Isoleucyl-tRNA synthetase depletion reveals vulnerabilities in Mycobacterium abscessus and Mycobacterium marinum.

Mycobacterium abscessus and Mycobacterium marinum are nontuberculous mycobacteria that pose significant challenges due to their high drug resistance and persistence in hostile host environments. Aminoacyl-tRNA synthetases, such as isoleucyl-tRNA synthetase (IleRS), are crucial for protein synthesis and represent promising targets for antimicrobial development. This study investigates the role of IleRS in mycobacterial growth, metabolism, and pathogenesis using conditional gene silencing combined with microbiological, metabolomic, and transcriptomic analyses. Our findings indicate that IleRS is essential for mycobacterial growth and survival during infection. Depletion of IleRS disrupts branched-chain amino acid and pantothenate biosynthesis, leading to metabolic vulnerabilities and impaired persistence in macrophages and in mouse infection models. Based on our metabolic findings, we tested drug susceptibility and found that depletion of IleRS enhances sensitivity to pyrazinamide, highlighting a synergistic effect that could improve tuberculosis treatment. Furthermore, global gene set enrichment analysis reveals that IleRS knockdown might promote bacterial clearance by upregulating cholesterol metabolism and lysosome organization processes in macrophages. These results establish IleRS as a potential therapeutic target, offering new insights into reducing drug resistance and enhancing current treatment regimens for mycobacterial infections, including tuberculosis.