A chloroplast envelope-transfer sequence functions as an export signal in Escherichia coli

The small subunit precursor of pea ribulose-1,5-bisphosphate carboxylase/ox ygenase engineered with prokaryotic elements was expressed in Escherichia c oli. This resulted in a dependable level of synthesis of the precursor prot ein in E. coli, The bacterially synthesised plant precursor protein was tra nslocated from the cytoplasm and targeted to the outer membrane of the enve lope zone. During the translocation step, a significant proportion of the p recursor was processed to a soluble, mature SSU and found localised in the periplasm, The determined amino acid sequence of the isolated precursor sho wed that it had a deletion of an arginine residue at position -15 in the tr ansit peptide. Expression of this transit peptide-appended mammalian cytoch rome b(5) in E. coli displayed a targeting profile of the chromogenic chime ra that was similar to that observed with the plant precursor protein. (C) 2000 Federation of European Biochemical Societies.