title: Structure and interaction with lipid membrane models of Semliki Forest virus fusion peptide.
abstract: Semliki Forest virus (SFV) is a well-characterized alphavirus that infects cells via endocytosis and an acid-triggered fusion step using class II fusion proteins. Membrane fusion is mediated by the viral spike protein, a heterotrimer of two transmembrane subunits, E1 and E2, and a peripheral protein, E3. Sequence analysis of the E1 ectodomain of a number of alphaviruses demonstrated the presence of a highly conserved hydrophobic domain on the E1 ectodomain. This sequence was proposed to be the fusion peptide of SFV and is believed to be the domain of E1 that interacts with the target membrane and triggers fusion. Here, we investigate the structure and the interaction with lipid membrane models of76YQCKVYTGVYPFMWGGAYCFC96sequence from SFV, named SFV21, using optical method (ellipsometry) and vibrational spectroscopiy approaches (Polarization Modulation infra-Red Reflection Absorption Spectroscopy, PMIRRAS, and polarized ATR-FTIR). We demonstrate a structural flexibility of SFV21 sequence whether the lateral pressure and the lipid environment. In a lipid environment that mimics eukaryotic cell membranes, a conformational transition from an α-helix to a β-sheet is induced in the presence of lipid by increasing the peptide to lipid ratio, which leads to important perturbations in the membrane organisation.
authors.affiliation: CBMN-UMR 5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy Saint Hilaire, 33600 Pessac, France.
authors.forename: A
authors.initials: A
authors.lastname: Agopian
authors.affiliation: CBMN-UMR 5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy Saint Hilaire, 33600 Pessac, France.
authors.forename: M
authors.initials: M
authors.lastname: Quetin
authors.affiliation: CBMN-UMR 5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy Saint Hilaire, 33600 Pessac, France. Electronic address: s.castano@cbmn.u-bordeaux.fr.
authors.forename: S
authors.initials: S
authors.lastname: Castano
mesh_terms: D000595:Amino Acid Sequence; D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008561:Membrane Fusion; D008563:Membrane Lipids / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D055503:Protein Multimerization; D012672:Semliki forest virus / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry; D014760:Viral Fusion Proteins / Q000737:chemistry*
chemical_list: D008563:Membrane Lipids; D010455:Peptides; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D053835:Unilamellar Liposomes; D014760:Viral Fusion Proteins; D002784:Cholesterol; C002773:dimyristoylphosphatidylglycerol; D004134:Dimyristoylphosphatidylcholine; C018525:1,2-dimyristoylphosphatidylethanolamine
keywords: Ellipsometry; IR spectroscopy; Lipid/peptide interaction; SFV fusion peptide; Secondary structure; Viral fusion mechanism