Nuclear genome-encoded factor involved in ribosome biogenesis in chloroplasts. Binds specific group II introns in chloroplasts and facilitates their splicing. Is required for rRNA maturation in plastids and may contribute to the assembly of the large (50S) ribosomal subunit. Required for normal development of chloroplasts. ATP + H2O = ADP + H(+) + phosphate The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Very pale yellow green leaf phenotype. Virescent leaf phenotype. Belongs to the DEAD box helicase family. DDX21/DDX50 subfamily. Truncated N-terminus.