Evidence of RNA editing in Leishmania braziliensis promastigotes

RNA editing in trypanosomatids is an elaborate form of post-transcriptional processing that inserts and deletes uridines in many mitochondrial pre-mRNAs, providing the genetic information needed to create functional transcripts. The process has been extensively analyzed in Trypanosoma brucei, Crithidia fasciculata, and Leishmania tarentolae. However, few data exist on this mechanism in pathogenic Leishmania species. Here, we show evidence that this process also operates in Leishmania braziliensis, being the first time that RNA editing has been described in a species of the Viannia subgenus. A partially edited transcript corresponding to the NADH dehydrogenase subunit 8 (ND8) gene was identified in L. braziliensis promastigotes. Sequence analysis allowed the identification of the maxicircle-encoded cryptogene, which shows a high degree of sequence conservation with the corresponding cryptogenes in other Leishmania species. Although an edition pattern could be postulated for the ND8 transcripts in L. braziliensis, attempts to isolate completely edited transcripts by RT-PCR were not fruitful; instead, many transcripts with partial and unexpected editing patterns were isolated. This data, together with our inability to detect full-size transcripts by Northern blotting in promastigotes of L. braziliensis, led us to the suggestion that the strain used in this study (M2904) lacks of critical RNA guides for a complete edition of ND8 transcripts.