THE INTERACTION OF CHEMICALLY SYNTHESIZED 21 BASE PAIR LAC OPERATOR WITH THE LAC REPRESSOR

The interaction of lac repressor with 21 base pair lac operator, chemically synthesized by a phosphotriester method, has been studied in considerable detail. The binding of the synthetic operator to the lac repressor is similar to that of natural operator in lambda plac DNA in its response to salt, temperature, and effector ligands. A good response is seen with IPTG, an inducer, and ONPF, an anti-inducer. The affinity of 21 base pair operator for repressor is less than that of natural operator in lambda plac, but the reduction in affinity is close to that predicted from a consideration of the involvement of unspecific interactions with adjacent DNA in the overall binding mechanism for natural operator.