The three Mycobacterium tuberculosis antigen 85 isoforms have unique substrates and activities determined by non-active site regions.

ABSTRACT: The three isoforms of antigen 85 (A, B, and C) are the most abundant secreted mycobacterial proteins and catalyze transesterification reactions that synthesize mycolated arabinogalactan, trehalose monomycolate (TMM), and trehalose dimycolate (TDM), important constituents of the outermost layer of the cellular envelope of Mycobacterium tuberculosis. These three enzymes are nearly identical at the active site and have therefore been postulated to exist to evade host immunity. Distal to the active site is a second putative carbohydrate-binding site of lower homology. Mutagenesis of the three isoforms at this second site affected both substrate selectivity and overall catalytic activity in vitro. Using synthetic and natural substrates, we show that these three enzymes exhibit unique selectivit

SUBMITTER: Backus KM 

PROVIDER: S-EPMC4155671 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature