Abstract
Chloroplast NDH complex in involved in PSI cyclic electron flow. Eleven subunits are encoded by the chloroplast genome. We screened Arabidopsis crr mutants specifically affected in NDH activity using chlorophyll fluorescence imaging. Accumulation of the NDH complex was reduced in crr2 and crr4. Both mutants are defective in members of PCMP/PPR family. Some members of this family were reported to function in the maturation of organellar RNA. While CRR2 is involved in the RNA processing between rps7 and ndhB, CRR4 is in RNA editing to create the translation initiation codon of ndhD. Despite the sequence similarity, CRR2 and CRR4 are involved in distinct steps of chloroplast RNA maturation, suggesting that PCMP/PPR proteins function to recognize the target RNA for RNA maturation.
