title: Evidence for a C-terminal turn in PBAN. An NMR and distance geometry study.
abstract: The solution conformation of the pheromone biosynthesis activating neuropeptide (PBAN) of the moth Helicoverpa zea has been determined using homonuclear two-dimensional nuclear magnetic resonance techniques and distance geometry-restrained energy minimization. The insect peptide hormone showed a random distribution of conformers in aqueous solution, whereas in a less polar medium of trifluoroethanol and water, a reordering process was observed. In particular, the C-terminal region (Phe-Ser-Pro-Arg-Leu-NH2) adopts a type I' beta-turn conformation, residues 20-27 are in a helix conformation, and residues 1-19 exhibit a high degree of flexibility. Direct observation of the C-terminal beta-turn configuration of PBAN is consistent with a previous report that showed a rigid, cyclic analog of the C-terminal pentapeptide of PBAN retained pheromonotropic activity [Nachman, R.J., Kuniyoshi, H., Roberts, V.A., Holman, G.M. & Suzuki, A. (1993). Biochem. Biophys. Res. Commun. 661-666]. Furthermore, our results show no interaction between the C-terminal turn and the rest of the polypeptide chain, thus providing further evidence that the C-terminal turn is indeed the important conformation recognized by the PBAN receptor.
authors.affiliation: Department of Chemistry, University at Stony Brook, New York, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Clark
authors.forename: G D
authors.initials: GD
authors.lastname: Prestwich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009036:Moths; D009479:Neuropeptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D009479:Neuropeptides; C079709:pheromone biosynthesis activating neuropeptide, Helicoverpa zea