In vivo mapping of a sequence required for interference with the yeast killer virus.
The Saccharomyces cerevisiae viruses are noninfectious double-stranded RNA viruses whose segments are separately encapsidated. A large viral double-stranded RNA (L1; 4580 base pairs) encodes all required viral functions. M1, a double-stranded RNA of 1.9 kilobases, encodes an extracellular toxin (killer toxin) and cellular immunity to that toxin. Some strains contain smaller, S, double-stranded RNAs, derived from M1 by internal deletion. Particles containing these defective interfering RNAs can displace M1 particles by faster replication and thus convert the host strain to a nonkiller phenotype. In this work, we report the development of an assay in which the expression of S plus-strand from an inducible plasmid causes the loss of M1 particles. This assay provides a convenient method for identifying in vivo cis-acting sequences important in viral replication and packaging. We have mapped the sequence involved in interference to a region of 132 base pairs that includes two sequences similar to the viral binding site sequence previously identified in L1 by in vitro experiments.
Huan
B F
BF
Department of Biological Sciences, State University of New York, Buffalo 14260.
Shen
Y Q
YQ
Bruenn
J A
JA
D001483:Base Sequence; D003001:Cloning, Molecular; D003673:Defective Viruses / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D015345:Oligonucleotide Probes; D012328:RNA Viruses / Q000235:genetics*; D012330:RNA, Double-Stranded / Q000235:genetics / Q000302:isolation & purification; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014170:Transformation, Genetic
D015345:Oligonucleotide Probes; D012330:RNA, Double-Stranded; D012331:RNA, Fungal; D012367:RNA, Viral