RESUMO
We demonstrate experimentally that anthrax toxin complexes rupture artificial lipid bilayer membranes when isolated from the blood of infected animals. When the solution pH is temporally acidified to mimic that process in endosomes, recombinant anthrax toxin forms an irreversibly bound complex, which also destabilizes membranes. The results suggest an alternative mechanism for the translocation of anthrax toxin into the cytoplasm.
Assuntos
Antígenos de Bactérias/toxicidade , Toxinas Bacterianas/toxicidade , Membrana Celular/efeitos dos fármacos , Bicamadas Lipídicas/química , Animais , Antígenos de Bactérias/genética , Toxinas Bacterianas/genética , Células Sanguíneas/efeitos dos fármacos , Endossomos/efeitos dos fármacos , Cobaias , Haplorrinos , Humanos , Membranas Artificiais , CoelhosRESUMO
Nonelectrolyte polymers of poly(ethylene glycol) (PEG) were used to estimate the diameter of the ion channel formed by the Bacillus anthracis protective antigen 63 (PA(63)). Based on the ability of different molecular weight PEGs to partition into the pore and reduce channel conductance, the pore appears to be narrower than the one formed by Staphylococcus aureus alpha-hemolysin. Numerical integration of the PEG sample mass spectra and the channel conductance data were used to refine the estimate of the pore's PEG molecular mass cutoff (approximately 1400 g/mol). The results suggest that the limiting diameter of the PA(63) pore is <2 nm, which is consistent with an all-atom model of the PA(63) channel and previous experiments using large ions.