7msn
SunS glycosin S-glycosyltransferase
Structural highlights
FunctionSUNS_BACSU Transfers a hexose moiety onto 'Cys-41' of bacteriocin sublancin-168 (SunA). Accepts UDP-glucose (UDP-Glc), UDP-N-acetylglucosamine (UDP-GlcNAc), UDP-galactose (UDP-Gal), UDP-xylose (UDP-Xyl) and GDP-mannose as substrate.[1] Publication Abstract from PubMedAttachment of sugars to nitrogen and oxygen in peptides is ubiquitous in biology, but glycosylation of sulfur atoms has only been recently described. Here, we characterize two S-glycosyltransferases SunS and ThuS that selectively glycosylate one of five Cys residues in their substrate peptides; substitution of this Cys with Ser results in a strong decrease in glycosylation activity. Crystal structures of SunS and ThuS in complex with UDP-glucose or a derivative reveal an unusual architecture in which a glycosyltransferase type A (GTA) fold is decorated with additional domains to support homodimerization. Dimer formation creates an extended cavity for the substrate peptide, drawing functional analogy with O-glycosyltransferases involved in cell wall biosynthesis. This extended cavity contains a sharp bend that may explain the site selectivity of the glycosylation because the target Cys is in a Gly-rich stretch that can accommodate the bend. These studies establish a molecular framework for understanding the unusual S-glycosyltransferases. Structural and mechanistic investigations of protein S-glycosyltransferases.,Fujinami D, Garcia de Gonzalo CV, Biswas S, Hao Y, Wang H, Garg N, Lukk T, Nair SK, van der Donk WA Cell Chem Biol. 2021 Dec 16;28(12):1740-1749.e6. doi:, 10.1016/j.chembiol.2021.06.009. Epub 2021 Jul 21. PMID:34283964[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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