AN IMPORT-COMPETENT PRECURSOR OF SMALL SUBUNIT OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE GENERATED BY FACTOR-XA CLEAVAGE FROM A BETA-GALACTOSIDASE FUSION EXPRESSED IN ESCHERICHIA-COLI

A plasmid-encoding fusion protein interlinked by factor Xa recognition sequence between β-galactosidase and a precursor of the small subunit of wheat ribulose-1,5-bisphosphate carboxylase has been constructed. The plasmid directed abundant synthesis of the fusion protein in Escherichia coli. The recombinant protein was accumulated in an aggregated form that was associated with the bacterial membranes. A procedure was developed to isolate the fusion protein in a relatively pure and soluble form. Bovine factor Xa cleaved the isolated chimera to generate the complete chloroplast precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase from the fused β-galactosidase. The cleaved precursor protein was imported into the isolated chloroplasts and processed to yield its mature counterpart. © 1992.