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. 2007 Nov 30;28(4):652-64.
doi: 10.1016/j.molcel.2007.09.016.

Structural mechanism of organic hydroperoxide induction of the transcription regulator OhrR

Kate J Newberry  1 , Mayuree Fuangthong, Warunya Panmanee, Skorn Mongkolsuk, Richard G Brennan
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Free article

Structural mechanism of organic hydroperoxide induction of the transcription regulator OhrR

Kate J Newberry et al. Mol Cell. .
Free article

Abstract

The Xanthomonas campestris transcription regulator OhrR contains a reactive cysteine residue (C22) that upon oxidation by organic hydroperoxides (OHPs) forms an intersubunit disulphide bond with residue C127'. Such modification induces the expression of a peroxidase that reduces OHPs to their less toxic alcohols. Here, we describe the structures of reduced and OHP-oxidized OhrR, visualizing the structural mechanism of OHP induction. Reduced OhrR takes a canonical MarR family fold with C22 and C127' separated by 15.5 A. OHP oxidation results in the disruption of the Y36'-C22-Y47' interaction network and dissection of helix alpha5, which then allows the 135 degrees rotation and 8.2 A translation of C127', formation of the C22-C127' disulphide bond, and alpha6-alpha6' helix-swapped reconfiguration of the dimer interface. These changes result in the 28 degrees rigid body rotations of each winged helix-turn-helix motif and DNA dissociation. Similar effector-induced rigid body rotations are expected for most MarR family members.

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