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Role of the small protein Mco6 in the mitochondrial sorting and assembly machinery

Jon V Busto1, Iniyan Ganesan1, Hannah Mathar2

  • 1Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Cell Reports
|February 20, 2024
PubMed

Insights

The sorting and assembly machinery (SAM) complex, including Mco6 and Mdm10, is crucial for mitochondrial outer membrane biogenesis. This study reveals SAM

Area of Science:

  • Mitochondrial biogenesis
  • Protein import and assembly
  • Molecular cell biology

Background:

  • Mitochondrial precursor proteins are primarily imported via the Tom40 β-barrel channel.
  • The sorting and assembly machinery (SAM) complex is vital for inserting β-barrel proteins into the outer membrane, essential for translocase of the outer membrane (TOM) complex assembly.

Purpose of the Study:

  • To investigate the role of the α-helical outer membrane protein Mco6 within the SAM machinery.
  • To elucidate the functional relationship between Mco6 and Mdm10 in mitochondrial outer membrane biogenesis.

Main Methods:

  • Genetic interaction analysis (mco6-mdm10 double mutant).
  • Assessing levels of the TOM complex in yeast mutants.
  • Investigating protein assembly defects in Mco6-deficient cells.

Main Results:

  • Mco6 co-assembles with Mdm10 as part of the SAM machinery.
  • A negative genetic interaction exists between MCO6 and MDM10.
  • The mco6-mdm10 double mutant shows reduced TOM complex levels.
  • Loss of Mco6 impacts Mdm10 levels and causes TOM complex assembly defects.

Conclusions:

  • The SAMMco6 complex plays a significant role in the biogenesis of the mitochondrial outer membrane.
  • Mco6 is essential for the proper assembly and function of the TOM complex.
  • This study identifies a novel function for the SAM complex in mitochondrial protein import.
Keywords:
CP: Cell biologyERMES complexMdm10SAM complexTOM complexmitochondriaouter membraneprotein importprotein translocationβ-barrel protein

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