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Glycobiology

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https://www.readbyqxmd.com/read/28633290/planning-evaluating-and-vetting-receptor-signaling-studies-to-assesshyaluronan-size-dependence-and-specificity
#1
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. Though 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...
June 13, 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/28535302/inhibition-of-n-acetylglucosaminyltransferase-v-enhances-the-cetuximab-induced-radiosensitivity-of-nasopharyngeal-carcinoma-cells-likely-through-egfr-n-glycan-alterations
#8
Xiaomin Huang, Ting Liu, Qiongyao Wang, Weiliang Zhu, Hui Meng, Linlang Guo, Ting Wei, Jian Zhang
N-acetylglucosaminyltransferase V (GnT-V), an enzyme that catalyses the formation of the N-linked β-1-6 branching of oligosaccharides, is related to the radiosensitivity of nasopharyngeal carcinoma (NPC). Cetuximab (C225) is an epidermal growth factor receptor (EGFR) inhibitor used as a radiosensitizer in the treatment of NPC. In this study, we used GnT-V as a molecular target to further sensitize cetuximab-treated NPC cells to radiation. The results from two NPC cell lines (CNE1 and CNE2) revealed that the silencing of GnT-V enhanced cetuximab-induced radiosensitivity by decreasing the β-1-6 branching of oligosaccharides on the EGFR...
May 23, 2017: Glycobiology
https://www.readbyqxmd.com/read/28535208/sodium-glucose-cotransporter-2-in-mesangial-cells-and-retinal-pericytes-and-its-implications-for-diabetic-nephropathy-and-retinopathy
#9
Masarori Wakisaka, Tetsuhiko Nagao
Retinopathy and nephropathy are life-threatening diabetic complications that decrease patient quality of life. Although the mechanisms underlying these conditions have been extensively studied, they remain unknown. Recent reports have demonstrated the presence of SGLT2 in retinal pericytes and mesangial cells. Hyperglycemia results in functional and morphological changes in these cells, but these effects are attenuated by phlorizin, a non-selective SGLT inhibitor. Based on these findings, we hypothesized that SGLT2 plays a pivotal role in the development of diabetic nephropathy and retinopathy and that SGLT2 inhibitors may directly protect against these complications...
May 23, 2017: Glycobiology
https://www.readbyqxmd.com/read/28535204/colocalization-of-receptors-for-shiga-toxins-with-lipid-rafts-in-primary-human-renal-glomerular-endothelial-cells-and-influence-of-d-pdmp-on-synthesis-and-distribution-of-glycosphingolipid-receptors
#10
Nadine Legros, Gottfried Pohlentz, Jana Runde, Stefanie Dusny, Hans-Ulrich Humpf, Helge Karch, Johannes Müthing
Damage of human renal glomerular endothelial cells (HRGECs) of the kidney represents the linchpin in the pathogenesis of the hemolytic uremic syndrome (HUS) caused by Shiga toxins (Stxs) of enterohemorrhagic Escherichia coli (EHEC). We performed a comprehensive structural analysis of the Stx receptor glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer, Galα4alβ4Glcβ1Cer) and globotetraosylceramide (Gb4Cer, GalNAcβ3Galα4Galβ4Glcβ1Cer) and their distribution in lipid raft analogue detergent-resistant membranes (DRMs) and nonDRMs prepared from primary HRGECs...
May 23, 2017: Glycobiology
https://www.readbyqxmd.com/read/28510705/crystal-structure-of-octocoral-lectin-sll-2-complexed-with-forssman-antigen-tetrasaccharide
#11
Akiko Kita, Mitsuru Jimbo, Ryuichi Sakai, Yukio Morimoto, Ryota Takeuchi, Hiroshi Tanaka, Takashi Takahashi, Kunio Miki
A symbiosis-related lectin, SLL-2, from the octocoral Sinularia lochmodes, distributes densely on the cell surface of microalgae, Symbiodinium sp., an endosymbiotic dinoflagellate of the coral, and is also shown to be a chemical cue that transforms dinoflagellates into a non-motile (coccoid) symbiotic state. SLL-2 binds to the sugar chain of the molecule similar to Forssman antigen pentasaccharide (GalNAcα1-3GalNAcβ1-3 Galα1-4 Galβ1-4Glc) on the surface of microalgae with high affinity. Here we report the crystal structure of the complex between SLL-2 and Forssman antigen tetrasaccharide (GalNAcα1-3GalNAcβ1-3 Galα1-4 Galβ) at 3...
May 16, 2017: Glycobiology
https://www.readbyqxmd.com/read/28510654/asn-linked-oligosaccharide-chain-of-a-crenarchaeon-pyrobaculum-calidifontis-is-reminiscent-of-the-eukaryotic-high-mannose-type-glycan
#12
Daisuke Fujinami, Yuya Taguchi, Daisuke Kohda
Pyrobaculum calidifontis is a hyperthermophilic archaeon that belongs to the phylum Crenarchaeota. In contrast to the phylum Euryarchaeota, only the N-glycan structure of the genus Sulfolobus is known in Crenarchaeota. Here, we enriched glycoproteins from cultured P. calidifontis cells, by ConA lectin chromatography. The MASCOT search identified proteins with at least one potential N-glycosylation site. The MS/MS analysis of twelve small tryptic glycopeptides confirmed the canonical N-glycosylation consensus in P...
May 16, 2017: Glycobiology
https://www.readbyqxmd.com/read/28498962/an-iterative-glycosyltransferase-ents-catalyzes-transfer-and-extension-of-o-and-s-linked-monosaccharide-in-enterocin-96
#13
Rupa Nagar, Alka Rao
Glycosyltransferases are essential tools for in vitro-glycoengineering. Bacteria harbor an unexplored variety of protein glycosyltransferases. Here, we describe a peptide glycosyltransferase (EntS) encoded by ORF0417 of Enterococcus faecalis TX0104. EntS di-glycosylates linear peptide of enterocin 96- a known antibacterial, in vitro. It is capable of transferring as well as extending the glycan onto the peptide in an iterative sequential dissociative manner. It can catalyze multiple linkages: Glc/Gal(-O)Ser/Thr, Glc/Gal(-S)Cys and Glc/Gal(β)Glc/Gal(-O/S)Ser/Thr/Cys, in one pot...
May 12, 2017: Glycobiology
https://www.readbyqxmd.com/read/28486620/what-is-special-about-200-kda-hyaluronan-that-activates-hyaluronan-receptor-signaling
#14
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...
May 9, 2017: Glycobiology
https://www.readbyqxmd.com/read/28486580/enterocyte-glycosylation-is-responsive-to-changes-in-extracellular-conditions-implications-for-membrane-functions
#15
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 (ii) cell culture parameters relevant to intestinal epithelial cell growth and survival...
May 9, 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
#16
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...
April 28, 2017: Glycobiology
https://www.readbyqxmd.com/read/28531294/tatsushi-toda-and-tamao-endo-win-107th-japan-academy-prize
#17
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
#18
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
https://www.readbyqxmd.com/read/28460052/the-direct-and-indirect-effects-of-glycans-on-immune-function
#19
Linda G Baum, Brian A Cobb
The biological impact of glycans is as diverse and complex as the impact of proteins on biology. Familiar roles include those as a protein folding checkpoint in the endoplasmic reticulum and as a modulator of the serum half-life of secreted glycoproteins, but it has become clear over the last several decades that glycans are key signaling moieties, participate in cell-cell interactions and modulate the function of individual proteins, to name but a few examples. In the immune system, the majority of microbial "patterns" are glycans or glycoconjugates, while virtually all cell surface receptors are glycoproteins, and antibody glycosylation critically influences antibody function...
July 1, 2017: Glycobiology
https://www.readbyqxmd.com/read/28430973/biological-functions-of-fucose-in-mammals
#20
Michael Schneider, Esam Al-Shareffi, Robert S Haltiwanger
Fucose is a 6-deoxy hexose in the l-configuration found in a large variety of different organisms. In mammals, fucose is incorporated into N-glycans, O-glycans and glycolipids by 13 fucosyltransferases, all of which utilize the nucleotide-charged form, GDP-fucose, to modify targets. Three of the fucosyltransferases, FUT8, FUT12/POFUT1 and FUT13/POFUT2, are essential for proper development in mice. Fucose modifications have also been implicated in many other biological functions including immunity and cancer...
July 1, 2017: Glycobiology
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