A genetic system to study the in vivo role of transcriptional regulators in Escherichia coli.

A genetic system for studying in vivo the interactions between a transcriptional regulatory protein and its target DNA has been developed for Escherichia coli. It is composed of two compatible plasmids: one high-copy-number promoter-probe vector, and one low-copy-number vector in which the gene encoding the desired protein is cloned under the control of an inducible promoter. The system was successfully tested for its specificity and for dosage analysis by using a combination of the plasmid pLS1-encoded RepA repressor and its target DNA.