Expression of the synthetic gene of an artificial DDT-binding polypeptide in Escherichia coli

This paper reports the expression of an artificial functionalpolypeptide in bacteria. The gene of a designed 24-residue DDT-bindingpolypeptide (DBP) was inserted between the BamHI and PstI cleavagesites of plasmid pUR291. The hybrid plasmid, pUR291-DBP, wascloned in Escherichia coli JM109. After induction by isopropyl-ß-D-thiogalactopyranosidea fusion protein was expressed in which DBP was linked to theCOOH-termiuus of ß-galactosidase. DBP, which is stableto trypsin, was obtained by tryptic digestion of the fusionprotein and subsequent fractionation of the tryptic peptidesby reversed-phase h.p.l.c. Recombinant and chemically synthesizedDBP showed identical chromatographic properties, amino acidcomposition, and chymotryptic digestion patterns. Both the ß-galactosidase-DBPfusion and isolated recombinant DBP bound DDT. The fusion proteinwas 25 times as potent as the designed 24-residue DBP in activatinga cytochrome P-450 model system using equimolar catalytic amountsof the two proteins.