Volume 270,
Number 17,
Issue of April 28, pp. 10323-10327, 1995
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
Overproduction
and Physical Characterization of SoxR, a 
2Fe-2S
Protein
That Governs an Oxidative Response Regulon in Escherichia coli
Jie
Wu
,
William
R.
Dunham
,
Bernard
Weiss
SoxR protein governs the soxRS (superoxide response)
regulon of Escherichia coli by becoming a transcriptional
activator when the cells are exposed to compounds that mediate
univalent redox reactions, many of which produce superoxide as a
by-product. SoxR was overproduced and purified to near homogeneity from
a strain bearing an expression vector. It could bind specifically to
the soxS operator even in the absence of RNA polymerase. The
aerobically purified protein, which is readily autooxidized, could
activate the transcription of soxS DNA even without exposure
to known inducing agents. SoxR is a globular homodimer. It contains one
[2Fe-2S] cluster per polypeptide chain, as demonstrated by
optical and EPR spectroscopy combined with stoichiometric analysis of
iron content, unpaired-electron-spin density, and reduction by
dithionite. The protein is active in its oxidized
([2Fe-2S]
) state. The presence of a
prosthetic group capable of univalent redox reactions may help to
explain the activation of the regulon in vivo by compounds
that can mediate such reactions.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
