title: Rapid fusion of synaptic vesicles with reconstituted target SNARE membranes.
abstract: Neurotransmitter release at neuronal synapses occurs on a timescale of 1 ms or less. Reconstitution of vesicle fusion from purified synaptic proteins and lipids has played a major role in elucidating the synaptic exocytotic fusion machinery with ever increasing detail. However, one limitation of most reconstitution approaches has been the relatively slow rate of fusion that can be produced in these systems. In a related study, a notable exception is an approach measuring fusion of single reconstituted vesicles bearing the vesicle fusion protein synaptobrevin with supported planar membranes harboring the presynaptic plasma membrane proteins syntaxin and SNAP-25. Fusion times of ∼20 ms were achieved in this system. Despite this advance, an important question with reconstituted systems is how well they mimic physiological systems they are supposed to reproduce. In this work, we demonstrate that purified synaptic vesicles from rat brain fuse with acceptor-SNARE containing planar bilayers equally fast as equivalent reconstituted vesicles and that their fusion efficiency is increased by divalent cations. Calcium boosts fusion through a combined general electrostatic and synaptotagmin-specific mechanism.
authors.affiliation: Center for Membrane Biology and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Volker
authors.initials: V
authors.lastname: Kiessling
authors.forename: Saheeb
authors.initials: S
authors.lastname: Ahmed
authors.forename: Marta K
authors.initials: MK
authors.lastname: Domanska
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Holt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jahn
authors.forename: Lukas K
authors.initials: LK
authors.lastname: Tamm
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008561:Membrane Fusion; D051381:Rats; D013572:Synaptic Vesicles / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism*; D050863:Synaptotagmin I / Q000378:metabolism*; D050988:Vesicle-Associated Membrane Protein 2 / Q000378:metabolism*
chemical_list: D008081:Liposomes; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D050863:Synaptotagmin I; C494312:Syt1 protein, rat; C494706:Vamp2 protein, rat; D050988:Vesicle-Associated Membrane Protein 2