Uridine insertion/deletion RNA editing in trypanosome mitochondria - a review

The uridine insertion/deletion RNA editing in trypanosome mitochondria is a unique posttranscriptional RNA maturation process that involves the additi on or removal of uridine residues at precise sites usually within the codin g regions of mitochondrial transcripts. This process creates initiation and termination codons, corrects frameshifts and even builds entire open-readi ng frames from nonsense sequences. The development of several in-vitro edit ing assays has provided much insight into the molecular mechanism of RNA ed iting, which appears to involve cleavage, U addition, exonuclease trimming and ligation, essentially as proposed in the original 'enzyme cascade' mode l (Blum, B., Bakalara, N., Simpson, L., 1990. A model for RNA editing in ki netoplastid mitochondria: 'Guide' RNA molecules transcribed from maxicircle DNA provide the edited information. Cell 60, 189-198). However, little is known about the biochemical properties of the proteins involved and the sig nificance and role of this process. This article is a review of recent find ings on uridine-insertion/deletion editing in trypanosome mitochondria, wit h an emphasis on the proteins isolated and characterized that may have a ro le in this process. (C) 1999 Elsevier Science B.V. All rights reserved.