Cleavage of the human respiratory syncytial virus fusion protein at two distinct sites is required for activation of membrane fusion.
Preparations of purified full-length fusion (F) protein of human respiratory syncytial virus (HRSV) expressed in recombinant vaccinia-F infected cells, or of an anchorless mutant (F(TM(-))) lacking the C-terminal 50 amino acids secreted from vaccinia-F(TM(-))-infected cells contain a minor polypeptide that is an intermediate product of proteolytic processing of the F protein precursor F0. N-terminal sequencing of the intermediate demonstrated that it is generated by cleavage at a furin-motif, residues 106-109 of the F sequence. By contrast, the F1 N terminus derives from cleavage at residue 137 of F0 which is also C-terminal to a furin recognition site at residues 131-136. Site-directed mutagenesis indicates that processing of F0 protein involves independent cleavage at both sites. Both cleavages are required for the F protein to be active in membrane fusion as judged by syncytia formation, and they allow changes in F structure from cone- to lollipop-shaped spikes and the formation of rosettes by anchorless F.
González-Reyes
L
L
Centro Nacional de Biología Fundamental, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Ruiz-Argüello
M B
MB
García-Barreno
B
B
Calder
L
L
López
J A
JA
Albar
J P
JP
Skehel
J J
JJ
Wiley
D C
DC
Melero
J A
JA
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003588:Cytopathogenic Effect, Viral; D010450:Endopeptidases / Q000378:metabolism; D015726:Giant Cells; D006801:Humans; D007668:Kidney; D008561:Membrane Fusion / Q000502:physiology*; D008647:Mesocricetus; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000502:physiology; D012136:Respiratory Syncytial Viruses / Q000235:genetics / Q000502:physiology*; D013329:Structure-Activity Relationship; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure
D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins; D014764:Viral Proteins; D010450:Endopeptidases