title: A biophysical characterization of the interaction of a hepatitis C virus membranotropic peptide with micelles.
abstract: Membrane fusion is a highly regulated process that allows enveloped viruses to enter cells and replicate. Viral glycoproteins trigger membrane fusion by means of internal sequences known as fusion peptides. The hepatitis C virus (HCV) genome encodes the envelope glycoproteins E1 and E2, but their specific roles in the fusion step and the localization of the fusion peptide remain uncharacterized. Here, we studied the biophysics of the interactions between the glycoprotein E2 peptide HCV421-445 and four different micellar systems providing ionic, non-ionic and zwitterionic surfaces to investigate the importance of electrostatic interactions for peptide-membrane binding. Circular dichroism, fluorescence spectroscopy and calorimetry were used to characterize peptide-micelle interactions and structural changes. Fluorescence quenching showed that HCV421-445 interacts with SDS or CTAB ionic, n-OGP non-ionic and DPC zwitterionic micelles. The indole ring of Trp seems to anchor the peptide in micelles. Trp residues seem to be more deeply inserted in ionic and non-ionic micelles where peptide interactions are more stable than with DPC zwitterionic micelles. The interaction with zwitterionic micelles appears to occur at the surface. Both interaction types are exothermic because of peptide-micelle interactions and a gain of secondary structure in the helical conformation. HCV421-445 interacts with detergent monomers and micelles. Peptide-micelle interaction is pH-independent. HCV421-445 interacts with membranes, promoting aggregation and coalescence of vesicles with content leakage, suggesting that HCV421-445 may participate in membrane fusion. This structural characterization contributes to our understanding of the molecular process that promotes fusion, which is important in the further development of new antiviral therapies.
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: N S
authors.initials: NS
authors.lastname: Alves
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Y S
authors.initials: YS
authors.lastname: Mendes
authors.affiliation: Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: T L F
authors.initials: TL
authors.lastname: Souza
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Bianconi
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: J L
authors.initials: JL
authors.lastname: Silva
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil. Electronic address: amog@bioqmed.ufrj.br.
authors.forename: A M O
authors.initials: AM
authors.lastname: Gomes
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil. Electronic address: cheble@bioqmed.ufrj.br.
authors.forename: A C
authors.initials: AC
authors.lastname: Oliveira
mesh_terms: D000595:Amino Acid Sequence; D016174:Hepacivirus / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008823:Micelles; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014759:Viral Envelope Proteins / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008823:Micelles; D014759:Viral Envelope Proteins
keywords: Hepacivirus; Hepatitis C virus; Peptide structure; Peptide–micelle interaction