Anthrax toxin

Anthrax toxin is a tripartite exotoxin produced by the bacterium Bacillus anthracis, the causative agent of anthrax[1]. It consists of three protein subunits: protective antigen (PA), edema factor (EF), and lethal factor (LF). PA binds to specific host cell receptors (TEM8 or CMG2), is proteolytically activated, and forms oligomeric complexes that facilitate cell entry of EF and LF[2][3][5]. EF is a calmodulin-dependent adenylate cyclase that elevates intracellular cAMP, causing fluid accumulation and immune disruption, while LF is a zinc-dependent metalloprotease that cleaves MAP kinase kinases, leading to cell death—especially in immune cells[1][6][7]. These coordinated actions allow Bacillus anthracis to subvert host immunity, promote its own dissemination, and can rapidly lead to shock and death[1][4]. The toxin is a prototypical A-B exotoxin, with PA as the cell-binding (B) component, and EF/LF as enzymatic (A) components. Anthrax toxin components—and especially PA—are the targets of monoclonal antibody therapies (raxibacumab, obiltoxaximab) used to treat or prevent anthrax in high-risk scenarios[6].

Other names

Bacillus anthracis toxinTripartite anthrax toxin

Raxibacumab, Obiltoxaximab, and AIGIV: Neutralize the protective antigen (PA), thereby preventing entry of toxin enzymes into host cells. EF and LF inhibitors (experimental): Block edema factor (adenylate cyclase) or lethal factor (metalloprotease) catalytic activity.