Anthrax toxin: Structure-function relationships

Anthrax is an often fatal, rather uncommon, bacterial infection caused by the spore-former, rod-shaped, Gram-positive bacterium Bacillus anthracis. After entering into the body through skin abrasions, inhalation or ingestion, B. anthracis spores germinate in macrophages, causing septicemia and toxemia; these systemic effects can lead to the death of the host. Anthrax toxin is a binary enzyme A-B toxin composed of protective antigen (PA), lethal factor (LF), and edema factor (EF). PA mediates the entry of either LF or EF into the cytosol of host cells. LF is a zinc metalloprotease that inactivates mitogen-activated protein kinases kinase inducing cell death, and EF is an adenylyl cyclase impairing host defences. Anthrax toxin has also been exploited as a therapeutic agent against cancer.