Structure Guided Lead Generation toward Nonchiral <i>M. tuberculosis</i> Thymidylate Kinase Inhibitors

In recent years, thymidylate kinase (TMPK), an enzyme indispensable for bacterial DNA biosynthesis, has been pursued for the development of new antibacterial agents including against <i>Mycobacterium tuberculosis</i>, the causative agent for the widespread infectious disease tuberculosis (TB). In response to a growing need for more effective anti-TB drugs, we have built upon our previous efforts toward the exploration of novel and potent <i>Mycobacterium tuberculosis</i> TMPK (<i>Mt</i>TMPK) inhibitors, and reported here the design of a novel series of non-nucleoside inhibitors of <i>Mt</i>TMPK. The inhibitors display hitherto unexplored interactions in the active site of <i>Mt</i>TMPK, offering new insights into structure–activity relationships. To investigate the discrepancy between enzyme inhibitory activity and the whole-cell activity, experiments with efflux pump inhibitors and efflux pump knockout mutants were performed. The minimum inhibitory concentrations of particular inhibitors increased significantly when determined for the efflux pump <i>mmr</i> knockout mutant, which partly explains the observed dissonance