Open AccessIn vivo kinetics of a redox-regulated transcriptional switch
Author(s) -
Huangen Ding,
Bruce Demple
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.16.8445
Subject(s) - superoxide , redox , nitric oxide , in vivo , chemistry , oxidative stress , biochemistry , microbiology and biotechnology , biophysics , transcription (linguistics) , oxidative phosphorylation , biology , activator (genetics) , gene , enzyme , genetics , linguistics , philosophy , organic chemistry
SoxR is a transcription activator governing a cellular response to superoxide and nitric oxide inEscherichia 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 proteinin 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-reducedin vivo once the oxidative stress was removed. Thein vivo kinetics of SoxR [2Fe–2S] cluster oxidation and reduction exactly paralleled the increase and decrease of transcription ofsoxS , the target gene for SoxR. The kinetic analysis also revealed that an oxidative stress-linked decrease insoxS mRNA stability contributes to the rapid attainment of a new steady state after SoxR activation. Such a redox stress-related change insoxS mRNA stability may represent a new level of biological control.