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RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes
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Published on: July 22, 2014

Dyskinetoplastic Trypanosoma brucei contains functional editing complexes

Gonzalo J Domingo1, Setareh S Palazzo, Bingbing Wang

  • 1Seattle Biomedical Research Institute, Seattle, Washington 98109, USA.

Eukaryotic Cell
|June 11, 2003
PubMed

Insights

Kinetoplastid protozoa utilize RNA editing for functional mRNAs. Surprisingly, RNA editing complexes remain functional even without their natural substrates, pre-mRNA and guide RNA (gRNA).

Area of Science:

  • Molecular Biology
  • Genetics
  • Parasitology

Background:

  • Mitochondrial pre-mRNAs in kinetoplastids require posttranscriptional RNA editing, guided by small guide RNAs (gRNAs), to become functional mRNAs.
  • This editing process is catalyzed by a multienzyme protein complex and involves genetic material encoded in the maxicircle and minicircle components of kinetoplastid mitochondrial DNA (kDNA).

Purpose of the Study:

  • To investigate the necessity of pre-mRNA and gRNAs for the formation and function of RNA-editing complexes in kinetoplastids.
  • To determine if RNA-editing complexes retain their catalytic activities in the absence of their natural substrates.

Main Methods:

  • Analysis of Trypanosoma evansi AnTat3/3 (lacking maxicircles) and a dyskinetoplastic Trypanosoma brucei mutant (devoid of kDNA).
  • Immunoprecipitation and sedimentation assays to characterize the editing complexes.
  • In vitro assays to assess the catalytic activities of the isolated editing complexes.

Main Results:

  • Both T. evansi and T. brucei mutants retained genes and proteins essential for the RNA-editing complex.
  • These proteins formed complexes that immunoprecipitated and sedimented similarly to wild-type complexes.
  • The isolated complexes demonstrated catalytic activity in precleaved insertion/deletion and full-round deletion editing in vitro.

Conclusions:

  • Functional RNA-editing complexes can form and retain catalytic activity independently of pre-mRNA and gRNAs.
  • Neither the pre-mRNA nor the gRNA is required for the assembly or function of these essential RNA-editing complexes in vitro.
  • This finding challenges the substrate-dependent model for RNA-editing complex formation in kinetoplastids.

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