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DNA binding shifts the redox potential of the transcription factor SoxR

Gorodetsky, Alon A. and Dietrich, Lars E. P. and Lee, Paul E. and Demple, Bruce and Newman, Dianne K. and Barton, Jacqueline K. (2008) DNA binding shifts the redox potential of the transcription factor SoxR. Proceedings of the National Academy of Sciences of the United States of America, 105 (10). pp. 3684-3689. ISSN 0027-8424. PMCID PMC2268809. doi:10.1073/pnas.0800093105.

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Electrochemistry measurements on DNA-modified electrodes are used to probe the effects of binding to DNA on the redox potential of SoxR, a transcription factor that contains a [2Fe-2S] cluster and is activated through oxidation. A DNA-bound potential of +200 mV versus NHE (normal hydrogen electrode) is found for SoxR isolated from Escherichia coli and Pseudomonas aeruginosa. This potential value corresponds to a dramatic shift of +490 mV versus values found in the absence of DNA. Using Redmond red as a covalently bound redox reporter affixed above the SoxR binding site, we also see, associated with SoxR binding, an attenuation in the Redmond red signal compared with that for Redmond red attached below the SoxR binding site. This observation is consistent with a SoxR-binding-induced structural distortion in the DNA base stack that inhibits DNA-mediated charge transport to the Redmond red probe. The dramatic shift in potential for DNA-bound SoxR compared with the free form is thus reconciled based on a high-energy conformational change in the SoxR–DNA complex. The substantial positive shift in potential for DNA-bound SoxR furthermore indicates that, in the reducing intracellular environment, DNA-bound SoxR is primarily in the reduced form; the activation of DNA-bound SoxR would then be limited to strong oxidants, making SoxR an effective sensor for oxidative stress. These results more generally underscore the importance of using DNA electrochemistry to determine DNA-bound potentials for redox-sensitive transcription factors because such binding can dramatically affect this key protein property.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Gorodetsky, Alon A.0000-0002-3811-552X
Newman, Dianne K.0000-0003-1647-1918
Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2008 by the National Academy of Sciences. Contributed by Jacqueline K. Barton, January 4, 2008 (sent for review December 7, 2007). Published online before print March 3, 2008. This work was supported by National Institutes of Health Grant GM61077 (to J.K.B.), the Howard Hughes Medical Institute (D.K.N.), and a European Molecular Biology Organization Long-Term Fellowship (to L.E.P.D.). Author contributions: A.A.G. and L.E.P.D. contributed equally to this work; A.A.G., L.E.P.D., P.E.L., B.D., D.K.N., and J.K.B. designed research; A.A.G., L.E.P.D., and P.E.L. performed research; A.A.G., L.E.P.D., P.E.L., B.D., D.K.N., and J.K.B. analyzed data; and A.A.G., L.E.P.D., P.E.L., B.D., D.K.N., and J.K.B. wrote the paper. The authors declare no conflict of interest.
Funding AgencyGrant Number
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
European Molecular Biology Organization (EMBO)UNSPECIFIED
Subject Keywords:DNA electrochemistry; iron-sulfur proteins; oxidative stress
Issue or Number:10
PubMed Central ID:PMC2268809
Record Number:CaltechAUTHORS:GORpnas08
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Official Citation:Alon A. Gorodetsky, Lars E. P. Dietrich, Paul E. Lee, Bruce Demple, Dianne K. Newman, and Jacqueline K. Barton DNA binding shifts the redox potential of the transcription factor SoxR PNAS 2008 105 (10) 3684-3689; published ahead of print March 3, 2008, doi:10.1073/pnas.0800093105
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11186
Deposited By: Tony Diaz
Deposited On:22 Jul 2008 22:32
Last Modified:08 Nov 2021 21:34

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