Role of MINOS in Mitochondrial Membrane Architecture: Cristae Morphology and Outer Membrane Interactions Differentially Depend on Mitofilin Domains
07.05.2012
Zerbes RM, Bohnert M, Stroud DA, von der Malsburg K, Kram A, Oeljeklaus S, Warscheid B, Becker T, Wiedemann N, Veenhuis M, van der Klei IJ, Pfanner N, van der Laan M.
J Mol Biol. 2012; 422(2):183-91
The mitochondrial inner membrane organizing system (MINOS) is a large protein complex crucial for the maintenance of mitochondrial membrane architecture with inner boundary and cristae membrane domains . MINOS is required for the formation of both, crista junctions and contact sites between inner and outer mitochondrial membranes. We generated different mutants of mitofilin/Fcj1, a central subunit of MINOS, to study the structural and functional relationship between outer membrane interactions and maintenance of cristae morphology. Deletion of the conserved C-terminal domain of mitofilin/Fcj1 strongly impaired the formation of MINOS complexes and crista junction structures, but did not affect the association with the general protein translocase of outer membrane (TOM) and the sorting assembly machinery (SAM). Deletion of the central coiled-coil domain also disrupted the MINOS complex as well as crista junctions and partially inhibited the interaction with the SAM, but not the TOM complex. We conclude that different domains of mitofilin/Fcj1 have distinct functions in the formation of membrane contacts sites and crista junctions. Our findings demonstrate that the interaction of MINOS with the TOM and SAM complexes is not sufficient for the maintenance of the characteristic morphology of the inner mitochondrial membrane.
