Induction of the soxRS regulon of Escherichia coli by superoxide.
The soxRS regulon orchestrates a multifaceted defense against oxidative stress, by inducing the transcription of approximately 15 genes. The induction of this regulon by redox agents, known to mediate O-2 production, led to the view that O-2 is one signal to which it responds. However, redox cycling agents deplete cellular reductants while producing O-2, and one may question whether the regulon responds to the depletion of some cytoplasmic reductant or to O-2, or both. We demonstrate that raising [O-2] by mutational deletion of superoxide dismutases and/or by addition of paraquat, both under aerobic conditions, causes induction of a member of the soxRS regulon and that a mutational defect in soxRS eliminates that induction. This establishes that O-2, directly or indirectly, can cause induction of this defensive regulon.
Liochev
S I
SI
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
Benov
L
L
Touati
D
D
Fridovich
I
I
D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D005649:Fumarate Hydratase / Q000096:biosynthesis / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008956:Models, Chemical; D018085:Regulon / Q000187:drug effects*; D017384:Sequence Deletion; D013481:Superoxides / Q000494:pharmacology*; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D013481:Superoxides; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli; C095842:fumarase C; D005649:Fumarate Hydratase