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Updated: Mar 14, 2026

Mapping the Binding Site of an Aptamer on ATP Using MicroScale Thermophoresis
Published on: January 7, 2017
A Second, Druggable Binding Site in UDP-Galactopyranose Mutase from Mycobacterium tuberculosis?
Yun Shi1, Cinzia Colombo1, Jijin R A Kuttiyatveetil2
1Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
Abstract:
UDP-galactopyranose mutase (UGM), a key enzyme in the biosynthesis of mycobacterial cell walls, is a potential target for the treatment of tuberculosis. In this work, we investigate binding models of a non-substrate-like inhibitor, MS-208, with M. tuberculosis UGM. Initial saturation transfer difference (STD) NMR experiments indicated a lack of direct competition between MS-208 and the enzyme substrate, and subsequent kinetic assays showed mixed inhibition. We thus hypothesized that MS-208 binds at an allosteric binding site (A-site) instead of the enzyme active site (S-site). A candidate A-site was identified in a subsequent computational study, and the overall hypothesis was supported by ensuing mutagenesis studies of the A-site. Further molecular dynamics studies led us to propose that MS-208 inhibition occurs by preventing complete closure of an active site mobile loop that is necessary for productive substrate binding. The results suggest the presence of an A-site with potential druggability, opening up new opportunities for the development of novel drug candidates against tuberculosis.
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