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PDBsum entry 1pnr
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Transcription/DNA
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PDB id
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1pnr
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Crystal structure of laci member, Purr, Bound to DNA: minor groove binding by alpha helices.
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Authors
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M.A.Schumacher,
K.Y.Choi,
H.Zalkin,
R.G.Brennan.
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Ref.
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Science, 1994,
266,
763-770.
[DOI no: ]
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PubMed id
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Abstract
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The three-dimensional structure of a ternary complex of the purine repressor,
PurR, bound to both its corepressor, hypoxanthine, and the 16-base pair purF
operator site has been solved at 2.7 A resolution by x-ray crystallography. The
bipartite structure of PurR consists of an amino-terminal DNA-binding domain and
a larger carboxyl-terminal corepressor binding and dimerization domain that is
similar to that of the bacterial periplasmic binding proteins. The DNA-binding
domain contains a helix-turn-helix motif that makes base-specific contacts in
the major groove of the DNA. Base contacts are also made by residues of
symmetry-related alpha helices, the "hinge" helices, which bind deeply
in the minor groove. Critical to hinge helix-minor groove binding is the
intercalation of the side chains of Leu54 and its symmetry-related mate, Leu54',
into the central CpG-base pair step. These residues thereby act as "leucine
levers" to pry open the minor groove and kink the purF operator by 45
degrees.
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