Abstract
RNA editing is one of the posttranscriptional processes involved in transcript maturation. RNA editing in plant organelles alters a specific C residue to U. An Arabidopsis mutant, crr4 (chlororespiratory reduction), was identified based on its defective NAD(P)H dehydrogenase (NDH) activity. The CRR4 gene encodes a member of the PPR protein family. In crr4, the RNA editing creating an initiation codon of ndhD was specifically affected. These results indicate that a PPR protein is essential for RNA editing in plastids. PPR proteins are involved in varieties of RNA maturation steps in organelles. CRR4 contains eleven PPR motifs but does not include any possible domain responsible for the activity of cytidine deaminase, suggesting that CRR4 is a site-specific factor. To study this possibility, we are investigating whether CRR4 binds to its target RNA.
