Involved in RNA editing events in chloroplasts. Required for the editing of a single site in ndhB and ndhF transcripts, which are two plastid-encoded subunits of the chloroplast NAD(P)H dehydrogenase (NDH) complex. Required for the editing of a single site in psbZ. Required for optimal activity of the NDH complex of the photosynthetic electron transport chain. No visible phenotype under normal growth conditions. Belongs to the PPR family. PCMP-H subfamily. Truncated N-terminus.