Structure and subunit arrangement of Mycobacterial F1FO ATP synthase and novel features of the unique mycobacterial subunit δ

Kamariah, Neelagandan; Huber, Roland G.; Nartey, Wilson; Bhushan, Shashi; Bond, Peter J.; Grüber, Gerhard

doi:10.1016/j.jsb.2019.05.008

Cited by 25 publications

(43 citation statements)

References 45 publications

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“…The pumping of protons generates a transmembrane pH gradient and contributes to the membrane potential, both of which are components of the proton motive force [38]. This force drives the rotation of the F-ATP synthase c-ring, which consequently drives ATP synthesis at the enzyme's α3β3 catalytic headpiece via the enzyme's central stalk subunits γ and ε [38][39][40][41].…”

Section: Mechanisms Of Action Of Bdq-before Tbaj-876′s Discoverymentioning

confidence: 99%

Re-Understanding the Mechanisms of Action of the Anti-Mycobacterial Drug Bedaquiline

2019

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Bedaquiline (BDQ) inhibits ATP generation in Mycobacterium tuberculosis by interfering with the F-ATP synthase activity. Two mechanisms of action of BDQ are broadly accepted. A direct mechanism involves BDQ binding to the enzyme's c-ring to block its rotation, thus inhibiting ATP synthesis in the enzyme's catalytic α 3 β 3 -headpiece. An indirect mechanism involves BDQ uncoupling electron transport in the electron transport chain from ATP synthesis at the F-ATP synthase. In a recently uncovered second direct mechanism, BDQ binds to the enzyme's ε-subunit to disrupt its ability to link c-ring rotation to ATP synthesis at the α 3 β 3 -headpiece. However, this mechanism is controversial as the drug's binding affinity for the isolated ε-subunit protein is moderate and spontaneous resistance mutants in the ε-subunit cannot be isolated. Recently, the new, structurally distinct BDQ analogue TBAJ-876 was utilized as a chemical probe to revisit BDQ's mechanisms of action. In this review, we first summarize discoveries on BDQ's mechanisms of action and then describe the new insights derived from the studies of TBAJ-876. The TBAJ-876 investigations confirm the c-ring as a target, while also supporting a functional role for targeting the ε-subunit. Surprisingly, the new findings suggest that the uncoupler mechanism does not play a key role in BDQ's anti-mycobacterial activity.Concentration (MIC) of 0.002-0.013 µg/mL [10,11]). This potent activity holds true in vivo where BDQ has demonstrated accelerated sterilizing activity [12], with four months of BDQ treatment being as efficacious as six months of first-line drug treatment of Mtb-infected mice [13]. Importantly, BDQ also displays bactericidal activity against non-replicating Mtb at therapeutically attainable concentrations [14,15]. In the clinical setting, the usage of BDQ has produced promising results. Studies have shown that the usage of the drug for drug-resistant TB treatment improved sputum conversion and reduced chemotherapy duration and relapse [16][17][18][19]. Hence, new BDQ-containing drug regimens are currently being explored in Phase III clinical trials, such as the STREAM and SimpliciTB trials [20]. One such trial, the Nix-TB trial, resulted in the recent US FDA approval of the BDQ-pretomanid-linezolid six months, all-oral regimen for the treatment of drug-resistant TB [21,22].

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Section: Mechanisms Of Action Of Bdq-before Tbaj-876′s Discoverymentioning

confidence: 99%

Re-Understanding the Mechanisms of Action of the Anti-Mycobacterial Drug Bedaquiline

2019

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“…The mycobacterial enzyme is composed of a membrane‐embedded F O complex (subunits a : b : b ′: c 9 ), which are responsible for H + ‐translocation from the periplasmic space to the cytoplasmic side, and the F 1 part (subunits α 3 :β 3 :γ:ϵ), which uses the proton‐motive force to synthesize ATP within the three catalytic αβ‐pairs (Figure A). This catalytic α 3 β 3 ‐headpiece is linked with the F O part via the two rotating central stalk subunits γ and ϵ, as well as the peripheral stalk subunits b , b ′ and δ …”

Section: Introductionmentioning

confidence: 99%

Discovery of a Novel Mycobacterial F‐ATP Synthase Inhibitor and its Potency in Combination with Diarylquinolines

Hotra

Ragunathan

et al. 2020

Angewandte Chemie

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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.

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“…The mycobacterial F-ATP synthase is composed of two parts, a membrane-embedded F O domain and a cytoplasmic F 1 domain (1, 2). The F O domain is made up of subunits a and b and the c ring (composed of nine c subunits [3]), while the F 1 domain is made up of subunits γ, δ, and ε and the α 3 :β 3 headpiece (4).…”

Section: Introductionmentioning

confidence: 99%

“…The F O domain is made up of subunits a and b and the c ring (composed of nine c subunits [3]), while the F 1 domain is made up of subunits γ, δ, and ε and the α 3 :β 3 headpiece (4). The α 3 :β 3 headpiece is connected to the c ring via a central stalk composed of subunits ε and γ and a peripheral stalk composed of subunits b and δ (2). Proton translocation from the periplasmic space to the cytoplasmic side is associated with rotation of the c ring.…”

Section: Introductionmentioning

confidence: 99%

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TBAJ-876 Retains Bedaquiline’s Activity against Subunits c and ε of Mycobacterium tuberculosis F-ATP Synthase

Sarathy

Ragunathan

Shin

et al. 2019

Antimicrob Agents Chemother

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The antituberculosis drug bedaquiline (BDQ) inhibits Mycobacterium tuberculosis F-ATP synthase by interfering with two subunits. Drug binding to the c subunit stalls the rotation of the c ring, while binding to the ε subunit blocks coupling of c ring rotation to ATP synthesis at the catalytic α3:β3 headpiece. BDQ is used for the treatment of drug-resistant tuberculosis. However, the drug is highly lipophilic, displays a long terminal half-life, and has a cardiotoxicity liability by causing QT interval prolongation. Recent medicinal chemistry campaigns have resulted in the discovery of 3,5-dialkoxypyridine analogues of BDQ that are less lipophilic, have higher clearance, and display lower cardiotoxic potential. TBAJ-876, which is a new developmental compound of this series, shows attractive antitubercular activity and efficacy in a murine tuberculosis model. Here, we asked whether TBAJ-876 and selected analogues of the compound retain BDQ’s mechanism of action. Biochemical assays showed that TBAJ-876 is a potent inhibitor of mycobacterial F-ATP synthase. Selection of spontaneous TBAJ-876-resistant mutants identified missense mutations at BDQ’s binding site on the c subunit, suggesting that TBAJ-876 retains BDQ’s targeting of the c ring. Susceptibility testing against a strain overexpressing the ε subunit and a strain harboring an engineered mutation in BDQ’s ε subunit binding site suggest that TBAJ-876 retains BDQ’s activity on the ε subunit. Nuclear magnetic resonance (NMR) titration studies confirmed that TBAJ-876 binds to the ε subunit at BDQ’s binding site. We show that TBAJ-876 retains BDQ’s antimycobacterial mode of action. The developmental compound inhibits the mycobacterial F-ATP synthase via a dual-subunit mechanism of interfering with the functions of both the enzyme’s c and ε subunits.

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Structure and subunit arrangement of Mycobacterial F1FO ATP synthase and novel features of the unique mycobacterial subunit δ

Cited by 25 publications

References 45 publications

Re-Understanding the Mechanisms of Action of the Anti-Mycobacterial Drug Bedaquiline

Re-Understanding the Mechanisms of Action of the Anti-Mycobacterial Drug Bedaquiline

Discovery of a Novel Mycobacterial F‐ATP Synthase Inhibitor and its Potency in Combination with Diarylquinolines

TBAJ-876 Retains Bedaquiline’s Activity against Subunits c and ε of Mycobacterium tuberculosis F-ATP Synthase

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