Identification of a potential anti-nontuberculous mycobacterial drug candidate targeting a mycothiol disulfide reductase.

The resistance of nontuberculous mycobacteria (NTM) to conventional anti-tuberculosis drugs and its growing infection rate year by year urgently require new treatment strategies. Structure-based virtual screening, which can greatly improve efficiency and reduce costs in the early stage of drug development, is an indispensable part of modern drug discovery. In this study, the crystal structure of the mycothiol disulfide reductase from Mycobacterium abscessus (MabMtr) was determined. Through virtual screening, compound AK-968/11492032 was identified as a promising candidate capable of fitting well into the potential MSSM-binding pocket of MabMtr. It was discovered that AK-968/11492032 and its derivatives (Y6B and Y6C) could produce antimicrobial effects on the Mycobacterial type strain Mycobacterium smegmatis. Moreover, microscale thermophoresis analysis was employed to evaluate the high binding affinity of the compounds to MabMtr. Furthermore, the key residues (S14, I47, H451) of MabMtr involved in the interaction with AK-968/11492032 were predicted and confirmed through molecular docking and mutational analysis, MabMtr was verified as the target for it to exert antibacterial effects through in vitro enzyme activity and in vivo gene knockout, complementation, and overexpression. These findings provide a potential development target to develop effective and specific anti-NTM drugs.