title: One-step purification of plant ferredoxin-NADP+ oxidoreductase expressed in Escherichia coli as fusion with glutathione S-transferase.
abstract: Complementary DNA sequences encoding the mature form of pea ferredoxin-NADP+ reductase were cloned in-frame at the 3' end of the Schistosoma japonicum glutathione S-transferase gene in the expression vector pGEX-3X (Smith and Johnson, Gene 67, 31-40, 1988). A spacer sequence linking the two genes was modified to provide a proteolytic site just before the first amino acid residue of mature pea reductase. When introduced into competent Escherichia coli cells and induced, the resulting plasmid (pGF205) directed the expression of a 60-kDa immunoreactive peptide that results from the fusion between glutathione S-transferase and ferredoxin-NADP+ reductase sequences. The fused protein could be purified in a single step by selective absorption onto glutathione-agarose beads, followed by elution with free glutathione. It showed both transferase and reductase activities. Removal of the transferase portion by cleavage with the restriction protease Xa rendered ferredoxin-NADP+ reductase electrophoretically homogeneous. The purified transgenic enzyme showed kinetic and spectroscopic properties that were similar to those reported for the plant flavoprotein, indicating that, even when fused to the 27-kDa transferase portion, the reductase was still able to assemble FAD and to acquire an active conformation in the bacterial host. The expression-purification protocol employed here allows the isolation of up to 1 mg of active ferredoxin-NADP+ reductase/g of transformed cells. The system is potentially useful for the purification of activity-impaired forms of the flavoprotein.
authors.affiliation: Departamento de Ciencias Biológicas, Facultad de Ciencias Bioquímicas Farmacéuticas, Universidad Nacional de Rosario, Argentina.
authors.forename: E C
authors.initials: EC
authors.lastname: Serra
authors.forename: N
authors.initials: N
authors.lastname: Carrillo
authors.forename: A R
authors.initials: AR
authors.lastname: Krapp
authors.forename: E A
authors.initials: EA
authors.lastname: Ceccarelli
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D010450:Endopeptidases / Q000378:metabolism; D007887:Fabaceae / Q000201:enzymology* / Q000235:genetics; D005287:Ferredoxin-NADP Reductase / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D005982:Glutathione Transferase / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010946:Plants, Medicinal; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D005287:Ferredoxin-NADP Reductase; D005982:Glutathione Transferase; D010450:Endopeptidases