title: RNA editing in Trypanosoma brucei requires three different editosomes.
abstract: Trypanosoma brucei has three distinct approximately 20S editosomes that catalyze RNA editing by the insertion and deletion of uridylates. Editosomes with the KREN1 or KREN2 RNase III type endonucleases specifically cleave deletion and insertion editing site substrates, respectively. We report here that editosomes with KREPB2, which also has an RNase III motif, specifically cleave cytochrome oxidase II (COII) pre-mRNA insertion editing site substrates in vitro. Conditional repression and mutation studies also show that KREPB2 is an editing endonuclease specifically required for COII mRNA editing in vivo. Furthermore, KREPB2 expression is essential for the growth and survival of bloodstream forms. Thus, editing in T. brucei requires at least three compositionally and functionally distinct approximately 20S editosomes, two of which distinguish between different insertion editing sites. This unexpected finding reveals an additional level of complexity in the RNA editing process and suggests a mechanism for how the selection of sites for editing in vivo is controlled.
authors.affiliation: Seattle Biomedical Research Institute, 307 Westlake Ave N, Suite 500, Seattle, WA 98109, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Carnes
authors.forename: James Raffaello
authors.initials: JR
authors.lastname: Trotter
authors.forename: Adam
authors.initials: A
authors.lastname: Peltan
authors.forename: Michele
authors.initials: M
authors.lastname: Fleck
authors.forename: Kenneth
authors.initials: K
authors.lastname: Stuart
mesh_terms: D000818:Animals; D001483:Base Sequence; D003576:Electron Transport Complex IV / Q000378:metabolism; D047150:Eosinophil Cationic Protein / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D015388:Organelles / Q000201:enzymology* / Q000235:genetics*; D017393:RNA Editing; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D003576:Electron Transport Complex IV; D047150:Eosinophil Cationic Protein