Protein synthesis in mitochondria from yeast strains carrying nam and mim suppressor genes.
Yeast mitochondria isolated from two different wild type strains (gal+ and gal-), whether grown on galactose or glucose, synthesize all mitochondrial polypeptides with similar efficiencies and in proportions approximating those detected in vivo. Mitochondria isolated from mit- mutants synthesize in vitro a mutant pattern of mitochondrial proteins, indistinguishable from the in vivo products. The mutant pattern is restored to the wild type one in mitochondria isolated from pseudorevertant strains carrying an additional nuclear (nam3-1 and R705) or mitochondrial (mim3-1) informational suppressor gene. Suppression is expressed in isolated mitochondria without the obligatory presence of cytosol at the level of both respiratory control and specific polypeptide synthesis. Translation in isolated mitochondria is sensitive to paromomycin. The antibiotic differentiates between translation in mitochondria from wild type strains and that in nam-type gene carrying strains. This strongly suggests that nam-type mutations affect the mitoribosome, enhancing ambiguity of translation, thus allowing for the pseudoreversion of mit- phenotypes.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D004734:Energy Metabolism; D005800:Genes, Fungal; D007656:Ketoglutaric Acids / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D009154:Mutation; D010303:Paromomycin / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000187:drug effects; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000648:ultrastructure; D013489:Suppression, Genetic
D007656:Ketoglutaric Acids; D000244:Adenosine Diphosphate; D010303:Paromomycin; D000255:Adenosine Triphosphate; D008274:Magnesium; D011188:Potassium