title: Topological analysis of the complex formed between neurokinin A and the NK2 tachykinin receptor.
abstract: Neurokinin A stimulates physiological responses in the peripheral and central nervous systems upon interacting primarily with the tachykinin NK2 receptor (NK2R). In this study, the structure of NKA bound to the NK2R is characterised by use of fluorescence resonance energy transfer. Four fluorescent NKA analogues with Texas red introduced at amino acid positions 1, 4, 7 and 10 were prepared. When bound to a NK2R carrying enhanced green fluorescent protein at the N-terminus, all peptides reduce green fluorescent protein fluorescence from 10% to 50% due to energy transfer. The derived donor-acceptor distances are 46, 55, 59 and 69 A for the fluorophore linked to positions 1-10, respectively. The monotonic increase in distance clearly indicates that the peptide adopts an extended structure when bound to its receptor. The present data are used, in combination with rhodopsin structure, fluorescence studies, photoaffinity labelling and site-directed mutagenesis data to design a computer model of the NKA-NK2R complex. We propose that the N-terminus of NKA is exposed and accessible to the extracellular medium. Subsequent amino acids of the NKA peptide become progressively more buried residues up to approximately one-third of the transmembrane-spanning domain.
authors.affiliation: IFR 85, UMR-CNRS7175, Département Récepteurs et Protéines Membranaires, Ecole Supérieure de Biotechnologie de Strasbourg, Boulevard Sébastien Brant, Illkirch, France.
authors.forename: Sannah
authors.initials: S
authors.lastname: Zoffmann
authors.forename: Sonia
authors.initials: S
authors.lastname: Bertrand
authors.forename: Quoc-Tuan
authors.initials: QT
authors.lastname: Do
authors.forename: Daniel
authors.initials: D
authors.lastname: Bertrand
authors.forename: Didier
authors.initials: D
authors.lastname: Rognan
authors.forename: Marcel
authors.initials: M
authors.lastname: Hibert
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Galzi
mesh_terms: D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D009420:Nervous System / Q000378:metabolism*; D015288:Neurokinin A / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D018041:Receptors, Neurokinin-2 / Q000819:agonists / Q000737:chemistry / Q000378:metabolism*; D014966:Xanthenes
chemical_list: D046911:Macromolecular Substances; D010455:Peptides; D018041:Receptors, Neurokinin-2; D014966:Xanthenes; D049452:Green Fluorescent Proteins; C034657:Texas red; D015288:Neurokinin A