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Acceptor substrate discrimination in phosphatidyl-myo-inositol mannoside synthesis: structural and mutational analysis of mannosyltransferase corynebacterium glutamicum pimb'

DOI: 10.1074/jbc.M110.165407 DOI Help
PMID: 20843801 PMID Help

Authors: S. M. Batt (University of Birmingham) , T. Jabeen (University of Birmingham) , A. K. Mishra (University of Birmingham) , N. Veerapen (University of Birmingham) , K. Krumbach (Institut für Biotechnologie I, Forschungszentrum Jülich) , L. Eggeling (Institut für Biotechnologie I, Forschungszentrum Jülich) , G. S. Besra (University of Birmingham) , K. Futterer (University of Birmingham)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Biological Chemistry , VOL 285 (48) , PAGES 37741 - 37752

State: Published (Approved)
Published: November 2010
Diamond Proposal Number(s): 6388

Abstract: Long term survival of the pathogen Mycobacterium tuberculosis in humans is linked to the immunomodulatory potential of its complex cell wall glycolipids, which include the phosphatidylinositol mannoside (PIM) series as well as the related lipomannan and lipoarabinomannan glycoconjugates. PIM biosynthesis is initiated by a set of cytosolic α-mannosyltransferases, catalyzing glycosyl transfer from the activated saccharide donor GDP-α-d-mannopyranose to the acceptor phosphatidyl-myo-inositol (PI) in an ordered and regio-specific fashion. Herein, we report the crystal structure of mannosyltransferase Corynebacterium glutamicum PimB′ in complex with nucleotide to a resolution of 2.0 Å. PimB′ attaches mannosyl selectively to the 6-OH of the inositol moiety of PI. Two crystal forms and GDP- versus GDP-α-d-mannopyranose-bound complexes reveal flexibility of the nucleotide conformation as well as of the structural framework of the active site. Structural comparison, docking of the saccharide acceptor, and site-directed mutagenesis pin regio-selectivity to a conserved Asp residue in the N-terminal domain that forces presentation of the correct inositol hydroxyl to the saccharide donor.

Journal Keywords: Binding; Corynebacterium; Crystallography; X-Ray; Mannosyltransferases; Mutagenesis; Site-Directed; Mutation; Phosphatidylinositols; Substrate Specificity

Subject Areas: Biology and Bio-materials


Instruments: I04-Macromolecular Crystallography