Translation of equine infectious anemia virus bicistronic tat-rev mRNA requires leaky ribosome scanning of the tat CTG initiation codon.
We have examined the translational regulation of the equine infectious anemia virus (EIAV) bicistronic tat-rev mRNA. Site-directed mutagenesis of the tat leader region followed by expression of the tat-rev cDNA both in vitro and in transiently transfected cells established that tat translation is initiated exclusively at a CTG codon. Increasing the efficiency of tat translation by altering the CTG initiator to ATG resulted in a dramatic decrease in translation of the downstream (rev) cistron, indicating that leaky scanning of the tat CTG initiation codon permitted translation of the downstream rev cistron. Since the tat leader sequences precede the major EIAV splice donor and are therefore present at the 5' termini of both spliced and unspliced viral mRNAs, the expression of all EIAV structural and regulatory proteins is dependent on leaky scanning of the tat initiator.
Laboratory of Viral Carcinogenesis, National Cancer Institute-Frederick Cancer Research Center, Maryland 21702-1201.
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002474:Cell-Free System; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003062:Codon; D004274:DNA, Recombinant; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral / Q000235:genetics*; D015757:Genes, rev / Q000235:genetics; D015756:Genes, tat / Q000235:genetics; D005822:Genetic Vectors; D004860:Infectious Anemia Virus, Equine / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010442:Peptide Chain Initiation, Translational; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D015678:Viral Structural Proteins / Q000235:genetics*
D003062:Codon; D004274:DNA, Recombinant; D012333:RNA, Messenger; D012367:RNA, Viral; D015678:Viral Structural Proteins; D015500:Chloramphenicol O-Acetyltransferase