title: The m-AAA protease processes cytochrome c peroxidase preferentially at the inner boundary membrane of mitochondria.
abstract: The m-AAA protease is a conserved hetero-oligomeric complex in the inner membrane of mitochondria. Recent evidence suggests a compartmentalization of the contiguous mitochondrial inner membrane into an inner boundary membrane (IBM) and a cristae membrane (CM). However, little is known about the functional differences of these subdomains. We have analyzed the localizations of the m-AAA protease and its substrate cytochrome c peroxidase (Ccp1) within yeast mitochondria using live cell fluorescence microscopy and quantitative immunoelectron microscopy. We find that the m-AAA protease is preferentially localized in the IBM. Likewise, the membrane-anchored precursor form of Ccp1 accumulates in the IBM of mitochondria lacking a functional m-AAA protease. Only upon proteolytic cleavage the mature form mCcp1 moves into the cristae space. These findings suggest that protein quality control and proteolytic activation exerted by the m-AAA protease take place preferentially in the IBM pointing to significant functional differences between the IBM and the CM.
authors.affiliation: Department of NanoBiophotonics/Mitochondrial Structure and Dynamics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: Ida E
authors.initials: IE
authors.lastname: Suppanz
authors.forename: Christian A
authors.initials: CA
authors.lastname: Wurm
authors.forename: Dirk
authors.initials: D
authors.lastname: Wenzel
authors.forename: Stefan
authors.initials: S
authors.lastname: Jakobs
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D003578:Cytochrome-c Peroxidase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000201:enzymology* / Q000648:ultrastructure; D024101:Mitochondrial Proteins; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D011498:Protein Precursors; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D003578:Cytochrome-c Peroxidase; D008666:Metalloendopeptidases; C114583:m-AAA proteases; D000251:Adenosine Triphosphatases; C102166:YTA12 protein, S cerevisiae; C090045:AFG3 protein, S cerevisiae