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Two distinct effects on neurotransmission in a temperature-sensitive SNAP-25 mutant
S S Rao1, B A Stewart, P K Rivlin
1Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
The EMBO Journal
|December 1, 2001
Summary
A mutation in SNAP-25 (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) affects synaptic vesicle fusion. This SNAP-25 mutant enhances neurotransmitter release at low temperatures but impairs it at high temperatures.
Area of Science:
- Molecular Biology
- Neuroscience
- Cell Biology
Background:
- Vesicle fusion in eukaryotic cells relies on SNARE proteins.
- SNAP-25 is a critical t-SNARE for synaptic vesicle fusion in neurons.
- The precise function of SNAP-25 in this process remains unclear.
Purpose of the Study:
- To investigate the role of SNAP-25 in synaptic vesicle fusion.
- To characterize a novel temperature-sensitive mutant of SNAP-25 in Drosophila.
Main Methods:
- Isolation and characterization of a Drosophila SNAP-25 temperature-sensitive mutant (SNAP-25(ts)).
- Analysis of SNARE complex stability in vitro at different temperatures.
- Assessment of neurotransmitter release in SNAP-25(ts) larvae at varying temperatures.
Main Results:
- The SNAP-25(ts) mutation (Gly50 to Glu) affects the amphipathic helix domain, conserved in yeast secretion.
- Mutant SNARE complexes show temperature-dependent stability and multimerization.
- Neurotransmitter release is increased at 22°C and decreased at 37°C in SNAP-25(ts) mutants.
Conclusions:
- The SNAP-25 mutation alters SNARE complex function, impacting fusion competence.
- At permissive temperatures, the mutation enhances fusion; at restrictive temperatures, it causes instability and fusion incompetence.
- This study highlights the conserved role of the SNAP-25 amphipathic helix in regulated secretion.
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