Clostridium septicum alpha-toxin forms pores and induces rapid cell necrosis.
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.
Knapp
Oliver
O
Institut Pasteur, Bactéries anaérobies et Toxines, 28 rue du Dr Roux, F-75724 Paris cedex 15, France.
Maier
Elke
E
Mkaddem
Sanae Ben
SB
Benz
Roland
R
Bens
Marcelle
M
Chenal
Alexandre
A
Geny
Blandine
B
Vandewalle
Alain
A
Popoff
Michel R
MR
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
D001427:Bacterial Toxins; D008051:Lipid Bilayers; D011994:Recombinant Proteins; C064270:hemolytic toxin, Clostridium septicum; D000255:Adenosine Triphosphate; D011188:Potassium