Multiple intermediates in SNARE-induced membrane fusion

Tae Young Yoon, Burak Okumus, Fan Zhang, Yeon Kyun Shin, Taekjip Ha

Research output: Contribution to journalArticlepeer-review

Abstract

Membrane fusion in eukaryotic cells is thought to be mediated by a highly conserved family of proteins called SNAREs (soluble N-ethyl maleimide sensitive-factor attachment protein receptors). The vesicle-associated v-SNARE engages with its partner t-SNAREs on the target membrane to form a coiled coil that bridges two membranes and facilitates fusion. As demonstrated by recent findings on the hemifusion state, identifying intermediates of membrane fusion can help unveil the underlying fusion mechanism. Observation of SNARE-driven fusion at the single-liposome level has the potential to dissect and characterize fusion intermediates most directly. Here, we report on the real-time observation of lipid-mixing dynamics in a single fusion event between a pair of SNARE-reconstituted liposomes. The assay reveals multiple intermediate states characterized by discrete values of FRET between membrane-bound fluorophores. Hemifusion, flickering of fusion pores, and kinetic transitions between intermediates, which would be very difficult to detect in ensemble assays, are now identified. The ability to monitor the time course of fusion events between two proteoliposomes should be useful for addressing many important issues in SNARE-mediated membrane fusion.

Original languageEnglish (US)
Pages (from-to)19731-19736
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number52
DOIs
StatePublished - Dec 26 2006

Keywords

  • FRET
  • Lipid mixing
  • Single-molecule spectroscopy

ASJC Scopus subject areas

  • General

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