title: Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees.
abstract: The 3 angstrom resolution crystal structure of the Escherichia coli catabolite gene activator protein (CAP) complexed with a 30-base pair DNA sequence shows that the DNA is bent by 90 degrees. This bend results almost entirely from two 40 degrees kinks that occur between TG/CA base pairs at positions 5 and 6 on each side of the dyad axis of the complex. DNA sequence discrimination by CAP derives both from sequence-dependent distortion of the DNA helix and from direct hydrogen-bonding interactions between three protein side chains and the exposed edges of three base pairs in the major groove of the DNA. The structure of this transcription factor--DNA complex provides insights into possible mechanisms of transcription activation.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.
authors.forename: S C
authors.initials: SC
authors.lastname: Schultz
authors.forename: G C
authors.initials: GC
authors.lastname: Shields
authors.forename: T A
authors.initials: TA
authors.lastname: Steitz
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases