Required for the activity of the plastid-encoded RNA polymerase (PEP) and full expression of genes transcribed by PEP (PubMed:24246379, PubMed:25599833). Required for the proper build-up and formation of the PEP-complex. Binds single-stranded (ss) DNA and RNA, but not double-stranded (ds) DNA (PubMed:25599833). Component of the plastid-encoded plastid RNA polymerase (PEP) complex. Pale yellow-green leaf phenotype. Reduced levels of plastid ribosomes and defects in plastid mRNA metabolism.