The core membrane fusion complex governs the probability of synaptic vesicle fusion but not transmitter release kinetics.
Synaptic vesicle fusion is driven by the formation of a four-helical bundle composed of soluble N-ethylmaleimide sensitive factor (NSF) attachment protein receptors (SNAREs). Exactly how the structural interactions that lead to the formation of this complex relate to neurotransmitter release is not well understood. To address this question, we used a strategy to "rescue" synaptic transmission after proteolytic cleavage of the synaptosome-associated protein of 25 kDa (SNAP-25) by botulinum neurotoxin E (BoNtE). Transfection of CA3 hippocampal pyramidal cells with BoNtE-resistant SNAP-25 restored synaptic transmission. Additional mutations that alter the interaction between SNAP-25 C-terminal coil and the other SNARE coils dramatically reduce transmitter release probability but leave the kinetics of synaptic responses unaltered. These data indicate that at synapses, SNARE interactions are necessary for fusion but are not the rate-limiting step of neurotransmission.
Finley
Michael F A
MF
Howard Hughes Medical Institute and Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, USA.
Patel
Sejal M
SM
Madison
Daniel V
DV
Scheller
Richard H
RH
D000818:Animals; D019470:Biolistics; D001905:Botulinum Toxins / Q000494:pharmacology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D017930:Genes, Reporter; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism; D050600:SNARE Proteins; D013329:Structure-Activity Relationship; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25; D014162:Transfection; D033921:Vesicular Transport Proteins
D046911:Macromolecular Substances; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D050600:SNARE Proteins; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; D001905:Botulinum Toxins; C096326:botulinum toxin type E