title: ATP-dependent proteolysis in yeast mitochondria.
abstract: An ATP-dependent proteolysis system in yeast mitochondria was characterized by examining the hydrolysis of mitochondrial translation products in isolated mitochondria. Degradation of [35S]methionine-labeled polypeptides synthesized in isolated yeast mitochondria was activated by exogenously added ATP. ADP, GTP, and CTP substituted for ATP to some extent, but nonhydrolyzable ATP analogues did not. Adenosine-5'-O-(3'-thio-triphosphate) effectively competed with ATP as activator. Carboxyatractyloside, an inhibitor of adenine nucleotide translocation across the mitochondrial inner membrane, and the metal chelator o-phenanthroline inhibited the ATP-dependent proteolysis. The latter inhibition was abolished by subsequent addition of Mn2+ or Co2+ but not Ca2+ or Zn2+. Hemin inhibited the ATP-dependent proteolysis of mitochondrial translation products with a half-maximum inhibition at 12 microM. Analysis by SDS-polyacrylamide gel electrophoresis showed that [35S]methionine-labeled polypeptides were rapidly degraded into low-molecular-weight species. Submitochondrial particles retained the ATP-dependent proteolytic activity and had the same spectrum of inhibitors as intact mitochondria except for a reduced effect of carboxyatractyloside. These results indicate that yeast mitochondria contain an ATP-dependent and hemin-sensitive proteolysis system which is associated with the inner membrane and can hydrolyze mitochondrial translation products, and that a chelator-sensitive protease is probably involved in this system.
authors.affiliation: Meiji Institute of Health Science, Kanagawa.
authors.forename: T
authors.initials: T
authors.lastname: Yasuhara
authors.forename: Y
authors.initials: Y
authors.lastname: Mera
authors.forename: T
authors.initials: T
authors.lastname: Nakai
authors.forename: A
authors.initials: A
authors.lastname: Ohashi
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D006427:Hemin / Q000494:pharmacology; D006868:Hydrolysis; D007202:Indicators and Reagents; D008322:Mammals; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009711:Nucleotides / Q000494:pharmacology; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013045:Species Specificity
chemical_list: D007202:Indicators and Reagents; D009711:Nucleotides; D011506:Proteins; D006427:Hemin; D000255:Adenosine Triphosphate