Solution structure and mutational analysis of pituitary adenylate cyclase-activating polypeptide binding to the extracellular domain of PAC1-RS.Sun, C., Song, D., Davis-Taber, R.A., Barrett, L.W., Scott, V.E., Richardson, P.L., Pereda-Lopez, A., Uchic, M.E., Solomon, L.R., Lake, M.R., Walter, K.A., Hajduk, P.J., Olejniczak, E.T.
(2007) Proc.Natl.Acad.Sci.Usa 104: 7875-7880
- PubMed: 17470806
- DOI: 10.1073/pnas.0611397104
- PubMed Abstract:
The pituitary adenylate cyclase-activating polypeptide (PACAP) receptor is a class II G protein-coupled receptor that contributes to many different cellular functions including neurotransmission, neuronal survival, and synaptic plasticity. The soluti ...
The pituitary adenylate cyclase-activating polypeptide (PACAP) receptor is a class II G protein-coupled receptor that contributes to many different cellular functions including neurotransmission, neuronal survival, and synaptic plasticity. The solution structure of the potent antagonist PACAP (residues 6'-38') complexed to the N-terminal extracellular (EC) domain of the human splice variant hPAC1-R-short (hPAC1-R(S)) was determined by NMR. The PACAP peptide adopts a helical conformation when bound to hPAC1-R(S) with a bend at residue A18' and makes extensive hydrophobic and electrostatic interactions along the exposed beta-sheet and interconnecting loops of the N-terminal EC domain. Mutagenesis data on both the peptide and the receptor delineate the critical interactions between the C terminus of the peptide and the C terminus of the EC domain that define the high affinity and specificity of hormone binding to hPAC1-R(S). These results present a structural basis for hPAC1-R(S) selectivity for PACAP versus the vasoactive intestinal peptide and also differentiate PACAP residues involved in binding to the N-terminal extracellular domain versus other parts of the full-length hPAC1-R(S) receptor. The structural, mutational, and binding data are consistent with a model for peptide binding in which the C terminus of the peptide hormone interacts almost exclusively with the N-terminal EC domain, whereas the central region makes contacts to both the N-terminal and other extracellular parts of the receptor, ultimately positioning the N terminus of the peptide to contact the transmembrane region and result in receptor activation.
Global Pharmaceutical Discovery Division, Abbott Laboratories, Abbott Park, IL 60064, USA.