N-terminal sequence analysis of equine herpesvirus 1 glycoproteins D and B and evidence for internal cleavage of the gene 71 product.
Signal cleavage sites of equine herpesvirus 1 (EHV-1) glycoproteins D and B (gD and gB) and an endoproteolytic cleavage site of EHV-1 gB were determined by N-terminal amino acid sequencing and compared with known cleavage sites of homologues in other herpesvirus. Signal cleavage of EHV-1 gD occurred between Arg35 and Ala36 in a region of basic amino acids resembling the endoproteolytic cleavage sites of viral glycoproteins, nine amino acids downstream of the predicted site, while EHV-1 gB was cleaved as predicted between Ala85 and Val86. Endoproteolytic cleavage of EHV-1 gB occurred between Arg548 and Ala549, 28 amino acids downstream of the cleavage site predicted from conserved sequences of other herpesvirus gB homologous. One interpretation of these data is that EHV-1 gB is cleaved internally at both sites, a possibility which was supported by the apparent molecular masses of the unglycosylated gB subunits produced in the presence of tunicamycin. This double cleavage would release a stretch of amino acids which is not present in sequenced gB molecules of other herpesviruses. Experiments with glycosylation inhibitors indicated that cleavage of EHV-1 gB can occur in the absence of glycosylation. N-terminal sequencing also determined that a 42 kDa EHV-1 glycoprotein was a product of internal cleavage of the protein encoded by gene 71. Staggered endoproteolytic cleavage after adjacent arginine residues 506 and 507 separates the 42 kDa C-terminal subunit containing all the cysteine residues from the serine and threonine rich N-terminal region.
Wellington
J E
JE
School of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia.
Gooley
A A
AA
Love
D N
DN
Whalley
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D010450:Endopeptidases / Q000378:metabolism; D006031:Glycosylation; D004861:Herpesvirus 1, Equid / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D021382:Protein Sorting Signals / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D021382:Protein Sorting Signals; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C090199:gene 71 protein, Equid herpesvirus 1; C040495:glycoprotein B, Simplexvirus; C488988:glycoprotein D, Equid herpesvirus 1; D010450:Endopeptidases