Comparative studies of the core gene products of two different hepatitis C virus isolates: two alternative forms determined by a single amino acid substitution.
We have compared the expression of the core gene of two different hepatitis C virus (HCV) isolates, HCV-1 and HCV-RH, using the in vitro translation assay. In the absence of the downstream E1 envelope protein sequence, a 16-kDa protein (P16) was the dominant protein product synthesized from the HCV-1 core gene sequence. On the other hand, a 21-kDa protein (P21) was the dominant protein product synthesized from the HCV-RH sequence. Domain-swapping and site-directed mutagenesis experiments indicated that codon 9 of the core protein coding sequence played a crucial role on the synthesis of the core protein: a lysine codon at this position led to the synthesis of P16 and an arginine codon at this position led to the synthesis of P21. For HCV-1 and HCV-RH, this codon encodes lysine and arginine, respectively. Further analyses indicated that P16 was likely co-amino-terminal with P21. In the presence of the downstream E1 envelope protein sequence and microsomal membranes, P16 as well as P21 were synthesized from the HCV-1 core gene sequence whereas P21 remained the only detectable protein product synthesized from the HCV-RH core gene sequence. These results indicate that the pathway leading to the synthesis of the HCV core protein may be more complicated than originally envisioned.
Lo
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Department of Microbiology, University of Southern California, Los Angeles 90033.
Selby
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Tong
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Ou
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D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004279:DNA, Viral; D015870:Gene Expression; D005814:Genes, Viral; D016174:Hepacivirus / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D014758:Viral Core Proteins / Q000235:genetics*
C085973:16 kDa protein, hepatitis C virus; C085975:21 kDa protein, hepatitis C virus; D004279:DNA, Viral; D014758:Viral Core Proteins