Mutagenesis of a conserved fusion peptide-like motif and membrane-proximal heptad-repeat region of hepatitis C virus glycoprotein E1.
The E1E2 glycoprotein heterodimer of Hepatitis C virus mediates viral entry. E2 attaches the virus to cellular receptors; however, the function of E1 is unknown. We tested the hypothesis that E1 is a truncated class II fusion protein. We mutated amino acids within a predicted fusion peptide (residues 276-286) and a truncated C-terminal stem-like motif, containing a membrane-proximal heptad-repeat sequence (residues 330-347). The fusion peptide mutation F285A abolished viral entry, while mutation of other hydrophobic residues had no effect. Alanine replacement of heptad-repeat residues blocked entry in three of five cases, whereas substitution with the helix breaker, Pro, led to loss of entry function in all cases. The mutations did not affect glycoprotein expression, heterodimerization with E2 or global folding, in contrast to the effects of mutations in the fusion motifs of prototypical class II fusion proteins. Our data suggest that E1 is unlikely to function in an analogous manner to other class II fusion glycoproteins.
Drummer
Heidi E
HE
Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia.
Boo
Irene
I
Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia.
Poumbourios
Pantelis
P
Macfarlane Burnet Institute for Medical Research and Public Health Ltd, GPO Box 2284, Melbourne 3001, Australia.
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019281:Dimerization; D015870:Gene Expression; D016174:Hepacivirus / Q000235:genetics* / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D017510:Protein Folding; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D053586:Virus Internalization
C087035:E1 protein, Hepatitis C virus; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins