Contributes to the degradation of host DNA, permitting the scavenging of host-derived nucleotides for phage DNA synthesis (PubMed:19666720, PubMed:18539732). Sequence-specific endonuclease. Catalyzes nicking of the bottom strand of double-stranded DNA between the first and second base pair to the right of a top-strand CCGC motif. Does not cleave native phage DNA, which contains 5-hydroxymethylcytosine instead of cytosine. Endonucleolytic nicking and cleavage of cytosine-containing double-stranded DNA. Homotetramer.