5E9U: Crystal Structure Of Gtfa/b Complex Bound To Udp And Glcnac

Citation:
Abstract
O-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.
PDB ID: 5E9UDownload
MMDB ID: 137012
PDB Deposition Date: 2015/10/15
Updated in MMDB: 2017/10
Experimental Method:
x-ray diffraction
Resolution: 3.84  Å
Source Organism:
Similar Structures:
Biological Unit for 5E9U: tetrameric; determined by author and by software (PISA)
Molecular Components in 5E9U
Label Count Molecule
Proteins (4 molecules)
2
Glycosyltransferase Gtf1
Molecule annotation
2
Glycosyltransferase-stabilizing Protein Gtf2
Molecule annotation
Chemicals (4 molecules)
1
1
2
1
3
2
* Click molecule labels to explore molecular sequence information.

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