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Glycobiology

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https://www.readbyqxmd.com/read/28673046/generation-and-characterization-of-a-monoclonal-antibody-to-the-cytoplasmic-tail-of-muc16
#1
Ilene K Gipson, Ulla Mandel, Balaraj Menon, Sandra Michaud, Ann Tisdale, Diana Campos, Henrik Clausen
MUC16 is a large transmembrane mucin expressed on the apical surfaces of the epithelium covering the ocular surface, respiratory system and female reproductive tract. The transmembrane mucin is overexpressed by ovarian carcinomas, it is one of the most frequently used diagnostic markers for the disease and it is considered a promising target for immunotherapeutic intervention. Immunodetection of the mucin has to date been through antibodies that recognize its exceptionally large ectodomain. Similar to other membrane anchored mucins, MUC16 has a short cytoplasmic tail (CT), but studies of the biological relevance of the C-terminal domain of MUC16 has been limited by lack of availability of monoclonal antibodies that recognize the native CT...
June 30, 2017: Glycobiology
https://www.readbyqxmd.com/read/28595377/characterization-of-tools-to-detect-and-enrich-human-and-mouse-o-glcnacase
#2
Jennifer A Groves, Natasha E Zachara
O-linked β-N-acetylglucosamine (O-GlcNAc) is an essential regulatory post-translational modification of thousands of nuclear, cytoplasmic, and mitochondrial proteins. O-GlcNAc is dynamically added and removed from proteins by the O-GlcNAc transferase and the O-GlcNAcase (OGA), respectively. Dysregulation of O-GlcNAc-cycling is implicated in the etiology of numerous diseases including tumorigenesis, metabolic dysfunction, and neurodegeneration. To facilitate studies focused on the role of O-GlcNAc and OGA in disease, we sought to identify commercially available antibodies that enable the enrichment of full-length OGA from lysates of mouse and human origin...
June 8, 2017: Glycobiology
https://www.readbyqxmd.com/read/28575295/high-resolution-crystal-structures-and-std-nmr-mapping-of-human-abo-h-blood-group-glycosyltransferases-in-complex-with-trisaccharide-reaction-products-suggest-a-molecular-basis-for-product-release
#3
Susannah M L Gagnon, Max S G Legg, Nora Sindhuwinata, James A Letts, Asha R Johal, Brock Schuman, Svetlana N Borisova, Monica M Palcic, Thomas Peters, Stephen V Evans
The human ABO(H) blood group A- and B-synthesizing glycosyltransferases GTA and GTB have been structurally characterized to high-resolution in complex with their respective trisaccharide antigen products. These findings are particularly timely and relevant given the dearth of glycosyltransferase structures collected in complex with their saccharide reaction products. GTA and GTB utilize the same acceptor substrates, oligosaccharides terminating with α-L-Fucp-(1→2)-β-D-Galp-OR (where R is a glycolipid or glycoprotein), but use distinct UDP donor sugars, UDP-N-acetylgalactosamine and UDP-galactose, to generate the blood group A (α-L-Fucp-(1→2)[α-D-GalNAcp-(1→3)]-β-D-Galp-OR) and blood group B (α-L-Fucp-(1→2)[α-D-Galp-(1→3)]-β-D-Galp-OR) determinant structures, respectively...
June 2, 2017: Glycobiology
https://www.readbyqxmd.com/read/28575298/chemo-enzymatic-synthesis-of-lipid-linked-glcnac2man5-oligosaccharides-using-recombinant-alg1-alg2-and-alg11-proteins
#4
Ana S Ramírez, Jérémy Boilevin, Chia-Wei Lin, Bee Ha Gan, Daniel Janser, Markus Aebi, Tamis Darbre, Jean-Louis Reymond, Kaspar P Locher
The biosynthesis of eukaryotic lipid-linked oligosaccharides (LLOs) that act as donor substrates in eukaryotic protein N-glycosylation starts on the cytoplasmic side of the endoplasmic reticulum and includes the sequential addition of five mannose units to dolichol-pyrophosphate-GlcNAc2. These reactions are catalyzed by the Alg1, Alg2 and Alg11 gene products and yield Dol-PP-GlcNAc2Man5, an LLO intermediate that is subsequently flipped to the lumen of the endoplasmic reticulum. While the purification of active Alg1 has previously been described, Alg11 and Alg2 have been mostly studied in vivo...
June 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28575441/transmembrane-motions-of-pglb-induced-by-llo-are-coupled-with-el5-loop-conformational-changes-necessary-for-ost-activity
#5
Hui Sun Lee, Wonpil Im
N-linked glycosylation is an enzymatic reaction where an oligosaccharide is transferred en bloc onto an asparagine residue of an acceptor polypeptide, catalyzed by oligosaccharyltransferase (OST). Despite the available crystal structures, the role of the external loop EL5, which is critical for the catalytic cycle, is still enigmatic as EL5 in the crystal structures is partially absent or blocks a pathway of lipid-linked oligosaccharide to the active site. Here we report the molecular origin of EL5 conformational changes through a series of molecular dynamics simulations of a bacterial OST, Campylobacter lari PglB...
May 30, 2017: Glycobiology
https://www.readbyqxmd.com/read/28575294/impaired-coordination-of-nucleophile-and-increased-hydrophobicity-in-the-1-subsite-shift-levansucrase-activity-towards-transfructosylation
#6
Maria Elena Ortiz-Soto, Christian Possiel, Julian Görl, Andreas Vogel, Ramona Schmiedel, Jürgen Seibel
Bacterial levansucrases produce β(2,6)-linked levan-type polysaccharides using sucrose or sucrose analogues as donor/acceptor substrates. However, the dominant reaction of Bacillus megaterium levansucrase (Bm-LS) is hydrolysis. Single domain levansucrases from Gram-positive bacteria display a wide substrate-binding pocket with open access to water, challenging engineering for transfructosylation-efficient enzymes. We pursued a shift in reaction specificity by either modifying the water distribution in the active site or the coordination of the catalytic acid/base (E352) and the nucleophile (D95), thus affecting the fructosyl-transfer rate and allowing acceptors other than water to occupy the active site...
May 30, 2017: Glycobiology
https://www.readbyqxmd.com/read/28549117/engineering-of-recombinant-wisteria-floribunda-agglutinin-specifically-binding-to-galnac%C3%AE-1-4glcnac-lacdinac
#7
Takashi Sato, Hiroaki Tateno, Hiroyuki Kaji, Yasunori Chiba, Tomomi Kubota, Jun Hirabayashi, Hisashi Narimatsu
Wisteria floribunda agglutinin (WFA) is a useful probe for distinguishing glycan structural alterations in diseases such as intrahepatic bile duct carcinoma and hepatic fibrosis; however, the gene encoding WFA has not been identified. Here, we identified the gene encoding WFA, and recombinant WFA was expressed in Escherichia coli and purified. The natural cDNA sequence obtained from wisteria seeds contained an open reading frame of 861 nucleotides encoding a WFA precursor, which included a hydrophobic signal peptide at the N-terminus, a propeptide at the C-terminus and a single cysteine (Cys) residue for dimer formation...
May 26, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810664/bacterial-phosphoglycosyl-transferases-initiators-of-glycan-biosynthesis-at-the-membrane-interface
#8
Vinita Lukose, Marthe T C Walvoort, Barbara Imperiali
Phosphoglycosyl transferases (PGTs) initiate the biosynthesis of both essential and virulence-associated bacterial glycoconjugates including lipopolysaccharide, peptidoglycan and glycoproteins. PGTs catalyze the transfer of a phosphosugar moiety from a nucleoside diphosphate sugar to a polyprenol phosphate, to form a membrane-bound polyprenol diphosphosugar product. PGTs are integral membrane proteins, which include between 1 and 11 predicted transmembrane domains. Despite this variation, common motifs have been identified in PGT families through bioinformatics and mutagenesis studies...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810663/different-properties-of-polysialic-acids-synthesized-by-the-polysialyltransferases-st8sia2-and-st8sia4
#9
Airi Mori, Masaya Hane, Yuki Niimi, Ken Kitajima, Chihiro Sato
Polysialic acid (polySia) is mainly found as a modification of neural cell adhesion molecule (NCAM) in whole embryonic brains, as well as restricted areas of adult vertebrate brains, including the hippocampus. PolySia shows not only repulsive effects on NCAM-involved cell-cell interactions due to its bulky and hydrated properties, but also attractive effects on the interaction with neurologically active molecules, which exerts a reservoir function. Two different polysialyltransferases, ST8SIA2 and ST8SIA4, are involved in the synthesis of polySia chains; however, to date, the differences of the properties between polySia chains synthesized by these two enzymes remain unknown...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810662/galectin-9-binds-to-o-glycans-on-protein-disulfide-isomerase
#10
Katrin Schaefer, Nicholas E Webb, Mabel Pang, Jenny E Hernandez-Davies, Katharine P Lee, Pascual Gonzalez, Martin V Douglass, Benhur Lee, Linda G Baum
Changes in the T cell surface redox environment regulate critical cell functions, such as cell migration, viral entry and cytokine production. Cell surface protein disulfide isomerase (PDI) contributes to the regulation of T cell surface redox status. Cell surface PDI can be released into the extracellular milieu or can be internalized by T cells. We have found that galectin-9, a soluble lectin expressed by T cells, endothelial cells and dendritic cells, binds to and retains PDI on the cell surface. While endogenous galectin-9 is not required for basal cell surface PDI expression, exogenous galectin-9 mediated retention of cell surface PDI shifted the disulfide/thiol equilibrium on the T cell surface...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810661/identification-of-lectin-counter-receptors-on-cell-membranes-by-proximity-labeling
#11
Gang Wu, Manjula Nagala, Paul R Crocker
Lectin-glycan interactions play important roles in many biological systems, but the nature of glycoprotein counter-receptors expressed on cell membranes is often poorly understood. To help overcome this problem, we developed a method based on proximity labeling technology. Using a peroxidase-coupled lectin, addition of H2O2 and tyramide-biotin substrates leads to generation of short-range biotin radicals that biotinylate proteins in the immediate vicinity of the bound lectin, which can subsequently be identified...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810660/recent-advancements-in-understanding-mammalian-o-mannosylation
#12
M Osman Sheikh, Stephanie M Halmo, Lance Wells
The post-translational glycosylation of select proteins by O-linked mannose (O-mannose or O-man) is a conserved modification from yeast to humans and has been shown to be necessary for proper development and growth. The most well studied O-mannosylated mammalian protein is α-dystroglycan (α-DG). Hypoglycosylation of α-DG results in varying severities of congenital muscular dystrophies, cancer progression and metastasis, and inhibited entry and infection of certain arenaviruses. Defects in the gene products responsible for post-translational modification of α-DG, primarily glycosyltransferases, are the basis for these diseases...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28810659/hyaluronic-acid-conjugation-facilitates-clearance-of-intracellular-bacterial-infections-by-streptomycin-with-neglectable-nephrotoxicity
#13
Yuanhao Qiu, Yilin Hou, Feifei Sun, Peng Chen, Dongdong Wang, Haibo Mu, Xiaoli Zhang, Kan Ding, Jinyou Duan
Antibiotics such as β-lactams and aminoglycosides are often subtherapeutic to intracellular infections due to their high hydrophilicity, resulting in low effectiveness against intracellular pathogens and the emergence of antibiotic resistance. Here we reported that an endogenous aminoglycan, hyaluronic acid could be an effective carbohydrate carrier of the aminoglycoside antibiotic, streptomycin against intracellular pathogens. This conjugation could enhance phagocytic activity, and facilitated the entry of streptomycin into host cells via a CD44-mediated pathway...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28633290/planning-evaluating-and-vetting-receptor-signaling-studies-to-assess-hyaluronan-size-dependence-and-specificity
#14
Paul H Weigel
Exciting discoveries in many diverse fields of hyaluronan (HA) biology over the last 40 years have centered around the ability of HA to bind cell surface HA receptors (e.g., CD44, Layilin, LYVE-1, HARE/Stab2 and RHAMM) and sometimes also to activate intracellular signal transduction pathways, frequently involving ERK1/2. Although perplexing, a major characteristic of HA-mediated signal pathway activation for some receptors has been a dependence on the size of the bound HA. Receptors that directly interact with HA, which may not include TLR2/4, bind very well to any HA molecule >8-20 sugars, depending on the receptor...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28486620/what-is-special-about-200-kda-hyaluronan-that-activates-hyaluronan-receptor-signaling
#15
Paul H Weigel, Bruce A Baggenstoss
The polydispersity of hyaluronan (HA) presents challenges for analyzing its solution properties, such as the relationship between mass and particle size. The broad mass range of natural HA (≤50-fold) makes molecular characterization difficult and ambiguous compared to molecules with known molecular weights (e.g., proteins). Biophysical studies show that large >MDa HA behaves like a random coil, whereas very small (e.g., 10 kDa) HA behaves like a rod. However, the mass range for this conformational transition is not easily determined in natural polydisperse HA...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28486580/enterocyte-glycosylation-is-responsive-to-changes-in-extracellular-conditions-implications-for-membrane-functions
#16
Dayoung Park, Gege Xu, Mariana Barboza, Ishita M Shah, Maurice Wong, Helen Raybould, David A Mills, Carlito B Lebrilla
Epithelial cells in the lining of the intestines play critical roles in maintaining homeostasis while challenged by dynamic and sudden changes in luminal contents. Given the high density of glycosylation that encompasses their extracellular surface, environmental changes may lead to extensive reorganization of membrane-associated glycans. However, neither the molecular details nor the consequences of conditional glycan changes are well understood. Here we assessed the sensitivity of Caco-2 and HT-29 membrane N-glycosylation to variations in (i) dietary elements, (ii) microbial fermentation products and (iii) cell culture parameters relevant to intestinal epithelial cell growth and survival...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28460017/structural-and-genetic-analyses-of-glycan-o-acetylation-in-a-bacterial-protein-glycosylation-system-evidence-for-differential-effects-on-glycan-chain-length
#17
Jan Haug Anonsen, Bente Børud, Åshild Vik, Raimonda Viburiene, Michael Koomey
O-acetylation is a common modification of bacterial glycoconjugates. By modifying oligosaccharide structure and chemistry, O-acetylation has important consequences for biotic and abiotic recognition events and thus bacterial fitness in general. Previous studies of the broad-spectrum O-linked protein glycosylation in pathogenic Neisseria species (including N. gonorrhoeae and N. meningitidis) have revealed O-acetylation of some of their diverse glycoforms and identified the committed acetylase, PglI. Herein, we extend these observations by using mass spectrometry to examine a complete set of all glycan variants identified to date...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28369425/the-%C3%AE-reducing-end-in-%C3%AE-2-8-polysialic-acid-constitutes-a-unique-structural-motif
#18
Hugo F Azurmendi, Marcos D Battistel, Jasmin Zarb, Flora Lichaa, Alejandro Negrete Virgen, Joseph Shiloach, Darón I Freedberg
Over the years, structural characterizations of α(2-8)-polysialic acid (polySia) in solution have produced inconclusive results. Efforts for obtaining detailed information in this important antigen have focused primarily on the α-linked residues and not on the distinctive characteristics of the terminal ones. The thermodynamically preferred anomeric configuration for the reducing end of sialic acids is β, which has the [I]CO2- group equatorial and the OH ([I]OH2) axial, while for all other residues the CO2- group is axial...
September 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28531294/tatsushi-toda-and-tamao-endo-win-107th-japan-academy-prize
#19
Motoi Kanagawa, Hiroshi Manya
No abstract text is available yet for this article.
July 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28460072/exploring-the-structure-of-fucosylated-chondroitin-sulfate-through-bottom-up-nuclear-magnetic-resonance-and-electrospray-ionization-high-resolution-mass-spectrometry-approaches
#20
Gustavo Rc Santos, Ana Co Porto, Paulo Ag Soares, Eduardo Vilanova, Paulo As Mourão
Fucosylated chondroitin sulfate (FCS) from sea cucumbers is composed of a chondroitin sulfate (CS) central core and branches of sulfated fucose. The structure of this complex glycosaminoglycan is usually investigated via nuclear magnetic resonance (NMR) analyses of the intact molecule, ergo through a top-down approach, which often yield spectra with intricate sets of signals. Here we employed a bottom-up approach to analyze the FCSs from the sea cucumbers Isostichopus badionotus and Ludwigothurea grisea from their basic constituents, viz...
July 1, 2017: Glycobiology
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