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Bacteriophage P4 integrase, C-terminal catalytic domain P4-like integrases are found in temperate bacteriophages, integrative plasmids, pathogenicity and symbiosis islands, and other mobile genetic elements. The P4 integrase mediates integrative and excisive site-specific recombination between two sites, called attachment sites, located on the phage genome and the bacterial chromosome. The phage attachment site is often found adjacent to the integrase gene, while the host attachment sites are typically situated near tRNA genes. This family belongs to the superfamily of DNA breaking-rejoining enzymes, which share the same fold in their catalytic domain and the overall reaction mechanism. The catalytic domain contains six conserved active site residues. Their overall reaction mechanism involves cleavage of a single strand of a DNA duplex by nucleophilic attack of a conserved tyrosine to give a 3' phosphotyrosyl protein-DNA adduct. In the second rejoining step, a terminal 5' hydroxyl attacks the covalent adduct to release the enzyme and generate duplex DNA. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",