Alpha-hemolysin

α-Hemolysin is a pore-forming toxin produced by Staphylococcus aureus. This virulence factor is responsible for the lysis of red blood cells and can also damage various cell types, contributing to the pathogenesis of infections. The toxin acts by forming pores in cell membranes, leading to cell swelling and eventual lysis.

Hemolysins or haemolysins are lipids and proteins that cause lysis of red blood cells by destroying their cell membrane. Although the lytic activity of some microbe-derived hemolysins on red blood cells may be of great importance for nutrient acquisition, many hemolysins produced by pathogens do not cause significant destruction of red blood cells during infection. Although hemolysins are capable of doing this for red blood cells in vitro.

Alpha-toxin, also known as alpha-hemolysin (Hla), is the major cytotoxic agent released by bacterium Staphylococcus aureus and the first identified member of the pore forming beta-barrel toxin family. This toxin consists mostly of beta-sheets (68%) with only about 10% alpha-helices. The hla gene on the S. aureus chromosome encodes the 293 residue protein monomer, which forms heptameric units on the cellular membrane to form a complete beta-barrel pore. This structure allows the toxin to perform its major function, development of pores in the cellular membrane, eventually causing cell death.