Functional reconstitution of the Mycobacterium tuberculosis long-chain acyl-CoA carboxylase and identification of new acyl-CoA carboxylase inhibitors

DIACOVICH L; GRAMAJO HUGO; COLACCINI F; BAZET LYONET BERNARDO; GAGO GABRIELA

Lucca

Conferencia; New Approaches, New Chemical Entities and New Targets for Tuberculosis Drugs. Tuberculosis Drug Discovery & Development.; 2017

Gordon Research Conference

M. tuberculosis produces a large number of structurally diverse lipids that have been implicated in the pathogenicity, persistence and antibiotic resistance of this organism. Most building blocks involved in the biosynthesis of all these lipids are generated by acyl-CoA carboxylases (ACCase) whose subunit composition and physiological roles have not yet been clearly established. A rather controversial data in the literature refers to the exact protein composition and substrate specificity of the enzyme complex that produces the long-chain α-carboxy-acyl-CoAs; one of the substrates involved in the last step of condensation mediated by the polyketide synthase Pks13 to synthesize mature mycolic acids. Here we have successfully reconstituted the so called long-chain acyl-CoA carboxylase complex (LCC) from its purified components: the α-subunit AccA3, the ε-subunit AccE5 and the two β-subunits AccD4 and AccD5, and demonstrated that the four subunits are essential for its LCC activity. Furthermore, we also showed by substrate competition experiments and the use of a specific inhibitor of the AccD5 subunit, that its role in the carboxylation of the long acyl-CoAs, as part of the LCC complex, was structural rather than catalytic. Our work and others have demonstrated that ACCase5 and 6 are also essential for Mycobacterium viability, suggesting that they are good targets for identifying and developing new antimycobacterial compounds. We have now screened several libraries and found new promising ACCase inhibitors that hit these two enzyme complexes.