title: RNA binding and core complexes constitute the U-insertion/deletion editosome.
abstract: Enzymes embedded into the RNA editing core complex (RECC) catalyze the U-insertion/deletion editing cascade to generate open reading frames in trypanosomal mitochondrial mRNAs. The sequential reactions of mRNA cleavage, U-addition or removal, and ligation are directed by guide RNAs (gRNAs). We combined proteomic, genetic, and functional studies with sequencing of total and complex-bound RNAs to define a protein particle responsible for the recognition of gRNAs and pre-mRNA substrates, editing intermediates, and products. This approximately 23-polypeptide tripartite assembly, termed the RNA editing substrate binding complex (RESC), also functions as the interface between mRNA editing, polyadenylation, and translation. Furthermore, we found that gRNAs represent only a subset of small mitochondrial RNAs, and yet an inexplicably high fraction of them possess 3' U-tails, which correlates with gRNA's enrichment in the RESC. Although both gRNAs and mRNAs are associated with the RESC, their metabolic fates are distinct: gRNAs are degraded in an editing-dependent process, whereas edited mRNAs undergo 3' adenylation/uridylation prior to translation. Our results demonstrate that the well-characterized editing core complex (RECC) and the RNA binding particle defined in this study (RESC) typify enzymatic and substrate binding macromolecular constituents, respectively, of the ∼40S RNA editing holoenzyme, the editosome.
authors.affiliation: Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA.
authors.forename: Inna
authors.initials: I
authors.lastname: Aphasizheva
authors.affiliation: Section of Computational Biomedicine, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Liye
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.
authors.forename: Robyn M
authors.initials: RM
authors.lastname: Kaake
authors.affiliation: Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
authors.affiliation: Section of Computational Biomedicine, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Stefano
authors.initials: S
authors.lastname: Monti
authors.affiliation: Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA ruslana@bu.edu.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Aphasizhev
mesh_terms: D001483:Base Sequence; D008928:Mitochondria / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D010441:Peptide Chain Elongation, Translational / Q000235:genetics*; D026723:Polyadenylation / Q000235:genetics; D015800:Protozoan Proteins / Q000378:metabolism; D012313:RNA / Q000235:genetics; D017393:RNA Editing / Q000235:genetics*; D034622:RNA Interference; D016337:RNA, Catalytic / Q000235:genetics; D017394:RNA, Guide, Kinetoplastida / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan / Q000235:genetics; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000235:genetics; D017423:Sequence Analysis, RNA; D014346:Trypanosoma brucei brucei / Q000235:genetics*
chemical_list: D015800:Protozoan Proteins; D016337:RNA, Catalytic; D012333:RNA, Messenger; D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012313:RNA; D017394:RNA, Guide, Kinetoplastida