Related Experiment Videos
Characterization of a putative fusogen encoded in a mitochondrial plasmid of Physarum polycephalum
Hiroyoshi Takano1, Shigeyuki Kawano, Narie Sasaki
1Department of Biological Science, Faculty of Science, Kumamoto University, Kumamoto 860-8555, Japan, takano@kumamoto-u.ac.jp
Abstract:
The mitochondrial plasmid mF induces mitochondrial fusion in zygotes and during sporulation in the true slime mold Physarum polycephalum. There are nine open reading frames (ORFs) in the mF plasmid, and it has been suggested that ORF640 encodes the mitochondrial fusogen. We prepared antisera directed against the ORF640 protein (ORF640p) in rabbits, and used it to localize this protein in mitochondria. Western blot analysis showed that ORF640p was produced only in the mitochondria of mF(+) strains, i.e., in cells that carried the mF plasmid. Proteinase K treatment of mitochondria isolated from the mF(+) strain suggested that the C-terminus coiled-coil (CC) region of ORF640p was exported from the matrix to the cytosol. Digitonin treatment confirmed this localization. West-Western blot analysis suggested that the CC region of ORF640p formed multimers and could interfere with an unknown mitochondrial protein in normal mitochondria. These results suggest that ORF640p is related to fusion of the outer mitochondrial membrane.
Insights
The mitochondrial plasmid mF protein ORF640p is essential for mitochondrial fusion in Physarum polycephalum. This protein localizes to the outer mitochondrial membrane, suggesting its role in membrane fusion processes.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The mF plasmid in Physarum polycephalum is known to induce mitochondrial fusion.
- Nine open reading frames (ORFs) exist on the mF plasmid, with ORF640 being a candidate for the mitochondrial fusogen.
Purpose of the Study:
- To investigate the role of ORF640 protein (ORF640p) in mitochondrial fusion.
- To determine the localization and function of ORF640p within the mitochondria.
Main Methods:
- Antisera production against ORF640p for protein localization.
- Western blot analysis to detect ORF640p expression in mF(+) strains.
- Proteinase K and digitonin treatment of isolated mitochondria to assess protein localization.
- West-Western blot analysis to investigate protein interactions.
Main Results:
- ORF640p was exclusively detected in mitochondria of mF(+) strains.
- The C-terminus coiled-coil (CC) region of ORF640p was localized to the cytosol, exported from the mitochondrial matrix.
- The CC region of ORF640p was found to form multimers and potentially interact with other mitochondrial proteins.
Conclusions:
- ORF640p is involved in mitochondrial fusion, likely by acting on the outer mitochondrial membrane.
- The localization and multimerization of ORF640p suggest a mechanism for mediating mitochondrial membrane fusion.