title: Structure of a complex of catabolite gene activator protein and cyclic AMP refined at 2.5 A resolution.
abstract: 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.
authors.affiliation: Center for Chemical Physics, National Bureau of Standards, Gaithersburg, MD 20899.
authors.forename: I T
authors.initials: IT
authors.lastname: Weber
authors.forename: T A
authors.initials: TA
authors.lastname: Steitz
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D000242:Cyclic AMP / Q000378:metabolism*; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D004926:Escherichia coli / Q000032:analysis; D006860:Hydrogen Bonding; D046911:Macromolecular Substances; D008958:Models, Molecular; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D002373:Cyclic AMP Receptor Protein; D046911:Macromolecular Substances; D000242:Cyclic AMP