The N-terminal half of the heavy chain of botulinum type A neurotoxin forms channels in planar phospholipid bilayers

Abstract

The heavy chain of botulinum type A neurotoxin forms channels in planar phospholipid bilayer membranes. Channel activity is confined to the N-terminal half of this chain; the C-terminal half is inactive. Channel activity is stimulated by low pH (4.5–5.5) on the cis side (the side to which protein is added), neutral pH on the opposite ( trans) side, and cis positive voltages. These findings are strikingly similar to those previously reported for analogous fragments of diphtheria and tetanus toxins.