Clostridium septicum alpha-toxin forms pores and induces rapid cell necrosis.

Abstract : Alpha-toxin is the unique lethal virulent factor produced by Clostridium septicum, which causes traumatic or non-traumatic gas gangrene and necrotizing enterocolitis in humans. Here, we analyzed channel formation of the recombinant septicum alpha-toxin and characterized its activity on living cells. Recombinant septicum alpha-toxin induces the formation of ion-permeable channels with a single-channel conductance of about 175pS in 0.1M KCl in lipid bilayer membranes, which is typical for a large diffusion pore. Septicum alpha-toxin channels remained mostly in the open configuration, displayed no lipid specificity, and exhibited slight anion selectivity. Septicum alpha-toxin caused a rapid decrease in the transepithelial electrical resistance of MDCK cell monolayers grown on filters, and induced a rapid cell necrosis in a variety of cell lines, characterized by cell permeabilization to propidium iodide without DNA fragmentation and activation of caspase-3. Septicum alpha-toxin also induced a rapid K(+) efflux and ATP depletion. Incubation of the cells in K(+)-enriched medium delayed cell death caused by septicum alpha-toxin or epsilon-toxin, another potent pore-forming toxin, suggesting that the rapid loss of intracellular K(+) represents an early signal of pore-forming toxins-mediated cell necrosis.
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Oliver Knapp, Elke Maier, Sanae Ben Mkaddem, Roland Benz, Marcelle Bens, et al.. Clostridium septicum alpha-toxin forms pores and induces rapid cell necrosis.. Toxicon, Elsevier, 2010, 55 (1), pp.61-72. 〈http://www.sciencedirect.com/science/article/pii/S0041010109003432〉. 〈10.1016/j.toxicon.2009.06.037〉. 〈pasteur-01509604〉

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