Fig. 1.

The cytochrome bc₁:aa₃ is the sole respiratory terminal oxidase in classical M. ulcerans strains. a A single-nucleotide polymorphism (692G>A) converting the tryptophan-encoding codon TGG into the stop codon TAG is present in cydA of all classical M. ulcerans strains. b The cydAB operon present in classical M. ulcerans strains does not encode a functional cyt-bd. Q203-treated M. bovis BCGΔcydAB strains complemented with the cydAB operon from classical lineage, or from Japanese ancestral lineage strains were incubated with Q203 (100 nM) in sealed tubes containing 0.001% methylene blue used as an oxygen sensor. Pictures were taken immediately after closing the tubes (day 0), and 5 days after incubation at 37 °C. Bedaquiline (1 mM) and DMSO (−) were used as controls. c Oxidative phosphorylation pathway in classical M. ulcerans strains, the molecular targets of Q203 and bedaquiline (BDQ) are shown