Synaptic vesicle membrane fusion complex: action of clostridial neurotoxins on assembly

EMBO J. 1994 Nov 1;13(21):5051-61. doi: 10.1002/j.1460-2075.1994.tb06834.x.


Clostridial neurotoxins inhibit neurotransmitter release by selective and specific intracellular proteolysis of synaptobrevin/VAMP, synaptosomal-associated protein of 25 kDa (SNAP-25) or syntaxin. Here we show that in binary reactions synaptobrevin binds weakly to both SNAP-25 and syntaxin, and SNAP-25 binds to syntaxin. In the presence of all three components, a dramatic increase in the interaction strengths occurs and a stable sodium dodecyl sulfate-resistant complex forms. Mapping of the interacting sequences reveals that complex formation correlates with the presence of predicted alpha-helical structures, suggesting that membrane fusion involves intermolecular interactions via coiled-coil structures. Most toxins only attack the free, and not the complexed, proteins, and proteolysis of the proteins by different clostridial neurotoxins has distinct inhibitory effects on the formation of synaptobrevin-syntaxin-SNAP-25 complexes. Our data suggest that synaptobrevin, syntaxin and SNAP-25 associate into a unique stable complex that functions in synaptic vesicle exocytosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Botulinum Toxins / pharmacology*
  • Brain / physiology
  • Exocytosis / physiology
  • Macromolecular Substances
  • Membrane Fusion / drug effects
  • Membrane Fusion / physiology*
  • Membrane Proteins / metabolism*
  • Models, Biological
  • Nerve Tissue Proteins / metabolism*
  • Neurotoxins / pharmacology*
  • Neurotransmitter Agents / metabolism
  • Protein Binding
  • Protein Conformation
  • R-SNARE Proteins
  • Rats
  • Receptors, Cell Surface / metabolism
  • Sodium Dodecyl Sulfate / pharmacology
  • Structure-Activity Relationship
  • Synaptic Vesicles / drug effects
  • Synaptic Vesicles / physiology*
  • Synaptosomal-Associated Protein 25


  • Macromolecular Substances
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Neurotoxins
  • Neurotransmitter Agents
  • R-SNARE Proteins
  • Receptors, Cell Surface
  • Snap25 protein, rat
  • Synaptosomal-Associated Protein 25
  • Sodium Dodecyl Sulfate
  • Botulinum Toxins