The Leishmania kinetoplast-mitochondrion contains terminal uridylyltransferase and RNA ligase activities.

Purified mitochondria of Leishmania tarentolae contain 3'-terminal uridylyltransferase and RNA ligase activities which can be solubilized by detergent lysis of the organelle. Run-off transcription of maxicircle and minicircle DNA also occurs in intact and Triton-lysed mitochondria, using [32P]GTP as the labeled precursor. Heparin inhibits the solubilized terminal uridylyltransferase activity but does not affect the labeling of endogenous RNAs in intact mitochondria with [32P]UTP. Clarification of the mitochondrial Triton lysate causes an increase in terminal uridylyltransferase activity with exogenous substrates. These two activities are candidates for involvement in a post-transcriptional RNA editing process of mitochondrial transcripts.