PORE-FORMING TOXINS - EXPERIMENTS WITH S-AUREUS ALPHA-TOXIN, CLOSTRIDIUM-PERFRINGENS THETA-TOXIN AND ESCHERICHIA-COLI HEMOLYSIN IN LIPID BILAYERS, LIPOSOMES AND INTACT-CELLS

Three quite different bacterial toxins (S. aureus α-toxin, C. perfringens θ-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+ > Ca2+ > 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 (θ-toxin ≫ haemolysin > α-toxin), in Lettre cells the lesions appear more uniform, suggestive of a limiting effect in cells. © 1990.