Crystal structures of an archaeal oligosaccharyltransferase provide insights into the catalytic cycle of N-linked protein glycosylation. X-ray structure of a bacterial oligosaccharyltransferase. Lizak, C., Gerber, S., Numao, S., Aebi, M. The carbohydrate-active enzymes database (CAZy) in 2013. Lombard, V., Golaconda Ramulu, H., Drula, E., Coutinho, P. The eukaryotic linear motif resource-2018 update. High-throughput generation of synthetic antibodies from highly functional minimalist phage-displayed libraries. Structure of the yeast oligosaccharyltransferase complex gives insight into eukaryotic N-glycosylation. Characterization of the single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei using synthetic peptides and lipid-linked oligosaccharide analogs. Chemo-enzymatic synthesis of lipid-linked GlcNAc 2Man 5 oligosaccharides using recombinant Alg1, Alg2 and Alg11 proteins. ALG6-CDG: a recognizable phenotype with epilepsy, proximal muscle weakness, ataxia and behavioral and limb anomalies. Clinical utility gene card for: ALG6 defective congenital disorder of glycosylation. Congenital disorders of glycosylation: an update on defects affecting the biosynthesis of dolichol-linked oligosaccharides. Isolation of the ALG6 locus of Saccharomyces cerevisiae required for glucosylation in the N-linked glycosylation pathway. Reiss, G., te Heesen, S., Zimmerman, J., Robbins, P. Two yeast mutations in glucosylation steps of the asparagine glycosylation pathway. Emerging structural insights into glycosyltransferase-mediated synthesis of glycans. Three monophyletic superfamilies account for the majority of the known glycosyltransferases. The dolichol pathway of N-linked glycosylation. Assembly of asparagine-linked oligosaccharides. Our results define the architecture of ER-luminal GT-C enzymes and provide a structural basis for understanding their catalytic mechanisms. This residue is conserved in the GT-C superfamily. Functional analysis of ALG6 variants identified a catalytic aspartate residue that probably acts as a general base. A second cryo-electron microscopy structure of ALG6 bound to an analogue of dolichylphosphate-glucose at 3.9 Å resolution revealed the active site of the enzyme. We used synthetic analogues of dolichylphosphate-linked and dolichylpyrophosphate-linked sugars and enzymatic glycan extension to generate donor and acceptor substrates using purified enzymes of the ALG pathway to recapitulate the activity of ALG6 in vitro. Comparison with reported GT-C structures suggests that GT-C enzymes contain a modular architecture with a conserved module and a variable module, each with distinct functional roles. Here we present the cryo-electron microscopy structure of yeast ALG6 at 3.0 Å resolution, which reveals a previously undescribed transmembrane protein fold. The responsible enzymes-ALG3, ALG9, ALG12, ALG6, ALG8 and ALG10-are glycosyltransferases of the C-superfamily (GT-Cs), which are loosely defined as containing membrane-spanning helices and processing an isoprenoid-linked carbohydrate donor substrate 3, 4. The final seven steps occur in the lumen of the endoplasmic reticulum (ER) and require dolichylphosphate-activated mannose and glucose as donor substrates 2. In eukaryotic protein N-glycosylation, a series of glycosyltransferases catalyse the biosynthesis of a dolichylpyrophosphate-linked oligosaccharide before its transfer onto acceptor proteins 1.
0 Comments
Leave a Reply. |