title: Genetic and molecular analysis of the SOE1 gene: a tRNA(3Glu) missense suppressor of yeast cdc8 mutations.
abstract: The CDC8 gene of Saccharomyces cerevisiae encodes deoxythymidylate (dTMP) kinase and is required for nuclear and mitochondrial DNA replication in both the mitotic and meiotic cell cycles. All cdc8 temperature-sensitive mutants are partially defective in meiotic and mitochondrial functions at the permissive temperature. In a study of revertants of temperature-sensitive cdc8 mutants, the SOE201 and SOE1 mutants were isolated. The SOE201 mutant is a disome of chromosome X to which the cdc8 gene maps. Using the chromosome X aneuploids to vary cdc8 gene dosage, we demonstrate that different levels of dTMP kinase activity are required for mitotic, meiotic or mitochondrial DNA replication. The SOE1 mutant contains a dominant suppressor that suppresses five different cdc8 alleles but does not suppress a complete cdc8 deletion. The SOE1 gene is located less than 1.5 cM from the CYH2 gene on chromosome VII and is adjacent to the TSM437-CYH2 region, with the gene order being SOE1-TSM437-CYH2. SOE1 is an inefficient suppressor that can neither suppress the cdc8 hypomorphic phenotype nor restore dTMP kinase activity in vitro. SOE1 is a single C to T mutation in the anticodon of a tRNA(3Glu) gene and thereby, produces a missense suppressor tRNA capable of recognizing AAA lysine codons. We propose that the resultant lysine to glutamate change stabilizes thermo-labile dTMP kinase molecules in the cell.
authors.affiliation: Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, Denver 80262.
authors.forename: J Y
authors.initials: JY
authors.lastname: Su
authors.forename: L
authors.initials: L
authors.lastname: Belmont
authors.forename: R A
authors.initials: RA
authors.lastname: Sclafani
mesh_terms: D000483:Alleles; D001483:Base Sequence; D015825:Chromosomes, Fungal; D004261:DNA Replication; D004271:DNA, Fungal / Q000378:metabolism; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics* / Q000378:metabolism; D010770:Phosphotransferases / Q000235:genetics*; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D012352:RNA, Transfer, Glu / Q000235:genetics*; D011995:Recombination, Genetic; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013489:Suppression, Genetic
chemical_list: D004271:DNA, Fungal; D012345:RNA, Transfer, Amino Acid-Specific; D012352:RNA, Transfer, Glu; D010770:Phosphotransferases; D009703:Nucleoside-Phosphate Kinase; C020093:dTMP kinase