The dynamic interaction of the N- and C-terminal domains of mycobacterial F-ATP synthase subunit ε is proposed to contribute to efficient coupling of H+-translocation and ATP synthesis. Here, we investigate crosstalk between both subunit ε domains by introducing chromosomal atpC missense mutations in the C-terminal helix 2 of ε predicted to disrupt inter domain and subunit ε-α crosstalk and therefore coupling. The ε mutant εR105A,R111A,R113A,R115A (ε4A) showed decreased intracellular ATP, slower growth rates and lower molar growth yields on non-fermentable carbon sources. Cellular respiration and metabolism were all accelerated in the mutant strain indicative of dysregulated oxidative phosphorylation. The ε4A mutant exhibited an altered colony morphology and was hypersusceptible to cell wall-acting antimicrobials suggesting defective cell wall biosynthesis. In silico screening identified a novel mycobacterial F-ATP synthase inhibitor disrupting ε’s coupling activity demonstrating the potential to advance this regulation as a new area for mycobacterial F-ATP synthase inhibitor development.

The F1FO‐ATP synthase is required for growth and viability of Mycobacterium tuberculosis and is a validated clinical target. A mycobacterium‐specific loop of the enzyme's rotary γ subunit plays a role in the coupling of ATP synthesis within the enzyme complex. We report the discovery of a novel antimycobacterial, termed GaMF1, that targets this γ subunit loop. Biochemical and NMR studies show that GaMF1 inhibits ATP synthase activity by binding to the loop. GaMF1 is bactericidal and is active against multidrug‐ as well as bedaquiline‐resistant strains. Chemistry efforts on the scaffold revealed a dynamic structure activity relationship and delivered analogues with nanomolar potencies. Combining GaMF1 with bedaquiline or novel diarylquinoline analogues showed potentiation without inducing genotoxicity or phenotypic changes in a human embryonic stem cell reporter assay. These results suggest that GaMF1 presents an attractive lead for the discovery of a novel class of anti‐tuberculosis F‐ATP synthase inhibitors.

In contrast to most bacteria, the mycobacterial F1FO‐ATP synthase (α3:β3:γ:δ:ε:a:b:b’:c9) does not perform ATP hydrolysis‐driven proton translocation. Although subunits α, γ and ε of the catalytic F1‐ATPase component α3:β3:γ:ε have all been implicated in the suppression of the enzyme’s ATPase activity, the mechanism remains poorly defined. Here, we brought the central stalk subunit ε into focus by generating the recombinant Mycobacterium smegmatis F1‐ATPase (MsF1‐ATPase), whose 3D low‐resolution structure is presented, and its ε‐free form MsF1αβγ, which showed an eightfold ATP hydrolysis increase and provided a defined system to systematically study the segments of mycobacterial ε’s suppression of ATPase activity. Deletion of four amino acids at ε’s N terminus, mutant MsF1αβγεΔ2‐5, revealed similar ATP hydrolysis as MsF1αβγ. Together with biochemical and NMR solution studies of a single, double, triple and quadruple N‐terminal ε‐mutants, the importance of the first N‐terminal residues of mycobacterial ε in structure stability and latency is described. Engineering ε’s C‐terminal mutant MsF1αβγεΔ121 and MsF1αβγεΔ103‐121 with deletion of the C‐terminal residue D121 and the two C‐terminal ɑ‐helices, respectively, revealed the requirement of the very C terminus for communication with the catalytic α3β3‐headpiece and its function in ATP hydrolysis inhibition. Finally, we applied the tools developed during the study for an in silico screen to identify a novel subunit ε‐targeting F‐ATP synthase inhibitor.

The F1FO‐ATP synthase is required for growth and viability of Mycobacterium tuberculosis and is a validated clinical target. A mycobacterium‐specific loop of the enzyme's rotary γ subunit plays a role in the coupling of ATP synthesis within the enzyme complex. We report the discovery of a novel antimycobacterial, termed GaMF1, that targets this γ subunit loop. Biochemical and NMR studies show that GaMF1 inhibits ATP synthase activity by binding to the loop. GaMF1 is bactericidal and is active against multidrug‐ as well as bedaquiline‐resistant strains. Chemistry efforts on the scaffold revealed a dynamic structure activity relationship and delivered analogues with nanomolar potencies. Combining GaMF1 with bedaquiline or novel diarylquinoline analogues showed potentiation without inducing genotoxicity or phenotypic changes in a human embryonic stem cell reporter assay. These results suggest that GaMF1 presents an attractive lead for the discovery of a novel class of anti‐tuberculosis F‐ATP synthase inhibitors.

No abstract

The F 1 F O -ATP synthase is required for the viability of tuberculosis (TB) and nontuberculous mycobacteria (NTM) and has been validated as a drug target. Here, we present the cryo-EM structures of the Mycobacterium smegmatis F 1 -ATPase and the F 1 F O -ATP synthase with different nucleotide occupation within the catalytic sites and visualize critical elements for latent ATP hydrolysis and efficient ATP synthesis.

No abstract

Zika virus (ZIKV) relies on its nonstructural protein 5 (NS5) for capping and synthesis of the viral RNA. Recent small‐angle X‐ray scattering (SAXS) data of recombinant ZIKV NS5 protein showed that it is dimeric in solution. Here, we present insights into the critical residues responsible for its dimer formation. SAXS studies of the engineered ZIKV NS5 mutants revealed that R681A mutation on NS5 (NS5R681A) disrupts the dimer formation and affects its RNA‐dependent RNA polymerase activity as well as the subcellular localization of NS5R681A in mammalian cells. The critical residues involved in the dimer arrangement of ZIKV NS5 are discussed, and the data provide further insights into the diversity of flaviviral NS5 proteins in terms of their propensity for oligomerization.