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Free keywords:
Adenosine Triphosphatases/physiology
Adenosine Triphosphate/metabolism
Cell Membrane/*metabolism
Cell Proliferation
Cytochrome-c Peroxidase/metabolism
Electrophoresis, Polyacrylamide Gel
Gene Deletion
Immunoprecipitation
Metalloendopeptidases/metabolism/*physiology
Mitochondria/*metabolism
Mitochondrial Proteins
Mutagenesis
Oxygen Consumption
Protein Conformation
Protein Structure, Tertiary
Saccharomyces cerevisiae/metabolism
Saccharomyces cerevisiae Proteins/physiology
Temperature
Time Factors
Abstract:
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.
