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PDBsum entry 2pex
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Transcription regulator
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PDB id
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2pex
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References listed in PDB file
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Key reference
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Title
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Structural mechanism of organic hydroperoxide induction of the transcription regulator ohrr.
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Authors
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K.J.Newberry,
M.Fuangthong,
W.Panmanee,
S.Mongkolsuk,
R.G.Brennan.
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Ref.
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Mol Cell, 2007,
28,
652-664.
[DOI no: ]
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PubMed id
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Abstract
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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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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.
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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).
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2007,
28,
652-664)
copyright 2007.
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Secondary reference #1
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Title
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Novel organic hydroperoxide-Sensing and responding mechanisms for ohrr, A major bacterial sensor and regulator of organic hydroperoxide stress.
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Authors
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W.Panmanee,
P.Vattanaviboon,
L.B.Poole,
S.Mongkolsuk.
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Ref.
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J Bacteriol, 2006,
188,
1389-1395.
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PubMed id
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