RNA ligase and its involvement in guide RNA/mRNA chimera formation. Evidence for a cleavage-ligation mechanism of Trypanosoma brucei mRNA editing.
Abstract
RNA editing in Trypanosoma brucei results in the addition and deletion of uridine residues within several mitochondrial mRNAs. Editing is thought to be directed by guide RNAs and may proceed via a chimeric guide RNA/mRNA intermediate. We have previously shown that chimera-forming activity sediments with 19 S and 35-40 S mitochondrial ribonucleoprotein particles (RNPs). In this report we examine the involvement of RNA ligase in the production of chimeric molecules in vitro. Two adenylylated proteins of 50 and 57 kDa co-sediment on glycerol gradients with RNA ligase activity as components of the ribonucleoprotein particles. The two adenylylated proteins differ in sequence and contain AMP linked via a phosphoamide bond. Both proteins are deadenylylated by the addition of ligatable RNA substrate with the concomitant release of AMP and by the addition of pyrophosphate to yield ATP. Incubation with nonligatable RNA substrate results in an accumulation of the adenylylated RNA intermediate. These experiments identify the adenylylated proteins as RNA ligases. AMP release from the mitochondrial RNA ligase is also concomitant with chimera formation. Inhibition by nonhydrolyzable analogs indicates that both RNA ligase and chimera-forming a...Continue Reading
References
Formation of a 2'-phosphomonoester, 3',5'-phosphodiester linkage by a novel RNA ligase in wheat germ
Citations
Kinetoplastid RNA editing ligases: complex association, characterization, and substrate requirements
TbMP44 is essential for RNA editing and structural integrity of the editosome in Trypanosoma brucei.
KREPA4, an RNA binding protein essential for editosome integrity and survival of Trypanosoma brucei.
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