BREX systems (bacteriophage exclusion) provide immunity against bacteriophage. Part of a type 2 BREX system (Probable). Previously called the phage growth limitation (Pgl) system, it confers protection against bacteriophage phiC31. The bacteria allows one cycle of phage infection, but subsequent cycles are impaired, protecting the original bacterial colony (PubMed:7642495) (Probable). The system undergoes high rates (10(-3) to 10(-4)) of phase reversion, i.e. loss and regain of phiC31 resistance (PubMed:8446035). When the pglW-pglX-pglY-pglZ genes are transformed into a susceptible S.lividans (strain 1326) they confer resistance to infection by phage phiC31 and phiBT1; all 4 genes are necessary (PubMed:11972785). Hydrolyzes ATP but not AMP, ADP, GMP, GDP or GTP; activity is inhibited by the non-hydrolyzable ATP analog 5-adenylyl beta,gamma-imidodiphosphate. Constitutively expressed, not induced by bacteriophage phiC31, probably part of a pglY-pglZ operon. Strain is no longer resistant to plaque formation by bacteriophage phiC31 (a Pgl- phenotype).