Required for the translation of the chloroplast petA and petD mRNAs. Required for the processing of the petD mRNA from a polycistronic precursor (PubMed:8039510). Binds with high affinity to the 5'-UTR of the chloroplastic petA transcript (PubMed:18669444). Activates psaC and petA translation by binding their 5'-UTRs (PubMed:16141451, PubMed:23735295). Component of a multisubunit complex. Pale green leaf phenotype. Seedling lethality. Belongs to the PPR family. P subfamily.