title: Membrane topology of a 14-mer model amphipathic peptide: a solid-state NMR spectroscopy study.
abstract: We have investigated the interaction between a synthetic amphipathic 14-mer peptide and model membranes by solid-state NMR. The 14-mer peptide is composed of leucines and phenylalanines modified by the addition of crown ethers and forms a helical amphipathic structure in solution and bound to lipid membranes. To shed light on its membrane topology, 31P, 2H, 15N solid-state NMR experiments have been performed on the 14-mer peptide in interaction with mechanically oriented bilayers of dilauroylphosphatidylcholine (DLPC), dimyristoylphosphatidylcholine (DMPC), and dipalmitoylphosphatidylcholine (DPPC). The 31P, 2H, and 15N NMR results indicate that the 14-mer peptide remains at the surface of the DLPC, DMPC, and DPPC bilayers stacked between glass plates and perturbs the lipid orientation relative to the magnetic field direction. Its membrane topology is similar in DLPC and DMPC bilayers, whereas the peptide seems to be more deeply inserted in DPPC bilayers, as revealed by the greater orientational and motional disorder of the DPPC lipid headgroup and acyl chains. 15N{31P} rotational echo double resonance experiments have also been used to measure the intermolecular dipole-dipole interaction between the 14-mer peptide and the phospholipid headgroup of DMPC multilamellar vesicles, and the results indicate that the 14-mer peptide is in contact with the polar region of the DMPC lipids. On the basis of these studies, the mechanism of membrane perturbation of the 14-mer peptide is associated to the induction of a positive curvature strain induced by the peptide lying on the bilayer surface and seems to be independent of the bilayer hydrophobic thickness.
authors.affiliation: Département de Chimie, Centre de Recherche sur la Fonction, la Structure et l'Ingénierie des Protéines, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Québec, Canada G1K 7P4.
authors.forename: Marise
authors.initials: M
authors.lastname: Ouellet
authors.forename: Jean-Daniel
authors.initials: JD
authors.lastname: Doucet
authors.forename: Normand
authors.initials: N
authors.lastname: Voyer
authors.forename: Michèle
authors.initials: M
authors.lastname: Auger
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D035843:Biomedical Research; D002247:Carbon Isotopes / Q000737:chemistry; D002474:Cell-Free System; D043844:Crown Ethers / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D010759:Phosphorus Isotopes / Q000737:chemistry; D012107:Research Design
chemical_list: D002247:Carbon Isotopes; D043844:Crown Ethers; D008051:Lipid Bilayers; D008081:Liposomes; D008567:Membranes, Artificial; D009587:Nitrogen Isotopes; D010455:Peptides; D010713:Phosphatidylcholines; D010759:Phosphorus Isotopes; C015153:1,2-dilauroylphosphatidylcholine; D015060:1,2-Dipalmitoylphosphatidylcholine; D003903:Deuterium; D004134:Dimyristoylphosphatidylcholine