Resolving the function of distinct Munc18-1/SNARE protein interaction modes in a reconstituted membrane fusion assay
Sec1p/Munc18 proteins and SNAP receptors (SNAREs) are key components of the intracellular membrane fusion machinery. Compartment-specific v-SNAREs on a transport vesicle pair with their cognate t-SNAREs on the target membrane and drive lipid bilayer fusion. In a reconstituted assay that dissects the...
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| Main Authors: | , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
[2 September 2011]
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| In: |
The journal of biological chemistry
Year: 2011, Volume: 286, Issue: 35, Pages: 30582-30590 |
| ISSN: | 1083-351X |
| DOI: | 10.1074/jbc.M111.269886 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1074/jbc.M111.269886 Verlag, lizenzpflichtig, Volltext: https://www.sciencedirect.com/science/article/pii/S0021925820723409 
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| Author Notes: | Yvette Schollmeier, Jean Michel Krause, Susanne Kreye, Jörg Malsam, and Thomas H. Söllner (from the Heidelberg University Biochemistry Center) |
| Summary: | Sec1p/Munc18 proteins and SNAP receptors (SNAREs) are key components of the intracellular membrane fusion machinery. Compartment-specific v-SNAREs on a transport vesicle pair with their cognate t-SNAREs on the target membrane and drive lipid bilayer fusion. In a reconstituted assay that dissects the sequential assembly of t-SNARE (syntaxin 1·SNAP-25) and v-/t-SNARE (VAMP2·syntaxin 1·SNAP-25) complexes, and finally measures lipid bilayer merger, we resolved the inhibitory and stimulatory functions of the Sec1p/Munc18 protein Munc18-1 at the molecular level. Inhibition of membrane fusion by Munc18-1 requires a closed conformation of syntaxin 1. Remarkably, the concurrent preincubation of Munc18-1-inhibited syntaxin 1 liposomes with both VAMP2 liposomes and SNAP-25 at low temperature releases the inhibition and effectively stimulates membrane fusion. VAMP8 liposomes can neither release the inhibition nor exert the stimulatory effect, demonstrating the need for a specific Munc18-1/VAMP2 interaction. In addition, Munc18-1 binds to the N-terminal peptide of syntaxin 1, which is obligatory for a robust stimulation of membrane fusion. In contrast, this interaction is neither required for the inhibitory function of Munc18-1 nor for the release of this block. These results indicate that Munc18-1 and the neuronal SNAREs already have the inherent capability to function as a basic stage-specific off/on switch to control membrane fusion. |
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| Item Description: | Gesehen am 25.10.2022 |
| Physical Description: | Online Resource |
| ISSN: | 1083-351X |
| DOI: | 10.1074/jbc.M111.269886 |