t-SNARE Protein Conformations Patterned by the Lipid Microenvironment

Colin Rickman, Claire N. Medine, Alison R. Dun, David J. Moulton, Ondrej Mandula, Nagaraj D. Halemani, Silvio O. Rizzoli, Luke H. Chamberlain, Rory R. Duncan

Research output: Contribution to journalArticlepeer-review

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 languageEnglish
Pages (from-to)13535-13541
Number of pages7
JournalJournal of Biological Chemistry
Volume285
Issue number18
DOIs
Publication statusPublished - 30 Apr 2010

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