A putative Mycobacterium tuberculosis glyoxalase Rv0801 promotes bacterial fitness by alleviating methylglyoxal stress and blunts NRF2-mediated antioxidant defenses.

INTRODUCTION: Methylglyoxal (MG), a toxic metabolic byproduct, functions as a potent antibacterial weapon deployed by macrophages. The glyoxalase system represents the primary microbial defense against MG, yet its role in Mycobacterium tuberculosis pathogenesis remains incompletely defined.

METHODS: To define the function of the putative M. tuberculosis glyoxalase Rv0801 and its homolog MSMEG_5827, we used genetic engineering in Mycobacterium smegmatis MC2-155, coupled with growth and macrophage infection assays. Host mechanisms were dissected via transcriptomic and biochemical analysis of the KEAP1-NRF2 antioxidant pathway and pro-inflammatory responses.

RESULTS: We demonstrate that Rv0801, conferring robust MG tolerance in a mycothiol (MSH)-dependent manner, is essential for bacterial fitness under MG stress. Mechanistically, Rv0801 orchestrates a dual-pathway interference within infected macrophages: by detoxifying MG, it suppresses the host KEAP1-NRF2 antioxidant pathway and concurrently dampens immunoprotective responses. This coordinated suppression compromises macrophage-mediated bacterial clearance.

DISCUSSION: These findings establish Rv0801-mediated MG stress management as a critical virulence mechanism and highlight the bacterial glyoxalase as a promising target for tuberculosis therapy.