Promoters of the phr gene in Escherichia coli K-12.

We have identified two promoters of the Escherichia coli phr gene by DNA deletion mapping, S1 mapping of transcripts and sequence homology. The weaker promoter, P2, located approximately 530 bp upstream from the start codon, extends beyond the previously known nucleotide sequence. The stronger, P1, lies 90 bp from the gene and is distinct from three previously described promoter-like sequences nearby. beta-Galactosidase production from a plasmid-borne gene, promoted by a synthetic copy of P1, increases after DNA damage, but the increase does not depend on the SOS-box-like sequences normally present in the vicinity of P1. Induction still requires intact recA and lexA genes, and also intact sulA.