DHS Summer Student Project Report

摘要

Tetanus and botulinum neurotoxins are among the post potent toxins known to man (Montecucco et al., 1995). Produced by the Clostridium tetani and Clostridium botulinum bacteria, respectively, these toxins concentrate in presynaptic axons and inhibit the release of neurotransmitters leading to paralysis and possibly death. Due to the potency of this lethal class of neurotoxins, we have undertaken a project to develop high affinity ligands that specifically bind to these toxins. Such compounds can have significant implications in both the design of detection systems to monitor for the possible release of these neurotoxins into the public and also the design of possible therapeutics to treat individuals exposed to tetanus or botulinum neurotoxins. The Clostridial neurotoxins are synthesized as 150 kDa proteins that are post-translationally cleaved into N- and C-terminal fragments held together by a single disulfide bond. The tetanus C-terminal fragment (TetC) has been shown to bind specifically to gangliosides present on the neuronal membrane surface and facilitate endocytosis of the toxin (Morris et al., 1980). Once the toxin is internalized in a membrane-bound vesicle, the light chain (N-terminal fragment) translocates to the cytosol where it interferes with neurotransmitter release.