[16] Production and purification of anthrax toxin

This chapter describes the production and purification of anthrax toxin. Bacillus anthracis secretes three proteins that are collectively known as anthrax toxin. The protective antigen (PA, 85 kDa), lethal factor (LF, 83 kDa), and edema factor (EF, 89 kDa) proteins individually have no known toxic activities. Simultaneous injection of PA and LF causes death of rats, while PA and EF together produce edema in skin. Thus, “anthrax toxin” is actually two toxins, each of which is like staphylococcal leukocidin and botulinum C2 toxin in having receptor-binding and effecter domains on separate proteins. The PA protein appears to play a dual role as the B moiety for two different A proteins. Binding studies have shown that PA must be present in order for EF to bind to cells. Study of anthrax toxin is essential in improving for understanding of the virulence of B. anthracis and in design of improved vaccines. In addition, study of the anthrax toxins may show them to be useful tools in cell biology.