Yeast killer dsRNA plasmids are transcribedin vivoto produce full and partial-length plus-stranded RNAs

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Abstract
In vivo transcripts of the L (4.5 kb) and M (1.9 kb) dsRNA plasmids were examined in type I killers of Saccharomyces cerevisiae. Transcripts for both plasmids include full-length (l, m) and partial-length (la, ma) single–stranded species. Both L–dsRNA transcripts (l, la) havein vitro mRNA activity for L-Pl, previously shown to be identical to ScV-Pl, the 88,000 dalton major capsid protein of the virus-like particles containing L- and M –dsRNAs. 1, but not la, is bound to poly (U) -sepharose and may be polyadenylated. Other L-dsRNA gene products and their transcripts may exist. For M-dsRNA, both species (m, ma) have in vitro mRNA activity for M,–P1, the 32,000 dalton pre-protoxin encoded by M1 -dsRNA. Both m and ma are bound to poly(U) –Sepharose and ma is probably a 5′ terminal fragment of m. A functional model for M1 -dsRNA killer plasmid structure is presented.