Tripartite protein complex secreted by virulent strains of Bacillus anthracis
Anthrax toxin lethal factor middle domain
X-ray crystal structure of the anthrax lethal factor bound to a small molecule inhibitor, bi-mfm3, 3-{5-[5-(4-chloro-phenyl)-furan-2-ylmethylene]-4-oxo-2-thioxo-thiazolidin-3-yl}-propionic acid.
Figure 1. Electron micrograph of the anthrax causing bacteria, Bacillus anthracis.
Anthrax toxin is a three-proteinexotoxin secreted by virulent strains of the bacterium, Bacillus anthracis—the causative agent of anthrax. The toxin was first discovered by Harry Smith in 1954.[1] Anthrax toxin is composed of a cell-binding protein, known as protective antigen (PA), and two enzyme components, called edema factor (EF) and lethal factor (LF). These three protein components act together to impart their physiological effects. Assembled complexes containing the toxin components are endocytosed. In the endosome, the enzymatic components of the toxin translocate into the cytoplasm of a target cell. Once in the cytosol, the enzymatic components of the toxin disrupt various immune cell functions, namely cellular signaling and cell migration. The toxin may even induce cell lysis, as is observed for macrophage cells. Anthrax toxin allows the bacteria to evade the immune system, proliferate, and ultimately kill the host animal.[2] Research on anthrax toxin also provides insight into the generation of macromolecular assemblies, and on protein translocation, pore formation, endocytosis, and other biochemical processes.
^Maldonado-Arocho; et al. (2009). "Anthrax Toxin". Microbial Toxins: Current Research and Future Trends. Caister Academic Press. ISBN978-1-904455-44-8.
