Mechanism of HS-mediated protection against oxidative stress in .

Endogenous hydrogen sulfide (HS) renders bacteria highly resistant to oxidative stress, but its mechanism remains poorly understood. Here, we report that 3-mercaptopyruvate sulfurtransferase (3MST) is the major source of endogenous HS in Cellular resistance to HO strongly depends on the activity of , a gene that encodes 3MST. Deletion of the ferric uptake regulator (Fur) renders ∆ cells hypersensitive to HO Conversely, induction of chromosomal from a strong pLtetO-1 promoter (P -) renders ∆ cells fully resistant to HO Furthermore, the endogenous level of HS is reduced in ∆ or ∆ ∆ cells but restored after the addition of an iron chelator dipyridyl.