Using a novel cyanelle isolation procedure we showed that pre-ferredoxin-NADP+-oxidoreductase (pre-FNR) from C. paradoxa is translocated in vitro across the peptidoglycancontaining cyanelle envelope. Efficient import was also observed in a heterologous system with pea chloroplasts as the recipient organelles. These results support the conclusion derived from comparative analysis of plastid genome organization, that all plastids originate from a common semi-autonomous endosymbiotic ancestor.
