Sphingomyelinase C (Beta-toxin) (Hlb)

Beta-toxin of Staphylococcus aureus, also known as sphingomyelinase C, is a significant exotoxin and virulence factor produced by many strains of S. aureus, particularly those associated with animal infections like bovine mastitis. It functions as a neutral sphingomyelinase that specifically hydrolyzes sphingomyelin in the plasma membrane of host cells into ceramide and phosphorylcholine (UniProt: P09916). This enzymatic degradation results in the characteristic "hot-cold" hemolysis, where erythrocytes sensitized at 37°C undergo rapid lysis when shifted to lower temperatures (PubMed: 16109935). Beyond its role as a hemolysin, beta-toxin is crucial for the formation of biofilms; it acts by cross-linking extracellular DNA into a high-molecular-weight nucleoprotein matrix, which protects the bacterial community from host defenses and antibiotics (PubMed: 23319606). In clinical settings, the toxin contributes to the pathogenesis of pneumonia and skin infections by damaging lung epithelial cells and modulating the immune response (PubMed: 21690361). Although there are currently no FDA-approved drugs that specifically target beta-toxin, it is considered a promising target for anti-virulence strategies designed to attenuate bacterial pathogenicity without exerting the selective pressure associated with traditional antibiotics (PubMed: 30254100).

Other names

Beta-hemolysinStaphylococcal beta-toxinSphingomyelin phosphodiesteraseHot-cold hemolysin

Hydrolysis of sphingomyelin in host cell membranes to ceramide and phosphorylcholine, leading to membrane destabilization and promoting biofilm assembly via DNA cross-linking.