title: Pentatricopeptide repeat proteins stimulate mRNA adenylation/uridylation to activate mitochondrial translation in trypanosomes.
abstract: The majority of trypanosomal mitochondrial pre-mRNAs undergo massive uridine insertion/deletion editing, which creates open reading frames. Although the pre-editing addition of short 3' A tails is known to stabilize transcripts during and after the editing, the processing event committing the fully edited mRNAs to translation remained unknown. Here, we show that a heterodimer of pentatricopeptide repeat-containing (PPR) proteins, termed kinetoplast polyadenylation/uridylation factors (KPAFs) 1 and 2, induces the postediting addition of A/U heteropolymers by KPAP1 poly(A) polymerase and RET1 terminal uridyltransferase. Edited transcripts bearing 200- to 300-nucleotide-long A/U tails, but not short A tails, were enriched in translating ribosomal complexes and affinity-purified ribosomal particles. KPAF1 repression led to a selective loss of A/U-tailed mRNAs and concomitant inhibition of protein synthesis. These results establish A/U extensions as the defining cis-elements of translation-competent mRNAs. Furthermore, we demonstrate that A/U-tailed mRNA preferentially interacts with the small ribosomal subunit, whereas edited substrates and complexes bind to the large subunit.
authors.affiliation: Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA.
authors.forename: Inna
authors.initials: I
authors.lastname: Aphasizheva
authors.forename: Dmitri
authors.initials: D
authors.lastname: Maslov
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wang
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
authors.forename: Ruslan
authors.initials: R
authors.lastname: Aphasizhev
mesh_terms: D001483:Base Sequence; D018105:DNA, Kinetoplast / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D017393:RNA Editing; D034622:RNA Interference; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D016053:RNA, Protozoan / Q000235:genetics* / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000235:genetics* / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D018105:DNA, Kinetoplast; D015800:Protozoan Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D016053:RNA, Protozoan; D039221:mRNA Cleavage and Polyadenylation Factors