PMID:8969171
| Citation |
Ding, H, Hidalgo, E and Demple, B (1996) The redox state of the [2Fe-2S] clusters in SoxR protein regulates its activity as a transcription factor. J. Biol. Chem. 271:33173-5 |
|---|---|
| Abstract |
SoxR protein is a redox-responsive transcription factor that governs a regulon of oxidative stress and antibiotic resistance genes in Escherichia coli. Purified SoxR contains oxidized [2Fe-2S] clusters and stimulates in vitro transcription of its target gene soxS up to 100-fold. SoxR transcriptional activity, but not DNA binding, is completely dependent on the [2Fe-2S] clusters; apo-SoxR prepared in vitro binds the soxS promoter with unchanged affinity but does not have transcription activity. Thus, modulation of the SoxR [2Fe-2S] clusters was proposed to control the protein's function in transcription. Here, we provide evidence that SoxR with reduced [2Fe-2S] clusters is inactive. Redox titration of purified SoxR revealed a midpoint potential of -285 +/- 10 mV (pH 7.6). In vitro transcription assays showed that SoxR was inactivated when the [2Fe-2S] cluster was reduced (-380 mV), and full activity was restored upon reoxidation (+100 mV). The results suggest that one-electron oxidation and reduction of the [2Fe-2S] cluster regulate SoxR transcriptional activity. |
| Links | |
| Keywords |
Anaerobiosis; Bacterial Proteins/metabolism; Escherichia coli; Iron-Sulfur Proteins/metabolism; Oxidation-Reduction; Plasmids/metabolism; Transcription Factors/metabolism |
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