Preferred conformations of N-glycan core pentasaccharide in solution and in glycoproteins
N-linked glycans are on protein surfaces and have direct and water/ion-mediated interactions with surrounding amino acids. Such contacts could restrict their conformational freedom compared to the same glycans free in solution. In this work, we have examined the conformational freedom of the N-glycan core pentasaccharide moiety in solution using standard molecular dynamics (MD) simulations as well as temperature replica-exchange MD simulations. Both simulations yield the comparable conformational variability of the pentasaccharide in solution, indicating the convergence of both simulations. The glycoprotein crystal structu...
Source: Glycobiology - December 7, 2015 Category: Biology Authors: Jo, S., Qi, Y., Im, W. Tags: Computational Biology Source Type: research
Identification and biological consequences of the O-GlcNAc modification of the human innate immune receptor, Nod2
The objective of this study is to further characterize this protein by determining whether Nod2 is posttranslationally modified by O-N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is one type of posttranslational modification in which the O-GlcNAc transferase transfers GlcNAc from UDP-GlcNAc to selected serine and threonine residues of intracellular proteins. We found that wild-type Nod2 and a Nod2 Crohn's-associated variant are O-GlcNAcylated and this modification affects Nod2's ability to signal via the nuclear factor kappa B pathway. (Source: Glycobiology)
Source: Glycobiology - December 7, 2015 Category: Biology Authors: Hou, C.-W., Mohanan, V., Zachara, N. E., Grimes, C. L. Tags: Immunology Source Type: research
Fucoidanases
In recent years, the research of fucoidans has steadily increased. The interest in these substances is due to their various biological activities. Despite a wide range of biological activity and the lack of oral toxicity, fucoidans remain relatively unexploited as a source of medicines because of their heterogeneity. Enzymes that degrade polyanionic polysaccharides are widely used for establishing their structures and structure–activity relationships. Sometimes, to obtain preparations of polysaccharides with standard characteristics, for example, medicines and food supplements, enzymatic treatment can be also applied...
Source: Glycobiology - December 7, 2015 Category: Biology Authors: Kusaykin, M. I., Silchenko, A. S., Zakharenko, A. M., Zvyagintseva, T. N. Tags: REVIEW Source Type: research
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Source: Glycobiology - December 7, 2015 Category: Biology Tags: Cover/Standing Material Source Type: research
Structural determinants of heparin-transforming growth factor-{beta}1 interactions and their effects on signaling
Transforming growth factor-β1 (TGF-β1, Uniprot: P01137) is a heparin-binding protein that has been implicated in a number of physiological processes, including the initiation of chondrogenesis by human mesenchymal stem cells (hMSCs). Here, we identify the molecular features in the protein and in heparin required for binding and their effects on the potentiation of TGF-β1's activity on hMSCs. Using a proteomics "Protect and Label" approach, lysines K291, K304, K309, K315, K338, K373, K375 and K388 were identified as being directly involved in binding heparin (Data are available via ProteomeXchange with identi...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Lee, J., Wee, S., Gunaratne, J., Chua, R. J. E., Smith, R. A. A., Ling, L., Fernig, D. G., Swaminathan, K., Nurcombe, V., Cool, S. M. Tags: Structural Biology Source Type: research
Databases of Conformations and NMR Structures of Glycan Determinants
The present study reports a comprehensive nuclear magnetic resonance (NMR) characterization and a systematic conformational sampling of the conformational preferences of 170 glycan moieties of glycosphingolipids as produced in large-scale quantities by bacterial fermentation. These glycans span across a variety of families including the blood group antigens (A, B and O), core structures (Types 1, 2 and 4), fucosylated oligosaccharides (core and lacto-series), sialylated oligosaccharides (Types 1 and 2), Lewis antigens, GPI-anchors and globosides. A complementary set of about 100 glycan determinants occurring in glycoprotei...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Sarkar, A., Drouillard, S., Rivet, A., Perez, S. Tags: Structural Biology Source Type: research
Surface expression patterns of defined glycan antigens change during Schistosoma mansoni cercarial transformation and development of schistosomula
During the complex lifecycle of Schistosoma mansoni, a large variety of glycans is expressed. To many of these glycans, antibodies are induced by the infected host and some might be targets for vaccines or diagnostic tests. Spatial changes in glycan expression during schistosome development are largely unexplored. To study the surface-exposed glycans during the important initial stages of infection, we analyzed the binding of a panel of anti-glycan monoclonal antibodies (mAbs) to cercariae and schistosomula up to 72 h after transformation by immunofluorescence microscopy. The mAb specificity toward their natural targets wa...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Smit, C. H., Homann, A., van Hensbergen, V. P., Schramm, G., Haas, H., van Diepen, A., Hokke, C. H. Tags: Microbial Biology Source Type: research
Activation of human naïve Th cells increases surface expression of GD3 and induces neoexpression of GD2 that colocalize with TCR clusters
CD4+ T helper lymphocytes (Th) orchestrate the immune response after their activation by antigen-presenting cells. Activation of naïve Th cells is reported to generate the reduction in surface epitopes of sialic acid (Sia) in α2,3 and α2,6 linkages. In this work, we report that in spite of this glycophenotype, anti-CD3/anti-CD28-activated purified human naïve Th cells show a significant increase in surface Sia, as assessed by metabolic labeling, compared with resting naïve Th cells, suggesting an increased flux of Sia toward Siaα2,8 glycoconjugates. To understand this increase as a...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Villanueva-Cabello, T. M., Mollicone, R., Cruz-Munoz, M. E., Lopez-Guerrero, D. V., Martinez-Duncker, I. Tags: Immunology Source Type: research
Sialylation potentials of the silkworm, Bombyx mori; B. mori possesses an active {alpha}2,6-sialyltransferase
N-Glycosylation is an important post-translational modification in most secreted and membrane-bound proteins in eukaryotic cells. However, the insect N-glycosylation pathway and the potentials contributing to the N-glycan synthesis are still unclear because most of the studies on these subjects have focused on mammals and plants. Here, we identified Bombyx mori sialyltransferase (BmST), which is a Golgi-localized glycosyltransferase and which can modify N-glycans. BmST was ubiquitously expressed in different organs and in various stages of development and localized at the Golgi. Biochemical analysis using Sf9-expressed BmS...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Kajiura, H., Hamaguchi, Y., Mizushima, H., Misaki, R., Fujiyama, K. Tags: Glycan Synthesis Source Type: research
Cloning and expression of 3-deoxy-D-manno-oct-2-ulosonic acid {alpha}-ketoside hydrolase from oyster hepatopancreas
We have previously reported that oyster hepatopancreas contained three unusual α-ketoside hydrolases: (i) a 3-deoxy-d-manno-oct-2-ulosonic acid α-ketoside hydrolase (α-Kdo-ase), (ii) a 3-deoxy-d-glycero-d-galacto-non-2-ulosonic acid α-ketoside hydrolase and (iii) a bifunctional ketoside hydrolase capable of cleaving both the α-ketosides of Kdn and Neu5Ac (Kdn-sialidase). After completing the purification of Kdn-sialidase, we proceeded to clone the gene encoding this enzyme. Unexpectedly, we found that instead of expressing Kdn-sialidase, our cloned gene expressed α-Kdo-ase activity. The ...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Nakagawa, T., Shimada, Y., Pavlova, N. V., Li, S.-C., Li, Y.-T. Tags: Glycan Metabolism Source Type: research
Characterization of an N-acetylglucosaminyltransferase involved in Aspergillus fumigatus zwitterionic glycoinositolphosphoceramide biosynthesis
In this study, we identified an A. fumigatus N-acetylglucosaminyltransferase, named GntA, and demonstrate its involvement in the initiation of zwitterionic GIPC biosynthesis. Targeted deletion of the gene encoding GntA in A. fumigatus resulted in complete absence of zwitterionic GIPC; a phenotype that could be reverted by episomal expression of GntA in the mutant. The N-acetylhexosaminyltransferase activity of GntA was substantiated by production of N-acetylhexosamine-IPC in the yeast Saccharomyces cerevisiae upon GntA expression. Using an in vitro assay, GntA was furthermore shown to use UDP-N-acetylglucosamine as donor s...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Engel, J., Schmalhorst, P. S., Krüger, A. T., Müller, C. T., Buettner, F. F. R., Routier, F. H. Tags: Glycan Metabolism Source Type: research
The regulation of ER export and Golgi retention of ST3Gal5 (GM3/GM4 synthase) and B4GalNAcT1 (GM2/GD2/GA2 synthase) by arginine/lysine-based motif adjacent to the transmembrane domain
In the Golgi maturation model, the Golgi cisternae dynamically mature along a secretory pathway. In this dynamic process, glycosyltransferases are transported from the endoplasmic reticulum (ER) to the Golgi apparatus where they remain and function. The precise mechanism behind this maturation process remains unclear. We investigated two glycosyltransferases, ST3Gal5 (ST3G5) and B4GalNAcT1 (B4GN1), involved in ganglioside synthesis and examined their signal sequences for ER export and Golgi retention. Reports have suggested that the [R/K](X)[R/K] motif functions as an ER exporting signal; however, this signal sequence is i...
Source: Glycobiology - November 5, 2015 Category: Biology Authors: Uemura, S., Shishido, F., Kashimura, M., Inokuchi, J.-i. Tags: Cell Biology Source Type: research
