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A mitofusin-dependent docking ring complex triggers mitochondrial fusion in vitro.
Tobias Brandt1, Laetitia Cavellini2, Werner Kühlbrandt1
1Max Planck Institute of Biophysics, Frankfurt, Germany.
Elife
|June 3, 2016
Summary
Mitochondrial outer membrane fusion, essential for organelle function, is mediated by mitofusins. This study visualizes the fusion process, revealing a docking ring complex that forms and triggers membrane merging during GTP hydrolysis.
Area of Science:
- Cell Biology
- Mitochondrial Dynamics
- Membrane Biology
Background:
- Mitochondrial outer membrane fusion is vital for cellular health and function.
- Mitofusins, large GTPases, are key regulators of this process.
- The precise mechanistic steps of mitochondrial attachment and fusion remain unclear.
Purpose of the Study:
- To elucidate the discrete steps involved in mitochondrial outer membrane fusion.
- To visualize the molecular complexes mediating mitochondrial attachment and fusion in vitro.
- To understand the role of GTP hydrolysis in driving the fusion process.
Main Methods:
- Utilized an in vitro mitochondrial fusion assay.
- Employed electron cryo-tomography (cryo-ET) to visualize mitochondrial junctions.
- Isolated mitochondria from Saccharomyces cerevisiae for analysis.
Main Results:
- Observed novel complexes mediating mitochondrial attachment.
- Demonstrated that GTP hydrolysis cycles progressively form a docking ring structure at extended contact sites.
- Showed that further GTP hydrolysis initiates local outer membrane fusion at the contact periphery.
Conclusions:
- Unraveled key mechanistic features of mitofusin-dependent outer membrane fusion.
- Provided a high-resolution visualization of mitochondrial fusion intermediates.
- Advanced the understanding of how mitochondria connect and merge, crucial for organelle homeostasis.
Keywords:
S. cerevisiaebiophysicscell biologycryo-EMdynamin-related-proteinsmembrane fusionmitochondriamitochondrial dynamicsmitofusinstructural biologyMore Related Videos
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