Integrase is necessary for integration of the phage into the host genome by site-specific recombination. In conjunction with excisionase, integrase is also necessary for excision of the prophage from the host genome (By similarity). A possible member of the dormancy regulon. Induced in response to reduced oxygen tension (hypoxia). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. Belongs to the 'phage' integrase family.