Project name: Trypanosoma brucei strain:Lister427

Description: In Trypanosoma brucei, most mitochondrial mRNAs undergo internal sequence changes by U-insertion/deletion editing and 3′ end modifications. The temporally separated and functionally distinct modifications are manifested by adenylation prior to editing, and by the extension of a short A-tail into a long A/U-heteropolymer upon completion of editing. The A-tail stabilizes partially- and fully- edited mRNAs while the A/U-tail enables mRNA to binding to the ribosome. Here, we identify an essential pentatricopeptide repeat-containing RNA binding protein, termed kinetoplast polyadenylation factor 3 (KPAF3), and demonstrate its role in protecting pre-mRNA against degradation by the mitochondrial processome. We show that KPAF3 recruits KPAP1 poly(A) polymerase to the 3′ terminus, thus leading to pre-mRNA stabilization, or decay, depending on the occurrence and extent of editing. In vitro, KPAF3 stimulates KPAP1 activity and inhibits mRNA uridylation by RET1 TUTase. Our findings indicate that KPAF3 selectively directs pre-mRNA toward adenylation rather than uridylation, which is a default post-processing modification characteristic of ribosomal and guide RNAs. As a quality control mechanism, KPAF3 binding ensures that mRNAs entering the editing pathway are adenylated and, therefore, competent for post-editing A/U-tailing, and translational activation.

Data type: raw sequence reads

Sample scope: Monoisolate

Relevance: ModelOrganism

Last updated: 2017-02-20