1.C.67.1.3
Phospholipase C, Hlb, of 330 aas.  Bacterial hemolysins are exotoxins that attack blood cell membranes and cause cell rupture. Beta-hemolysin is a phospholipase C with specific activity toward sphingomyelins. It has a high specificity for sphingomyelin, hydrolyzes lysophosphatidylcholine at a much lower rate, but has no activity towards phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. S. aureus β-hemolysin impairs oxygen transport without causing hemolysis.  A novel role for Hlb as a sphingomyelinase in impairing RBC function under non-lytic conditions, sheds light on the mechanism behind hypoxia associated with S. aureus infection (Li et al. 2025).