5hec | pdb_00005hec
CgT structure in dimer
Structural highlights
FunctionPublication Abstract from PubMedSerine-rich repeat glycoproteins (SRRPs) conserved in streptococci and staphylococci are important for bacterial colonization and pathogenesis. Fap1, a well-studied SRRP is a major surface constituent of Streptococcus parasanguinis and is required for bacterial adhesion and biofilm formation. Biogenesis of Fap1 is a multi-step process that involves both glycosylation and secretion. A series of glycosyltransferases catalyze sequential glycosylation of Fap1. We have identified a unique hybrid protein dGT1(dual glycosyltransferase 1) that contains two distinct domains. N-terminal DUF1792 is a novel GT-D type glycosyltransferase, transferring Glc residues to Glc-GlcNAc-modified Fap1. C-terminal dGT1 (CgT) is predicted to possess a typical GT-A type glycosyltransferase, however the activity remains unknown. In this study, we determine that CgT is a distinct glycosyltransferase, transferring GlcNAc residues to Glc-Glc-GlcNAc-modified Fap1. 2.4 A X-ray crystal structure reveals that CgT has a unique binding domain consisting of three alpha helices in addition to a typical GT-A type glycosyltransferase domain. The helical domain is crucial for the oligomerization of CgT. Structural and biochemical studies revealed that the helix domain is required for the protein-protein interaction and crucial for the glycosyltransferase activity of CgT in vitro and in vivo. As the helix domain presents a novel structural fold, we conclude that CgT represents a new member of GT-A type glycosyltransferases. A New Helical Binding Domain Mediates a Unique Glycosyltransferase Activity of a Bifunctional Protein.,Zhang H, Zhou M, Yang T, Haslam SM, Dell A, Wu H J Biol Chem. 2016 Aug 17. pii: jbc.M116.731695. PMID:27539847[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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