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Yanlei Yu, Yin Chen, Paiyz Mikael, Fuming Zhang, Apryll M Stalcup, Rebecca German, Francois Gould, Jocelyn Ohlemacher, Hong Zhang, Robert J Linhardt
Heparin, a member of a family of molecules called glycosaminoglycans, is biosynthesized in mucosal mast cells. This important anticoagulant polysaccharide is primarily produced by extraction of the mast cell-rich intestinal mucosa of hogs. There is concern about our continued ability to supply sufficient heparin to support the worldwide growth of advanced medical procedures from the static population of adult hogs used as food animals. While the intestinal mucosa of adult pigs is rich in anticoagulant heparin (containing a few hundred milligrams per animal), little is known about how the content of heparin changes with animal age...
October 15, 2016: Glycobiology
Niël van Wyk, Michel Drancourt, Bernard Henrissat, Laurent Kremer
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 remodelling, β-glycan hydrolysis and α-demannosylation...
October 3, 2016: Glycobiology
Pablo H H Lopez, Susan Aja, Kazuhiro Aoki, Marcus M Seldin, Xia Lei, Gabriele V Ronnett, G William Wong, Ronald L Schnaar
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 3-position 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...
September 28, 2016: Glycobiology
ThirumalaiSelvi Ulaganathan, Rong Shi, Deqiang Yao, Ruo-Xu Gu, Marie-Line Garron, Maia Cherney, D Peter Tieleman, Eric Sterner, Guoyun Li, Lingyun Li, Robert J Linhardt, Miroslaw Cygler
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...
September 12, 2016: Glycobiology
Amanda L Lewis, Lloyd S Robinson, Kavita Agarwal, Warren G Lewis
Sialic acids are nine-carbon backbone carbohydrates found in prominent outermost positions of glycosylated molecules in mammals. Mimicry of sialic acid (N-acetylneuraminic acid, Neu5Ac) enables some pathogenic bacteria to evade host defenses. Fusobacterium nucleatum is a ubiquitous oral bacterium also linked with invasive infections throughout the body. We employed multidisciplinary approaches to test predictions that F. nucleatum engages in de novo synthesis of sialic acids. Here we show that F. nucleatum sbsp...
September 9, 2016: Glycobiology
Tim Steffens, Katarzyna Duda, Buko Lindner, Frank-Jörg Vorhölter, Hanna Bednarz, Karsten Niehaus, Otto Holst
Xanthomonas translucens pv. translucens (Xtt) is a Gram-negative pathogen of crops from the plant family Poaceae The lipopolysaccharide (LPS) of Xtt was isolated and chemically characterized. The analyses revealed the presence of rhamnose, xylose, mannose, glucose, galacturonic acid, phosphates, 3-deoxy-D-manno-oct-2-ulopyranosonic acid (Kdo) and fatty acids (10:0, 11:0, 11:0(3-OH) i/a, 11:0(3-OH), 12:0(3-OH) i/a, 12:0(3-OH), 12:0, 13:0(3-OH) i, 13:0(3-OH) a, 13:0(3-OH), 14:0(3-OH) i/a, 14:0(3-OH) and 16:0)...
September 9, 2016: Glycobiology
Viktoria Dotz, Rüdiger Adam, Günter Lochnit, Horst Schroten, Clemens Kunz
Beneficial effects have been proposed for human milk oligosaccharides (HMO), as deduced from in vitro and animal studies. To date, in vivo evidence of the link between certain oligosaccharide structures in milk and their consumption by infant gut microbiota is still missing, although likely. Whereas many studies have described HMO patterns in human milk from larger cohorts, data on the excretion of HMO and possible metabolites produced in the infant gut are still very limited. From smaller-scale studies, an age-dependency according to infant gut maturation and microbiota adaptation has previously been hypothesized...
September 9, 2016: Glycobiology
Luis M Bredeston, Cristina Marino-Buslje, Vanesa S Mattera, Lucila I Buzzi, Armando J Parodi, Cecilia D'Alessio
UDP-Glc entrance into the endoplasmic reticulum (ER) of eukaryotic cells is a key step in the quality control of glycoprotein folding, a mechanism requiring transfer of a Glc residue from the nucleotide sugar (NS) to glycoprotein folding intermediates by the UDP-Glc:glycoprotein glucosyltransferase (UGGT). According to a bioinformatics search there are only eight genes in the Schizosaccharomyces pombe genome belonging to the three Pfam families to which all known nucleotide-sugar transporters (NSTs) of the secretory pathway belong...
September 1, 2016: Glycobiology
Uri Galili
Humans produce multiple natural antibodies against carbohydrate antigens on gastrointestinal bacteria. Two such antibodies appeared in primates in recent geological times. Anti-Gal, abundant in humans, apes and Old-World monkeys, appeared 20-30 million years ago (mya) following inactivation of the α1,3GT gene (GGTA1). This gene encodes in other mammals the enzyme α1,3galactosyltransferase (α1,3GT) that synthesizes α-gal epitopes (Galα1-3 Galα1-4GlcNAc-R) which bind anti-Gal. Anti-Neu5Gc, found only in humans, appeared in hominins <6 mya, following elimination of N-glycolylneuraminic-acid (Neu5Gc) because of inactivation of CMAH, the gene encoding hydroxylase that converts N-acetylneuraminic-acid (Neu5Ac) into Neu5Gc...
August 27, 2016: Glycobiology
Ajit Varki
Simple and complex carbohydrates (glycans) have long been known to play major metabolic, structural and physical roles in biological systems. Targeted microbial binding to host glycans has also been studied for decades. But such biological roles can only explain some of the remarkable complexity and organismal diversity of glycans in nature. Reviewing the subject about two decades ago, one could find very few clear-cut instances of glycan-recognition-specific biological roles of glycans that were of intrinsic value to the organism expressing them...
August 24, 2016: Glycobiology
Patricia R Pereira, Jennifer L Meagher, Harry C Winter, Irwin J Goldstein, Vânia M F Paschoalin, Joab T Silva, Jeanne A Stuckey
Tarin, the Colocasia esculenta lectin from the superfamily of α-d-mannose-specific plant bulb lectins, is a tetramer of 47 kDa composed of two heterodimers. Each heterodimer possesses homologous monomers of ~11.9 (A chain) and ~12.7 (B chain) kDa. The structures of apo and carbohydrate-bound tarin were solved to 1.7 Å and 1.91 Å, respectively. Each tarin monomer forms a canonical β-prism II fold, common to all members of Galanthus nivalis agglutinin (GNA) family, which is partially stabilized by a disulfide bond and a conserved hydrophobic core...
August 24, 2016: Glycobiology
Bruce A Baggenstoss, Edward N Harris, Jennifer L Washburn, Andria P Medina, Long Nguyen, Paul H Weigel
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 (K(398)-X7-R(406)-X7-K(414)), by testing the effects of 27 site-specific scanning mutations and 7 C-terminal truncations on HA synthesis activity and weight-average mass...
August 24, 2016: Glycobiology
Nadine Legros, Stefanie Dusny, Hans-Ulrich Humpf, Gottfried Pohlentz, Helge Karch, Johannes Müthing
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, the less effective Stx receptor) of primary human brain microvascular endothelial cells and their association with lipid rafts...
August 24, 2016: Glycobiology
Justyna M Dobruchowska, Jon O Jonsson, Olafur H Fridjonsson, Arnthor Aevarsson, Jakob K Kristjansson, Josef Altenbuchner, Hildegard Watzlawick, Gerrit J Gerwig, Lubbert Dijkhuizen, Johannis P Kamerling, Gudmundur O Hreggvidsson
Recently, we have shown that glycoside hydrolases enzymes of family GH17 from proteobacteria (genera Pseudomonas, Azotobacter) catalyze elongation transfer reactions with laminari-oligosaccharides generating (β1→3) linkages preferably and to a lesser extent (β1→6) or (β1→4) linkages. In the present study, the cloning and characterization of the gene encoding the structurally very similar GH17 domain of the NdvB enzyme from Bradyrhizobium diazoefficiens, designated Glt20, as well as its catalytic properties are described...
August 22, 2016: Glycobiology
Yuta Sugiyama, Aina Gotoh, Toshihiko Katoh, Yuji Honda, Erina Yoshida, Shin Kurihara, Hisashi Ashida, Hidehiko Kumagai, Kenji Yamamoto, Motomitsu Kitaoka, Takane Katayama
Fucα1-2 Gal linkages, or H-antigens, constitute histo-blood group antigens and are involved in various physiological processes. In addition, recent studies have shown that the H-antigen-containing glycans play an important role, not only in establishing harmonious relationship between gut microbes and the host, but also in preventing gut dysbiosis-related diseases. Therefore, development of an efficient method for introducing Fuc residue at Gal residue at the non-reducing end of glycans via α-(1→2) linkage is desired for research as well as medicinal purposes...
August 22, 2016: Glycobiology
Pierre-André Gilormini, Cédric Lion, Maxence Noel, Marie-Ange Krzewinski-Recchi, Anne Harduin-Lepers, Yann Guérardel, Christophe Biot
Natural and synthetically modified CMP-activated sialic acids are essential research tools in the field of glycobiology: among other applications, they can be used to probe glycans, detect sialylation defects at the cell surface, or carry out detailed studies of sialyltransferase activities. However, these chemical tools are notoriously unstable because of hydrolytic decomposition, and are very time-consuming and costly to obtain. They are nigh impossible to store with satisfactory purity, and their preparation requires multiple laborious purification steps that usually lead to heavy product loss...
August 19, 2016: Glycobiology
Roger A Kroes, Joseph R Moskal
The mechanism of transcriptional silencing of ST6Gal1 in gliomas has not yet been elucidated. Multiple independent promoters govern the expression of the ST6Gal I gene. Here, we investigated whether epigenetic abnormalities involving DNA methylation affect ST6Gal1 expression. Transcript-specific qRT-PCR following exposure of glioma cell lines to 5-aza-2'-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, resulted in the re-expression of the normally quiescent ST6Gal1 mRNA driven exclusively by the P3 promoter sequence...
August 10, 2016: Glycobiology
Alvaro Mallagaray, Christoph Rademacher, Francisco Parra, Grant Hansman, Thomas Peters
Recently, combined nuclear magnetic resonance (NMR), native 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 sexually transmitted disease 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 distinct binding events...
August 3, 2016: Glycobiology
Ismael N L Queiroz, Ana-Cristina E S Vilela-Silva, Vitor H Pomin
Here we have performed an NMR-based study on the ring and chain conformations as well as dynamics of oligosaccharides generated by acid hydrolysis on two structurally resembling glycans, a 3-linked 2-sulfated alpha-L-galactan and a 3-linked 2-sulfated alpha-L-fucan. Results derived from scalar couplings have confirmed the (1)C4 chair configuration to both alpha-L-fucose and alpha-L-galactose, and a similar solution 3D structure for the oligosaccharide chains of both sulfated glycans as seen on the basis of NOE patterns...
August 3, 2016: Glycobiology
Lucy X Li, Angel Ashikov, Hong Liu, Cara L Griffith, Hans Bakker, Tamara L Doering
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 regulation of the nucleotide sugar transporters (NSTs) responsible for importing them into luminal organelles remain elusive...
August 3, 2016: Glycobiology
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