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The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria

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Item Type:Article
Title:The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria
Creators Name:Koerner, C. and Barrera, M. and Dukanovic, J. and Eydt, K. and Harner, M. and Rabl, R. and Vogel, F. and Rapaport, D. and Neupert, W. and Reichert, A.S.
Abstract:Crista junctions (CJ) are tubular invaginations of the inner membrane of mitochondria that connect the inner boundary with the cristae membrane. These architectural elements are critical for mitochondrial function. The yeast inner membrane protein Fcj1, called mitofilin in mammals, was reported to be preferentially located at CJ and crucial for their formation. Here we investigated the functional roles of individual domains of Fcj1. The most conserved part of Fcj1, the C-terminal domain, is essential for Fcj1 function. In its absence, formation of CJ is strongly impaired and irregular, stacked cristae are present. This domain interacts with full-length Fcj1 suggesting a role in oligomer formation. It also interacts with Tob55 of the TOB/SAM complex which is required for the insertion of beta-barrel proteins into the outer membrane. The association of the TOB/SAM complex with contact sites depended on the presence of Fcj1. The biogenesis of beta-barrel proteins was not significantly affected in the absence of Fcj1. However, down-regulation of the TOB/SAM complex led to altered cristae morphology and to a moderate reduction in the number of CJ. We propose that the C-terminal domain of Fcj1 is critical for the interaction of Fcj1 with the TOB/SAM complex and thereby for stabilizing CJ in close proximity to the outer membrane. These results assign novel functions to both, the C-terminal domain of Fcj1 and the TOB/SAM complex.
Keywords:Conserved Sequence, Down-Regulation, Mitochondria, Mitochondrial Proteins, Protein Binding, Protein Biosynthesis, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Secondary Protein Structure, Structure-Activity Relationship, Tertiary Protein Structure
Source:Molecular Biology of the Cell
Publisher:American Society for Cell Biology
Page Range:2143-2155
Date:June 2012
Official Publication:https://doi.org/10.1091/mbc.E11-10-0831
PubMed:View item in PubMed

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