RET1-catalyzed uridylylation shapes the mitochondrial transcriptome in Trypanosoma brucei.
RNA uridylylation is critical for the expression of the mitochondrial genome in trypanosomes. Short U tails are added to guide RNAs and rRNAs, while long A/U heteropolymers mark 3' ends of most mRNAs. Three divergent mitochondrial terminal uridylyl transferases (TUTases) are known: RET1 catalyzes guide RNA (gRNA) uridylylation, RET2 executes U insertion mRNA editing, and MEAT1 associates with the editosome-like complex. However, the activities responsible for 3' uridylylation of rRNAs and mRNAs, and the roles of these modifications, are unclear. To dissect the functions of mitochondrial TUTases, we investigated the effects of their repression and overexpression on abundance, processing, 3'-end status, and in vivo stability of major mitochondrially encoded RNA classes. We show that RET1 adds U tails to gRNAs, rRNAs, and select mRNAs and contributes U's into A/U heteropolymers. Furthermore, RET1's TUTase activity is required for the nucleolytic processing of gRNA, rRNA, and mRNA precursors. The U tail's presence does not affect the stability of gRNAs and rRNAs, while transcript-specific uridylylation triggers 3' to 5' mRNA decay. We propose that the minicircle-encoded antisense transcripts, which are stabilized by RET1-catalyzed uridylylation, may direct a nucleolytic cleavage of multicistronic precursors.
Aphasizheva
Inna
I
Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, California 92697, USA.
Aphasizhev
Ruslan
R
D000818:Animals; D055162:Biocatalysis; D049109:Cell Proliferation; D018105:DNA, Kinetoplast; D004789:Enzyme Activation; D020869:Gene Expression Profiling; D008928:Mitochondria / Q000235:genetics*; D010641:Phenotype; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism; D012316:RNA Nucleotidyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D016372:RNA, Antisense / Q000235:genetics; D017394:RNA, Guide, Kinetoplastida / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D014542:Uridine Monophosphate / Q000378:metabolism*
D018105:DNA, Kinetoplast; D015800:Protozoan Proteins; D012322:RNA Precursors; D016372:RNA, Antisense; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D014542:Uridine Monophosphate; D012316:RNA Nucleotidyltransferases; C031687:UTP-RNA uridylyltransferase; D017394:RNA, Guide, Kinetoplastida