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X-ray structure of a neuronal complexin-SNARE complex from squid
Andreas Bracher1, Jan Kadlec, Heinrich Betz
1European Molecular Biology Laboratory, 6 rue Jules Horowitz, 38042 Grenoble, France.
The Journal of Biological Chemistry
|May 11, 2002
Summary
This study reveals the crystal structure of a complexin-SNARE complex, crucial for neurotransmitter release. This finding offers insights into the molecular mechanisms regulating vesicle fusion and calcium-mediated exocytosis.
Area of Science:
- Molecular Biology
- Neuroscience
- Structural Biology
Background:
- Neurotransmitter release from nerve terminals relies on exocytosis, a process regulated by SNARE complexes and accessory proteins like complexins.
- Calcium ions (Ca2+) trigger this release by increasing intracellular Ca2+ levels.
Purpose of the Study:
- To determine the structural basis of complexin's regulation of the SNARE complex in neurotransmission.
- To elucidate the role of complexin in the late stages of vesicle fusion.
Main Methods:
- X-ray crystallography was used to determine the structure of a squid core complexin-SNARE complex.
- High-resolution structural analysis at 2.95-A.
Main Results:
- The crystal structure reveals a helical segment of complexin binding anti-parallel to the SNARE complex's four-helix bundle.
- Complexin interacts with syntaxin and synaptobrevin at the ionic zero layer, suggesting a role in late pre-fusion stages.
- The structure provides a molecular model for complexin's regulatory function in vesicle fusion.
Conclusions:
- The complexin-SNARE complex structure is integral to the machinery regulating late-stage vesicle fusion.
- Calcium ions may initiate membrane fusion by modulating complexin's activity, leading to SNARE complex conformational changes.
- This work advances our understanding of the molecular mechanisms underlying synaptic exocytosis.