title: Peptide agonist docking in the N-terminal ectodomain of a class II G protein-coupled receptor, the VPAC1 receptor. Photoaffinity, NMR, and molecular modeling.
abstract: The neuropeptide vasoactive intestinal peptide (VIP) strongly impacts on human pathophysiology and does so through interaction with class II G protein-coupled receptors named VIP pituitary adenylate cyclase-activating peptide (PACAP) receptors (VPACs). The molecular nature of VIP binding to receptors remains elusive. In this work, we have docked VIP in the human VPAC1 receptor by the following approach. (i) VIP probes containing photolabile residues in positions 6, 22, and 24 of VIP were used to photolabel the receptor. After receptor cleavage and Edman sequencing of labeled receptor fragments, it was shown that Phe6, Tyr22, and Asn24 of VIP are in contact with Asp107, Gly116, and Cys122 in the N-terminal ectodomain (N-ted) of the receptor, respectively. (ii) The structure of VIP was determined by NMR showing a central alpha helix, a disordered N-terminal His1-Phe6 segment and a 3(10) Ser25-Asn28 helix termination. (iii) A three-dimensional model of the N-ted of hVPAC1 was constructed by using the NMR structure of the N-ted of corticotropin-releasing factor receptor 2beta as a template. As expected, the fold is identified as a short consensus repeat with two antiparallel beta sheets and is stabilized by three disulfide bonds. (iv) Taking into account the constraints provided by photoaffinity, VIP was docked into the hVPAC1 receptor N-ted. The 6-28 fragment of VIP nicely lies in the N-ted C-terminal part, but the N terminus region of VIP is free for interacting with the receptor transmembrane region. The data provide a structural rationale to the proposed two-step activation mechanism of VPAC receptor and more generally of class II G protein-coupled receptors.
authors.affiliation: INSERM, U773, Centre de Recherche Biomedicale Bichat Beaujon CRB3, BP 416, F-75018, Paris, the Université Paris 7 Denis Diderot, site Bichat, BP 416, F-75018, Paris.
authors.forename: Yossan-Var
authors.initials: YV
authors.lastname: Tan
authors.forename: Alain
authors.initials: A
authors.lastname: Couvineau
authors.forename: Samuel
authors.initials: S
authors.lastname: Murail
authors.forename: Emilie
authors.initials: E
authors.lastname: Ceraudo
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Neumann
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Lacapère
authors.forename: Marc
authors.initials: M
authors.lastname: Laburthe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D003346:Corticotropin-Releasing Hormone / Q000737:chemistry; D006224:Cricetinae; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000819:agonists* / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry*; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D010455:Peptides; D043562:Receptors, G-Protein-Coupled; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D003346:Corticotropin-Releasing Hormone