Botulinum neurotoxins light chains

Li JY, Jahn R, Dahlstrom A (1994) Synaptotagmin I is present mainly in autonomic and sensory neurons of the rat peripheral nervous system. Neuroscience 63 837-50 Li L, Binz T, Niemann H, Singh BR (2000) Probing the mechanistic role of glutamate residue in the zinc-binding motif of type A botulinum neurotoxin light chain. Biochemistry 39 2399-2405 Ludlow CL, Hallett M, Rhew K, Cole R, Shimizu T et al. (1992) Therapeutic use of type F botulinum toxin. N Engl J Med 326 349-50... 

Koriazova, L.K., Mental, M. (2003). Translocation of botulinum neurotoxin light chain protease through the heavy chain channel. Nat. Struct. Biol. 10 13-18. 

Lomneth, R., Martin, T. F. J. and DasGupta, B. R., 1991, Botulinum neurotoxin light chain inhibits norepinephrine secretion in PC 12 cells at an intracellular membranous or cytoskeletal site. J. Neurochem. 57 1413-1421. 

Brunger, A.T., Briedenbach, M.A., Jin, R., Fischer, A., Santos, J.S., Montal, M. (2007). Botulinum neurotoxin heavy chain belt as an intramolecular chaperone for the light chain. FLOS Path. 3 1191. ... 

The most ingenious exocytosis toxins, however, come from the anaerobic bacteria Clostridium botulinum and Clostridium tetani. The former produces the seven botulinum neurotoxins (BoNTs) A-G the latter produces tetanus neurotoxin (TeNT). All eight toxins consist of a heavy (H) chain and a light (L) chain that are associated by an interchain S-S bond. The L-chains enter the cytosol of axon terminals. Importantly, BoNT L-chains mainly enter peripheral cholinergic terminals, whereas the TeNT L-chain mainly enters cerebral and spinal cord GABAergic and glycinergic terminals. The L-chains are the active domains of the toxins. They are zinc-endopeptidases and specifically split the three core proteins of exocytosis, i.e. the SNAREs (Fig. 1 inset). Each ofthe eight toxins splits a... 

Poulain, B., Mochida, S., Weller, U., Hogy, B., Habermann, E., Wadsworth, J. D., Shone, C.C., Dolly, J.O. and Tauc, L., Heterologous combinations of heavy and light chains from botulinum neurotoxin A and tetanus toxin inhibit neurotransmitter release in Aplysia, J. Biol. Chem., 266, 9580-9585, 1991. 

Arndt JW, Yu W, Bi F, Stevens RC (2005) Crystal structure of botulinum neurotoxin type g light chain serotype divergence in substrate recognition. Biochemistry 44 9574-80 Arndt JW, Chai Q, Christian T, Stevens RC (2006a) Structure of botulinum neurotoxin type D light chain at 1.65 a resolution repercussions for vamp-2 substrate specificity. Biochemistry 45 3255-62... 

Binz T, Bade S, Rummel A, Kollewe A, Alves J (2002) Arg(362) and tyr(365) of the botulinum neurotoxin type A light chain are involved in transition state stabilization. Biochemistry 41 1717-23... 

Rigoni M, Caccin P, Johnson EA, Montecucco C, Rossetto O (2001) Site-directed mutagenesis identifies active-site residues of the light chain of botulinum neurotoxin type A. Biochem Biophys Res Commun 288 1231-7... 

Bittner MA, DasGupta BR, Holz RW (1989 a) Isolated light chains of botulinum neurotoxins inhibit exocytosis. Studies in digitonin-permeabilized chromaffin cells. In J. Biol. Chem. 264 10354-60... 

Matsuda M, Lei DL, Sugimoto N, Ozutsumi K, OkabeT (1989) Isolation, purification and characterization of fragment B, the NH2-terminal half of the heavy chain of tetanus toxin. In Infect. Immun. 57 3588-93 Matthews BW (1988) Structural basis of the action of thermolysin and related zinc peptidases.In Acc. Chem. Res. 21 333-40 Mclnnes C, Dolly JO (1990) Ca -dependent noradrenaline release from perme-abilised PC 12 cells is blocked by botulinum neurotoxin A or its light chain. In FEBS Lett. 261 323-6... 

Agarwal, R., Binz, T., and Swaminathan, S. 2005. Structural analysis of botulinum neurotoxin serotype F light chain implications on substrate binding and inhibitor design. Biochemistry 44 11758-11765. 

Rupp, B. and Segelke, B. (2001) Questions about the structure of the botulinum neurotoxin B light chain in complex with a target peptide. Nat. Struct. Biol. 8, 663-664. 

Li and colleagues took advantage of the Cadogan-Sundberg indole synthesis to prepare botulinum neurotoxin A light chain (BoNT/A LC)... 

Fig. 4. Organization and fragmentation of botulinum neurotoxin. Botulinum neurotoxin is a protein with a molecular weight of 150,000 to 160,000. It is synthesized as a single chain polypeptide in the Clostridium bacteria. It is nicked by endogenous protease to yield a dichain molecule linked by a disulfide bond. This nicking is usually associated with activation of its toxicity. The nicked molecule is separated into heavy and light chains by reduction of the disulfide bond.

Amperometry at single PC 12 cells has also been used in conjunction with a genetic cell transfection protocol to examine the effects of toxin expression on basal and evoked exocytosis. PC 12 cells have been transfected with the specific endoprotease Botulinum neurotoxin Cl light chain (BoNT/Cl), which cleaves the proteins syntaxin and SNAP-25 [5], The molecular dissection of the mechanisms underlying exocytosis has been motivated by the SNARE hypothesis, which postulates that exocytosis requires the assembly of the plasma membrane proteins syntaxin 1, SNAP-25, and the vesicle associated membrane protein (VAMP) into a complex [5], This SNARE complex then acts as a receptor for cytosolic components of the proposed fusion machinery. Direct evidence for the role of the SNARE proteins in neurotransmission comes from molecular genetic studies in which syntaxin and VAMP have been shown to be required for neurotransmission in Drosophila [47 9] and Caenorhabditis elegans [50,51]. To assess the effects of the disruption of SNARE proteins on exocytosis in PC 12 cells, amperometry has been used in conjunction with a genetic cell transfection assay to establish a... 

BoNT Botulinum neurotoxin LC light chain HC heavy chain DDV drug delivery vehicle. 

Fern ndez-Salas, E., Steward, L.R, Ho, H., et al, 2004. Plasma membrane localization signals in the light chain of botulinum neurotoxin. Proc. Natl. Acad. 

Botulinum neurotoxins (seven serotypes, A-G) are relatively large water soluble proteins (150 kDa) produced by the Clostridium botulinum. Each protein has two polypeptide chains (a 100 kDa heavy chain and a 50 kDa light chain) linked through a disulfide bond (Fig. 2). In the proposed mode of action of botulinum and tetanus neurotoxins (Simpson, 1986, 1989), the C-terminal half of the heavy chain binds to the nerve membrane leading to internalization of the neurotoxin in the nerve cell through endocytosis. Subsequently, the pH of the endosome is lowered causing the heavy chain to get integrated in the membrane... 

Figure 2. Schematic diagram of botulinum neurotoxin showing its light and heavy chains. The two different domains of the heavy chain shaded with different patterns indicate the N-terminal and C-terminal halves (about 50 kDa each). These two domains are believed to play different functional roles during the intoxication process. The light chain has been shown to contain the toxic site.

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