Absence of the mitochondrial AAA protease Yme1p restores F0-ATPase subunit accumulation in an oxa1 deletion mutant of Saccharomyces cerevisiae.
The nuclear gene OXA1 encodes a protein located within the mitochondrial inner membrane that is required for the biogenesis of both cytochrome c oxidase (Cox) and ATPase. In the absence of Oxa1p, the translocation of the mitochondrially encoded subunit Cox2p to the intermembrane space (also referred to as export) is prevented, and it has been proposed that Oxa1p could be a component of a general mitochondrial export machinery. We have examined the role of Oxa1p in light of its relationships with two mitochondrial proteases, the matrix protease Afg3p-Rca1p and the intermembrane space protease Yme1p, by analyzing the assembly and activity of the Cox and ATPase complexes in Deltaoxa1, Deltaoxa1Deltaafg3, and Deltaoxa1Deltayme1 mutants. We show that membrane subunits of both complexes are specifically degraded in the absence of Oxa1p. Neither Afg3p nor Yme1p is responsible for the degradation of Cox subunits. However, the F(0) subunits Atp4p, Atp6p, and Atp17p are stabilized in the Deltaoxa1Deltayme1 double mutant, and oligomycin-sensitive ATPase activity is restored, showing that the increased stability of the ATPase subunits allows significant translocation and assembly to occur even in the absence of Oxa1p. These results suggest that Oxa1p is not essential for the export of ATPase subunits. In addition, although respiratory function is dispensable in Saccharomyces cerevisiae, we show that the simultaneous inactivation of AFG3 and YME1 is lethal and that the essential function does not reside in their protease activity.
Lemaire
C
C
Centre de Génétique Moléculaire du CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France. lemaire@cgm.cnrs-gif.fr
Hamel
P
P
Velours
J
J
Dujardin
G
G
D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000096:biosynthesis; D004734:Energy Metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005804:Genes, Lethal; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008666:Metalloendopeptidases; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000096:biosynthesis*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C090858:OXA1 protein; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D049069:ATP-Dependent Proteases; C082702:YME1 protein, S cerevisiae; D008666:Metalloendopeptidases; D000251:Adenosine Triphosphatases; C102166:YTA12 protein, S cerevisiae; C090045:AFG3 protein, S cerevisiae; D006180:Proton-Translocating ATPases