Regulation of the ban gene containing operon of prophage P1.

A physical map of the ban gene of P1 and sites relevant to its regulation has been deduced from cloning of the appropriate regions of P1 wild-type and of P1 ban regulatory mutants. The cloning required the presence of P1 repressor in the cell confirming the existence of a repressible ban operon (Austin et al. 1978). Evidence for additional member(s) of that operon is presented. Of particular interest for understanding the regulation of ban are the relative positions of a binding site for the P1 repressor and of the regulatory mutations bac and crr that render ban expression constitutive. The results reveal a repressible operon-like structure of about 4 kb within the P1 EcoRI-3 fragment that comprises a c1 repressor binding site/bac - additional gene(s) - crr/ban in the clockwise direction of the circular map of P1.