HS Functions as a Sink to Modulate Central Metabolism, Bioenergetics, and Drug Susceptibility.

HS is a potent gasotransmitter in eukaryotes and bacteria. Host-derived HS has been shown to profoundly alter () energy metabolism and growth. However, compelling evidence for endogenous production of HS and its role in physiology is lacking. We show that multidrug-resistant and drug-susceptible clinical strains produce HS, whereas HS production in non-pathogenic is barely detectable. We identified Rv3684 (Cds1) as an HS-producing enzyme in and show that disruption reduces, but does not eliminate, HS production, suggesting the involvement of multiple genes in HS production. We identified endogenous HS to be an effector molecule that maintains bioenergetic homeostasis by stimulating respiration primarily via cytochrome . Importantly, HS 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, -generated HS regulates redox homeostasis and susceptibility to anti-TB drugs clofazimine and rifampicin. These findings reveal previously unknown facets of physiology and have implications for routine laboratory culturing, understanding drug susceptibility, and improved diagnostics.