Direct oxidation of the [2Fe-2S] cluster in SoxR protein by superoxide: distinct differential sensitivity to superoxide-mediated signal transduction.

ABSTRACT: The [2Fe-2S] transcription factor SoxR is activated by reversible one-electron oxidation of its [2Fe-2S] cluster, leading to enhanced production of various antioxidant proteins through induction of the soxRS regulon in Escherichia coli. Recently, there has been considerable debate about whether superoxide (O(2)(•)) activates SoxR directly. To elucidate the underlying activation mechanism, we investigated SoxR interaction with O(2)(•) using pulse radiolysis. Radiolytically generated hydrated electrons reduced the oxidized form of the [2Fe-2S] cluster of SoxR within 2 μs. A subsequent increase in absorption in the visible region corresponding to reoxidation of the [2Fe-2S] cluster was observed on a time scale of milliseconds. Addition of human copper/zinc superoxide dismutase inhibited this

SUBMITTER: Fujikawa M 

PROVIDER: S-EPMC3471711 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature