Clostridial botulinum neurotoxins (BoNTs) inhibit synaptic exocytosis; intoxication requires
the di-chain protein to undergo conformational changes in response to pH and redox
gradients across the endosomal membrane with consequent formation of a protein-
conducting channel by the heavy chain (HC) that translocates the light chain (LC) protease
into the cytosol, colocalizing it with the substrate SNARE proteins. We investigate the
dynamics of protein translocation across membranes using a sensitive single-molecule …