Mutational Analysis of Mycobacterial F-ATP Synthase Subunit Leads to a Potent Enzyme Inhibitor

While many bacteria are able to bypass the requirement for oxidative phosphorylation when grown on carbohydrates, Mycobacterium tuberculosis is unable to do so. Differences of amino acid composition and structural features of the mycobacterial F-ATP synthase (alpha(3)beta(3):gamma:delta:epsilon:a:b:b':c(9)) compared to its prokaryotic or human counterparts were recently elucidated and paved avenues for the discovery of molecules interfering with various regulative mechanisms of this essential energy converter. In this context, the mycobacterial peripheral stalk subunit delta came into focus, which displays a unique N-terminal 111-amino acid extension. Here, mutants of recombinant mycobacterial subunit delta were characterized, revealing significant reduction in ATP synthesis and demonstrating essentiality of this subunit for effective catalysis. These results provided the basis for the generation of a four-feature model forming a delta receptor-based pharmacophore and to identify a potent subunit delta inhibitor DeMF1 via in silico screening. The successful targeting of the delta subunit demonstrates the potential to advance delta's flexible coupling as a new area for the development of F-ATP synthase inhibitors.