Transcription factor YcjW controls the emergency HS production in E. coli.

Prokaryotes and eukaryotes alike endogenously generate the gaseous molecule hydrogen sulfide (HS). Bacterial HS acts as a cytoprotectant against antibiotics-induced stress and promotes redox homeostasis. In E. coli, endogenous HS production is primarily dependent on 3-mercaptopyruvate sulfurtransferase (3MST), encoded by mstA. Here, we show that cells lacking 3MST acquire a phenotypic suppressor mutation resulting in compensatory HS production and tolerance to antibiotics and oxidative stress. Using whole genome sequencing, we identified a non-synonymous mutation within an uncharacterized LacI-type transcription factor, ycjW. We then mapped regulatory targets of YcjW and discovered it controls the expression of carbohydrate metabolic genes and thiosulfate sulfurtransferase PspE. Induction of pspE expression in the suppressor strain provides an alternative mechanism for HS biosynthesis. Our results reveal a complex interaction between carbohydrate metabolism and HS production in bacteria and the role, a hitherto uncharacterized transcription factor, YcjW, plays in linking the two.