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Updated: Aug 2, 2026
RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes
Published on: July 22, 2014
Guide RNAs for transcripts with developmentally regulated RNA editing are present in both life cycle stages of
D J Koslowsky1, G R Riley, J E Feagin
1Seattle Biomedical Research Institute, Washington 98109.
Abstract:
RNA editing of several mitochondrial transcripts in Trypanosoma brucei is developmentally regulated. The cytochrome b and cytochrome oxidase II mRNAs are edited in procyclic-form parasites but are primarily unedited in bloodstream forms. The latter forms lack the mitochondrial respiratory system present in procyclic forms. Editing of the NADH dehydrogenase 7 (ND7) and ND8 transcripts is also developmentally regulated but occurs preferentially in bloodstream forms. Other transcripts, cytochrome oxidase III and ATPase 6, are edited in both life forms. We have identified many minicircle-encoded guide RNAs (gRNAs) for ATPase 6, ND7, and ND8. The characteristics of these gRNAs reveal how extensively edited RNA can be edited in the 3'-to-5' direction. Northern (RNA) blot and primer extension analyses indicate that gRNAs for transcripts whose editing is developmentally regulated are present in both procyclic and bloodstream form parasites. These results suggest that the developmental regulation of editing in these transcripts is not controlled by the presence or absence of gRNAs.
Insights
RNA editing in Trypanosoma brucei mitochondria is developmentally controlled. Guide RNAs are present in both life stages, indicating regulation occurs post-transcriptionally.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Mitochondrial RNA editing in Trypanosoma brucei is crucial for parasite survival and exhibits developmental regulation.
- Specific transcripts like cytochrome b, cytochrome oxidase II, NADH dehydrogenase 7 (ND7), ND8, cytochrome oxidase III, and ATPase 6 undergo editing.
- The parasite's life cycle involves distinct forms (bloodstream and procyclic) with differing metabolic needs and mitochondrial activity.
Purpose of the Study:
- To investigate the developmental regulation of mitochondrial RNA editing in Trypanosoma brucei.
- To identify and characterize guide RNAs (gRNAs) involved in the editing of specific mitochondrial transcripts.
- To determine the role of gRNA presence in the developmental control of RNA editing.
Main Methods:
- Northern (RNA) blot analysis to detect transcript and gRNA levels.
- Primer extension assays to analyze RNA editing patterns and gRNA characteristics.
- Identification of minicircle-encoded gRNAs for ATPase 6, ND7, and ND8.
Main Results:
- Developmental regulation of editing was observed for cytochrome b, cytochrome oxidase II, ND7, and ND8 transcripts.
- ATPase 6 and cytochrome oxidase III transcripts are edited in both bloodstream and procyclic forms.
- gRNAs for developmentally regulated transcripts were found in both parasite forms, suggesting regulation is not gRNA-dependent.
Conclusions:
- The presence or absence of gRNAs does not solely control the developmental regulation of mitochondrial RNA editing in Trypanosoma brucei.
- RNA editing regulation likely involves post-transcriptional mechanisms beyond gRNA availability.
- Further research is needed to elucidate the precise mechanisms governing stage-specific RNA editing.
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