UMMS Affiliation

Department of Molecular Genetics and Microbiology

Date

9-1-1990

Document Type

Article

Subjects

Blotting, Northern; Capsid; DNA-Directed RNA Polymerases; Genotype; Nucleic Acid Hybridization; Peptide Mapping; Phenotype; RNA Viruses; RNA, Double-Stranded; RNA, Viral; Saccharomyces cerevisiae; Transfection

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The double-stranded RNA (dsRNA) viruses of Saccharomyces cerevisiae consist of 4.5-kilobase-pair (kb) L species and 1.7- to 2.1-kb M species, both found in cytoplasmic viruslike particles (VLPs). The L species encode their own capsid protein, and one (LA) has been shown to encode a putative capsid-polymerase fusion protein (cap-pol) that presumably provides VLPs with their transcriptase and replicase functions. The M1 and M2 dsRNAs encode the K1 and K2 toxins and specific immunity mechanisms. Maintenance of M1 and M2 is dependent on the presence of LA, which provides capsid and cap-pol for M dsRNA maintenance. Although a number of different S. cerevisiae killers have been described, only K1 and K2 have been studied in any detail. Their secreted polypeptide toxins disrupt cytoplasmic membrane functions in sensitive yeast cells. K28, named for the wine S. cerevisiae strain 28, appears to be unique; its toxin is unusually stable and disrupts DNA synthesis in sensitive cells. We have now demonstrated that 4.5-kb L28 and 2.1-kb M28 dsRNAs can be isolated from strain 28 in typical VLPs, that these VLPs are sufficient to confer K28 toxin and immunity phenotypes on transfected spheroplasts, and that the immunity of the transfectants is distinct from that of either M1 or M2. In vitro transcripts from the M28 VLPs show no cross-hybridization to denatured M1 or M2 dsRNAs, while L28 is an LA species competent for maintenance of M1. K28, encoded by M28, is thus the third unique killer system in S. cerevisiae to be clearly defined. It is now amenable to genetic analysis in standard laboratory strains.

Rights and Permissions

Citation: Mol Cell Biol. 1990 Sep;10(9):4807-15.

Related Resources

Link to Article in PubMed

Journal Title

Molecular and cellular biology

PubMed ID

2201903

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