The anti-mycobacterial activity of the cytochrome bcc inhibitor Q203 can be enhanced by small-molecule inhibition of cytochrome bd

• Published in: Scientific reports Vol. 8; no. 1; pp. 2625 - 7
• Main Authors: Lu, Ping, Asseri, Amer H, Kremer, Martijn, Maaskant, Janneke, Ummels, Roy, Lill, Holger, Bald, Dirk
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 08.02.2018; Nature Publishing Group UK; Nature Portfolio
• Subjects: Antitubercular Agents - pharmacology; Bactericidal activity; Cytochrome; Cytochrome bd; Cytochromes - antagonists & inhibitors; Drug development; Electron transport; Electron Transport - drug effects; Energy metabolism; Imidazoles - pharmacology; Membrane vesicles; Metabolism; Mitochondrial DNA; Mycobacterium smegmatis - drug effects; Mycobacterium tuberculosis; Mycobacterium tuberculosis - drug effects; Piperidines - pharmacology; Pyridines - pharmacology; Quinolones - pharmacology; Tuberculosis
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-20989-8

Mycobacterial energy metabolism currently attracts strong attention as new target space for development of anti-tuberculosis drugs. The imidazopyridine Q203 targets the cytochrome bcc complex of the respiratory chain, a key component in energy metabolism. Q203 blocks growth of Mycobacterium tuberculosis at nanomolar concentrations, however, it fails to actually kill the bacteria, which may limit the clinical applicability of this candidate drug. In this report we show that inhibition of cytochrome bd, a parallel branch of the mycobacterial respiratory chain, by aurachin D invoked bactericidal activity of Q203. In biochemical assays using inverted membrane vesicles from Mycobacterium tuberculosis and Mycobacterium smegmatis we found that inhibition of respiratory chain activity by Q203 was incomplete, but could be enhanced by inactivation of cytochrome bd, either by genetic knock-out or by inhibition with aurachin D. These results indicate that simultaneously targeting the cytochrome bcc and the cytochrome bd branch of the mycobacterial respiratory chain may turn out as effective strategy for combating M. tuberculosis.