Botulinum neurotoxin

Function

Botulinum neurotoxin (CBN) is produced by the bacterium Clostridium botulinum. CBP contains a light (residues 1-440) and a heavy (resides 441-875) chains (LC and HC). CBP LC proteolyzes SNARE substrates which are essential for synaptic vescicle fusion and neurotransmitter release thus causing paralysis. CBP HC acts as a channel and as transmembrane chaperone enabling the passage of the LC into the cytosol. For more details see Clostridium Botulinum Neurotoxin Type B.

Disease

CBP is the most lethal toxin known causing botulism.

Relevance

CBP type A is used by the cosmetics industry for smoothing wrinkles and is known commercially as Botox. In small quantities CBN can be used as muscle relaxant in cases of spasm and dystonia.

Structural highlights

CBP HC contains two modules: the N-terminal translocation domain and the C-terminal receptor-binding domain (residues 876-1296).