Structure and regulation of the mycobacterial F1-ATPase

Abstract

Tuberculosis infection has been the leading cause of mortality due to the infectious agent Mycobacterium tuberculosis (Mtb). The prevalence of antibiotic-resistant strains drives a need to develop inhibitors that target essential complexes in Mtb. One such complex is the F1FO ATP synthase, composed of a H+-pumping Fo- and the catalytic F1 sector. The F-ATP synthase is essential for the viability of Mtb and has been validated as a drug-target. Unlike other bacteria, the mycobacterial F-ATP synthase possess latent ATP hydrolysis, which prevents changes in the proton motive force of the metabolically dormant pathogen. In this study, we addressed how mycobacteria reserves its ATP pools and elucidated the structural features contributing to the suppression of ATPase activity. Mutagenesis and biochemical studies unravelled epitopes in the α-, γ- and ε subunits, that contribute to latent ATP hydrolysis. Of interest, a mycobacterial specific C-terminal extension in the α-subunit was identified to be the major contributor towards ATP hydrolysis inhibition. A 3.5 Å determined cryo-EM structure of the F1-ATPase visualized that this extension inhibits the enzyme from hydrolysing ATP by preventing rotation of subunit γ as visualized in a single molecule assay. The ɑ-γ interaction epitope opened the door to unravel a new inhibitor.