Cited by 731Mitochondrial Function and PathologyAutophagy in Disease and TherapyATP Synthase and ATPases Research

Mitofusin 1 and 2 play distinct roles in mitochondrial fusion reactions via GTPase activity

Ishihara, Naotada, Eura, Yuka, Mihara, Katsuyoshi·2004·Journal of Cell Science

Abstract

The mammalian homologues of yeast and Drosophila Fzo, mitofusin (Mfn) 1 and 2, are both essential for mitochondrial fusion and maintenance of mitochondrial morphology. Though the GTPase domain is required for Mfn protein function, the molecular mechanisms of the GTPase-dependent reaction as well as the functional division of the two Mfn proteins are unknown. To examine the function of Mfn proteins, tethering of mitochondrial membranes was measured in vitro by fluorescence microscopy using green fluorescence protein- or red fluorescent protein-tagged and Mfn1-expressing mitochondria, or by immunoprecipitation using mitochondria harboring HA- or FLAG-tagged Mfn proteins. These experiments revealed that Mfn1-harboring mitochondria were efficiently tethered in a GTP-dependent manner, whereas Mfn2-harboring mitochondria were tethered with only low efficiency. Sucrose density gradient centrifugation followed by co-immunoprecipitation revealed that Mfn1 produced oligomerized ∼250 kDa and ∼450 kDa complexes in a GTP-dependent manner. The ∼450 kDa complex contained oligomerized Mfn1 from distinct apposing membranes (docking complex), whereas the ∼250 kDa complex was composed of Mfn1 present on the same membrane or in the membrane-solubilized state (cis complex). These results were also confirmed using blue-native PAGE. Mfn1 exhibited higher activity for this reaction than Mfn2. Purified recombinant Mfn1 exhibited ∼eightfold higher GTPase activity than Mfn2. These findings indicate that the two Mfn proteins have distinct activities, and suggest that Mfn1 is mainly responsible for GTP-dependent membrane tethering.

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Crossref · 10.1242/jcs.01565

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Authors
Ishihara, N., Eura, Y., & Mihara, K.
Affiliations
Kyushu University (JP)
Venue
Journal of Cell Science
Published
2004-12-15
Volume
117
Issue
26
Pages
6535-6546
ISSN
  • 0021-9533 (ISSN-L)
  • 1477-9137
OpenAlex
W2171775338
Cited by
731
References
31
Citations by year
2026: 17 · 2025: 35 · 2024: 38 · 2023: 44 · 2022: 39 · 2021: 65 · 2020: 54 · 2019: 47 · 2018: 46 · 2017: 38 · 2016: 34 · 2015: 18 · 2014: 24 · 2013: 30 · 2012: 34
FWCI
5.92
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Cell Science (publishedVersion)
  • PubMed (publishedVersion)
  • HighWire Press Open Archive (submittedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Mitochondrial Function and Pathology
  • Health Sciences › Medicine › Epidemiology › Autophagy in Disease and Therapy
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › ATP Synthase and ATPases Research
Keywords
mitofusin 1, mitofusin 2, mitochondrial fusion, GTPase activity, mitochondrial morphology, protein oligomerization, cis complexes
MeSH terms
Centrifugation, Density Gradient, Electrophoresis, Polyacrylamide Gel, HeLa Cells, Humans, Membrane Fusion, Membrane Proteins, Mitochondria, Precipitin Tests, Recombinant Fusion Proteins, Microscopy, Confocal, GTP Phosphohydrolases, Mitochondrial Proteins, Membrane Transport Proteins, Mitochondrial Membrane Transport Proteins, Green Fluorescent Proteins

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