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Protein synthesis in mitochondria isolated from the trypanosomatid protozoan Crithidia fasciculata
1Department of Cell and Molecular Biology, University of Umeå, Sweden. Ivor.Tittawella@cmb.umu.se
Abstract:
Evidence presented over the years in support of mitochondrial translation in trypanosomes, based largely on studies using differential inhibitors such as cycloheximide and chloramphenicol, remains controversial. I have studied endogenous mRNA-dependent translation in a mitochondrial fraction isolated from the trypanosomatid protozoan Crithidia fasciculata. By using pancreatic ribonuclease to inactivate contaminating cytosolic activity, I show that these mitochondria can conduct protein synthesis in their own right. The mitochondrial translational products differed from cytosolic products as judged by SDS-PAGE, and had sizes expected of some proteins encoded in the mitochondrial genome of C. fasciculata and other trypanosomatids. Some evidence is provided suggesting that the seat of translation might be the kinetoplast.
Insights
This study demonstrates that Crithidia fasciculata mitochondria can perform their own protein synthesis, distinct from cytosolic activity. This finding supports endogenous mitochondrial translation in trypanosomes, with potential localization to the kinetoplast.
Area of Science:
- Molecular Biology
- Parasitology
- Cell Biology
Background:
- Mitochondrial translation in trypanosomes is debated, with previous studies relying on controversial inhibitor data.
- Understanding organelle-specific protein synthesis is crucial for parasitic protozoa.
Purpose of the Study:
- To investigate endogenous mRNA-dependent translation within isolated mitochondria of Crithidia fasciculata.
- To differentiate mitochondrial protein synthesis from cytosolic contamination.
Main Methods:
- Isolation of a mitochondrial fraction from Crithidia fasciculata.
- Use of pancreatic ribonuclease to eliminate cytosolic translational activity.
- Analysis of translational products using SDS-PAGE.
Main Results:
- Isolated mitochondria demonstrated independent protein synthesis capabilities.
- Mitochondrial translational products were distinct from cytosolic products.
- Product sizes corresponded to proteins encoded by the mitochondrial genome.
Conclusions:
- Crithidia fasciculata mitochondria possess their own functional translational machinery.
- Evidence suggests the kinetoplast may be the site of mitochondrial translation.
- This study provides robust support for endogenous mitochondrial translation in trypanosomes.