ausblenden:
Schlagwörter:
ATP-Dependent Proteases
Adenosine Triphosphatases/genetics/metabolism
Amino Acid Sequence
Catalytic Domain
Chromatography, Gel
Cloning, Molecular
Fungal Proteins/chemistry/genetics/metabolism
Genes, Fungal/genetics
Genetic Complementation Test
Intracellular Membranes/*enzymology/metabolism
Macromolecular Substances
Membrane Proteins/chemistry/genetics/metabolism
Metalloendopeptidases/*chemistry/genetics/*metabolism
Mitochondria/*enzymology
Molecular Sequence Data
Molecular Weight
Mutation
Neurospora crassa/cytology/*enzymology
Protein Folding
Protein Subunits
Saccharomyces cerevisiae Proteins/genetics/metabolism
Sequence Homology, Amino Acid
Temperature
Time Factors
Zusammenfassung:
Eukaryotic AAA proteases form a conserved family of membrane-embedded ATP-dependent proteases but have been analyzed functionally only in the yeast Saccharomyces cerevisiae. Here, we have identified two novel members of this protein family in the filamentous fungus Neurospora crassa, which were termed MAP-1 and IAP-1. Both proteins are localized to the inner membrane of mitochondria. They are part of two similar-sized high molecular mass complexes, but expose their catalytic sites to opposite membrane surfaces, namely, the intermembrane and the matrix space. Disruption of iap-1 by repeat-induced point mutation caused a slow growth phenotype at high temperature and stabilization of a misfolded inner membrane protein against degradation. IAP-1 could partially substitute for functions of its yeast homolog Yme1, demonstrating functional conservation. However, respiratory growth at 37 degrees C was not restored. Our results identify two components of the quality control system of the mitochondrial inner membrane in N. crassa and suggest that AAA proteases with catalytic sites exposed to opposite membrane surfaces are present in mitochondria of all eukaryotic cells.
