Evolutionary conservation of RNA editing in the genus Leishmania.

RNA editing in kinetoplastids is the process by which vital genetic informations are restored through insertion and deletion of uridine residues in coding sequences, particularly those of the mitochondrial pre-mRNA. Mammalian infecting Leishmania were not analyzed before for the presence of RNA editing to establish whether the mechanism is still in use in higher lineages of the genus. The Cytochrome Oxidase gene of Leishmania tarentolae is known to be edited at its 3' end with gRNA encoded in the region immediately downstream. We sequenced DNA and cDNA of the COII gene of Leishmania donovani and compared those to Leishmania tarentolae sequences from the database. The results reveal an insertion of uridines in a manner identical to L. tarentolae, leading to restoration of the amino acid sequence with relative conservation of the gRNA region. We conclude that RNA editing as a posttranscriptional mechanism is still conserved within higher evolutionary lineages of the genus Leishmania.