Evolution of immunity and host chromosome integration site of P2-like coliphages.

The amount and distribution of variation in the genomic region containing the genes in the lytic-lysogenic genetic switch and the sequence that determines the integration site into the host chromosome were analyzed for 38 P2-like phages from Escherichia coli. The genetic switch consists of two convergent mutually exclusive promoters, Pe and Pc, and two repressors, C and Cox. The immunity repressor C blocks the early Pe promoter, leading to the establishment of lysogeny.

Site-specific recombination links the evolution of P2-like coliphages and pathogenic enterobacteria.

The genome of the tailed temperate coliphage P2 (Myoviridae) contains some genes that probably are horizontally transferred additions to the genome. One of these genes, the Z/fun gene, was recently found intact in the genome of Neisseria meningitidis. We have investigated the presence of P2-like phages, and the genetic variation at the position corresponding to the phage P2 Z/fun locus, in the Escherichia coli reference collection (ECOR).