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The dynamin-related GTPase Dnm1 regulates mitochondrial fission in yeast
W Bleazard1, J M McCaffery, E J King
1Department of Biology, University of Utah, Salt Lake City 84112, USA.
Abstract:
The dynamin-related GTPase Dnm1 controls mitochondrial morphology in yeast. Here we show that dnm1 mutations convert the mitochondrial compartment into a planar 'net' of interconnected tubules. We propose that this net morphology results from a defect in mitochondrial fission. Immunogold labelling localizes Dnm1 to the cytoplasmic face of constricted mitochondrial tubules that appear to be dividing and to the ends of mitochondrial tubules that appear to have recently completed division. The activity of Dnm1 is epistatic to that of Fzo1, a GTPase in the outer mitochondrial membrane that regulates mitochondrial fusion. dnm1 mutations prevent mitochondrial fragmentation in fzo1 mutant strains. These findings indicate that Dnm1 regulates mitochondrial fission, assembling on the cytoplasmic face of mitochondrial tubules at sites at which division will occur.
Insights
The dynamin-related GTPase Dnm1 regulates mitochondrial fission in yeast. Mutations in Dnm1 cause mitochondria to form a net-like structure instead of dividing properly.
Area of Science:
- Cell Biology
- Molecular Biology
- Mitochondrial Dynamics
Background:
- Mitochondrial morphology is crucial for cellular function.
- The dynamin-related GTPase Dnm1 is known to influence mitochondrial shape in yeast.
Purpose of the Study:
- To investigate the role of Dnm1 in mitochondrial fission.
- To elucidate the mechanism by which Dnm1 controls mitochondrial morphology.
Main Methods:
- Generating and analyzing yeast strains with mutations in the Dnm1 gene.
- Utilizing immunogold labeling to localize Dnm1 within mitochondria.
- Examining the genetic interactions between Dnm1 and Fzo1, a mitochondrial fusion regulator.
Main Results:
- dnm1 mutations result in a planar 'net' morphology of interconnected mitochondrial tubules.
- Dnm1 localizes to the cytoplasmic face of constricted and recently divided mitochondrial tubules.
- Dnm1 activity is epistatic to Fzo1, and dnm1 mutations suppress mitochondrial fragmentation in fzo1 mutants.
Conclusions:
- Dnm1 is a key regulator of mitochondrial fission.
- Dnm1 assembles at specific sites on mitochondrial tubules to mediate division.
- The findings clarify the molecular mechanism of Dnm1-dependent mitochondrial fission.