title: 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.
authors.affiliation: Institut Pasteur, Bactéries anaérobies et Toxines, 28 rue du Dr Roux, F-75724 Paris cedex 15, France.
authors.forename: Oliver
authors.initials: O
authors.lastname: Knapp
authors.forename: Elke
authors.initials: E
authors.lastname: Maier
authors.forename: Sanae Ben
authors.initials: SB
authors.lastname: Mkaddem
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
authors.forename: Marcelle
authors.initials: M
authors.lastname: Bens
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chenal
authors.forename: Blandine
authors.initials: B
authors.lastname: Geny
authors.forename: Alain
authors.initials: A
authors.lastname: Vandewalle
authors.forename: Michel R
authors.initials: MR
authors.lastname: Popoff
mesh_terms: D016475:3T3 Cells; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects*; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002522:Chlorocebus aethiops; D052557:Clostridium septicum / Q000472:pathogenicity*; D004285:Dogs; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry; D051379:Mice; D009336:Necrosis / Q000139:chemically induced*; D011188:Potassium / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000633:toxicity*; D014709:Vero Cells
chemical_list: D001427:Bacterial Toxins; D008051:Lipid Bilayers; D011994:Recombinant Proteins; C064270:hemolytic toxin, Clostridium septicum; D000255:Adenosine Triphosphate; D011188:Potassium