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Title
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Structure of a complex of catabolite gene activator protein and cyclic AMP refined at 2.5 A resolution.
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Authors
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I.T.Weber,
T.A.Steitz.
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Ref.
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J Mol Biol, 1987,
198,
311-326.
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PubMed id
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Abstract
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The structure of a dimer of the Escherichia coli catabolite gene activator
protein has been refined at 2.5 A resolution to a crystallographic R-factor of
20.7% starting with coordinates fitted to the map at 2.9 A resolution. The two
subunits are in different conformations and each contains one bound molecule of
the allosteric activator, cyclic AMP. The amino-terminal domain is linked to the
smaller carboxy-terminal domain by a nine-residue hinge region that exists in
different conformations in the two subunits, giving rise to approximately a 30
degree rotation between the positions of the small domains relative to the
larger domains. The amino-terminal domain contains an antiparallel beta-roll
structure in which the interstrand hydrogen bonding is well-determined. The
beta-roll can be described as a long antiparallel beta-ribbon that folds into a
right-handed supercoil and forms part of the cyclic AMP binding site. Each
cyclic AMP molecule is in an anti conformation and has ionic and hydrogen bond
interactions with both subunits.
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