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Proc Natl Acad Sci U S A. 1997 Apr 1;94(7):2843-7.

The structure of a CAP-DNA complex having two cAMP molecules bound to each monomer.

Author information

1
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.

Abstract

The 2.2 A resolution crystal structure of the Escherichia coli catabolite gene activator protein (CAP) complexed with cAMP and a 46-bp DNA fragment reveals a second cAMP molecule bound to each protein monomer. The second cAMP is in the syn conformation and is located on the DNA binding domain interacting with the helix-turn-helix, a beta-hairpin from the regulatory domain and the DNA (via water molecules). The presence of this second cAMP site resolves the apparent discrepancy between the NMR and x-ray data on the conformation of cAMP, and explains the cAMP concentration-dependent behaviors of the protein. In addition, this site's close proximity to mutations affecting transcriptional activation and its water-mediated interactions with a DNA recognition residue (E181) and DNA raise the possibility that this site has biological relevance.

PMID:
9096308
PMCID:
PMC20284
DOI:
10.1073/pnas.94.7.2843
[Indexed for MEDLINE]
Free PMC Article

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