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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / metabolism*
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Animals
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Cytochrome-c Peroxidase / genetics
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Cytochrome-c Peroxidase / metabolism*
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Humans
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Metalloendopeptidases / genetics
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Metalloendopeptidases / metabolism*
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Mitochondria / enzymology
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Mitochondria / ultrastructure
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Mitochondrial Membranes / enzymology*
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Mitochondrial Membranes / ultrastructure
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Mitochondrial Proteins
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Protein Precursors / genetics
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Protein Precursors / metabolism
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
Substances
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Mitochondrial Proteins
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Protein Precursors
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Protein Subunits
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Cytochrome-c Peroxidase
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Metalloendopeptidases
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m-AAA proteases
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Adenosine Triphosphatases
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YTA12 protein, S cerevisiae
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AFG3 protein, S cerevisiae