Download MendeleyRIalpha subunit of PKA: a cAMP-free structure reveals a hydrophobic capping mechanism for docking cAMP into site B.
Wu, J., Brown, S., Xuong, N.H., Taylor, S.S.(2004) Structure 12: 1057-1065
- PubMed: 15274925
- DOI: https://doi.org/10.1016/j.str.2004.03.022
- Primary Citation of Related Structures:
1RL3 - PubMed Abstract:
In eukaryotes the primary target for cAMP, a ubiquitous second messenger, is cAMP-dependent protein kinase (PKA). Understanding how binding and release of cAMP changes the cAMP binding domains and then triggers long-range allosteric responses is an important challenge. This conformational switching requires structure solutions of cAMP binding domains in cAMP-bound and cAMP-free states. We describe for the first time a crystal structure of the cAMP binding domains of PKA type Ialpha regulatory subunit where site A is occupied by cGMP and site B is unoccupied. The structure reveals that the carboxyl terminus of domain B serves as a hydrophobic cap, locking the cyclic nucleotide via its adenine ring into the beta-barrel. In the absence of cAMP, the "cap" is released via an extension of the C-terminal helix. This simple hinge mechanism for binding and release of cAMP also provides a mechanism for allosteric communication between sites A and B.
Organizational Affiliation:
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
