RNA editing in mitochondria of Leishmania tarentolae and Crithidia fasciculata.

The uridine sequence of mitochondrial pre-mRNAs in trypanosomes is post-transcriptionally altered by an RNA editing process, the information for which is provided by small guide (g)RNAs. Current editing models are based on the occurrence in mitochondrial RNA of chimeric molecules in which a gRNA is covalently linked to an editing site through its 3' end. This review describes some of the work done in Leishmania tarentolae that led to the construction of these models, in comparison to data obtained in Crithidia fasciculata. In spite of the virtually complete conservation of editing patterns and genomic organization between the two species, the properties of gRNAs and chimeric molecules in C. fasciculata put the editing models in a slightly different perspective.