PMID:18089746
| Citation |
Vassilaki, N, Kalliampakou, KI and Mavromara, P (2008) Differences in the expression of the hepatitis C virus core+1 open reading frame between a nuclear and a cytoplasmic expression system. J. Gen. Virol. 89:222-31 |
|---|---|
| Abstract |
The hepatitis C virus (HCV) genome possesses an open reading frame (ORF) overlapping the core gene at +1 nucleotide (core+1 ORF). Initial in vitro studies suggested that the core+1 ORF is translated by a ribosomal -2/+1 frameshift mechanism during elongation of the viral polyprotein. Recent studies, however, based on transfection of mammalian cells with reporter constructs have shown that translation of the core+1 ORF is mediated from internal core+1 codons. To resolve the apparent discrepancies associated with the mechanism of core+1 translation, we examined the expression of the HCV-1 and HCV-1a (H) core+1 ORF in a cytoplasmic transcription system based on Huh-7/T7 cells that constitutively synthesize the T7 RNA polymerase in comparison to that in Huh-7 cells. We showed that the efficiency of both the -2/+1 and -1/+2 frameshift events operating at the HCV-1 core codons 8-11 is significantly enhanced in the Huh-7/T7 cytoplasmic transcription system and is dependent on the presence of the consecutive adenine (A) residues within core codons 8-11. In contrast, internal translation initiation at core+1 codons 85/87 occurs in both the nuclear and cytoplasmic transcription systems and is not repressed by the ribosomal frameshifting event. Finally, although core+1 codons 85/87 is the most efficient site for internal initiation of core+1 translation, it may not be unique, as additional internal core+1 codon(s) appear to drive translation at low levels. |
| Links |
PubMed Online version:10.1099/vir.0.83260-0 |
| Keywords |
Amino Acid Sequence; Base Sequence; Carcinoma, Hepatocellular/virology; Cell Line; Cell Nucleus/virology; Codon/genetics; Cytoplasm/virology; Gene Expression Regulation, Viral; Hepacivirus/genetics; Humans; Liver Neoplasms/virology; Molecular Sequence Data; Mutagenesis, Insertional; Mutagenesis, Site-Directed; Open Reading Frames; Plasmids; Promoter Regions, Genetic; Transfection; Viral Core Proteins/chemistry; Viral Core Proteins/genetics |
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