Plays a key role in the innate immune response following bacterial infection by inserting into the bacterial surface to form pores (By similarity). By breaching the surface of phagocytosed bacteria, allows antimicrobial effectors to enter the bacterial periplasmic space and degrade bacterial proteins such as superoxide dismutase sodC which contributes to bacterial virulence (By similarity). Shows antibacterial activity against a wide spectrum of Gram-positive, Gram-negative and acid-fast bacteria (By similarity). Reduces the viability of the intracytosolic pathogen L.monocytogenes by inhibiting acidification of the phagocytic vacuole of host cells which restricts bacterial translocation from the vacuole to the cytosol (By similarity). Required for the antibacterial activity of reactive oxygen species and nitric oxide (By similarity). Bacterial infection induces translocation of the cytoplasmic vesicles to bacterium-containing phagocytic vesicles and fusing of the vesicles. Monoubiquitinated in response to bacterial infection; ubiquitination is required for vesicular localization and antibacterial activity and can be blocked by bacterial cell cycle inhibiting factor (cif) (By similarity). Belongs to the MPEG1 family.