Anthrax Biosensor, Protective Antigen Ion Channel Asymmetric Blockade

摘要

Bacillus anthracis secretes three proteins (protective antigen, PA; lethal factor, LF; and edema factor, EF) that are the basis for anthrax infection. We present electrophysiological measurements that demonstrate the effect of full-length LF and EF on ion channels formed by the proteolytically activated species of PA (PA63) in planar lipid bilayer membranes. LF and EF convert the heptameric PA63 channel current-voltage relationship from slightly nonlinear to one that is highly rectifying and diode-like at pH 6.6. This striking effect provides an innovative method for characterizing functional toxin interactions and can be applied as an anthrax therapeutic biosensor.