title: Rapid SNARE-Mediated Fusion of Liposomes and Chromaffin Granules with Giant Unilamellar Vesicles.
abstract: Soluble N-ethylmaleimide-sensitive factor activating protein receptor (SNARE) proteins are the main catalysts for membrane fusion in the secretory pathway of eukaryotic cells. In vitro, SNAREs are sufficient to mediate effective fusion of both native and artificial membranes. Here we have established, to our knowledge, a new platform for monitoring SNARE-mediated docking and fusion between giant unilamellar vesicles (GUVs) and smaller liposomes or purified secretory granules with high temporal and spatial resolution. Analysis of fusion is restricted to the free-standing part of the GUV-membrane exhibiting low curvature and a lack of surface contact, thus avoiding adhesion-mediated interference with the fusion reaction as in fusion with supported bilayers or surface-immobilized small vesicles. Our results show that liposomes and chromaffin granules fuse with GUVs containing activated SNAREs with only few milliseconds delay between docking and fusion. We conclude that after initial contact in trans, SNAREs alone can complete fusion at a rate close to fast neuronal exocytosis.
authors.affiliation: Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; International Max Planck Research School for Molecular Biology at the University of Göttingen, Göttingen, Germany.
authors.forename: Agata
authors.initials: A
authors.lastname: Witkowska
authors.affiliation: Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany. Electronic address: rjahn@gwdg.de.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jahn
mesh_terms: D000818:Animals; D002837:Chromaffin Granules / Q000378:metabolism*; D004058:Diffusion; D004926:Escherichia coli; D036681:Fluorescence Recovery After Photobleaching; D008051:Lipid Bilayers / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology*; D008853:Microscopy; D008954:Models, Biological; D051381:Rats; D050600:SNARE Proteins / Q000378:metabolism*; D013997:Time Factors
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D050600:SNARE Proteins