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PDBsum entry 2fbk
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Transcription
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PDB id
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2fbk
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References listed in PDB file
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Key reference
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Title
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The crystal structure of the transcriptional regulator hucr from deinococcus radiodurans reveals a repressor preconfigured for DNA binding.
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Authors
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T.Bordelon,
S.P.Wilkinson,
A.Grove,
M.E.Newcomer.
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Ref.
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J Mol Biol, 2006,
360,
168-177.
[DOI no: ]
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PubMed id
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Abstract
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We report here the 2.3 A resolution structure of the hypothetical uricase
regulator (HucR) from Deinococcus radiodurans R1. HucR, a member of the MarR
family of DNA-binding proteins, was previously shown to repress its own
expression as well as that of a uricase, a repression that is alleviated both in
vivo and in vitro upon binding uric acid, the substrate for uricase. As uric
acid is a potent scavenger of reactive oxygen species, and as D. radiodurans is
known for its remarkable resistance to DNA-damaging agents, these observations
indicate a novel oxidative stress response mechanism. The crystal structure of
HucR in the absence of ligand or DNA reveals a dimer in which the DNA
recognition helices are preconfigured for DNA binding. This configuration of
DNA-binding domains is achieved through an apparently stable dimer interface
that, in contrast to what is observed in other MarR homologs for which
structures have been determined, shows little conformational heterogeneity in
the absence of ligand. An additional amino-terminal segment, absent from other
MarR homologs, appears to brace the principal helix of the dimerization
interface. However, although HucR is preconfigured for DNA binding, the presence
of a stacked pair of symmetry-related histidine residues at a central pivot
point in the dimer interface suggests a mechanism for a conformational change to
attenuate DNA binding.
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Figure 2.
Figure 2. Superposition of HucR and OhrR structures. The
DNA-bound structure of OhrR (1Z9C) is in magenta and HucR is in
blue. The recognition helices are in lighter shades.
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Figure 5.
Figure 5. A region of the 2F[o]-F[c] electron density map.
The map is contoured at 1s. The region corresponds to the dimer
interface and the stacking of symmetry-related His51 residues is
apparent.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
360,
168-177)
copyright 2006.
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