DNA sequences of bacteriophage P2 early genes cox and B and their regulatory sites

Part of the early operon of the temperate phage P2 of Escherichia coli, including genes cox (involved in prophage excision) and B (required for phage specific DNA synthesis), was sequenced. The results are consistent with an early promoter spanning the repressor binding sites, a leader sequence of about 80 bases which overlaps the leader sequence of the repressor gene for about 30 bases, and coordinate transcription of genes cox and B with a termination signal after the B gene. In addition, the data provide amino acid sequences for the Cox and B proteins of 91 and 166 residues, respectively and reveal a hitherto undetected coding sequence between genes cox and B that has the potential to produce a very basic polypeptide of 56 residues. Slight structural similarities between the P2 Cox protein and the analogous Xis protein of phage lambda were noted and the P2 B gene product was compared with proteins that interact with the DnaB protein of E. coli.