Chemical and enzymatic synthesis of lactose operator of Escherichia coli and its binding to lactose repressor.

The 21-nucleotide-long duplex DNA constituting the lactose operator sequence of E. coli has been synthesized by both chemical and enzymatic methods. The synthetic duplex has the essential feature of the lactose operator as seen by its binding to the lactose repressor. The binding of the synthetic operator fragment to the lactose repressor is specific because it is inhibited by the inducing ligand isopropyl-beta-D-thiogalactoside. Thus, it is now possible to show that a chemically synthesized oligodeoxynucleotide can be specifically recognized by its natural regulatory protein.