PDBsum entry 2pex

Transcription regulator

PDB id: 2pex

Contents

Protein chains

136 a.a. *

Ligands

FMT ×7

Waters ×175

* Residue conservation analysis

PDB id:

2pex

Name:

Transcription regulator

Title:

Structure of reduced c22s ohrr from xanthamonas campestris

Structure:

Transcriptional regulator ohrr. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Xanthomonas campestris. Organism_taxid: 339. Gene: ohrr. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.236 R-free: 0.278

Authors:

R.G.Brennan,K.J.Newberry

Key ref:

K.J.Newberry et al. (2007). Structural mechanism of organic hydroperoxide induction of the transcription regulator OhrR. Mol Cell, 28, 652-664. PubMed id: 18042459 DOI: 10.1016/j.molcel.2007.09.016

Date:

03-Apr-07 Release date: 11-Dec-07

Protein chains

Q93R11  (Q93R11_XANCH) -  Organic hydroperoxide resistance transcriptional regulator from Xanthomonas campestris pv. phaseoli

Seq: 153 a.a.

Struc: 136 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.molcel.2007.09.016

Mol Cell 28:652-664 (2007)

PubMed id: 18042459

Structural mechanism of organic hydroperoxide induction of the transcription regulator OhrR.

K.J.Newberry, M.Fuangthong, W.Panmanee, S.Mongkolsuk, R.G.Brennan.

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.

Selected figure(s)

Figure 5.
Figure 5. Structural Changes Resulting from OHP Oxidation of OhrR
(A) Rearrangement of tyrosines surrounding C22 upon OHP oxidation. Oxidized OhrR is colored teal and light blue, and reduced OhrR is colored magenta and light pink. Hydrogen bonds are shown as black dashed lines, and key residues are shown as sticks.
(B) Steric clash of Y36 with α5 upon OHP oxidation of C22. van der Waals contacts are shown as magenta dashed lines for the reduced and teal dashed lines for the oxidized form. Key residues are shown as sticks.

Figure 6.
Figure 6. Key Interactions Centered about Helix α2 in the Reduced and Oxidized Forms of Xc OhrR
(A) van der Waals contacts made by L17 in the reduced OhrR structure are shown as dotted lines. Residues making direct and networked contacts to L17 are shown as blue sticks. The OHP sensor cysteine residue is shown as yellow sticks, and Y36 and Y47 are shown as red sticks.
(B) Rearrangement of the L17 hydrophobic pocket and disorder of helix 1b upon oxidation. Residues interacting with L17 in the reduced form are shown in their new positions in the oxidized form. The side-chain color scheme is the same as in (A).

The above figures are reprinted by permission from Cell Press: Mol Cell (2007, 28, 652-664) copyright 2007.

Figures were selected by an automated process.