The Bacillus subtilis spx gene encodes a global transcriptional regulator that mediates the cellular response to oxidative stress through interactions with RNA polymerase. This work identifies and characterizes a novel intergenic promoter, P3, that drives spx expression in response to thiol‑specific oxidative stress. P3 is recognized by σᴀ‑RNA polymerase and is negatively regulated by the transcriptional repressors PerR and YodB. Biochemical and genetic analyses demonstrate that oxidative conditions relieve repression by impairing repressor binding. In addition to regulating spx, YodB controls genes involved in detoxification of thiol‑reactive compounds, revealing overlapping stress‑response networks that protect cells from oxidative damage.
