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RNA editing as a source of genetic variation
1Department of Cellular and Developmental Biology, Harvard University Biological Laboratories, Cambridge, Massachusetts 02138.
Nature
|May 13, 1993
Summary
RNA editing in kinetoplastids modifies mitochondrial transcripts, creating new reading frames. This process, particularly in Herpetomonas, introduces frameshift mutations, accelerating protein evolution compared to unedited versions.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Genetics
Background:
- Kinetoplastid RNA editing extensively modifies mitochondrial transcripts by adding/deleting uridines.
- This process can double the length of open reading frames.
- While Trypanosoma brucei shows full COIII gene editing, Leishmania tarentolae and Crithidia fasciculata exhibit limited 5' end editing.
Purpose of the Study:
- Investigate the evolution of edited genes using a comparative approach.
- Determine the extent to which RNA editing conserves protein sequences.
- Explore the role of RNA editing in protein evolution across different trypanosome species.
Main Methods:
- Comparative analysis of RNA editing in mitochondrial genes.
- Sequencing and analysis of COIII genes in four Herpetomonas species.
- Evolutionary rate analysis of edited versus unedited protein sequences.
Main Results:
- Extensive RNA editing was observed in the mitochondria of four Herpetomonas species.
- RNA editing was identified as a novel source of evolutionary frameshift mutations.
- Edited proteins accumulated mutations at nearly twice the rate of unedited proteins.
Conclusions:
- RNA editing in kinetoplastids significantly impacts protein evolution.
- The editing process can lead to rapid accumulation of mutations, challenging protein sequence conservation.
- Herpetomonas species may represent evolutionary precursors, offering insights into the origins of RNA editing.