Non-electrolyte polymers of poly(ethylene glycol), PEG, were used to estimate the diameter of the ion channel formed by Bacillus anthracis protective antigen 63, PA63. Based on the ability of different molecular weight PEGs to partition into the pore and reduce the 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 (approx. 1,400 g/mol). The results suggest that the limiting diameter of the PA63 pore is less than 2 nm, which is consistent with an all-atom model of the PA63 channel and previous experiments using large ions.
Citation: Biophysical Journal
Pub Type: Journals
anthrax, channel size, edema factor, ion channel, lethal factor, poly(ethylene glycol), protective antigen