title: Synthetic lethality of sep1 (xrn1) ski2 and sep1 (xrn1) ski3 mutants of Saccharomyces cerevisiae is independent of killer virus and suggests a general role for these genes in translation control.
abstract: Strand exchange protein 1 (Sep1) (also referred to as exoribonuclease I [Xrn1]) from Saccharomyces cerevisiae has been implicated in DNA recombination, RNA turnover, karyogamy, and G4 DNA pairing among other disparate cellular processes. Using a genetic approach to study the role of SEP1/XRN1 in mitotic yeast cells, we identified mutations in the genes superkiller 2 (SKI2) and superkiller 3 (SKI3) as synthetically lethal with an sep1 null mutation. The SKI genes are thought to comprise an intracellular antiviral system controlling the expression of killer toxin from double-stranded RNA virus found in many yeast strains. However, the lethality of sep1 ski2 and sep1 ski3 mutants was independent of the L-A and M viruses, suggesting that the SKI genes act in a general cellular process in addition to virus control. We propose that Sep1/Xrn1 and Ski2 both act to block translation on transcripts targeted for degradation. Using a temperature-sensitive allele of SEP1/XRN1, we show that double mutants display a synthetic cell cycle arrest in late G1 at Start.
authors.affiliation: Division of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Johnson
authors.forename: R D
authors.initials: RD
authors.lastname: Kolodner
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D003851:Deoxyribonucleases / Q000235:genetics; D005095:Exoribonucleases; D005656:Fungal Proteins / Q000235:genetics; D016193:G1 Phase / Q000235:genetics; D005800:Genes, Fungal; D005804:Genes, Lethal; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000821:virology; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; C081929:SKI2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003851:Deoxyribonucleases; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae