Mitochondrial RNA Editing and Processing in Diplonemid Protists

RNA editing and processing in the mitochondrion of Diplonema papillatum and other diplonemids are arguably the most complex processes of their kind described in any organelle so far. Prior to translation, each transcript has to be accurately trans-spliced from gene fragments encoded on different circular chromosomes. About half of the transcripts are massively edited by several types of substitution editing and addition of blocks of uridines. Comparative analysis of mitochondrial RNA processing among the three euglenozoan groups, diplonemids, kinetoplastids, and euglenids, highlights major differences between these lineages. Diplonemids remain poorly studied, yet they were recently shown to be extremely diverse and abundant in the ocean and hence are rapidly attracting increasing attention. It is therefore important to turn them into genetically tractable organisms, and we report here that they indeed have the potential to become such.