Lysogenization By Satellite Phage-P4

Satellite phage P4 attaches to the E. coli K-12 chromosome at a preferred site near 96 min. The attachment site on the P4 genome is 31.4–36.5% from the left cohesive end, which has been redefined as the end with the same base sequence as the P2 helper phage left end. The P4 int gene is in the region from 27.5 to 31.4%. Immunity-sensitive clear plaque mutants define two P4 genes. One is likely to code for repressor and maps very near the P4 gene which is needed to derepress a helper prophage. The other is probably not involved in lysogenization and maps near the left end of the P4 genome, among nonessential genes.