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PDBsum entry 2wc2
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Transcription regulator
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PDB id
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2wc2
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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 basis for camp-Mediated allosteric control of the catabolite activator protein.
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Authors
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N.Popovych,
S.R.Tzeng,
M.Tonelli,
R.H.Ebright,
C.G.Kalodimos.
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Ref.
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Proc Natl Acad Sci U S A, 2009,
106,
6927-6932.
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PubMed id
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Abstract
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The cAMP-mediated allosteric transition in the catabolite activator protein
(CAP; also known as the cAMP receptor protein, CRP) is a textbook example of
modulation of DNA-binding activity by small-molecule binding. Here we report the
structure of CAP in the absence of cAMP, which, together with structures of CAP
in the presence of cAMP, defines atomic details of the cAMP-mediated allosteric
transition. The structural changes, and their relationship to cAMP binding and
DNA binding, are remarkably clear and simple. Binding of cAMP results in a
coil-to-helix transition that extends the coiled-coil dimerization interface of
CAP by 3 turns of helix and concomitantly causes rotation, by approximately 60
degrees , and translation, by approximately 7 A, of the DNA-binding domains
(DBDs) of CAP, positioning the recognition helices in the DBDs in the correct
orientation to interact with DNA. The allosteric transition is stabilized
further by expulsion of an aromatic residue from the cAMP-binding pocket upon
cAMP binding. The results define the structural mechanisms that underlie
allosteric control of this prototypic transcriptional regulatory factor and
provide an illustrative example of how effector-mediated structural changes can
control the activity of regulatory proteins.
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