Neurotoxin Type E Light Chain Protein, Botulinum (His, Myc)

Neurotoxin Type E Light Chain Protein, a component of botulinum toxin, induces flaccid paralysis by inhibiting neurotransmitter (acetylcholine) release from the presynaptic membranes of nerve terminals in the skeletal and autonomic nervous systems of eukaryotic hosts, often resulting in heart or respiratory failure. As a precursor of botulinum neurotoxin E, it engages two coreceptors—complex polysialylated gangliosides on neural tissue and specific membrane-anchored proteins in synaptic vesicles. Receptor proteins become exposed on the host's presynaptic cell membrane during neurotransmitter release, initiating binding with the toxin's heavy chain (HC). Following endocytic uptake and a pH-dependent structural rearrangement, the HC's N-terminus forms pores, facilitating the translocation of the light chain (LC) into the cytosol. Once in the cytosol, the disulfide bond between the subunits is reduced, allowing LC to cleave its target protein on synaptic vesicles, preventing their fusion with the cytoplasmic membrane and thus blocking neurotransmitter release. The proteolytic activity of LC, specifically hydrolyzing the '180-Arg-|-Ile-181' bond in SNAP25, is essential for its inhibitory effect on neurotransmission.