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pH‐dependent permeabilization of the plasma membrane of mammalian cells by anthrax protective antigen
Author(s) -
Milne Jill C.,
Collier R. John
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb00936.x
Subject(s) - anthrax toxin , membrane , biophysics , biology , endosome , toxin , vesicle , liposome , efflux , effector , ion channel , lipid bilayer , microbiology and biotechnology , pore forming toxin , intracellular , biochemistry , microbial toxins , receptor , recombinant dna , gene , fusion protein
Summary Protective antigen (PA) of anthrax toxin forms ion‐conductive channels in planar lipid bilayers and liposomes under acidic pH conditions. We show here that PA has a similar permeabilizing action on the plasma membranes of CHO‐K1 and three other mammalian cell lines (J774A.1, RAW264.7 and Vero). Changes in membrane permeability were evaluated by measuring the efflux of the K + analogue, 86 Rb + , from prelabelled cells, and the influx of 22 Na + . The permeabilizing activity of PA was limited to a proteolytically activated form (PA N ) and was dependent on acidic pH for membrane insertion (optimal at pH 5.0), but not for sustained ion flux. The flux was reduced in the presence of several known channel blockers: tetrabutyl‐, tetrapentyl‐, and tetrahexylammonium bromides. PA N facilitated the membrane translocation of anthrax edema factor under the same conditions that induced changes in membrane permeability to ions. These results indicate that PA N permeabilizes cellular membranes under conditions that are believed to prevail in the endosomal compartment of toxin‐sensitive cells; and they provide a basis for more detailed studies of the relationship between channel formation and translocation of toxin effector moieties in vivo.