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Role of MINOS in mitochondrial membrane architecture: cristae morphology and outer membrane interactions

Ralf M Zerbes1, Maria Bohnert, David A Stroud

  • 1Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany.

Journal of Molecular Biology
|May 12, 2012
PubMed

Insights

The mitochondrial inner membrane organizing system (MINOS) maintains cristae structure. Its core component, mitofilin, interacts with outer membrane complexes, but these interactions don't solely maintain inner membrane architecture.

Area of Science:

  • Cell Biology
  • Mitochondrial Biology
  • Membrane Dynamics

Background:

  • The mitochondrial inner membrane organizing system (MINOS) is essential for mitochondrial structure.
  • MINOS maintains cristae junctions and interacts with outer mitochondrial membrane complexes.
  • Mitofilin (Fcj1) is a core component of MINOS with transmembrane and intermembrane space domains.

Purpose of the Study:

  • To investigate the relationship between outer membrane interactions and cristae morphology maintenance.
  • To determine the specific roles of mitofilin domains in MINOS integrity and outer membrane complex interactions.

Main Methods:

  • Generation and analysis of mutant mitofilin forms lacking specific domains (C-terminal, coiled-coil, intermembrane space domains).
  • Assessment of MINOS complex integrity and cristae morphology.
  • Analysis of mitofilin interactions with the translocase of the outer membrane (TOM) and sorting and assembly machinery (SAM) complexes.

Main Results:

  • Deletion of the C-terminal domain disrupted MINOS and cristae, but enhanced mitofilin interactions with TOM and SAM.
  • Deletion of the coiled-coil domain also disrupted MINOS and cristae, with differential effects on TOM and SAM interactions.
  • Deletion of both intermembrane space domains impaired MINOS integrity and interactions with TOM and SAM.

Conclusions:

  • The intermembrane space domains of mitofilin play distinct roles in maintaining MINOS integrity and cristae morphology.
  • Interactions between MINOS and outer membrane complexes (TOM, SAM) are not sufficient for maintaining inner mitochondrial membrane architecture.
  • Mitofilin's structure is critical for coordinating inner and outer mitochondrial membrane organization.

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