title: The role of the amino terminus of F1 of the Newcastle disease virus fusion protein in cleavage and fusion.
abstract: Phenylalanine is the amino acid at the amino terminus of the F1 protein of all paramyxovirus fusion proteins with the exception of the avirulent strains of Newcastle disease virus, which have a leucine residue in this position (Toyoda et al. (1989) Virology 169, 273-282). To explore the role of this phenylalanine in the fusion activity of the protein, this residue, amino acid 117 in the fusion protein sequence, was changed to leucine (F117L) or to glycine (F117G) by site-specific mutagenesis while maintaining the cleavage site sequence of virulent strains of NDV. While both wild-type and the F117G protein were proteolytically cleaved and F1 was detected, the F117L protein was not cleaved. In the presence of the HN protein, both wild-type F and F117G proteins stimulated fusion, but the F117L protein was inactive in fusion. However, incubation in trypsin activated the fusion activity of the protein. Thus the phenylalanine at the amino terminus of the F1 component of the fusion protein is not required for the fusion activity of the protein. The presence of a leucine at this position blocks cleavage even though the cleavage site sequence is unchanged.
authors.affiliation: Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655.
authors.forename: T
authors.initials: T
authors.lastname: Morrison
authors.forename: C
authors.initials: C
authors.lastname: McQuain
authors.forename: T
authors.initials: T
authors.lastname: Sergel
authors.forename: L
authors.initials: L
authors.lastname: McGinnes
authors.forename: J
authors.initials: J
authors.lastname: Reitter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002459:Cell Fusion; D002460:Cell Line; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009522:Newcastle disease virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D009838:Oligodeoxyribonucleotides; D010649:Phenylalanine; D014162:Transfection; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D009838:Oligodeoxyribonucleotides; D014760:Viral Fusion Proteins; D010649:Phenylalanine