Studies on the fusion peptide of a paramyxovirus fusion glycoprotein: roles of conserved residues in cell fusion.
The role of residues in the conserved hydrophobic N-terminal fusion peptide of the paramyxovirus fusion (F) protein in causing cell-cell fusion was examined. Mutations were introduced into the cDNA encoding the simian virus 5 (SV5) F protein, the altered F proteins were expressed by using an eukaryotic vector, and their ability to mediate syncytium formation was determined. The mutant F proteins contained both single- and multiple-amino-acid substitutions, and they exhibited a variety of intracellular transport properties and fusion phenotypes. The data indicate that many substitutions in the conserved amino acids of the simian virus 5 F fusion peptide can be tolerated without loss of biological activity. Mutant F proteins which were not transported to the cell surface did not cause cell-cell fusion, but all of the mutants which were transported to the cell surface were fusion competent, exhibiting fusion properties similar to or better than those of the wild-type F protein. Mutant F proteins containing glycine-to-alanine substitutions had altered intracellular transport characteristics, yet they exhibited a great increase in fusion activity. The potential structural implications of this substitution and the possible importance of these glycine residues in maintaining appropriate levels of fusion activity are discussed.
Horvath
C M
CM
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500.
Lamb
R A
RA
D000595:Amino Acid Sequence; D001692:Biological Transport; D002459:Cell Fusion; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010252:Paramyxoviridae / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000737:chemistry* / Q000378:metabolism
D014760:Viral Fusion Proteins