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The mitochondrial intermembrane space protein mitofissin drives mitochondrial fission required for mitophagy

Tomoyuki Fukuda1, Kentaro Furukawa1, Tatsuro Maruyama2

  • 1Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.

Molecular Cell
|May 16, 2023
PubMed

Insights

Researchers discovered mitofissin (Atg44) as a crucial protein for mitochondrial fission during mitophagy. This protein enables the fragmentation of mitochondria, allowing their degradation and maintaining cellular health.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitophagy is essential for maintaining mitochondrial homeostasis through selective degradation.
  • Mitochondrial fragmentation is necessary for engulfment by autophagosomes during mitophagy.
  • Known mitochondrial fission factors (Dnm1/DNM1L) are not required for mitophagy.

Purpose of the Study:

  • To identify novel factors involved in mitochondrial fission during mitophagy.
  • To elucidate the mechanism by which mitochondria are fragmented for mitophagy.

Main Methods:

  • Yeast genetics and cell biology techniques.
  • Mitochondrial morphology analysis in wild-type and mutant cells.
  • In vitro lipid membrane binding and fission assays.

Main Results:

  • Atg44 was identified as a novel mitochondrial fission factor essential for mitophagy in yeast.
  • Atg44 and its orthologs were named mitofissin.
  • Mitofissin deficiency impairs mitochondrial fragmentation, hindering autophagosome engulfment.
  • Mitofissin directly binds to lipid membranes and induces membrane fragility, promoting fission.

Conclusions:

  • Mitofissin is a key mediator of mitochondrial fission required for mitophagy.
  • Mitofissin functions by directly acting on lipid membranes to drive fission.
  • This discovery provides new insights into the regulation of mitophagy and mitochondrial quality control.
Keywords:
Atg44autophagycrystal structure analysisdynamin-related proteinhigh-speed atomic force microscopymitochondriamitochondrial fissionmitofissinmitophagyyeast

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