title: PET111, a Saccharomyces cerevisiae nuclear gene required for translation of the mitochondrial mRNA encoding cytochrome c oxidase subunit II.
abstract: Mutations in the nuclear gene PET111 are recessive and specifically block accumulation of cytochrome c oxidase subunit II (coxII), the product of a mitochondrial gene. However, the coxII mRNA is present in pet111 mutants at a level approximately one-third that of wild type. The simplest explanation for this phenotype is that PET111 is required for translation of the coxII mRNA. The reduced steady-state level of this mRNA is probably a secondary effect, caused by increased degradation of the untranslated transcript. Mitochondrial suppressors of pet111, carried on rho-mtDNAs, bypass the requirement for PET111 in coxII translation. Three suppressors are fusions between the coxII structural gene and other mitochondrial genes, that encode chimeric proteins consisting of the N-terminal portions of other mitochondrially coded proteins fused to the coxII precursor protein. When present together with rho+ mtDNA in a heteroplasmic state, these suppressors allow coxII synthesis in pet111 mutants. Thus in wild type, the PET111 product, or something under its control, probably acts at a site coded in the proximal portion of the gene for coxII to promote translation of the mRNA. PET111 was isolated by molecular cloning and genetically mapped to a position approximately midway between rna1 and SUP8 on chromosome XIII.
mesh_terms: D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004262:DNA Restriction Enzymes; D003576:Electron Transport Complex IV / Q000235:genetics*; D005796:Genes; D005800:Genes, Fungal; D005808:Genes, Recessive; D005838:Genotype; D046911:Macromolecular Substances; D008928:Mitochondria / Q000201:enzymology*; D009154:Mutation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
chemical_list: D046911:Macromolecular Substances; D012333:RNA, Messenger; D003576:Electron Transport Complex IV; D004262:DNA Restriction Enzymes