Staphylococcal Toxins

Alpha Toxin from Staphylococcus aureus

Staphylococcus aureus alpha toxin

Alpha toxin, produced by Staphylococcus aureus, also known as alpha hemolysin, is one of many virulence factors produced by Staphylococcus aureus. Alpha Toxin is a single polypeptide chain having a molecular weight of 33,000 Daltons.  Many cell types are sensitive to cytolysis by alpha toxin. Under controlled conditions, however, nucleated cells can be treated with alpha toxin without causing lysis. Under these conditions, alpha toxin monomers bind the cell membrane and form a heptamer which functions as a hydrophilic pore of diameter 1-3 nm. The molecular weight cut-off of material passing through the pore is approximately 2000 to 4000 Daltons and the pore is somewhat ion selective. The cell becomes permeablilized to small molecules, while large enzymes and carbohydrates are excluded. Alpha toxin has been utilized to introduce ions, substrates, inhibitors, nucleotides and other pharmacological agents into cells and thereby regulate cell physiology or function.

Alpha toxin from List Biological Laboratories, Inc. is produced by Staphylococcus aureus strain Wood 46.  Biological activity is assessed by measuring hemolysis of rabbit erythrocytes.