The pentatricopeptide repeat (PPR) protein OTP82 is required for RNA editing of plastid ndhB and ndhG transcripts

Abstract

In RNA editing, specific cytidine nucleotides are altered to uridine in RNA in plant organelles, frequently. Although the involvement of PPR proteins in RNA editing of plant organelles is already beyond any doubt, questions still remain about the site-recognition mechanisms. To progress our understanding of this process, we are performing the comprehensive survey of the plant-specific classes of PPR proteins. We found that PPR protein OTP82 is essential for RNA editing of the ndhB-9 and ndhG-1 sites in plastids. Despite the defects in RNA editing, otp82 did not show any phenotypes in NDH activity, stability or interaction with photosystem I, suggesting that the RNA editing events mediated by OTP82 are functionally silent even though they induce amino acid alterations. In agreement with this result, both sites are partially edited even in the wild type, implying the possibility that a single gene produces heterogeneous proteins that are functionally equivalent.