The structure of a CAP-DNA complex having two cAMP molecules bound to each monomer.
Article Details
- CitationCopy to clipboard
Passner JM, Steitz TA
The structure of a CAP-DNA complex having two cAMP molecules bound to each monomer.
Proc Natl Acad Sci U S A. 1997 Apr 1;94(7):2843-7.
- PubMed ID
- 9096308 [ View in PubMed]
- 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.