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Structural and Enzymatic Analysis of MshA from Corynebacterium glutamicum

Journal Article · · Journal of Biological Chemistry

The glycosyltransferase termed MshA catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to 1-l-myo-inositol-1-phosphate in the first committed step of mycothiol biosynthesis. The structure of MshA from Corynebacterium glutamicum was determined both in the absence of substrates and in a complex with UDP and 1-l-myo-inositol-1-phosphate. MshA belongs to the GT-B structural family whose members have a two-domain structure with both domains exhibiting a Rossman-type fold. Binding of the donor sugar to the C-terminal domain produces a 97 rotational reorientation of the N-terminal domain relative to the C-terminal domain, clamping down on UDP and generating the binding site for 1-l-myo-inositol-1-phosphate. The structure highlights the residues important in binding of UDP-N-acetylglucosamine and 1-l-myo-inositol-1-phosphate. Molecular models of the ternary complex suggest a mechanism in which the {beta}-phosphate of the substrate, UDP-N-acetylglucosamine, promotes the nucleophilic attack of the 3-hydroxyl group of 1-l-myo-inositol-1-phosphate while at the same time promoting the cleavage of the sugar nucleotide bond.

Research Organization:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Organization:
Doe - Office Of Science
DOE Contract Number:
AC02-98CH10886
OSTI ID:
959584
Report Number(s):
BNL--82570-2009-JA
Journal Information:
Journal of Biological Chemistry, Journal Name: Journal of Biological Chemistry Journal Issue: 23 Vol. 283; ISSN 0021-9258; ISSN JBCHA3
Country of Publication:
United States
Language:
English