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Temperature-sensitive paralytic mutations demonstrate that synaptic exocytosis requires SNARE complex assembly and
J T Littleton1, E R Chapman, R Kreber
1Laboratory of Genetics, University of Wisconsin, Madison 53706, USA.
Neuron
|September 5, 1998
Summary
This study shows that SNARE complex assembly and disassembly are crucial for synaptic membrane trafficking in vivo. Disrupting syntaxin or NSF function in Drosophila rapidly impairs synaptic transmission, supporting this model.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- The neuronal SNARE complex, comprising synaptobrevin, syntaxin, and SNAP-25, is essential for membrane fusion.
- Spontaneous SNARE complex assembly occurs, but disassembly requires NSF ATPase activity.
- The role of SNARE complex cycling in driving membrane trafficking in vivo remains unproven.
Purpose of the Study:
- To investigate the in vivo function of SNARE complex assembly and disassembly in membrane trafficking.
- To provide evidence for the hypothesis that SNARE complex cycling drives lipid bilayer fusion at synapses.
Main Methods:
- Isolation of a Drosophila temperature-sensitive paralytic mutation in syntaxin.
- Analysis of the effect of syntaxin and NSF mutations on synaptic transmission and SNARE complex formation.
- Observation of SNARE complex accumulation in synaptic vesicles.
Main Results:
- A syntaxin mutation rapidly blocked synaptic transmission and decreased synaptobrevin binding, preventing 7S SNARE complex assembly.
- Temperature-sensitive NSF mutations (comatose) also blocked synaptic transmission but with slower kinetics.
- NSF mutations led to the accumulation of syntaxin and SNARE complexes on synaptic vesicles.
Conclusions:
- SNARE complex assembly and disassembly cycles are essential for synaptic membrane trafficking in vivo.
- This study provides direct in vivo evidence supporting the role of SNARE complex dynamics in driving membrane fusion events at synapses.