Assembly of intermediates for rapid membrane fusion
1From the Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-3844.
The Journal of Biological Chemistry
|December 7, 2017
Summary
This study reveals the ordered steps of membrane fusion, identifying key intermediates in SNARE complex assembly. This clarifies the pathway for rapid fusion, essential for cellular processes.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- Membrane fusion is critical for cellular functions like protein sorting and secretion.
- Sec1-Munc18 (SM) proteins and SNARE complexes mediate rapid membrane fusion.
- The vacuolar HOPS complex tethers membranes and catalyzes SNARE assembly, but the precise order is unknown.
Purpose of the Study:
- To elucidate the ordered assembly pathway of SNARE complexes during yeast vacuole membrane fusion.
- To identify and characterize key intermediates in the HOPS-mediated fusion process.
Main Methods:
- Utilized yeast Saccharomyces cerevisiae vacuole systems.
- Investigated the assembly of HOPS complex with vacuolar SNAREs (R, Qa, Qb, Qc).
- Monitored fusion events upon addition of specific SNAREs and Sec17/αSNAP.
Main Results:
- Identified a prefusion intermediate involving HOPS, R, Qa, and Qc SNAREs.
- Demonstrated that Qb-SNARE and Sec17/αSNAP addition triggers rapid fusion of this intermediate.
- Established a sequential pathway: Rab- and HOPS-tethered membranes, HOPS:R:Qa:Qc complex, HOPS:4-SNARE complex, Sec17 engagement, and lipid rearrangement.
Conclusions:
- The R:Qa:Qc SNARE complex forms early in the fusion pathway.
- This complex, along with Ypt7, HOPS, and trans-SNAREs, acts as a functional intermediate.
- Subsequent addition of Qb-SNARE and Sec17/αSNAP drives rapid membrane fusion.
Keywords:
SNARE proteinsSaccharomyces cerevisiaemembrane fusionmembrane reconstitutionprotein complexMore Related Videos
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