Mycobacterium tuberculosis H(2)S Functions as a Sink to Modulate Central Metabolism, Bioenergetics, and Drug Susceptibility

H(2)S is a potent gasotransmitter in eukaryotes and bacteria. Host-derived H(2)S has been shown to profoundly alter M. tuberculosis (Mtb) energy metabolism and growth. However, compelling evidence for endogenous production of H(2)S and its role in Mtb physiology is lacking. We show that multidrug-resistant and drug-susceptible clinical Mtb strains produce H(2)S, whereas H(2)S production in non-pathogenic M. smegmatis is barely detectable. We identified Rv3684 (Cds1) as an H(2)S-producing enzyme in Mtb and show that cds1 disruption reduces, but does not eliminate, H(2)S production, suggesting the involvement of multiple genes in H(2)S production. We identified endogenous H(2)S to be an effector molecule that maintains bioenergetic homeostasis by stimulating respiration primarily via cytochrome bd. Importantly, H(2)S plays a key role in central metabolism by modulating the balance between oxidative phosphorylation and glycolysis, and it functions as a sink to recycle sulfur atoms back to cysteine to maintain sulfur homeostasis. Lastly, Mtb-generated H(2)S regulates redox homeostasis and susceptibility to anti-TB drugs clofazimine and rifampicin. These findings reveal previously unknown facets of Mtb physiology and have implications for routine laboratory culturing, understanding drug susceptibility, and improved diagnostics.