Clostridium septicum alpha toxin (AT) (AT)

Clostridium septicum alpha toxin is the principal virulence factor produced by the Gram-positive, anaerobic bacterium Clostridium septicum (UniProt P17023). It is secreted as an inactive 46 kDa protoxin that requires proteolytic activation, typically by host cell surface proteases like furin, which removes a C-terminal peptide (Knapp et al., J. Biol. Chem., 1997). Once activated, the toxin binds to glycosylphosphatidylinositol (GPI)-anchored proteins on the host cell membrane, where it oligomerizes to form a heptameric prepore (Gordon et al., J. Biol. Chem., 1999). This prepore then inserts into the membrane to create a stable aqueous pore, leading to the rapid efflux of potassium ions, influx of calcium, and eventual cell lysis or apoptosis (Kennedy et al., Mol. Microbiol., 2005). In clinical settings, this toxin is the primary driver of gas gangrene (clostridial myonecrosis) and is frequently associated with underlying malignancies, particularly of the gastrointestinal tract (StatPearls, 2023). Therapeutic strategies focus on the use of antitoxins to neutralize the toxin's activity and antibiotics to eliminate the source bacteria, as the toxin's rapid action often leads to high mortality rates if not addressed immediately (Stevens et al., Clin. Infect. Dis., 2014).

Other names

Alpha-toxinC. septicum alpha-toxinLethal toxinPore-forming toxin alpha

Neutralization of the toxin by specific antibodies to prevent binding to host cell receptors and subsequent pore formation (Mol. Microbiol., 2005).