The pentatricopeptide repeat protein MEF26 participates in RNA editing in mitochondrial cox3 and nad4 transcripts

• Mitochondrial Editing Factor 26 is a DYW-PPR protein involved in editing at 2 sites.
• The two sites cox3-311 and nad4-166 share similar cis-elements.
• Both sites conform to the amino acid code for RNA recognition by PPR proteins.
• In a mef26 knockout mutant, RNA editing is completely lost only at site cox3-311.
• MEF26 orthologs are not present in all plant species able to edit these sites.

In angiosperms most members of the large nuclear-encoded family of pentatricopeptide repeat (PPR) proteins are predicted to play relevant roles in the maturation of organellar RNAs. Here we report the novel Mitochondrial Editing Factor 26, a DYW-PPR protein involved in RNA editing at two sites. While at one site, cox3-311, editing is abolished in the absence of MEF26, the other site, nad4-166, is still partially edited. These sites share similar cis-elements and application of the recently proposed amino acid code for RNA recognition by PPR proteins ranks them at first and second positions of the most probable targets.