Transmission at the squid giant synapse was blocked by tetanus toxin by affecting synaptobrevin, a vesicle-bound protein.
1. The effect of whole tetanus toxin (TeTX) and of its light chain (TeTX L-chain) on transmitter release was determined by presynaptic pressure-injection in the squid giant synapse. 2. The results indicate that whole TeTX does not modify transmission while the L-chain blocks transmission within 20-30 min. This block does not involve changes in the sodium or potassium conductances responsible for spike generation or the voltage-dependent presynaptic calcium current responsible for transmitter release. 3. Western blotting of protein fractions from the squid optic lobe demonstrated the presence of a protein which reacted with specific antibodies against mammalian synaptobrevin, a vesicular protein. In addition, this protein was enzymatically cleaved by the L-chain component of the toxin in a similar fashion to its mammalian counterpart. 4. These results demonstrate that TeTX L-chain toxin acts directly on a squid synaptobrevin and prevents synaptic release probably by interfering with the docking-fusion synaptic vesicles at the active zone.
Llinás
R
R
Department of Physiology and Biophysics, New York University Medical Center, NY 10016.
Sugimori
M
M
Chu
D
D
Morita
M
M
Blasi
J
J
Herreros
J
J
Jahn
R
R
Marsal
J
J
D000818:Animals; D015153:Blotting, Western; D049832:Decapodiformes; D004591:Electrophoresis, Polyacrylamide Gel; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism*; D009899:Optic Lobe, Nonmammalian; D011188:Potassium / Q000378:metabolism; D050683:R-SNARE Proteins; D051381:Rats; D012964:Sodium / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*; D013574:Synaptosomes / Q000187:drug effects; D013744:Tetanus Toxin / Q000494:pharmacology*
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; D013744:Tetanus Toxin; D012964:Sodium; D011188:Potassium