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Mol Cell. 2011 Apr 8;42(1):106-17. doi: 10.1016/j.molcel.2011.02.021.

Pentatricopeptide repeat proteins stimulate mRNA adenylation/uridylation to activate mitochondrial translation in trypanosomes.

Author information

1
Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA.

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.

PMID:
21474072
PMCID:
PMC3073060
DOI:
10.1016/j.molcel.2011.02.021
[Indexed for MEDLINE]
Free PMC Article

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