Pore-forming toxins: experiments with S. aureus alpha-toxin, C. perfringens theta-toxin and E. coli haemolysin in lipid bilayers, liposomes and intact cells.
Three quite different bacterial toxins (S. aureus alpha-toxin, C. perfringens theta-toxin and E. coli haemolysin) induce the leakage of phosphorylated metabolites from Lettre cells and of calcein from liposomes; in each case leakage is inhibited by Zn2+ greater than Ca2+ greater than Mg2+. Inhibition is not due to displacement of toxin from the membrane, since divalent cations inhibit leakage through pre-formed pores. Electrical conductivity across phospholipid bilayers is induced by each of the three toxins; in each case the probability of channels being in the open state is reduced by divalent cations. Although the pores induced in phospholipid bilayers and liposomes vary greatly in size (theta-toxin much greater than haemolysin greater than alpha-toxin), in Lettre cells the lesions appear more uniform, suggestive of a limiting effect in cells.
Dipartimento di Fisica, Università di Trento, Italy.
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G
Menestrina
C L
CL
Bashford
C A
CA
Pasternak
D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D002413:Cations, Divalent / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D003016:Clostridium perfringens / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D006460:Hemolysin Proteins / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000494:pharmacology; D051379:Mice; D009994:Osmolar Concentration; D010743:Phospholipids / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D013211:Staphylococcus aureus / Q000378:metabolism; D013462:Sulfur Radioisotopes; D010738:Type C Phospholipases / Q000494:pharmacology
D001427:Bacterial Toxins; D002413:Cations, Divalent; D003911:Dextrans; D005452:Fluoresceins; D006460:Hemolysin Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D008081:Liposomes; D008565:Membrane Proteins; D010743:Phospholipids; D011506:Proteins; D013462:Sulfur Radioisotopes; C052526:fluorescein-dextran; C020452:Clostridium perfringens theta-toxin; D007770:L-Lactate Dehydrogenase; D010738:Type C Phospholipases