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Hemifusion in SNARE-mediated membrane fusion
Yibin Xu1, Fan Zhang, Zengliu Su
1Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.
Nature Structural & Molecular Biology
|April 12, 2005
Summary
Soluble NSF Attachment Protein Receptors (SNAREs) mediate membrane fusion. This study reveals that SNARE-mediated fusion can proceed through a hemifusion intermediate, identified by analyzing a key yeast v-SNARE's structure.
Area of Science:
- Cell Biology
- Biochemistry
- Structural Biology
Background:
- Soluble NSF Attachment Protein Receptors (SNAREs) are critical proteins that drive intracellular membrane fusion events.
- Understanding the precise mechanisms of SNARE-mediated fusion, including potential intermediates, is crucial for deciphering cellular transport pathways.
Purpose of the Study:
- To determine the structure of the transmembrane domain (TMD) of the yeast vesicle (v)-SNARE Snc2p.
- To investigate the role of the v-SNARE TMD in membrane fusion and identify potential fusion intermediates.
Main Methods:
- Electron Paramagnetic Resonance (EPR) spectroscopy was employed to determine the structure of the Snc2p TMD.
- Liposome-based assays were utilized to assess membrane fusion upon reconstitution with wild-type and mutant SNAREs.
Main Results:
- The structure of the Snc2p TMD was elucidated, providing insights into its role in membrane interaction.
- A v-SNARE mutant lacking approximately half of its TMD induced outer leaflet lipid mixing but not complete fusion.
- Hemifusion intermediates were observed with both wild-type SNAREs at low concentrations and the v-SNARE mutant.
Conclusions:
- SNARE-mediated membrane fusion can proceed through a distinct hemifusion intermediate stage.
- The TMD of v-SNAREs plays a critical role in regulating the progression of membrane fusion.
- Structural insights into SNAREs can guide the design of mutants to probe fusion mechanisms.