Chemoenzymatic Synthesis of a Type 2 Blood Group A Tetrasaccharide and Development of High-throughput Assays Enables a Platform for Screening Blood Group Antigen-cleaving Enzymes
A facile enzymatic synthesis of the methylumbelliferyl β-glycoside of the type 2 A blood group tetrasaccharide in good yields is reported. Using this compound, we developed highly sensitive fluorescence-based high-throughput assays for both endo-β-galactosidase and α-N-acetylgalactosaminidase activity specific for the oligosaccharide structure of the blood group A antigen. We further demonstrate the potential to use this assay to screen the expressed gene products of metagenomic libraries in the search for efficient blood group antigen-cleaving enzymes. (Source: Glycobiology)
Source: Glycobiology - July 1, 2015 Category: Biology Authors: Kwan, D. H., Ernst, S., Kotzler, M. P., Withers, S. G. Tags: COMMUNICATION Source Type: research
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Source: Glycobiology - July 1, 2015 Category: Biology Tags: Cover/Standing Material Source Type: research
Crystal structure of a Xenopus laevis skin proto-type galectin, close to but distinct from galectin-1
Xenopus laevis (African clawed frog) has two types of proto-type galectins that are similar to mammalian galectin-1 in amino acid sequence. One type, comprising xgalectin-Ia and -Ib, is regarded as being equivalent to galectin-1, and the other type, comprising xgalectin-Va and -Vb, is expected to be a unique galectin subgroup. The latter is considerably abundant in frog skin; however, its biological function remains unclear. We determined the crystal structures of two proto-type galectins, xgalectin-Ib and -Va. The structures showed that both galectins formed a mammalian galectin-1-like homodimer, and furthermore, xgalecti...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Nonaka, Y., Ogawa, T., Yoshida, H., Shoji, H., Nishi, N., Kamitori, S., Nakamura, T. Tags: ORIGINAL ARTICLES Source Type: research
Sialidases as regulators of bioengineered cellular surfaces
Human sialidases (NEUs) catalyze the removal of N-acetyl neuraminic acids from the glycome of the cell and regulate a diverse repertoire of nominal cellular functions, such as cell signaling and adhesion. A greater understanding of their substrate permissivity is of interest in order to discern their physiological functions in disease states and in the design of specific and effective small molecule inhibitors. Towards this, we have synthesized soluble fluorogenic reporters of mammalian sialidase activity bearing unnatural sialic acids commonly incorporated into the cellular glycocalyx via metabolic glycoengineering. We fo...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Zamora, C. Y., Ryan, M. J., d'Alarcao, M., Kumar, K. Tags: ORIGINAL ARTICLES Source Type: research
Reduced expression of the oligosaccharyltransferase exacerbates protein hypoglycosylation in cells lacking the fully assembled oligosaccharide donor
A defect in the assembly of the oligosaccharide donor (Dol-PP-GlcNAc2Man9Glc3) for N-linked glycosylation causes hypoglycosylation of proteins by the oligosaccharyltransferase (OST). Mammalian cells express two OST complexes that have different catalytic subunits (STT3A or STT3B). We monitored glycosylation of proteins in asparagine-linked glycosylation 6 (ALG6) deficient cell lines that assemble Dol-PP-GlcNAc2Man9 as the largest oligosaccharide donor. Based upon pulse labeling experiments, 30–40% of STT3A-dependent glycosylation sites and 20% of STT3B-dependent sites are skipped in ALG6-congenital disorders of glyco...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Shrimal, S., Gilmore, R. Tags: ORIGINAL ARTICLES Source Type: research
Sialyltransferases with enhanced legionaminic acid transferase activity for the preparation of analogs of sialoglycoconjugates
Legionaminic acids (Leg) are bacterial analogs of neuraminic acid, with the same stereochemistry but different substituents at C5, C7 and C9. Hence they may be incorporated into useful analogs of sialoglycoconjugates, and we previously reported two sialyltransferases that could utilize cytidine monophosphate (CMP)-Leg5Ac7Ac for preparation of Leg glycoconjugates, which were resistant to sialidases [Watson DC, Leclerc S, Wakarchuk WW, Young NM. 2011. Enzymatic synthesis and properties of glycoconjugates with legionaminic acid as a replacement for neuraminic acid. Glycobiology. 21:99–108.]. These were the porcine ST3Ga...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Watson, D. C., Wakarchuk, W. W., Leclerc, S., Schur, M. J., Schoenhofen, I. C., Young, N. M., Gilbert, M. Tags: ORIGINAL ARTICLES Source Type: research
Selective biochemical labeling of Campylobacter jejuni cell-surface glycoconjugates
The display of cell-surface glycolipids and glycoproteins is essential for the motility, adhesion and colonization of pathogenic bacteria such as Campylobacter jejuni. Recently, the cell-surface display of C. jejuni glycoconjugates has been the focus of considerable attention; however, our understanding of the roles that glycosylation plays in bacteria still pales in comparison with our understanding of mammalian glycosylation. One of the reasons for this is that carbohydrate metabolic labeling, a powerful tool for studying mammalian glycans, is difficult to establish in bacterial systems and has a significantly more limit...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Whitworth, G. E., Imperiali, B. Tags: ORIGINAL ARTICLES Source Type: research
Glycosaminoglycan sulfation determines the biochemical properties of prion protein aggregates
Prion diseases are transmissible neurodegenerative disorders associated with the conversion of the cellular prion protein, PrPC, to a misfolded isoform called PrPSc. Although PrPSc is a necessary component of the infectious prion, additional factors, or cofactors, have been shown to contribute to the efficient formation of transmissible PrPSc. Glycosaminoglycans (GAGs) are attractive cofactor candidates as they can be found associated with PrPSc deposits, have been shown to enhance PrP misfolding in vitro, are found in the same cellular compartments as PrPC and have been shown to be disease modifying in vivo. Here we inves...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Ellett, L. J., Coleman, B. M., Shambrook, M. C., Johanssen, V. A., Collins, S. J., Masters, C. L., Hill, A. F., Lawson, V. A. Tags: ORIGINAL ARTICLES Source Type: research
Heparosan-glucuronate 5-epimerase: Molecular cloning and characterization of a novel enzyme
Iduronic acid (IdoA) is a critical component of heparan sulfate in its interaction with functional proteins. Heparosan-N-sulfate-glucuronate 5-epimerase (HNSG-5epi) converts d-glucuronic acid (GlcA) residues in N-sulfated heparosan (NS-heparosan), as an intermediate in heparan sulfate biosynthesis, to IdoA. In the present study, the authors discovered a different 5-epimerase, designated HG-5epi (heparosan-glucuronate 5-epimerase), that is involved in acharan sulfate biosynthesis and possesses novel substrate specificity. A candidate cDNA of HG-5epi was cloned from the cDNA library of Achatina fulica. The cloned cDNA contai...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Mochizuki, H., Yamagishi, K., Suzuki, K., Kim, Y. S., Kimata, K. Tags: ORIGINAL ARTICLES Source Type: research
Comparative lectinology: Delineating glycan-specificity profiles of the chicken galectins using neoglycoconjugates in a cell assay
A major aspect of carbohydrate-dependent galectin functionality is their cross-linking capacity. Using a cell surface as biorelevant platform for galectin binding and a panel of 40 glycans as sensor part of a fluorescent polyacrylamide neoglycopolymer for profiling galectin reactivity, properties of related proteins can be comparatively analyzed. The group of the chicken galectins (CGs) is an especially suited system toward this end due to its relatively small size, compared with mammalian galectins. The experiments reveal particularly strong reactivity toward N-acetyllactosamine repeats for all tested CGs and shared react...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Rapoport, E. M., Matveeva, V. K., Kaltner, H., Andre, S., Vokhmyanina, O. A., Pazynina, G. V., Severov, V. V., Ryzhov, I. M., Korchagina, E. Y., Belyanchikov, I. M., Gabius, H.-J., Bovin, N. V. Tags: ORIGINAL ARTICLES Source Type: research
A new sequencing approach for N-unsubstituted heparin/heparan sulfate oligosaccharides
In this study, we developed and validated a simple and sensitive method for the sequence analysis of N-unsubstituted heparin/HS oligosaccharides. This protocol involves pH 4 nitrous acid (HNO2) degradation, size-exclusion HPLC and ion-pair reversed-phase liquid chromatography-ion trap/time-of-flight mass spectrometry (IPRP-LC-ITTOF MS). We unexpectedly found that absorbance at 232 nm (normally used for specific detection of C4–C5 unsaturated oligosaccharides) was, in most cases, still sufficiently sensitive to also simultaneously detect saturated oligosaccharides during HPLC, thus simplifying the positional analysis ...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Liang, Q. T., Xiao, X. M., Lin, J. H., Wei, Z. Tags: ORIGINAL ARTICLES Source Type: research
Matriglycan: a novel polysaccharide that links dystroglycan to the basement membrane
Associations between cells and the basement membrane are critical for a variety of biological events including cell proliferation, cell migration, cell differentiation and the maintenance of tissue integrity. Dystroglycan is a highly glycosylated basement membrane receptor, and is involved in physiological processes that maintain integrity of the skeletal muscle, as well as development and function of the central nervous system. Aberrant O-glycosylation of the α subunit of this protein, and a concomitant loss of dystroglycan's ability to function as a receptor for extracellular matrix (ECM) ligands that bear laminin ...
Source: Glycobiology - June 3, 2015 Category: Biology Authors: Yoshida-Moriguchi, T., Campbell, K. P. Tags: REVIEW Source Type: research
