Bactericidal mode of action of bedaquiline

Kiel Hards, Jennifer R. Robson, Michael Berney, Lisa Shaw, Dirk Bald, Anil Koul, Koen Andries, Gregory M. Cook

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Abstract

Objectives: It is not fully understood why inhibiting ATP synthesis in Mycobacterium species leads to death in non-replicating cells. We investigated the bactericidal mode of action of the anti-tubercular F1Fo-ATP synthase inhibitor bedaquiline (Sirturo™) in order to further understand the lethality of ATP synthase inhibition. Methods: Mycobacterium smegmatis strains were used for all the experiments. Growth and survival during a bedaquiline challenge were performed in multiple media types. A time-course microarray was performed during initial bedaquiline challenge in minimal medium. Oxygen consumption and proton-motive force measurements were performed on whole cells and inverted membrane vesicles, respectively. Results: A killing of 3 log.10 cfu/mL was achieved 4-fold more quickly in minimal medium (a glycerol carbon source) versus rich medium (LB with Tween 80) during bedaquiline challenge. Assessing the accelerated killing condition, we identified a transcriptional remodelling of metabolism that was consistent with respiratory dysfunction but inconsistent with ATP depletion. In glycerol-energized cell suspensions, bedaquiline caused an immediate 2.3-fold increase in oxygen consumption. Bedaquiline collapsed the transmembrane pH gradient, but not the membrane potential, in a dose-dependent manner. Both these effects were dependent on binding to the F.1F.o-ATP synthase. Conclusions: Challenge with bedaquiline results in an electroneutral uncoupling of respiration-driven ATP synthesis. This may be a determinant of the bactericidal effects of bedaquiline, while ATP depletion may be a determinant of its delayed onset of killing. We propose that bedaquiline binds to and perturbs the a-c subunit interface of the Fo, leading to futile proton cycling, which is known to be lethal to mycobacteria.

Original languageEnglish (US)
Article numberdkv054
Pages (from-to)2028-2037
Number of pages10
JournalJournal of Antimicrobial Chemotherapy
Volume70
Issue number7
DOIs
StatePublished - Dec 6 2015

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Keywords

  • Antimycobacterial agents
  • FF-ATP synthase
  • Mycobacteria
  • R207910
  • TMC207

ASJC Scopus subject areas

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

Cite this

Hards, K., Robson, J. R., Berney, M., Shaw, L., Bald, D., Koul, A., Andries, K., & Cook, G. M. (2015). Bactericidal mode of action of bedaquiline. Journal of Antimicrobial Chemotherapy, 70(7), 2028-2037. [dkv054]. https://doi.org/10.1093/jac/dkv054