Vesicle capture by membrane-bound Munc13-1 requires self-assembly into discrete clusters
Feng Li1,2, Ramalingam Venkat Kalyana Sundaram1,2, Alberto T Gatta1,2
1Department of Cell Biology, School of Medicine, Yale University, New Haven, CT, USA.
FEBS Letters
|July 6, 2021
Summary
Munc13-1 protein naturally forms nano-clusters essential for synaptic vesicle binding. Clusters of at least six Munc13-1 molecules efficiently capture vesicles via their C-terminal domain.
Area of Science:
- Neuroscience
- Molecular Biology
- Biophysics
Background:
- Munc13-1 protein regulates synaptic vesicle docking and fusion.
- Munc13-1 nano-assemblies are observed in neuronal active zones.
- The role of Munc13-1 clustering in synaptic function remains unclear.
Purpose of the Study:
- To investigate if Munc13-1 nano-clustering is inherent and functionally significant.
- To determine the Munc13-1 cluster size required for vesicle binding.
- To elucidate the role of the Munc13-1 C-terminal domain in vesicle capture.
Main Methods:
- Quantitative TIRF microscopy
- Step-wise photobleaching
- Reconstitution of Munc13-1 onto supported lipid bilayers
Main Results:
- Munc13-1 spontaneously forms clusters of 2-20 copies.
- Clusters require a minimum of 6 Munc13-1 copies for efficient vesicle capture.
- The C-terminal C2C domain is crucial for vesicle capture via electrostatic and hydrophobic interactions.
Conclusions:
- Munc13-1 nano-clustering is an intrinsic property required for synaptic vesicle binding.
- Specific cluster sizes regulate Munc13-1's ability to capture vesicles.
- The C-terminal domain mediates vesicle capture through membrane interactions.
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