Identification of inhibitors of Mycobacterium tuberculosis cytochrome bd oxidase and investigation of residues important for its function and regulation

The bacterium Mycobacterium tuberculosis is responsible for the highest number of deaths

caused by a single infectious agent. With almost a third of the global population infected with

M .tuberculosis it is imperative that new effective treatment options are identified. This need

for new inhibitors has been exacerbated by the rapid rise of drug resistance in M. tuberculosis

including resistance to drugs only recently approved for use. One area of study that has shown

great promise for the identification of new treatment options has been the electron transport

chain of M. tuberculosis. In particular the cytochrome bd oxidase, of which the structure has

recently been resolved, has shown promise as a candidate drug target. Dual inhibition of the

terminal oxidases, cytochrome bcc:aa3 super-complex and cytochrome bd oxidase has been

shown to be lethal to M. tuberculosis and inhibition of the cytochrome bd oxidase has been

shown to synergise with other electron transport chain inhibitors. In this study compounds

identified by in-silico screening were screened in vitro for the ability to effectively and

selectively inhibit the M. tuberculosis cytochrome bd oxidase. The methods developed allowed

for the identification of several lead compounds able to inhibit the M. tuberculosis cytochrome

bd oxidase and determination of their potency through IC50 assays. In addition, the study

investigated the impact of substitution mutations of key residues of M. tuberculosis cytochrome

bd oxidase and identified differing impacts.