title: A tRNA(TRP) gene mediates the suppression of cbs2-223 previously attributed to ABC1/COQ8.
abstract: The Saccharomyces cerevisiae gene ABC1 was originally isolated as a multicopy suppressor of a yeast strain harboring a mutation in a cytochrome b translational activator (cbs2-223). Based on this identification, Abc1p was postulated to activate the bc1 complex and function as a chaperone of cytochrome b. ABC1 was subsequently identified as COQ8 and found to be necessary for yeast coenzyme Q synthesis. In this work we show that a segment of yeast genomic DNA containing ABC1/COQ8 and neighboring genes suppresses the respiratory and Q-deficient phenotypes of the coq6 mutant, coq6-1. COQ6 is essential for yeast coenzyme Q biosynthesis. We show that a tRNA(TRP) gene located downstream of ABC1/COQ8 mediates suppression of the cbs2-223 and coq6-1 mutations, and each is identified here as containing UGA nonsense codons. The inability of ABC1/COQ8 to suppress the cbs2-223 allele in multicopy indicates it may not be a chaperone as previously reported.
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Hsieh
authors.forename: Jason B
authors.initials: JB
authors.lastname: Dinoso
authors.forename: Catherine F
authors.initials: CF
authors.lastname: Clarke
mesh_terms: D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D018832:Molecular Chaperones; D016297:Mutagenesis, Site-Directed; D012364:RNA, Transfer, Trp / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity; D013489:Suppression, Genetic / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014451:Ubiquinone / Q000235:genetics / Q000378:metabolism*
chemical_list: C401826:CBS2 protein, S cerevisiae; C099891:COQ8 protein, S cerevisiae; D018832:Molecular Chaperones; D012364:RNA, Transfer, Trp; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014451:Ubiquinone; C030778:ubiquinone 8