Contiguous RNA editing sites in the mitochondrial nad1 transcript of Arabidopsis thaliana are recognized by different proteins

► At3g25060 encodes an E+-subclass pentatricopeptide repeat (PPR) protein in Arabidopsis thaliana. ► AT3G25060 is an editing factor targeted to mitochondria (Mitochondrial Editing Factor, MEF25). ► MEF25 specifically addresses one of two contiguous RNA editing sites in the nad1 transcript. ► Two adjacent RNA editing sites must be recognized by at least two different editing factors. ► Lack of editing in mef25 mutants changes a conserved amino acid in NADH dehydrogenase subunit 1.