Processing of polycistronic guide RNAs is associated with RNA editing complexes in Trypanosoma brucei.


Publication Type:

Journal Article

Source:

EMBO J, Volume 19, Issue 20, p.5525-32 (2000)

Keywords:

Animals, Base Sequence, DNA, Kinetoplast, Genes, Macromolecular Substances, Mitochondria, Models, Genetic, Molecular Sequence Data, Molecular Weight, Nucleic Acid Conformation, Reverse Transcriptase Polymerase Chain Reaction, RNA, RNA Editing, RNA, Guide, RNA, Messenger, Transcription, Genetic, Trypanosoma brucei brucei

Abstract:

<p>In kinetoplastid mitochondrial mRNA editing, post-transcriptional insertion or deletion of uridines is templated by guide RNAs (gRNAs). Pre-mRNAs are encoded by maxicircles, while gRNAs are encoded by both maxicircles and minicircles. We have investigated minicircle transcription and the processing of gRNAs in Trypanosoma brucei. We find that minicircles are transcribed polycistronically and that transcripts are accurately processed by an approximately 19S complex. This gRNA processing activity co-purifies with RNA editing complexes, and both remain associated in 19S complexes. Furthermore, we show that RNA editing complexes associate preferentially with a polycistronic gRNA over non-processed RNAs. We propose that the approximately 19S complexes initially described as RNA editing complex I are gRNA processing complexes that cleave polycistronic gRNA transcripts into monocistrons.</p>