Inhibiting Mycobacterium tuberculosis CoaBC by targeting a new allosteric site

Coenzyme A (CoA) is a fundamental co-factor for all life, involved in numerous metabolic pathways and cellular processes and its biosynthetic pathway has raised substantial interest as a drug target against multiple pathogens including Mycobacterium tuberculosis. The biosynthesis of CoA is performed in five steps. However, in the vast majority of prokaryotes including M. tuberculosis, a single bifunctional protein, CoaBC, catalyses the second and third steps. Depletion of CoaBC was found to be bactericidal in M. tuberculosis. Here we report the first structure of a full length CoaBC, from the model organism Mycobacterium smegmatis, describe how it is organised as a dodecamer and regulated by CoA thioesters. A high-throughput biochemical screen focusing on CoaB identified two inhibitors with different chemical scaffolds. Hit expansion led to the discovery of potent inhibitors of M. tuberculosis CoaB. Crucially we further show that these compounds bind to a novel cryptic allosteric site within CoaB.