Helix-Turn-Helix DNA binding domain of the SoxR transcription regulator
Helix-turn-helix (HTH) transcriptional regulator SoxR. The global regulator, SoxR, up-regulates gene expression of another transcription activator, SoxS, which directly stimulates the oxidative stress regulon genes in E. coli. The soxRS response renders the bacterial cell resistant to superoxide-generating agents, macrophage-generated nitric oxide, organic solvents, and antibiotics. The SoxR proteins share the N-terminal DNA binding domain with other transcription regulators of the MerR superfamily that promote transcription by reconfiguring the unusually long spacer between the -35 and -10 promoter elements. They also harbor a regulatory C-terminal domain containing an iron-sulfur center.