PMID:9237996
| Citation |
Ding, H and Demple, B (1997) In vivo kinetics of a redox-regulated transcriptional switch. Proc. Natl. Acad. Sci. U.S.A. 94:8445-9 |
|---|---|
| Abstract |
SoxR is a transcription activator governing a cellular response to superoxide and nitric oxide in Escherichia coli. SoxR protein is a homodimer, and each monomer has a redox-active [2Fe-2S] cluster. Oxidation and reduction of the [2Fe-2S] clusters can reversibly activate and inactivate SoxR transcriptional activity. Here, we use electron paramagnetic resonance spectroscopy to follow the redox-switching process of SoxR protein in vivo. SoxR [2Fe-2S] clusters were in the fully reduced state during normal aerobic growth, but were completely oxidized after only 2-min aerobic exposure of the cells to superoxide-generating agents such as paraquat. The oxidized SoxR [2Fe-2S] clusters were rapidly re-reduced in vivo once the oxidative stress was removed. The in vivo kinetics of SoxR [2Fe-2S] cluster oxidation and reduction exactly paralleled the increase and decrease of transcription of soxS, the target gene for SoxR. The kinetic analysis also revealed that an oxidative stress-linked decrease in soxS mRNA stability contributes to the rapid attainment of a new steady state after SoxR activation. Such a redox stress-related change in soxS mRNA stability may represent a new level of biological control. |
| Links | |
| Keywords |
Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Gene Expression Regulation, Bacterial; Magnetic Resonance Spectroscopy; Oxidation-Reduction; Transcription Factors/genetics; Transcription Factors/metabolism; Transcription, Genetic |
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