Superposition of genetic sites in the regulatory region of the bipolar argECBH operon of Escherichia coli.

The nucleotide sequence of mutants in the regulatory region of the argECBH divergent operon of Escherichia coli explains the dual effect of these mutants on the rate of expression of both wings of the gene cluster and emphasizes the high degree of integration of the genetic sites at the argE-argC boundary.