The Use of Short lived Isotopes for Exploring Drug Binding Partners of Isoniazid in Mycobacterium Tuberculosis

Abstract

Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB), is a serious global health threat. The mycobacterial cell wall is composed of mycolic acids, which rely on the synthesis of long chain fatty acids by the fatty acid biosynthesis pathway (FASII) which is a target for some of the common anti‐TB drugs such as isoniazid. Following activation of isoniazid, it forms a covalent adduct with NAD(H) which inhibits InhA, the FASII enoyl reductase enzyme, in vitro. While it is clear that the adduct inhibits InhA, there is considerable evidence that the mode of action of isoniazid is complex and that it interacts with other proteins in the cell. In order to answer some of the questions concerning the protein targets, we are incorporating a short lived radioisotope into isoniazid. Bacteria will then be exposed to the labeled drug and fractionated under non‐denaturing conditions using methods such as size exclusion chromatography and isoelectric focusing with in‐line radiation detection to identify fractions containing protein‐drug complexes.