Accumulating evidence suggests that bactericidal activity of some antibiotics may not be directly initiated by target inhibition. The activity of isoniazid (INH), a key first-line bactericidal anti-tuberculosis drug currently known to inhibit mycolic acid synthesis, becomes extremely poor under stress conditions, such as hypoxia and starvation. This suggests that the target inhibition may not fully explain the bactericidal activity of the drug. Here, we report that INH rapidly increased M. bovis BCG cellular ATP levels and enhanced oxygen consumption. The INH-triggered ATP increase and bactericidal activity were strongly compromised by Q203 and bedaquiline inhibiting mycobacterial cytochrome bc₁ and F₀F₁ ATP synthase, respectively. Moreover, the antioxidant N-acetylcysteine (NAC) but not 4-hydroxy-TEMPO (TEMPOL) abrogated the INH-triggered ATP increase and killing. These results reveal a link between the energetic (ATP) perturbation and INH9s killing. Furthermore, the INH-induced energetic perturbation and killing was also abrogated by chemical inhibition of NADH dehydrogenases (NDHs) and succinate dehydrogenases (SDHs), linking INH9s bactericidal activity further to the electron transport chain (ETC) perturbation. This notion was also supported by the observation that INH dissipated mycobacterial membrane potential. Importantly, inhibition of cytochrome bd oxidase significantly reduced cell recovery during INH challenge in a culture settling model, suggesting that the respiratory reprogramming to the cytochrome bd oxidase contributes to the escape of INH killing. This study implicates mycobacterial ETC perturbation through NDHs, SDHs, cytochrome bc₁ and F₀F₁ ATP synthase in INH9s bactericidal activity and pinpoints the participation of the cytochrome bd oxidase in protection against this drug under stress conditions.

Mycobacterium abscessus is intrinsically resistant to most antibiotics, and treatment of its infections is highly challenging. The mechanisms of its intrinsic resistance remain not fully understood.

Mycobacterium abscessus is intrinsically resistant to most antimicrobial agents. The emerging infections caused by M. abscessus and the lack of effective treatment call for rapid attention. Here, we intended to construct a selectable marker-free autoluminescent M. abscessus strain (designated UAlMab) as a real-time reporter strain to facilitate the discovery of effective drugs and regimens for treating M. abscessus . The UAlMab strain was constructed using the dif /Xer recombinase system.

Mycobacterium tuberculosis , the causative agent of human tuberculosis, harbors a branched electron transport chain, preventing the bactericidal action of cytochrome bc ₁ inhibitors (e.g., TB47). Here, we investigated, using luminescent mycobacterial strains, the in vitro combination activity of cytochrome bc ₁ inhibitors and nitric oxide (NO) donors including pretomanid (PMD) and explored the mechanisms of combination activity.

The recalcitrance of pathogenic Mycobacterium tuberculosis, the agent of tuberculosis, to eradication is due to various factors allowing bacteria to escape from stress situations. The mycobacterial chaperone GroEL1, overproduced after macrophage entry and under oxidative stress, could be one of these key players. We previously reported that GroEL1 is necessary for the biosynthesis of phthiocerol dimycocerosate, a virulence-associated lipid and for reducing antibiotic susceptibility. In the present study, we showed that GroEL1, bearing a unique C-terminal histidine-rich region, is required for copper tolerance during Mycobacterium bovis BCG biofilm growth. Mass spectrometry analysis demonstrated that GroEL1 displays high affinity for copper ions, especially at its C-terminal histidine-rich region. Furthermore, the binding of copper protects GroEL1 from destabilization and increases GroEL1 ATPase activity. Altogether, these findings suggest that GroEL1 could counteract copper toxicity, notably in the macrophage phagosome, and further emphasizes that M. tuberculosis GroEL1 could be an interesting antitubercular target.