dopt%3DAbstract Authors: Ramamurthi KS Bacteria often sort proteins to specific subcellular locations, but many of the chemical beacons that specify those sites and subsequently recruit proteins have not been identified. Recent reports suggest that some bacterial proteins localize to specific subcellular sites by recognizing either convex or concave membrane curvature. Thus, degrees of membrane curvature, dictated by the shape of the cell, can define a geometric cue for the recruitment of curvature-sensing proteins. PMID: 20951078 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology) Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4088280 Tue, 12 Oct 2010 23:00:00 +0100 4088280 http://www.medworm.com/index.php?rid=4088279&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20951079%26dopt%3DAbstract Authors: Browning DF, Grainger DC, Busby SJ Bacterial nucleoid-associated proteins play a key role in the organisation, replication, segregation, repair and expression of bacterial chromosomes. Here, we review some recent progress in our understanding of the effects of these proteins on DNA and their biological role, focussing mainly on Escherichia coli and its chromosome. Certain nucleoid-associated proteins also regulate transcription initiation at specific promoters, and work in concert with dedicated transcription factors to regulate gene expression in response to growth phase and environmental change. Some specific examples, involving the E. coli IHF and Fis proteins, that illustrate new principles, are described in detail. PMID: 20951079 [PubMed - as supplied by publisher] (S... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4088279 Tue, 12 Oct 2010 23:00:00 +0100 4088279 http://www.medworm.com/index.php?rid=4077022&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20943430%26dopt%3DAbstract Authors: de Boer PA Much of what we know about cytokinesis in bacteria has come from studies with Escherichia coli, and efforts to comprehensively understand this fundamental process in this organism continue to intensify. Major recent advances include in vitro assembly of a membrane-tethered version of FtsZ into contractile rings in lipid tubules, in vitro dynamic patterning of the Min proteins and a deeper understanding of how they direct assembly of the FtsZ-ring to midcell, the elucidation of structures, biochemical activities and interactions of other key components of the cell fission machinery, and the uncovering of additional components of this machinery with often redundant but important roles in invagination of the three cell envelope layers. PMID: 20943430 [PubMed - as s... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4077022 Sun, 10 Oct 2010 23:00:00 +0100 4077022 http://www.medworm.com/index.php?rid=4042589&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20920882%26dopt%3DAbstract Authors: Bush K Resistance to β-lactams and other antibiotics in the Enterobacteriaceae is frequently associated with plasmidic resistance determinants that are easily transferred among species. β-Lactamase-mediated resistance is increasingly associated with plasmid-encoded extended-spectrum β-lactamases (ESBLs) and carbapenemases, specifically the CTX-M family of ESBLs, the KPC family of serine carbapenemases, and the VIM, IMP, and NDM-1 metallo-β-lactamases. Although clonal dispersion of resistant isolates was seen initially, more diverse genetic platforms are being observed as variations of mobile elements are transferred worldwide. These enzymes are now appearing in multiple combinations of ESBLs and carbapenemases, thereby conferring resistance to virtually all β-lactam antib... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042589 Wed, 29 Sep 2010 23:00:00 +0100 4042589 http://www.medworm.com/index.php?rid=4042588&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20920883%26dopt%3DAbstract Authors: Stegmann E, Frasch HJ, Wohlleben W Using molecular genetics, biochemistry and organic chemistry the biosynthesis of glycopeptides has been elucidated in detail. It can be categorised in three parts: precursor supply, linking of the peptide backbone and modification reactions. The important steps of the biosynthesis are carried out at a multi-enzyme complex consisting of three non-ribosomal peptide synthetases (NRPS), three oxygenases and one halogenase. Novel derivatives can be generated by precursor-directed biosynthesis or combinatorial approaches and the knowledge can be used to optimise the yield of production by metabolic engineering approaches. To protect themselves glycopeptide producers seem to have developed strategies which may differ from those of the resistant path... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042588 Wed, 29 Sep 2010 23:00:00 +0100 4042588 http://www.medworm.com/index.php?rid=4042587&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20920884%26dopt%3DAbstract Authors: Peñalva MA Endocytosis has been the Cinderella of membrane trafficking studies in filamentous fungi until recent work involving genetically tractable models has boosted interest in the field. Endocytic internalization predominates in the hyphal tips, spatially coupled to secretion. Early endosomes (EEs) show characteristic long-distance motility, riding on microtubule motors. The fungal tip contains a region baptised the 'dynein loading zone' where acropetally moving endosomes reaching the tip shift from a kinesin to dynein, reversing the direction of their movement. Multivesicular body biogenesis starts from these motile EEs. Maturation of EEs into late endosomes and vacuoles appears to be essential. The similarities between fungal and mammalian endocytic trafficking suggest... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042587 Wed, 29 Sep 2010 23:00:00 +0100 4042587 http://www.medworm.com/index.php?rid=4042591&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20888287%26dopt%3DAbstract Authors: Llarrull LI, Testero SA, Fisher JF, Mobashery S In the 80 years since their discovery the β-lactam antibiotics have progressed through structural generations, each in response to the progressive evolution of bacterial resistance mechanisms. The generational progression was driven by the ingenious, but largely empirical, manipulation of structure by medicinal chemists. Nonetheless, the true creative force in these efforts was Nature, and as the discovery of new β-lactams from Nature has atrophied while at the same time multi-resistant and opportunistic bacterial pathogens have burgeoned, the time for empirical drug discovery has passed. We concisely summarize recent developments with respect to bacterial resistance, the identity of the new β-lactams, and the emerging non-emp... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042591 Tue, 28 Sep 2010 23:00:00 +0100 4042591 http://www.medworm.com/index.php?rid=4042590&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20888288%26dopt%3DAbstract Authors: Croucher NJ, Thomson NR Genome-wide studies of bacterial gene expression are shifting from microarray technology to second generation sequencing platforms. RNA-seq has a number of advantages over hybridization-based techniques, such as annotation-independent detection of transcription, improved sensitivity and increased dynamic range. Early studies have uncovered a wealth of novel coding sequences and non-coding RNA, and are revealing a transcriptional landscape that increasingly mirrors that of eukaryotes. Already basic RNA-seq protocols have been improved and adapted to looking at particular aspects of RNA biology, often with an emphasis on non-coding RNAs, and further refinements to current techniques will improve our understanding of gene expression, and genome content, in... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042590 Tue, 28 Sep 2010 23:00:00 +0100 4042590 http://www.medworm.com/index.php?rid=4042595&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20884279%26dopt%3DAbstract Authors: Basse CW Faithful inheritance of mitochondria is essential for growth and development. Uniparental inheritance of mitochondria is a common phenomenon in sexual eukaryotes and has been reported for numerous fungal species. Uniparental inheritance is a genetically regulated process, aimed to gain a homoplasmic state within cells, and this is often associated with selective elimination of one parental mitochondria population. This review will focus on recent developments in our understanding of common and specified regulatory circuits of selective mitochondrial inheritance during sexual development. It further refers to the influence of mitochondrial fusion on generation of recombinant mitochondrial DNA molecules. The latter aspect appears rather exciting in the context of intron... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042595 Mon, 27 Sep 2010 23:00:00 +0100 4042595 http://www.medworm.com/index.php?rid=4042594&cid=s_35494_77_f&fid=35494&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20884280%26dopt%3DAbstract Authors: Fey PD It is well accepted that bacterial pathogens growing in a biofilm are recalcitrant to the action of most antibiotics and are resistant to the innate immune system. New treatment modalities are greatly warranted to effectively eradicate these infections. However, bacteria growing in a biofilm are metabolically unique in comparison to the bacteria growing in a planktonic state. Unfortunately, most antibiotics have been developed to inhibit the growth of bacteria in a planktonic mode of growth. This review focuses on the metabolism and physiology of biofilm growth with special emphasis on staphylococci. Future treatment options should include targeting unique metabolic niches found within bacterial biofilms in addition to the enzymes or compounds that inhibit biofilm accum... Current Opinion in Microbiology journals http://www.medworm.com/rss/comments.php?id=4042594 Mon, 27 Sep 2010 23:00:00 +0100 4042594