5e9t
From Proteopedia
Crystal structure of GtfA/B complex
Structural highlights
Function[GTF1_STRGN] An N-acetylglucosaminyl transferase that is part of the accessory SecA2/SecY2 system specifically required to export GspB, a serine-rich repeat cell wall protein usually encoded upstream in the same operon. Required for correct glycosylation of GspB. Upon coexpression in E.coli with Gtf2 (GtfB) glycosylates GspB constructs. Glycosylation probably occurs intracellularly.[1] [GTF2_STRGN] A stabilizing protein that is part of the accessory SecA2/SecY2 system specifically required to export GspB, a serine-rich repeat cell wall protein encoded upstream in the same operon. Required for correct glycosylation of GspB. Upon coexpression in E.coli with Gtf1 (GtfA) glycosylates GspB constructs. Stabilizes the glycosylation activity of Gtf1 (By similarity).[2] Publication Abstract from PubMedO-glycosylation of Ser and Thr residues is an important process in all organisms, which is only poorly understood. Such modification is required for the export and function of adhesin proteins that mediate the attachment of pathogenic Gram-positive bacteria to host cells. Here, we have analyzed the mechanism by which the cytosolic O-glycosyltransferase GtfA/B of Streptococcus gordonii modifies the Ser/Thr-rich repeats of adhesin. The enzyme is a tetramer containing two molecules each of GtfA and GtfB. The two subunits have the same fold, but only GtfA contains an active site, whereas GtfB provides the primary binding site for adhesin. During a first phase of glycosylation, the conformation of GtfB is restrained by GtfA to bind substrate with unmodified Ser/Thr residues. In a slow second phase, GtfB recognizes residues that are already modified with N-acetylglucosamine, likely by converting into a relaxed conformation in which one interface with GtfA is broken. These results explain how the glycosyltransferase modifies a progressively changing substrate molecule. Mechanism of a cytosolic O-glycosyltransferase essential for the synthesis of a bacterial adhesion protein.,Chen Y, Seepersaud R, Bensing BA, Sullam PM, Rapoport TA Proc Natl Acad Sci U S A. 2016 Feb 16. pii: 201600494. PMID:26884191[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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