Abstract
The spatial distribution of the target (t-)SNARE proteins (syntaxin and SNAP-25) on the plasma membrane has been extensively characterized. However, the protein conformations and interactions of the two t-SNAREs in situ remain poorly defined. By using super-resolution optical techniques and fluorescence lifetime imaging microscopy, we observed that within the t-SNARE clusters syntaxin and SNAP-25 molecules interact, forming two distinct conformations of the t-SNARE binary intermediate. These are spatially segregated on the plasma membrane with each cluster exhibiting predominantly one of the two conformations, representing the two- and three-helical forms previously observed in vitro. We sought to explain why these two t-SNARE intermediate conformations exist in spatially distinct clusters on the plasma membrane. By disrupting plasma membrane lipid order, we found that all of the t-SNARE clusters now adopted a single conformational state corresponding to the three helical t-SNARE intermediates. Together, our results define spatially distinct t-SNARE intermediate states on the plasma membrane and how the conformation adopted can be patterned by the underlying lipid environment.
Original language | English |
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Pages (from-to) | 13535-13541 |
Number of pages | 7 |
Journal | Journal of Biological Chemistry |
Volume | 285 |
Issue number | 18 |
DOIs | |
Publication status | Published - 30 Apr 2010 |
Keywords
- animals
- cell membrane
- membrane lipids
- PC12 cells
- protein structure, quaternary
- protein structure, secondary
- Qa-SNARE proteins
- rats
- synaptosomal-associated protein 25