Characterization of the developmental switch region of bacteriophage P2 Hy dis

In this work, the DNA sequence of the transcriptional switch that affects the development of the P2 Hy dis bacteriophage was determined. The switch contains two face-to-face-located promoters and two repressors, Cox and C. The locations of the Pc and Pe promoters were determined by primer extension analysis. The P2 Hy dis homolog of the P2 multifunctional Cox protein was shown to be able to substitute for P2 Cox in repression of the P2 Pc promoter, excision of the P2 prophage, and activation of the satellite phage P4 PLL promoter. A directly repeated sequence, flanking the--35 region of the Pe promoter, was found to be important for C repressor binding as well as for repression. The P4 E protein was shown to derepress the developmental switch of P2 Hy dis in a plasmid-based derepression assay.