Membrane protein turnover by the m-AAA protease in mitochondria depends on the transmembrane domains of its subunits.
AAA proteases are membrane-bound ATP-dependent proteases that are present in eubacteria, mitochondria and chloroplasts and that can degrade membrane proteins. Recent evidence suggests dislocation of membrane-embedded substrates for proteolysis to occur in a hydrophilic environment; however, next to nothing is known about the mechanism of this process. Here, we have analysed the role of the membrane-spanning domains of Yta10 and Yta12, which are conserved subunits of the hetero-oligomeric m-AAA protease in the mitochondria of Saccharomyces cerevisiae. We demonstrate that the m-AAA protease retains proteolytic activity after deletion of the transmembrane segments of either Yta10 or Yta12. Although the mutant m-AAA protease is still capable of processing cytochrome c peroxidase and degrading a peripheral membrane protein, proteolysis of integral membrane proteins is impaired. We therefore propose that transmembrane segments of m-AAA protease subunits have a direct role in the dislocation of membrane-embedded substrates.
Korbel
Daniel
D
Institut für Genetik, Universität zu Köln, Zülpicher Strasse 47, 50674 Köln, Germany.
Wurth
Stephanie
S
Käser
Michael
M
Langer
Thomas
T
D000251:Adenosine Triphosphatases / Q000502:physiology; D000255:Adenosine Triphosphate / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D049109:Cell Proliferation; D003578:Cytochrome-c Peroxidase / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D047468:Immunoprecipitation; D008666:Metalloendopeptidases / Q000378:metabolism / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D016296:Mutagenesis; D010101:Oxygen Consumption; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D013696:Temperature; D013997:Time Factors
D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D003578:Cytochrome-c Peroxidase; D008666:Metalloendopeptidases; C114583:m-AAA proteases; D000251:Adenosine Triphosphatases; C102166:YTA12 protein, S cerevisiae; C090045:AFG3 protein, S cerevisiae