Solution structure and mutational analysis of pituitary adenylate cyclase-activating polypeptide binding to the extracellular domain of PAC1-RS.
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.
Sun
Chaohong
C
Global Pharmaceutical Discovery Division, Abbott Laboratories, Abbott Park, IL 60064, USA.
Song
Danying
D
Davis-Taber
Rachel A
RA
Barrett
Leo W
LW
Scott
Victoria E
VE
Richardson
Paul L
PL
Pereda-Lopez
Ana
A
Uchic
Marie E
ME
Solomon
Larry R
LR
Lake
Marc R
MR
Walter
Karl A
KA
Hajduk
Philip J
PJ
Olejniczak
Edward T
ET
D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018019:Receptors, Corticotropin-Releasing Hormone / Q000737:chemistry; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / Q000737:chemistry* / Q000378:metabolism; D012996:Solutions
C101531:CRF receptor type 2; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018019:Receptors, Corticotropin-Releasing Hormone; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D012996:Solutions