A cholesterol-dependent pore-forming toxin, which is a major virulence factor required for the escape of bacteria from phagosomal vacuoles and entry into the host cytosol. After binding to target membranes, the protein undergoes a major conformation change, leading to its insertion in the host membrane and formation of an oligomeric pore complex. Listeriolysin O activates mitogen-activated protein (MAP) kinase activity in host cells, most likely as a result of the permeabilization of the host cell membrane. Also induces a proteasome-independent degradation of UBE2I (the SUMO-conjugating enzyme UBC9) and a proteasome-dependent degradation of some sumoylated proteins. Finally, is necessary and sufficient for spacious Listeria-containing phagosomes (SLAPs) formation, suggesting a role for listeriolysin O in promoting L.monocytogenes replication in vacuoles, leading to persistent infection. Recognized by serum from healthy humans exposed to L.monocytogenes as well from patients who have recovered from listeriosis

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