Circulating blood and platelets supply glycosyltransferases that enable extrinsic extracellular glycosylation
This study highlights the capability of circulatory glycosyltransferases, which are dynamically controlled by platelet activation, to remodel cell surface glycans and alter cell behavior. (Source: Glycobiology)
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Lee-Sundlov, M. M., Ashline, D. J., Hanneman, A. J., Grozovsky, R., Reinhold, V. N., Hoffmeister, K. M., Lau, J. T. Tags: Vascular Biology Source Type: research

Conformational flexibility of PL12 family heparinases: structure and substrate specificity of heparinase III from Bacteroides thetaiotaomicron (BT4657)
Glycosaminoglycans (GAGs) are linear polysaccharides comprised of disaccharide repeat units, a hexuronic acid, glucuronic acid or iduronic acid, linked to a hexosamine, N-acetylglucosamine (GlcNAc) or N-acetylgalactosamine. GAGs undergo further modification such as epimerization and sulfation. These polysaccharides are abundant in the extracellular matrix and connective tissues. GAGs function in stabilization of the fibrillar extracellular matrix, control of hydration, regulation of tissue, organism development by controlling cell cycle, cell behavior and differentiation. Niche adapted bacteria express enzymes called ...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Ulaganathan, T., Shi, R., Yao, D., Gu, R.-X., Garron, M.-L., Cherney, M., Tieleman, D. P., Sterner, E., Li, G., Li, L., Linhardt, R. J., Cygler, M. Tags: Structural Biology Source Type: research

Rational design of a thermostable glycoside hydrolase from family 3 introduces {beta}-glycosynthase activity
The thermostable β-glucosidase from Thermotoga neapolitana, TnBgl3B, is a monomeric three-domain representative from glycoside hydrolase family 3. By using chemical reactivation with exogenous nucleophiles in previous studies with TnBg13B, the catalytic nucleophile (D242) and corresponding acid/base residue (E458) were determined. Identifying these residues led to the attempt of converting TnBgl3B into a β-glucosynthase, where three nucleophilic variants were created (TnBgl3B_D242G, TnBgl3B_D242A, TnBgl3B_D242S) and all of them failed to exhibit glucosynthase activity. A deeper analysis of the TnBgl3B active site...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Pozzo, T., Romero-Garcia, J., Faijes, M., Planas, A., Nordberg Karlsson, E. Tags: Structural Biology Source Type: research

Hyaluronan synthase control of synthesis rate and hyaluronan product size are independent functions differentially affected by mutations in a conserved tandem B-X7-B motif
Hyaluronan synthases (HAS) normally make large (>MDa) hyaluronan (HA) products. Smaller HA fragments (e.g. 100–400 kDa) produced in vivo are associated with inflammation and cell signaling by HA receptors that bind small, but not large, HA. Although HA fragments can arise from breakdown by hyaluronidases, HAS might also be regulated directly to synthesize small HA. Here we examined the Streptococcus equisimilis HAS (SeHAS) C-terminus, which contains a tandem B-X7-B motif (K398-X7-R406-X7-K414), by testing the effects of 27 site-specific scanning mutations and 7 C-terminal truncations on HA synthesis activity and w...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Baggenstoss, B. A., Harris, E. N., Washburn, J. L., Medina, A. P., Nguyen, L., Weigel, P. H. Tags: Glycan Synthesis Source Type: research

Revisiting the human polypeptide GalNAc-T1 and T13 paralogs
Polypeptide GalNAc-transferases (GalNAc-Ts) constitute a family of 20 human glycosyltransferases (comprising 9 subfamilies), which initiate mucin-type O-glycosylation. The O-glycoproteome is thought to be differentially regulated via the different substrate specificities and expression patterns of each GalNAc-T isoforms. Here, we present a comprehensive in vitro analysis of the peptide substrate specificity of GalNAc-T13, showing that it essentially overlaps with the ubiquitous expressed GalNAc-T1 isoform found in the same subfamily as T13. We have also identified and partially characterized nine splice variants of GalNAc-...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Festari, M. F., Trajtenberg, F., Berois, N., Pantano, S., Revoredo, L., Kong, Y., Solari-Saquieres, P., Narimatsu, Y., Freire, T., Bay, S., Robello, C., Benard, J., Gerken, T. A., Clausen, H., Osinaga, E. Tags: Chemical Biology Source Type: research

Mice lacking sialyltransferase ST3Gal-II develop late-onset obesity and insulin resistance
Sialyltransferases are a family of 20 gene products in mice and humans that transfer sialic acid from its activated precursor, CMP-sialic acid, to the terminus of glycoprotein and glycolipid acceptors. ST3Gal-II (coded by the St3gal2 gene) transfers sialic acid preferentially to the three positions of galactose on the Galβ1-3GalNAc terminus of gangliosides GM1 and GD1b to synthesize GD1a and GT1b, respectively. Mice with a targeted disruption of St3gal2 unexpectedly displayed late-onset obesity and insulin resistance. At 3 months of age, St3gal2-null mice were the same weight as their wild type (WT) counterparts, but ...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Lopez, P. H., Aja, S., Aoki, K., Seldin, M. M., Lei, X., Ronnett, G. V., Wong, G. W., Schnaar, R. L. Tags: Cell Biology Source Type: research

Recombinant fungal lectin as a new tool to investigate O-GlcNAcylation processes
Glycosylation is a group of post-translational modifications that displays a large variety of structures and are implicated in a plethora of biological processes. Therefore, studying glycosylation requires different technical approaches and reliable tools, lectins being part of them. Here, we describe the use of the recombinant mushroom lectin PVL to discriminate O-GlcNAcylation, a modification consisting in the attachment of a single N-acetylglucosamine residue to proteins confined within the cytosolic, nuclear and mitochondrial compartments. Recombinant PVL (Psathyrella velutina lectin) (rPVL) displays significantly...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: Machon, O., Baldini, S. F., Ribeiro, J. P., Steenackers, A., Varrot, A., Lefebvre, T., Imberty, A. Tags: Glycan Recognition Source Type: research

Current perspectives on the families of glycoside hydrolases of Mycobacterium tuberculosis: their importance and prospects for assigning function to unknowns
Glycoside hydrolases (GHs) are enzymes that catalyze the hydrolysis of glycosidic bonds in glycoconjugates, oligo- and polysaccharides. A classification of these enzymes based on conserved sequence and structure motifs supported by the Carbohydrate Active Enzyme (CAZy) database has proven useful in the systematic groupings of similar enzymes into families. The human pathogen Mycobacterium tuberculosis employs 30 GHs to perform a variety of different functions, which can be divided into four broad categories: α-glucan metabolism, peptidoglycan remodeling, β-glycan hydrolysis and α-demannosylation. The revie...
Source: Glycobiology - January 4, 2017 Category: Biology Authors: van Wyk, N., Drancourt, M., Henrissat, B., Kremer, L. Tags: Review Source Type: research

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(Source: Glycobiology)
Source: Glycobiology - January 4, 2017 Category: Biology Tags: Glyco-Forum Section Source Type: research

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(Source: Glycobiology)
Source: Glycobiology - January 4, 2017 Category: Biology Tags: Cover/Standing Material Source Type: research

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(Source: Glycobiology)
Source: Glycobiology - January 4, 2017 Category: Biology Tags: Cover/Standing Material Source Type: research

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(Source: Glycobiology)
Source: Glycobiology - January 4, 2017 Category: Biology Tags: Cover/Standing Material Source Type: research

Shiga toxin glycosphingolipid receptors and their lipid membrane ensemble in primary human blood-brain barrier endothelial cells
Shiga toxin (Stx)-mediated injury to microvascular endothelial cells in the brain significantly contributes to the pathogenesis of the hemolytic-uremic syndrome caused by enterohemorrhagic Escherichia coli (EHEC). Stxs are AB5 toxins and the B-pentamers of the two major Stx subtypes Stx1a and Stx2a preferentially bind to the glycosphingolipid (GSL) globotriaosylceramide (Gb3Cer) expressed by human endothelial cells. Here we report on comprehensive structural analysis of the different lipoforms of Gb3Cer (Galα4Galβ4Glcβ1Cer) and globotetraosylceramide (Gb4Cer, GalNAcβ3Galα4Galβ4Glcβ1Cer,...
Source: Glycobiology - December 27, 2016 Category: Biology Authors: Legros, N., Dusny, S., Humpf, H.-U., Pohlentz, G., Karch, H., Müthing, J. Tags: Microbial Biology Source Type: research

Cryptococcus neoformans UGT1 encodes a UDP-Galactose/UDP-GalNAc transporter
Cryptococcus neoformans, an opportunistic fungal pathogen, produces a glycan capsule to evade the immune system during infection. This definitive virulence factor is composed mainly of complex polysaccharides, which are made in the secretory pathway by reactions that utilize activated nucleotide sugar precursors. Although the pathways that synthesize these precursors are known, the identity and the regulation of the nucleotide sugar transporters (NSTs) responsible for importing them into luminal organelles remain elusive. The UDP-galactose transporter, Ugt1, was initially identified by homology to known UGTs and glycan com...
Source: Glycobiology - December 27, 2016 Category: Biology Authors: Li, L. X., Ashikov, A., Liu, H., Griffith, C. L., Bakker, H., Doering, T. L. Tags: Glycan Synthesis Source Type: research

Saturation transfer difference nuclear magnetic resonance titrations reveal complex multistep-binding of L-fucose to norovirus particles
Recently, combined nuclear magnetic resonance (NMR), native mass spectrometry (MS) and X-ray crystallographic studies have demonstrated that binding of histo-blood group antigens (HBGAs) to norovirus capsid protein (P-dimers) is a cooperative process involving four binding pockets. Here, we show that binding to norovirus virus-like particles (VLPs) is even more complex. We performed saturation transfer difference (STD) NMR titration experiments with two representative genotypes of norovirus VLPs using l-fucose as a minimal HBGA. Compared to titrations with P-dimers, the corresponding binding isotherms reflect at least six ...
Source: Glycobiology - December 27, 2016 Category: Biology Authors: Mallagaray, A., Rademacher, C., Parra, F., Hansman, G., Peters, T. Tags: Glycan Recognition Source Type: research