Regulation of the soxRS Oxidative Stress Regulon

Gaudu, Philippe; Moon, Namdoo; Weiss, Bernard

doi:10.1074/jbc.272.8.5082

Cited by 133 publications

(76 citation statements)

References 26 publications

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“…The resting SoxR protein is a homodimer that coordinates one [2Fe-2S] + cluster per subunit. When redox-cycling agents were added to cells in which SoxR was overproduced, EPR spectroscopy detected the oxidation of the cluster to a +2 state (30,31). In vitro inspection showed that this oxidation event caused a conformational change in the dimeric protein, perhaps due to the gain of electrostatic repulsion between the two oxidized clusters.…”

Section: The Soxr(s) Regulator Of the Response To Superoxide Stressmentioning

confidence: 99%

Cellular Defenses against Superoxide and Hydrogen Peroxide

Imlay

2008

Annu. Rev. Biochem.

1,335

1,310

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Life evolved in an anaerobic world; therefore, fundamental enzymatic mechanisms and biochemical pathways were refined and integrated into metabolism in the absence of any selective pressure to avoid reactivity with oxygen. After photosystem 2 appeared, environmental oxygen levels rose very slowly. During this time microorganisms acquired oxygen tolerance by jettisoning enzymes that use glycyl radicals and low-potential iron-sulfur clusters, which can be directly poisoned by oxygen. They also developed mechanisms to defend themselves against O 2 − and hydrogen peroxide, partially reduced oxygen species that are generated as inadvertent by-products of aerobic metabolism. These species are more chemically reactive than is molecular oxygen itself. Contemporary organisms have inherited both the vulnerabilities and the defenses of these ancestral microbes. Current research seeks to identify these, and bacteria comprise an exceptionally accessible experimental system that has provided the many of the answers. This manuscript reviews recent developments and identifies remaining puzzles.

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Section: The Soxr(s) Regulator Of the Response To Superoxide Stressmentioning

confidence: 99%

Cellular Defenses against Superoxide and Hydrogen Peroxide

Imlay

2008

Annu. Rev. Biochem.

1,335

1,310

View full text Add to dashboard Cite

show abstract

“…In E. coli cells, SoxR is maintained in its reduced inactive form (8,9), but when cells are exposed to superoxide (O 2 . )-generating compounds, the [2Fe-2S] cluster of SoxR undergoes univalent oxidation to yield the oxidized active form (10). The only known target of activated SoxR is the soxS gene in E. coli (11).…”

Section: The [2fe-2s] Transcription Factor Soxr Is Activated By Revermentioning

confidence: 99%

Direct Oxidation of the [2Fe-2S] Cluster in SoxR Protein by Superoxide

Fujikawa

Kobayashi

Kozawa

2012

Journal of Biological Chemistry

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“…The ability of SoxR to activate transcription is controlled by the oxidation state of its [2Fe-2S] centers, which undergo one-electron oxidation/reduction with a midpoint redox potential of Ϫ285 mV (6,24,37,38). Therefore, the mere presence of [2Fe-2S] centers is not sufficient for SoxR activity, but rather, their ability to undergo oxidation/reduction is a critical feature.…”

Section: Redox Activity Of Soxr [2fe-2s] Centers-mentioning

confidence: 99%

“…As described above, the reduced [2Fe-2S] centers of SoxR produce a signature EPR spectrum. Oxidation of the [2Fe-2S] centers, however, eliminates this signal (6,24,37,38). Treatment of cells expressing WT SoxR with the potent redox-cycling agent PMS caused a significant decrease in the EPR signal amplitude, indicating oxidation of the [2Fe-2S] centers (Fig.…”

Section: Redox Activity Of Soxr [2fe-2s] Centers-mentioning

confidence: 99%

“…PMS has a midpoint redox potential (ϩ80 mV) significantly higher than that of PQ (Ϫ450 mV) (39) or SoxR (Ϫ285 mV) (6, 24), and PMS is more effective than PQ at redox-cycling and causing oxidative stress. We used PMS in the in vivo EPR experiments, because PQ is not an effective SoxR-activating agent in E. coli B strains such as BL21 (37). We, therefore, assayed ␤-galactosidase activity in cells expressing WT or mutant SoxR proteins from pSE380-based plasmids after a 1-h treatment with 15 M PMS.…”

Section: Redox Activity Of Soxr [2fe-2s] Centers-mentioning

confidence: 99%

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