title: Structure-function relationships in the neuropeptide S receptor: molecular consequences of the asthma-associated mutation N107I.
abstract: Neuropeptide S (NPS) and its receptor (NPSR) are thought to have a role in asthma pathogenesis; a number of single nucleotide polymorphisms within NPSR have been shown to be associated with an increased prevalance of asthma. One such single nucleotide polymorphism leads to the missense mutation N107I, which results in an increase in the potency of NPS for NPSR. To gain insight into structure-function relationships within NPS and NPSR, we first carried out a limited structural characterization of NPS and subjected the peptide to extensive mutagenesis studies. Our results show that the NH(2)-terminal third of NPS, in particular residues Phe-2, Arg-3, Asn-4, and Val-6, are necessary and sufficient for activation of NPSR. Furthermore, part of a nascent helix within the peptide, spanning residues 5 through 13, acts as a regulatory region that inhibits receptor activation. Notably, this inhibition is absent in the asthma-linked N107I variant of NPSR, suggesting that residue 107 interacts with the aforementioned regulatory region of NPS. Whereas this interaction may be at the root of the increase in potency associated with the N107I variant, we show here that the mutation also causes an increase in cell-surface expression of the mutant receptor, leading to a concomitant increase in the maximal efficacy (E(max)) of NPS. Our results identify the key residues of NPS involved in NPSR activation and suggest a molecular basis for the functional effects of the N107I mutation and for its putative pathophysiological link with asthma.
authors.affiliation: Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, Kirkland, Quebec H9H 3L1, Canada.
authors.forename: Virginie
authors.initials: V
authors.lastname: Bernier
authors.forename: Rino
authors.initials: R
authors.lastname: Stocco
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bogusky
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Joyce
authors.forename: Christine
authors.initials: C
authors.lastname: Parachoniak
authors.forename: Karl
authors.initials: K
authors.lastname: Grenier
authors.forename: Michael
authors.initials: M
authors.lastname: Arget
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Mathieu
authors.forename: Gary P
authors.initials: GP
authors.lastname: O'Neill
authors.forename: Deborah
authors.initials: D
authors.lastname: Slipetz
authors.forename: Michael A
authors.initials: MA
authors.lastname: Crackower
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Tan
authors.forename: Alex G
authors.initials: AG
authors.lastname: Therien
mesh_terms: D000595:Amino Acid Sequence; D001249:Asthma / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009479:Neuropeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: C484532:NPSR1 protein, human; D009479:Neuropeptides; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; C506531:neuropeptide S, human