title: Sequence elements of the fusion peptide of human respiratory syncytial virus fusion protein required for activity.
abstract: We have reported previously the expression and purification of an anchorless form of the human respiratory syncytial virus (HRSV) F protein (F(TM-)) representing the ectodomain of the full-length F. F(TM-) molecules are seen as unaggregated cones by electron microscopy but completion of proteolytic cleavage of the F0 monomers in the F(TM-) trimer leads to a change in shape from cones to lollipops that aggregate into rosettes. This aggregation apparently occurs by interaction of the fusion peptides of F(TM-) molecules that are exposed after cleavage. Since exposure of the fusion peptide is a key event in the process of membrane fusion, changes associated with F(TM-) cleavage may reflect those occurring in full-length F during membrane fusion. Deletions or substitutions that changed either the length, charge or hydrophobicity of the fusion peptide inhibited aggregation of F(TM-), and these mutants remained as unaggregated cones after cleavage. In contrast, more conservative changes did not inhibit the change of shape and aggregation of F(TM-). When the same changes were introduced in the fusion peptide of full-length F, only the mutations that inhibited aggregation of F(TM-) prevented membrane fusion. Thus, the conformational changes that follow completion of cleavage of the F(TM-) protein require a functional fusion peptide. These sequence constraints may restrict accumulation of sequence changes in the fusion peptide of HRSV F when compared with other hydrophobic regions of the molecule.
authors.affiliation: Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: Martín
authors.affiliation: National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Calder
authors.affiliation: Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain.
authors.forename: Blanca
authors.initials: B
authors.lastname: García-Barreno
authors.affiliation: National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
authors.forename: John J
authors.initials: JJ
authors.lastname: Skehel
authors.affiliation: Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Melero
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D015726:Giant Cells / Q000502:physiology; D006801:Humans; D008561:Membrane Fusion; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D017384:Sequence Deletion; D014760:Viral Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010455:Peptides; D014760:Viral Fusion Proteins