Elimination of L-A double-stranded RNA virus of Saccharomyces cerevisiae by expression of gag and gag-pol from an L-A cDNA clone.
We report that expression of a nearly full-length cDNA clone of the L-A double-stranded RNA virus causes virus loss in a wild-type strain of Saccharomyces cerevisiae. We show that in this system exclusion of the L-A virus is independent of the presence of the packaging site or of cis sites for replication and transcription and completely dependent on expression of functional recombinant gag and gag-pol fusion protein. Thus, this exclusion is not explained in terms of overexpression of packaging signals. Mutation of the chromosomal SKI2 gene, known to repress the copy number of double-stranded RNA cytoplasmic replicons of S. cerevisiae, nearly eliminates the exclusion. We suggest that exclusion is due to competition by proteins expressed from the plasmid for a possibly limiting cellular factor. Our hypotheses on exclusion of L-A proteins may also apply to resistance to plant viruses produced by expression of viral replicases in transgenic plants.
Valle
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RP
Section on Genetics of Simple Eukaryotes, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
Wickner
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RB
D000123:Acetyltransferases; D000595:Amino Acid Sequence; D001483:Base Sequence; D015685:Fusion Proteins, gag-pol / Q000096:biosynthesis / Q000235:genetics*; D015683:Gene Products, gag / Q000096:biosynthesis / Q000235:genetics*; D005814:Genes, Viral / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D008969:Molecular Sequence Data; D063210:N-Terminal Acetyltransferase B; D012328:RNA Viruses / Q000235:genetics* / Q000254:growth & development; D012330:RNA, Double-Stranded / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014762:Viral Interference / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics; D014779:Virus Replication
D015685:Fusion Proteins, gag-pol; D015683:Gene Products, gag; C077082:MAK10 protein, S cerevisiae; D012330:RNA, Double-Stranded; D012367:RNA, Viral; D029701:Saccharomyces cerevisiae Proteins; D014764:Viral Proteins; D000123:Acetyltransferases; D063210:N-Terminal Acetyltransferase B