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AR-C155858 is a potent inhibitor of monocarboxylate transporters MCT1 and MCT2 that binds to an intracellular site involving transmembrane helices 7-10Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper we characterise the properties of the potent MCT1 inhibitor, AR-C155858. Inhibitor titrations of L-lactate transport by MCT1 in rat erythrocytes were used to determine the Ki value and number of AR-C155858 binding sites (Et) on MCT1 and the transporter’s turnover number (Kcat). Derived values were 2.3 ± 1.4 nM, 1.29 ± 0.09 nmoles per ml packed cells and 12.2 ± 1.1 s-1 respectively. When expressed in Xenopus laevis oocytes MCT1 and MCT2 were potently inhibited by AR-C155858 whilst MCT4 was not. Inhibition of MCT1 was shown to be time-dependent, and the compound was also active when ...
Source: BJ Energy - November 20, 2009 Category: Biochemistry Authors: M J Ovens, A J Davies, M C Wilson, C M Murray, A P Halestrap Tags: BJ Energy Source Type: journals

Intermolecular cross-linking of monomers in H. pylori Na{+}/H{+} antiporter NhaA at dimer interface inhibits antiporter activityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We previously showed that the Na+/H+ antiporter of Helicobacter pylori (HPNhaA) forms an oligomer in a native membrane of Escherichia coli, and conformational changes of oligomer occur between monomers of the oligomer during ion transport. In the current study, we use Blue Native PAGE to show that HPNhaA forms a dimer. Cysteine-scanning mutagenesis of residues 55 to 61 in a putative β-sheet region of loop1 and subsequent functional analyses revealed that the Q58C mutation resulted in an intermolecular disulfide bond. G56C, I59C, and G60C were found to be cross-linked by bifunctional cross-linkers. Furt...
Source: BJ Energy - November 19, 2009 Category: Biochemistry Authors: A Karasawa, K Mitsui, M Matsushita, H Kanazawa Tags: BJ Energy Source Type: journals

Mitochondrial targeting of the electrophilic lipid 15-deoxy-{Delta}12,14-Prostaglandin J2 increases apoptotic efficacy via redox cell signaling mechanismsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Prototypical electrophiles such as the lipid 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) are well recognized for their therapeutic potential. Electrophiles modify signaling proteins in both the cytosol and mitochondrion which results in diverse cellular responses including cytoprotective effects and, at high doses, cell death. These findings led us to the hypothesis that targeting electrophiles to specific compartments in the cell can be used to fine-tune their biological effects. To examine this, we synthesized a novel mitochondrially-targeted analog of 15d-PGJ2 (mito-15d-PGJ2) and tested its effects on redox cell ...
Source: BJ Energy - November 16, 2009 Category: Biochemistry Authors: A R. Diers, A N. Higdon, K C. Ricart, M S. Johnson, A Agarwal, B Kalyanaraman, A Landar, V M. Darley-Usmar Tags: BJ Energy Source Type: journals

Characterization of the heme oxygenase protein family in Arabidopsis thaliana reveals a diversity of functionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Heme oxygenases (HOs) catalyze the oxidative cleavage of heme to biliverdin, iron and carbon monoxide. In plants, the product of the reaction is biliverdin IXα, the precursor of the phytochrome chromophore and is thus essential for proper photomorphogenesis. Arabidopsis thaliana contains one major biochemically characterized HO (HY1) and three additional putative HOs (HO2, HO3 and HO4). All four proteins are encoded in the nucleus but contain chloroplast translocation sequences at their N-termini. The transit peptides of all four proteins are sufficient for chloroplast translocalisation as shown by GFP reporter gene...
Source: BJ Energy - October 27, 2009 Category: Biochemistry Authors: B Gisk, Y Yasui, T Kohchi, N Frankenberg-Dinkel Tags: BJ Plant Source Type: journals

LYN-mediated mitochondrial tyrosine phosphorylation is required to preserve mitochondrial integrity in early liver regenerationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Functional alterations in mitochondria such as overproduction of reactive oxygen species and overloading of calcium, with subsequent change in the membrane potential, are traditionally regarded as pro-apoptotic conditions. Although such events occur in the early phases of liver regeneration after 2/3 partial hepatectomy, hepatocytes do not undergo apoptosis but continue to proliferate until the mass of the liver is restored. The aim of this study was to establish whether tyrosine phosphorylation, an emerging mechanism of regulation of mitochondrial function, participates in the response to liver injury following PH and is ...
Source: BJ Energy - October 15, 2009 Category: Biochemistry Authors: E Gringeri, A Carraro, E Tibaldi, F E D’Amico, M Mancon, A Toninello, M Angelo Pagano, C Vio, U Cillo, A Maria Brunati Tags: BJ Signal Source Type: journals

Structural and functional analysis of the intrinsic inhibitor subunit {epsilon} of F1-ATPase from photosynthetic organismsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ε subunit, a small subunit located in the F1 domain of ATP synthase and comprised of two distinct domains, an N-terminal β-sandwich structure and a C-terminal α-helical region, serves as an intrinsic inhibitor of ATP hydrolysis activity. This inhibitory function is especially important in photosynthetic organisms as the enzyme cannot synthesize ATP in the dark but may catalyze futile ATP hydrolysis reactions. To understand the structure-function relationship of this subunit in F1 from photosynthetic organisms, we solved the NMR structure of the ε subunit of ATP synthase obtained from thermop...
Source: BJ Energy - September 28, 2009 Category: Biochemistry Authors: H Yagi, H Konno, T Murakami-Fuse, A Isu, T Oroguchi, H Akutsu, M Ikeguchi, T Hisabori Tags: BJ Energy Source Type: journals

Uncoupling protein 1 inhibition by purine nucleotides is under control of the endogenous ubiquinone redox stateEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We studied free fatty acid-induced uncoupling of heterologously expressed rat UCP1 in yeast mitochondria as well as UCP1 in rat BAT mitochondria. The proton conductance curves and the relationship between ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sen...
Source: BJ Energy - September 10, 2009 Category: Biochemistry Authors: A Swida-Barteczka, A Woyda-Ploszczyca, F E. Sluse, W Jarmuszkiewicz Tags: BJ Energy Source Type: journals

Importance of the bioenergetic reserve capacity in response to cardiomyocyte stress induced by 4-hydroxynonenalEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Mitochondria play a critical role in mediating the cellular response to oxidants formed during acute and chronic cardiac dysfunction. It is widely assumed that, as cells are subject to stress, mitochondria are capable of drawing upon a “reserve capacity” which is available to serve the increased energy demands for maintenance of organ function, cellular repair, or detoxification of reactive species. This hypothesis further implies that impairment or depletion of this putative reserve capacity ultimately leads to excessive protein damage and cell death. However, it has been difficult to fully evaluate this hyp...
Source: BJ Energy - September 9, 2009 Category: Biochemistry Authors: B G Hill, B P Dranka, L Zou, J C Chatham, V Darley-Usmar Tags: BJ Energy Source Type: journals

A large-conductance calcium-activated potassium channel in potato tuber mitochondriaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the present study, we describe the existence of a novel potassium channel in the plant (potato tuber) mitochondrial inner membrane. We found that substances known to modulate large-conductance calcium-activated potassium channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 (a potassium channel opener) were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a potassium channel inhibitor) in a potassium-dependent manner. Additionally, the electrophysiological proper...
Source: BJ Energy - September 8, 2009 Category: Biochemistry Authors: I Koszela-Piotrowska, K Matkovic, A Szewczyk, W Jarmuszkiewicz Tags: BJ Energy Source Type: journals

The nadph oxidase nox4 restricts the replicative lifespan of human endothelial cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The free radical theory of ageing proposes that reactive oxygen species (ROS) are major driving forces of ageing, and are also critically involved in cellular senescence. Besides the mitochondrial respiratory chain, alternative sources of ROS have been described, which might contribute to cellular senescence. NADPH oxidases are well-known sources of superoxide, which contribute to the antimicrobial capabilities of macrophages, a process involving the prototypical member of the family referred to as Nox2. However, in the recent years non-phagocytic homologues of Nox2 have been identified, which are involved in processes oth...
Source: BJ Energy - August 13, 2009 Category: Biochemistry Authors: B Lener, R Koziel, H Pircher, E Hütter, R Greussing, D Herndler-Brandstetter, M Hermann, H Unterluggauer, P Jansen-Durr Tags: BJ Cell Source Type: journals

Nitric oxide stimulates myoglobin gene and protein expression in vascular smooth muscleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Myoglobin (Mb) is a haemoprotein present in cardiac, skeletal and smooth muscle and is primarily responsible for the storage and “facilitated transfer” of molecular oxygen from the cell membrane to mitochondria. Also, Mb plays a role in regulating nitric oxide (•NO) homeostasis through (i) binding •NO (Mb-NO complex), (ii) oxidation of •NO to nitrate, and (iii) formation of vasoactive S-nitroso-Mb [Rayner BS, Wu B-J, Raftery M, Stocker R, Witting PK. J. Biol. Chem. 2005;280, 9985-9993]. Pathological •NO concentrations affect mitochondrial function and decrease cell viability throug...
Source: BJ Energy - August 3, 2009 Category: Biochemistry Authors: B S. Rayner, S Hua, T Sabaretnam, P K. Witting Tags: BJ Cell Source Type: journals

Nitration of tyrosine 368 and 345 in {beta}-subunit elicits FoF1ATPase activity lossEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we determined the effect of nitration of Tyr345 and Tyr368 in β-subunit of the F1-ATPase using site-directed mutagenesis. Nitration of β-subunit, achieved by using tetranitromethane (TNM), resulted in 66% ATPase activity loss. This treatment resulted in the modification of several Asn, Met, and Tyr. However, nitrated Tyr and ATPase inactivation were decreased in reconstituted F1 with Y368F (54%), Y345F (28%) and Y345,368F (1%) β-subunits indicating a clear link between nitration at these positions and activity loss, regardless of the presence of other modifications. Kinetic studies indic...
Source: BJ Energy - August 3, 2009 Category: Biochemistry Authors: Y Fujisawa, K Kato, C Giulivi Tags: BJ Energy Source Type: journals

Origin of pyrimidine deoxyribonucleotide pools in perfused rat heartEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we used isotopic tracing to demonstrate that both TTP and dCTP are solely synthesized by phosphorylation of thymidine and deoxycytidine, respectively, with no evidence for synthesis from other precursors. We also showed that UTP and CTP are synthesized by phosphorylation of uridine and cytidine, respectively, with no detectable role for the de novo pyrimidine synthesis pathway. Lastly, we demonstrated that AZT decreased the TTP pool by 50% in 30 min of perfusion while having no effect on other dNTPs. In summary, this work demonstrated that adult rat heart has a limited mechanism for dCTP and TTP synthesis an...
Source: BJ Energy - June 25, 2009 Category: Biochemistry Authors: G W. Morris, T A. Iams, K G. Slepchenko, E E. McKee Tags: BJ Cell Source Type: journals

The steady state mechanism of cytochrome c oxidase: redox interactions between metal centresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a model where small anti-cooperative redox interactions occur between haem a-CuA-CuB (steady state potential ranges: CuA 212-258 mV; haem a: 254-281 mV; CuB 227- 272 mV). Contrary to static equilibrium measurements, in the catalytic steady state there are no high potential redox centres (> 300 mV). We find that the overall reaction is correctly described by the classical model in which the Michaelis intermediate is a ferrocytochrome c – enzyme complex. However, the oxidation of ferrocytochrome c in this complex is not the sole rate-determining step. Turnover is instead dependent upon electron transfer ...
Source: BJ Energy - June 16, 2009 Category: Biochemistry Authors: M G Mason, P Nicholls, C E Cooper Tags: BJ Energy Source Type: journals

Rescue of anemia and autoimmune responses in SOD1-deficient mice by transgenic expression of human SOD1 in erythrocytesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Oxidative stress has been implicated as a cause of various diseases such as anemia. We found that Cu,Zn-superoxide dismutase gene (SOD1)-deficiency causes anemia, and the production of autoantibodies against red blood cells (RBCs) and renal damage. In the present study, to further understand the role of oxidative stress in the autoimmune response triggered by SOD1 deficiency, we generated mice that had the human SOD1 (hSOD1) transgene under regulation of the GATA-1 promoter, and bred the transgene onto the SOD1−/− background (SOD1−/−;hSOD1tg/+). The lifespan of RBCs, levels of intracellul...
Source: BJ Energy - June 9, 2009 Category: Biochemistry Authors: Y Iuchi, F Okada, R Takamiya, N Kibe, S Tsunoda, O Nakajima, K Toyoda, R Nagae, M Suematsu, T Soga, K Uchida, J Fujii Tags: BJ Metabolism Source Type: journals

Acetylated tubulin associates with the fifth cytoplasmic domain of Na{+},K{+}-ATPase: possible anchorage site of microtubules to the plasma membraneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We showed previously that Na+,K+-ATPase interacts with acetylated tubulin resulting in inhibition of its catalytic activity. In the present work we determined that membrane acetylated tubulin, in the presence of detergent, behaves as an entity of discrete molecular weight (320-400 kDa) during molecular chromatography. We also found that microtubules assembled in vitro are able to bind Na+,K+-ATPase when incubated with a detergent-solubilized membrane preparation, and that isolated native microtubules have associated Na+,K+-ATPase. Furthermore, we determined that the fifth cytoplasm...
Source: BJ Energy - May 29, 2009 Category: Biochemistry Authors: G Gastón Zampar, M Eugenia Chesta, A Carbajal, N Luján Chanaday, N Maximiliano Díaz, C H Casale, C A Arce Tags: BJ Cell Source Type: journals

The respiratory complexes I from the mitochondria of two Pichia speciesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
NADH:ubiquinone oxidoreductase (complex I) is an entry point for electrons into the respiratory chain in many eukaryotes. It couples NADH oxidation and ubiquinone reduction to proton translocation across the mitochondrial inner membrane. Because complex I deficiencies occur in a wide range of neuromuscular diseases, including Parkinson’s disease, there is a clear need for model eukaryotic systems to facilitate structural, functional and mutational studies. Here, we describe the purification and characterization of the complexes I from two yeast species, Pichia pastoris and Pichia angusta. They are obligate aerobes w...
Source: BJ Energy - May 22, 2009 Category: Biochemistry Authors: H R Bridges, L Grgic, M E Harbour, J Hirst Tags: BJ BJ Energy Source Type: journals

Thioesterase superfamily member 2 (Them2)/acyl-CoA thioesterase 13 (Acot13): A homotetrameric hotdog fold thioesterase with selectivity for long chain fatty acyl-CoAsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Thioesterase superfamily member 2 (Them2) is a 140 aa protein of unknown biological function that comprises a single hotdog fold thioesterase domain. Based on its putative association with mitochondria, accentuated expression in oxidative tissues and interaction with StarD2, a regulator of fatty acid metabolism, we explored whether Them2 functions as a physiologically relevant fatty acyl-CoA thioesterase. In solution, Them2 formed a stable homotetramer, which denatured in a single transition at 59.3 °C. Them2 exhibited thioesterase activity for medium- and long-chain acyl-CoAs, with KM values that decreased exponent...
Source: BJ Energy - April 30, 2009 Category: Biochemistry Authors: J Wei, H Kang, D E. Cohen Tags: BJ BJ Energy Source Type: journals

Dynamic aspects of ascorbic acid metabolism in the circulation: Analysis by ascorbate oxidase with prolonged in vivo half-lifeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Because L-ascorbic acid (AA) scavenges various types of free radicals to form monodehydroascorbic acid (MDAA) and dehydroascorbic acid (DAA), its regeneration from the oxidized metabolites is critically important for humans and other animals that lack the ability to synthesize this antioxidant. To study the dynamic aspects of AA metabolism in the circulation, a long acting ascorbate oxidase (AOase) derivative was synthesized by covalently linking 2,4-bis[o-methoxy(polyethyleneglycol)]–6–chloro –S-triazine (PEG) to the enzyme. Fairly low concentrations of the modified enzyme (PEG-AOase) rapidly decrease...
Source: BJ Energy - April 23, 2009 Category: Biochemistry Authors: E Kasahara, M Kashiba, M Jikumaru, D Kuratsune, K Orita, Y Yamate, K Hara, A Sekiyama, E F Sato, M Inoue Tags: BJ Energy Source Type: journals

Inhibition of myeloperoxidase-mediated hypochlorous acid production by nitroxidesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Tissue damage resulting from the extracellular production of hypochlorous acid (HOCl) by the myeloperoxidase (MPO)-hydrogen peroxide-chloride system of activated phagocytes is implicated as a key event in the progression of a number of human inflammatory diseases. Consequently, there is considerable interest in the development of therapeutically-useful MPO inhibitors. Nitroxides are well-established antioxidant compounds of low toxicity that can attenuate oxidative damage in animal models of inflammatory disease. They are believed to exert protective effects principally by acting as superoxide dismutase-mimetics or radical...
Source: BJ Energy - April 20, 2009 Category: Biochemistry Authors: M D. Rees, S E. Bottle, K E. Fairfull-Smith, E Malle, J M. Whitelock, M J. Davies Tags: BJ Disease Source Type: journals

Mitochondrial peroxiredoxin 3 is more resilient to hyperoxidation than cytoplasmic peroxiredoxinsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, western blot methodology was developed to quantify hyperoxidation of individual 2-Cys Prxs in cells. It revealed that Prx 1 and 2 were hyperoxidised at lower doses of hydrogen peroxide than would be predicted from in vitro data, suggesting intracellular factors that promote hyperoxidation. In contrast, mitochondrial Prx 3 was considerably more resistant to hyperoxidation. The concentration of Prx 3 was estimated at 125 µM in the mitochondrial matrix of Jurkat T-lymphoma cells. While the local cellular environment could influence susceptibility, purified Prx 3 was also more resistant to hyperoxidation,...
Source: BJ Energy - April 8, 2009 Category: Biochemistry Authors: A G Cox, A G Pearson, J M Pullar, T J Jönsson, W Lowther, C Winterbourn, M B Hampton Tags: BJ Energy Source Type: journals

Role of nuclear encoded subunit Vb in the assembly and stability of cytochrome c oxidase complex: implications in mitochondrial dysfunction and ROS productionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cytochrome c Oxidase (CcO) is a multisubunit bigenomic protein complex which catalyzes the last step of the mitochondrial electron transport chain. The nuclear encoded subunits are thought to have roles either in the regulation or in the structural stability of the enzyme. Subunit Vb is a peripheral nuclear-encoded subunit of mammalian CcO that is dramatically reduced under hypoxia. Although subunit Vb contains different ligand binding sites and undergoes phosphorylation, its precise function remains unknown. In the present study we generated a cell line from RAW 264.7 murine macrophages, that contains 80% reduced subunit ...
Source: BJ Energy - April 1, 2009 Category: Biochemistry Authors: D Galati, S Srinivasan, H Raza, S K Prabu, M Hardy, K Chandran, M Lopez, B Kalyanaraman, N G. Avadhani Tags: BJ Energy Source Type: journals

Modulation of hepatic malonyl-CoA/carnitine palmitoyltransferase 1A partnership creates a metabolic switch allowing oxidation of de novo fatty acidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, this study highlights that CPT1A is a prime target to increase hepatic LCFA ß-oxidation and that acting directly on the degree of its malonyl-CoA sensitivity may be a relevant strategy to prevent and/or correct hepatic steatosis. (Source: BJ Energy)
Source: BJ Energy - March 20, 2009 Category: Biochemistry Authors: M Akkaoui, I Cohen, C Esnous, V Lenoir, M Sournac, J Girard, C Prip-Buus Tags: BJ Energy Source Type: journals

Hemolytic anemia and alterations in hepatic iron metabolism in aged mice lacking Cu,Zn-superoxide dismutaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The continuous recycling of heme iron following phagocytosis and catabolism of senescent and damaged red blood cells by macrophages is a crucial process in the maintenance of systemic iron homeostasis. However, little is known about macrophage iron handling in hemolytic states resulting from a deficiency in antioxidant defenses. Our observations indicate that recently described [Iuchi Y, Okada F, Onuma K, Onoda T, Asao H, Kobayashi M, Fuji J. Biochem. J. (2007) 402, 219-227] the chronic but moderate regenerative hemolytic anemia of old superoxide dismutase 1 (SOD1) knockout mice is associated with red blood cells modificat...
Source: BJ Energy - March 18, 2009 Category: Biochemistry Authors: R Radoslaw Starzyński, F Canonne-Hergaux, A Willemetz, M Antoni Gralak, J Woliński, A Styś, J Olszak, P Lipiński Tags: BJ Disease Source Type: journals

Functional characterization of the early steps of tetrapyrrole biosynthesis and modification in Desulfovibrio vulgaris HildenboroughEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The biosynthesis of the tetrapyrrole framework has been investigated in the sulphate reducing bacterium Desulfovibrio vulgaris Hildenborough by characterization of the enzymes required for the transformation of 5-aminolevulinic acid into sirohydrochlorin. Porphobilinogen synthase (HemB) was found to be a zinc-dependent enzyme that exists in its native state as a homohexamer. Porphobilinogen deaminase (HemC) was shown to contain the dipyrromethane cofactor. Uroporphyrinogen III synthase is found fused with a uroporphyrinogen III methyltransferase (HemD-CobA). Both activities could be demonstrated in this amalgamated protein...
Source: BJ Energy - March 6, 2009 Category: Biochemistry Authors: S A. L. Lobo, A Brindley, M J. Warren, L M. Saraiva Tags: BJ Energy Source Type: journals

Dual roles of Lys57 at the dimer interface of human mitochondrial NAD(P){+}-dependent malic enzymeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Human mitochondrial NAD(P)+-dependent malic enzyme (m-NAD(P)-ME) is a homotetramer, which is allosterically activated by the binding of fumarate. The fumarate binding site is located at the dimer interface of the NAD(P)-ME. In this paper, we decipher the functional role of the residue Lys57, which resides at the fumarate binding site and dimer interface and thus may be involved in the allosteric regulation and subunit-subunit interaction of the enzyme. In the present study, Lys57 is replaced with Ala, Cys, Ser and Arg. Site-directed mutagenesis and kinetic analysis strongly suggest that Lys57 (K57) is important for ...
Source: BJ Energy - February 24, 2009 Category: Biochemistry Authors: J Hsieh, J Liu, Y Fang, H Hung Tags: BJ Structure Source Type: journals

In vivo regulatory phosphorylation of the phosphoenolpyruvate carboxylase AtPPC1 in phosphate-starved Arabidopsis thalianaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled cytosolic enzyme situated at a major branchpoint in plant metabolism. Accumulating evidence indicates important functions for PEPC and PEPC protein kinase (PPCK) in plant acclimation to nutritional Pi deprivation. However, little is known about the genetic origin or phosphorylation status of native PEPCs from Pi-deficient (–Pi) plants. Transfer of Arabidopsis suspension cells or seedlings to –Pi growth media resulted in: (i) the marked transcriptional upregulation of genes encoding the PEPC isozyme AtPPC1, and PPCK isozymes AtPPCK1 and AtPPCK2, (i...
Source: BJ Energy - February 19, 2009 Category: Biochemistry Authors: A L. Gregory, B A. Hurley, H T. Tran, A J. Valentine, Y She, V L. Knowles, W C Plaxton Tags: BJ Plant Source Type: journals

Cholesteryl ester transfer protein (CETP) increases postprandial triglyceridemia and delays triglyceride plasma clearance in transgenic mice.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The cholesteryl ester transfer protein (CETP) is a plasma protein synthesized in several tissues, mainly liver, which reduces plasma HDL-cholesterol and increases the risk of atherosclerosis. The effect of CETP levels on postprandial intravascular metabolism of triglycerides (TG) is an often-overlooked aspect of the relationship between CETP and lipoprotein metabolism. Here, we tested the hypothesis that CETP delays the plasma clearance of TG rich lipoprotein by comparing human CETP expressing transgenic (Tg) and non-transgenic (Non-Tg) mice. After an oral fat load, the postprandial triglyceridemia curve was markedly incre...
Source: BJ Energy - February 4, 2009 Category: Biochemistry Authors: A G Salerno, P R Patrício, J A Berti, H C F Oliveira Tags: BJ Disease Source Type: journals

Branched-chain 2-oxoacids transamination increases {"}GABA-shunt{"} metabolism and insulin secretion in isolated isletsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion: 1. The transamination of branched-chain 2-oxoacids is more important to the stimulation of insulin secretion than their catabolism. 2. Transamination decreases islet GABA concentrations by promoting GABA metabolism. 3. Inhibition of 2-oxoglutarate dehydrogenase by branched-chain 2-oxoacids may increase metabolic flux in the “GABA-shunt” at the expense of reduced TCA cycle flux. (Source: BJ Energy)
Source: BJ Energy - January 28, 2009 Category: Biochemistry Authors: J Pizarro-Delgado, I Hernández-Fisac, R Martín-del-Río, J Tamarit-Rodriguez Tags: BJ Cell Source Type: journals

The permissive role of mitochondria in the induction of heme oxygenase-1 in endothelial cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Heme oxygenase 1 (HO-1) is an essential antioxidant enzyme in the cell that exerts its effects through removal of pro-oxidant heme groups and the formation of antioxidant molecules and carbon monoxide. Decreased HO-1 in the vasculature is associated with increased development of atherosclerosis and also leads to extensive damage to the mitochondrion. These findings have led us to the hypothesis that mitochondria may play an important role in induction of HO-1 in endothelial cells. To investigate this, the effects of mitochondrial parameters such as membrane potential, protein thiols, and reactive oxygen species formation o...
Source: BJ Energy - January 23, 2009 Category: Biochemistry Authors: K C. Ricart, S Bolisetty, M S. Johnson, J Perez, A Agarwal, M P Murphy, A Landar Tags: BJ Signal Source Type: journals

Cytochrome P450 oxidoreductase participates in nitric oxide consumption by rat brainEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In low nanomolar concentrations, nitric oxide (NO) functions as a transmitter in brain and other tissues whereas near-micromolar NO concentrations are associated with toxicity and cell death. Control of the NO concentration, therefore, is critical for proper brain function but, while its synthesis pathway is well-characterised, the major route of breakdown of NO in brain is unclear. Previous observations indicate that brain cells actively consume NO at a high rate. The mechanism of this consumption was pursued in the present study. NO consumption by a preparation of central glial cells was abolished by cell lysis and recov...
Source: BJ Energy - January 20, 2009 Category: Biochemistry Authors: C N. Hall, R G. Keynes, J Garthwaite Tags: BJ Cell Source Type: journals

Crystal structure of rat heme oxygenase-1 in complex with ferrous verdoheme: presence of a hydrogen bond network on the distal sideEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Heme oxygenase (HO) catalyses the degradation of heme to biliverdin, CO and ferrous iron via three successive oxygenation reactions, i.e. heme to α-hydroxyheme, α-hydroxyheme to α-verdoheme, and α-verdoheme to ferric biliverdin-iron chelate. Here, we determined the crystal structure of ferrous α-verdoheme-rat HO-1 complex at 2.2 Å resolution. The overall structure of the verdoheme complex was similar to that of the heme complex. H2O or OH- was coordinated to the verdoheme iron as a distal ligand. A hydrogen bond network consisting of water molecules and several amino acid residues ...
Source: BJ Energy - January 20, 2009 Category: Biochemistry Authors: H Sato, M Sugishima, H Sakamoto, Y Higashimoto, C Shimokawa, K Fukuyama, G Palmer, M Noguchi Tags: BJ Structure Source Type: journals

Etomoxir-induced partial CPT-I inhibition in vivo does not alter cardiac long-chain fatty acid uptake and oxidation ratesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although carnitine palmitoyltransferase-I (CPT-I) is generally regarded to present a major rate-controlling site in mitochondrial β-oxidation, it is incompletely understood whether CPT-I is rate-limiting in the overall long-chain fatty acid (LCFA) flux in the heart. Another important site of regulation of the LCFA flux in the heart is trans-sarcolemmal LCFA transport facilitated by CD36 and FABPpm. Therefore, we explored to what extent a chronic pharmacological blockade of the LCFA flux at the level of mitochondrial entry of LCFA-CoA would affect sarcolemmal LCFA uptake. Rats were injected daily with saline or etomo...
Source: BJ Energy - January 13, 2009 Category: Biochemistry Authors: J J.F.P. Luiken, H E.C. Niessen, S L.M. Coort, N Hoebers, W A. Coumans, R W. Schwenk, A Bonen, J F.C. Glatz Tags: BJ Energy Source Type: journals

Peroxiredoxin 5 confers protection against oxidative stress and apoptosis and also promotes longevity in DrosophilaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Peroxiredoxin 5 (Prx5) is a distinct isoform of the peroxiredoxin gene family. The antioxidative and anti-apoptotic functions of Prx5 have been extensively demonstrated in cell culture experiments. Here, we provide the first functional analysis of Prx5 in a multi-cellular organism, Drosophila melanogaster. Like its mammalian, yeast or human counterparts, Drosophila peroxiredoxin 5 (dPrx5) is expressed in several cellular compartments, including cytosol, nucleus and the mitochondrion. Global over-expression of dPrx5 in flies increased resistance to oxidative stress and extended their life span by up to 30% under normal cond...
Source: BJ Energy - January 7, 2009 Category: Biochemistry Authors: S N. Radyuk, K Michalak, V I. Klichko, J Benes, I Rebrin, R S Sohal, W C. Orr Tags: BJ Gene Source Type: journals

Variant c-type cytochromes as probes of the substrate specificity of the E. coli cytochrome c maturation (Ccm) apparatusEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
c-type cytochromes are normally characterised by covalent attachment of the iron cofactor heme to protein through two thioether bonds between the vinyl groups of heme and the thiols of a Cys-Xxx-Xxx-Cys-His motif. Heme attachment is an enzyme catalysed, post-translational modification. We have previously shown that co-expression of a variant of Escherichia coli cytochrome b562 containing a CXXCH heme-binding motif with the E. coli cytochrome c maturation (Ccm) proteins resulted in homogeneous maturation of a correctly formed c-type cytochrome. In contrast, without the Ccm apparatus, the product holocytochrome was heterogen...
Source: BJ Energy - December 17, 2008 Category: Biochemistry Authors: J W. A. Allen, E B Sawyer, M Ginger, P D Barker, S J Ferguson Tags: BJ Structure Source Type: journals

A region N-terminal to the tandem SH3 domain of p47phox plays a crucial role in activation of the phagocyte NADPH oxidaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The superoxide-producing NADPH oxidase in phagocytes is crucial for host defence; its catalytic core is the membrane-integrated protein gp91phox (a.k.a. Nox2), which forms a stable heterodimer with p22phox. Activation of the oxidase requires membrane translocation of the three cytosolic proteins p47phox, p67phox, and the small GTPase Rac. At the membrane, these proteins assemble with the gp91phox–p22phox heterodimer and induce a conformational change of gp91phox, leading to superoxide production. p47phox translocates to membranes using its tandemly-arranged two SH3 domains, which directly interact with p22phox, wher...
Source: BJ Energy - December 17, 2008 Category: Biochemistry Authors: M Taura, K Miyano, R Minakami, S Kamakura, R Takeya, H Sumimoto Tags: BJ Signal Source Type: journals

Mitochondrial calcium overload triggers complement-dependent superoxide-mediated programmed cell death in Trypanosoma cruziEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The epimastigote stage of Trypanosoma cruzi undergoes programmed cell death (PCD) when exposed to fresh human serum (FHS). Although it has been known for over 30 years that complement is responsible for FHS-induced death, the link between complement activation and triggering of PCD has not been established. We have previously shown that mitochondrion participates in the orchestration of PCD in this model. Several changes in mitochondrial function were described, and in particular it was shown that mitochondrion-derived superoxide (O2•-) is necessary for PCD. In the present work, we established mitochondrial Ca2+ ove...
Source: BJ Energy - December 3, 2008 Category: Biochemistry Authors: F Irigoín, N M. Inada, M P. Fernandes, L Piacenza, F R. Gadelha, A E. Vercesi, R Radi Tags: BJ Cell Source Type: journals

Isoform-specific differences in the nitrite reductase activity of nitric oxide synthases under hypoxiaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nitrite (NO2-) recycling to nitric oxide (NO) is catalyzed by a number of enzymes and induces a protective vasodilatory effect under hypoxia/ ischemia. In the present work, we tested the in vitro ability of the three NOS isoforms to release NO from nitrite under anoxia using electrochemical detection, chemiluminescence and absorption spectroscopy. The release of free NO from anoxic nitrite solutions at 15µM was specific to the endothelial isoform eNOS and did not occur with neuronal nNOS and inducible iNOS. Unlike xanthine oxidase, eNOS reductase domain did not recycle nitrite to NO and WT eNOS did not reduce nitrat...
Source: BJ Energy - December 1, 2008 Category: Biochemistry Authors: I Mikula, S Durocher, P Martasek, B Mutus, A Slama-Schwok Tags: BJ Structure Source Type: journals

An essential role for the Glut1 PDZ-binding motif in growth factor regulation of Glut1 degradation and traffickingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cell surface localization of the glucose transporter, Glut1, is a cytokine-controlled process essential to support the metabolism and survival of hematopoietic cells. Molecular mechanisms that regulate Glut1 trafficking, however, are not certain. Here we show a C-terminal PDZ-binding motif in Glut1 is critical to promote maximal cytokine-stimulated Glut1 cell surface localization and prevent Glut1 lysosomal degradation in the absence of growth factor. Disruption of this PDZ-binding sequence through deletion or point mutation sharply decreased surface Glut1 levels and led to rapid targeting of internalized Glut1 to lysosome...
Source: BJ Energy - November 19, 2008 Category: Biochemistry Authors: H L Wieman, S R Horn, S R Jacobs, B J Altman, S Kornbluth, J C Rathmell Tags: BJ Cell Source Type: journals

Intracellular catalase-peroxidase from the phytopathogenic fungus Magnaporthe grisea: expression analysis and biochemical characterization of the recombinant proteinEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phytopathogenic fungi like Magnaporthe grisea are unique in having two catalase-peroxidase (KatG) paralogs located either intracellularly (KatG1) or extracellularly (KatG2). The coding genes have recently been shown to derive from a lateral gene transfer from a (proteo)bacterial genome followed by gene duplication and diversification. Here we demonstrate that Magnaporthe grisea KatG1 is expressed constitutively in rice blast fungus. It is the first eukaryotic catalase-peroxidase to be expressed heterologously in E. coli in high amount and purity with almost 100% haem occupancy. Recombinant MagKatG1 is an acidic, mainly hom...
Source: BJ Energy - November 10, 2008 Category: Biochemistry Authors: M Zamocky, P G. Furtmüller, M Bellei, G Battistuzzi, J Stadlmann, J Vlasits, C Obinger Tags: BJ Gene Source Type: journals

Biochemical characterization and mutational analysis of the mononuclear non-heme Fe2+ site in Dke1, a Cupin-type dioxygenase from Acinetobacter johnsoniiEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
β-Diketone-cleaving enzyme Dke1 is a homotetrameric Fe2+-dependent dioxygenase from Acinetobacter johnsonii. The Dke1 protomer adopts a single-domain β-barrel fold characteristic of the Cupin superfamily of proteins and features a mononuclear non-heme Fe2+ centre where a triad of histidines, His-62, His-64, and His-104, coordinate the catalytic metal. To provide structure-function relationships for the peculiar metal site of Dke1 in relation to the more widespread 2-His-1-Glu/Asp binding site for non-heme Fe2+, we replaced each histidine individually by Glu and Asn and compared binding of Fe2+ and four non-na...
Source: BJ Energy - October 30, 2008 Category: Biochemistry Authors: S Leitgeb, G D Straganz, B Nidetzky Tags: BJ Structure Source Type: journals

Inhibition of energy-producing pathways of HepG2 cells by 3-bromopyruvateEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study it is reported that incubation of HepG2 cells with a low concentration of 3-BrPA for a short period (150 µM for 30 minutes) significantly affected both glycolysis and mitochondrial respiratory functions. The activity of mitochondrial hexokinase was not inhibited by 150 µM 3-BrPA, but this concentration caused more than 70% inhibition of glyceraldehyde 3-phosphate dehydrogenase and 3-phosphoglycerate kinase activities. Additionally, 3-BrPA treatment significantly impaired lactate production by HepG2 cells, even when glucose was withdrawn from the incubation medium. Oxygen consumption of HepG2 ...
Source: BJ Energy - October 22, 2008 Category: Biochemistry Authors: A Pereira da Silva, T El-Bacha, N Kyaw, R Sousa dos Santos, W Seixas da-Silva, F C.L. Almeida, A T Da Poian, A Galina Tags: BJ Energy Source Type: journals

Reactivity of nitric oxide with the [4Fe-4S] cluster of dihydroxyacid dehydratase from Escherichia coliEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although the nitric oxide (NO)-mediated modification of iron-sulfur proteins has been well documented in bacteria and mammalian cells, specific reactivity of NO with iron-sulfur proteins still remains elusive. Here, we report the first kinetic characterization of the reaction between NO and iron-sulfur clusters in protein using the Escherichia coli dihydroxyacid dehydratase (IlvD) [4Fe-4S] cluster as an example. Combining a sensitive NO electrode with the electron paramagnetic resonance (EPR) spectroscopy and the enzyme activity assay, we demonstrate that NO is rapidly consumed by the IlvD [4Fe-4S] cluster with the concomi...
Source: BJ Energy - October 22, 2008 Category: Biochemistry Authors: X Duan, J Yang, B Ren, G Tan, H Ding Tags: BJ Energy Source Type: journals

New insights into the role of Fur proteins: FurB (All2473) from Anabaena protects DNA and increases cell survival under oxidative stressEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ferric uptake regulator (Fur) is a prokaryotic transcriptional regulator that controls a large number of genes mainly related to iron metabolism. Frequently, several Fur homologues with different physiological roles are found in the same organism. The genome of the filamentous cyanobacterium Anabaena (Nostoc) sp. PCC 7120 codes for three different fur genes. FurA is an essential protein involved in iron homeostasis that also modulates dinitrogen fixation. FurA interacts with heme, impairing its DNA-binding ability. To explore functional differences between Fur homologues in Anabaena, factors affecting their regulation,...
Source: BJ Energy - October 22, 2008 Category: Biochemistry Authors: S López-Gomollón, E Sevilla, M Teresa Bes, M Luisa Peleato, M F Fillat Tags: BJ Gene Source Type: journals

Characterization of SCaMC-3-Like/slc25a41 a novel calcium-independent mitochondrial ATP-Mg/Pi carrierEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The SCaMCs constitute a subfamily of mitochondrial carriers responsible of the ATP-Mg/Pi exchange with at least three paralogues in vertebrates. SCaMCs members are proteins with two functional domains the C-terminal transporter domain and the N-terminal one which harbours Ca2+-binding EF-hands and facing the intermembrane space. Here, we have characterised a shortened fourth paralog, SCaMC-3-Like (also named as Slc25a41), which lacks the Ca2+-binding N-extension. SCaMC-3-Like orthologues are found exclusively in mammals showing around 60% identity to the carboxyl-half of SCaMC-3, its closest paralog. In mammalian genomes, ...
Source: BJ Energy - October 17, 2008 Category: Biochemistry Authors: J Traba, J Satrústegui, A del Arco Tags: BJ Gene Source Type: journals

Characterization of a phenylacetate-CoA ligase from Penicillium chrysogenumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Enzymatic activation of phenylacetic acid (PAA) to phenylacetyl-CoA is an important step in the biosynthesis of the β-lactam antibiotic penicillin G by the fungus Penicillium chrysogenum. CoA esters of PAA and phenoxyacetic acid (POA) act as acyl donor in the exchange of the aminoadipyl side chain of isopenicillin N to produce penicillin G or penicillin V. The phl gene, encoding a phenylacetate-CoA ligase, was cloned in Escherichia coli as a maltose binding protein fusion and the biochemical properties of the enzyme were characterized. The recombinant fusion protein converted PAA to phenylacetyl-CoA in an ATP- and m...
Source: BJ Energy - October 6, 2008 Category: Biochemistry Authors: M J. Koetsier, P A. Jekel, M A. van den Berg, R A. L. Bovenberg, D B. Janssen Tags: BJ Structure Source Type: journals

The copper-responsive repressor CopR of Lactococcus lactis is a 'winged helix' proteinEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
CopR of Lactococcus lactis is a copper-responsive repressor involved in copper homeostasis. It controls the expression of a total of eleven genes, the CopR regulon, in a copper-dependent manner. In the absence of copper, CopR binds to the promoters of the CopR regulon. Copper releases CopR from the promoters, allowing transcription of the downstream genes to proceed. CopR binds through its N terminal domain to a 'cop box' of consensus TACAxxTGTA, which is conserved in Firmicutes. We here solved the NMR solution structure of the N-terminal DNA binding domain of CopR. The protein fold has a winged helix structure resembling ...
Source: BJ Energy - October 6, 2008 Category: Biochemistry Authors: F Cantini, L Banci, M Solioz Tags: BJ Structure Source Type: journals

Glucose induces an autocrine activation of the Wnt/{beta}-catenin pathway in macrophage cell linesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The canonical Wnt signaling pathway acts by slowing the rate of ubiquitin mediated β-catenin degradation. This results in the accumulation and subsequent nuclear translocation of β-catenin, which induces expression of a number of genes involved in growth, differentiation and metabolism. The mechanisms regulating the Wnt signaling pathway in physiological contexts are still not fully understood. Here we provide evidence that changes in glucose levels within the physiological range can acutely regulate the levels of β-catenin in two macrophages cell lines (J774.2 and RAW264 cells). In particular we find ...
Source: BJ Energy - September 30, 2008 Category: Biochemistry Authors: S H Anagnostou, P R Shepherd Tags: BJ Signal Source Type: journals

Characterisation of cytochrome bo3 activity in a native-like surface-tethered membraneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have developed a simple native-like surface-tethered membrane system to investigate the activity of cytochrome bo3 (cbo3), a terminal oxidase in Escherichia coli. The tethered membranes consist of E. coli inner membrane extracts mixed with additional E. coli lipids containing various amounts of the cbo3 substrate ubiquinol-10 (UQ-10). Tethered membranes are formed by self assembly from vesicles onto gold electrodes functionalised with cholesterol derivatives. Cytochrome bo3 activity was monitored using cyclic voltammetry with electron transfer to cbo3 mediated by UQ-10. The apparent KM for oxygen with this system is 1.1...
Source: BJ Energy - September 26, 2008 Category: Biochemistry Authors: S A. Weiss, R J Bushby, S D. Evans, P Henderson, L J C Jeuken Tags: BJ Energy Source Type: journals

Functional analysis of rat liver citrate carrier promoter: differential responsiveness to polyunsaturated fatty acidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study provides evidence for SREBP-1c as a principal target for PUFA regulation of CiC transcription. In H4IIE cells overexpression of nSREBP-1c overrides arachidonic acid (C20:4, n-6) suppression but does not prevent the repression by docosahexaenoic acid (C22:6, n-3). ChIP assay in H4IIE cells showed that docosahexaenoic acid affects the binding of NF-Y, Sp1 and SREBP-1 to PUFA response region of CiC promoter whereas arachidonic acid alters only the binding of SREBP-1. Our data show that PUFA inhibition of hepatic Cic gene transcription is mediated not only by the nuclear level of SREBP-1c, but also might involve a ...
Source: BJ Energy - September 16, 2008 Category: Biochemistry Authors: F Damiano, G V Gnoni, L Siculella Tags: BJ Gene Source Type: journals