Sequence analysis of the membrane protein gene of human coronavirus OC43 and evidence for O-glycosylation.
The gene encoding the membrane (M) protein of the OC43 strain of human coronavirus (HCV-OC43) was amplified by a reverse transcription-polymerase chain reaction of viral RNA with HCV-OC43- and bovine coronavirus (BCV)-specific primers. The nucleotide sequence of the cloned 1.5 kb fragment revealed an open reading frame (ORF) of 690 nucleotides which was identified as the M protein gene from its homology to BCV. This ORF encodes a protein of 230 amino acids with an M(r) of 26416. The gene is preceded by the motif UCCAAAC, analogous to the consensus coronavirus transcription initiation sequence. The M protein of HCV-OC43 shows features typical of all coronavirus M proteins studied: a hydrophilic, presumably external N terminus including about 10% of the protein, and a potential N-glycosylation site followed by three major hydrophobic transmembrane domains. The amino acid sequence of the M protein of HCV-OC43 has 94% identity with that of the Mebus strain of BCV, and also contains six potential O-glycosylation sites in the exposed N-terminal domain. Indeed, the glycosylation of the M protein was not inhibited in the presence of tunicamycin, which is indicative of O-glycosylation, as previously reported for BCV and murine hepatitis virus. Virions released from tunicamycin-treated cells contained the M glycoprotein but were devoid of both peplomer (S) and haemagglutinin-esterase (HE) proteins. Thus, inhibition of the N-glycosylation of the S and HE structural proteins prevented their incorporation into progeny virions, an indication that they are dispensable for virion morphogenesis, unlike the M protein.
Mounir
S
S
Virology Research Center, Institut Armand-Frappier, Université du Québec, Laval, Canada.
Talbot
P J
PJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003332:Coronaviridae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D000086862:Coronavirus M Proteins; D005814:Genes, Viral / Q000235:genetics*; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D012367:RNA, Viral / Q000235:genetics*; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D014415:Tunicamycin / Q000494:pharmacology; D014763:Viral Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D015678:Viral Structural Proteins / Q000235:genetics*; D014771:Virion / Q000254:growth & development
D000086862:Coronavirus M Proteins; C000706232:M protein, Human coronavirus OC43; C000706234:M protein, Murine hepatitis virus; D012367:RNA, Viral; D014763:Viral Matrix Proteins; D015678:Viral Structural Proteins; D014415:Tunicamycin