title: NMR analysis of Caenorhabditis elegans FLP-18 neuropeptides: implications for NPR-1 activation.
abstract: Phe-Met-Arg-Phe-NH2 (FMRFamide)-like peptides (FLPs) are the largest neuropeptide family in animals, particularly invertebrates. FLPs are characterized by a C-N-terminal gradient of decreasing amino acid conservation. Neuropeptide receptor 1 (NPR-1) is a G-protein coupled receptor (GPCR), which has been shown to be a strong regulator of foraging behavior and aggregation responses in Caenorhabditis elegans. Recently, ligands for NPR-1 were identified as neuropeptides coded by the precursor genes flp-18 and flp-21 in C. elegans. The flp-18 gene encodes eight FLPs including DFDGAMPGVLRF-NH2 and EMPGVLRF-NH2. These peptides exhibit considerably different activities on NPR-1, with the longer one showing a lower potency. We have used nuclear magnetic resonance and biological activity to investigate structural features that may explain these activity differences. Our data demonstrate that long-range electrostatic interactions exist between N-terminal aspartates and the C-terminal penultimate arginine as well as N-terminal hydrogen-bonding interactions that form transient loops within DFDGAMPGVLRF-NH2. We hypothesize that these loops, along with peptide charge, diminish the activity of this peptide on NPR-1 relative to that of EMPGVLRF-NH2. These results provide some insight into the large amino acid diversity in FLPs.
authors.affiliation: McKnight Brain Institute, University of Florida, 100 South Newell Drive, Building 59, Room LG-150, Gainesville, Florida 32611, USA.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Dossey
authors.forename: Vincenzina
authors.initials: V
authors.lastname: Reale
authors.forename: Heather
authors.initials: H
authors.lastname: Chatwin
authors.forename: Cherian
authors.initials: C
authors.lastname: Zachariah
authors.forename: Mario
authors.initials: M
authors.lastname: deBono
authors.forename: Peter D
authors.initials: PD
authors.lastname: Evans
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Edison
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D017173:Caenorhabditis elegans / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D004305:Dose-Response Relationship, Drug; D005260:Female; D017238:Genes, Helminth; D015801:Helminth Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D019906:Nuclear Magnetic Resonance, Biomolecular; D009865:Oocytes / Q000378:metabolism; D017433:Protein Structure, Secondary; D017476:Receptors, Neuropeptide Y / Q000235:genetics / Q000378:metabolism*; D055672:Static Electricity; D014982:Xenopus laevis
chemical_list: D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; C468272:NPR-1 protein, C elegans; D009479:Neuropeptides; D017476:Receptors, Neuropeptide Y; D001224:Aspartic Acid; D001120:Arginine