title: Protein conformational changes of the oxidative stress sensor, SoxR, upon redox changes of the [2Fe-2S] cluster probed with ultraviolet resonance Raman spectroscopy.
abstract: The [2Fe-2S] transcription factor, SoxR, a member of the MerR family, functions as a bacterial sensor of oxidative stress in Escherichia coli. SoxR is activated by reversible one-electron oxidation of the [2Fe-2S] cluster and enhances the production of various antioxidant proteins through the SoxRS regulon. Ultraviolet resonance Raman (UVRR) spectroscopic analysis of SoxR revealed conformational changes upon reduction of the [2Fe-2S] cluster in the absence and presence of promoter oligonucleotide. UVRR spectra reflected the environmental or structural changes of Trp following reduction. Notably, the environment around Trp91 contacting the [2Fe-2S] cluster was altered to become more hydrophilic, whereas that around Trp98 exhibited a small change to become more hydrophobic. In addition, changes in cation-π interactions between the [2Fe-2S] cluster and Trp91 were suggested. On the other hand, the environment around Tyr was barely affected by the [2Fe-2S] reduction. Binding of the promoter oligonucleotide triggered changes in Tyr located in the DNA-binding domain, but not Trp. Furthermore, conformational changes induced upon reduction of DNA-bound SoxR were not significantly different from those of DNA-free SoxR.
authors: The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan. kobayasi@sanken.osaka-u.ac.jp
authors: Kazuo
authors: K
authors: Kobayashi
authors: Misao
authors: M
authors: Mizuno
authors: Mayu
authors: M
authors: Fujikawa
authors: Yasuhisa
authors: Y
authors: Mizutani
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D014157:Transcription Factors; C070724:SoxR protein, Bacteria