A bioluminescence-based chemical screen identifies a bactericidal naphthalen-1-ylmethanamine scaffold targeting MmpL3 in Mycobacterium abscessus

Abstract

Treatment of Mycobacterium abscessus pulmonary disease (Mabs-PD) is a growing global health challenge. The lack of bactericidal antibiotics effective at therapeutically relevant concentrations underscores an urgent need for drug discovery. Targeting cell wall synthesis is a promising strategy for drug discovery, as exemplified by the clinical success of broad-spectrum β-lactam antibiotics. Here, we employ a bioluminescence-based whole-cell assay optimized to identify compounds that disrupt both cell wall synthesis and oxidative phosphorylation. A focused drug library screen against Mabs reveals a chemically tractable naphthalen-1-ylmethanamine scaffold with potent bactericidal activity. The optimized derivative GM47-1 targets MmpL3, compromises cell wall integrity, induces ATP leakage, and uncouples respiration. Further chemical optimization yields a derivative with nanomolar minimum inhibitory concentration, bactericidal activity against intracellular Mabs, and efficacy in a zebrafish infection model. Together, these findings identify a promising scaffold for therapeutic development and demonstrate the utility of this bioluminescence-based platform for discovering bactericidal agents against Mabs.

Keywords: CP: microbiology; MmpL3; antimicrobial; bactericidal; bioenergetics; cell wall; cell wall inhibition; mycolic acid; non-tuberculous mycobacteria; tuberculosis; uncoupling.