title: SNARE proteins: one to fuse and three to keep the nascent fusion pore open.
abstract: Neurotransmitters are released through nascent fusion pores, which ordinarily dilate after bilayer fusion, preventing consistent biochemical studies. We used lipid bilayer nanodiscs as fusion partners; their rigid protein framework prevents dilation and reveals properties of the fusion pore induced by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor). We found that although only one SNARE per nanodisc is required for maximum rates of bilayer fusion, efficient release of content on the physiologically relevant time scale of synaptic transmission apparently requires three or more SNARE complexes (SNAREpins) and the native transmembrane domain of vesicle-associated membrane protein 2 (VAMP2). We suggest that several SNAREpins simultaneously zippering their SNARE transmembrane helices within the freshly fused bilayers provide a radial force that prevents the nascent pore from resealing during synchronous neurotransmitter release.
authors.affiliation: Department of Cell Biology, School of Medicine, Yale University, New Haven, CT 06520, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Qing-Tao
authors.initials: QT
authors.lastname: Shen
authors.forename: Alexander
authors.initials: A
authors.lastname: Kiel
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Melia
authors.forename: James E
authors.initials: JE
authors.lastname: Rothman
authors.forename: Frédéric
authors.initials: F
authors.lastname: Pincet
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004058:Diffusion; D008051:Lipid Bilayers; D008081:Liposomes; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018377:Neurotransmitter Agents / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000737:chemistry; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D050600:SNARE Proteins / Q000737:chemistry* / Q000378:metabolism*; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000737:chemistry* / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25 / Q000737:chemistry / Q000378:metabolism; D050827:Syntaxin 1 / Q000737:chemistry / Q000378:metabolism; D050988:Vesicle-Associated Membrane Protein 2 / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D008565:Membrane Proteins; D018377:Neurotransmitter Agents; D011510:Proteolipids; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D050988:Vesicle-Associated Membrane Protein 2; C020485:proteoliposomes; D002118:Calcium