title: Control of membrane gaps by synaptotagmin-Ca2+ measured with a novel membrane distance ruler.
abstract: Fast synchronous neurotransmitter release is triggered by calcium that activates synaptotagmin-1 (syt-1), resulting in fusion of synaptic vesicles with the presynaptic membrane. Syt-1 possesses two Ca(2+)-binding C2 domains that tether membranes via interactions with anionic phospholipids. It is capable of crosslinking membranes and has recently been speculated to trigger fusion by decreasing the gap between them. As quantitative information on membrane gaps is key to understanding general cellular mechanisms, including the role of syt-1, we developed a fluorescence-lifetime based inter-membrane distance ruler using membrane-anchored DNAs of various lengths as calibration standards. Wild-type and mutant data provide evidence that full-length syt-1 indeed regulates membrane gaps: without Ca(2+), syt-1 maintains membranes at distances of ~7-8 nm. Activation with 100 μM Ca(2+) decreases the distance to ~5 nm by binding the C2 domains to opposing membranes, respectively. These values reveal that activated syt-1 adjusts membrane distances to the level that promotes SNARE complex assembly.
authors.affiliation: Research Group Biomolecular Spectroscopy and Single-Molecule Detection, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Chao-Chen
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Research Group Nucleic Acid Chemistry, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Seikowski
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Angel
authors.initials: A
authors.lastname: Pérez-Lara
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jahn
authors.affiliation: 1] Research Group Nucleic Acid Chemistry, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany [2] Institute for Organic and Biomolecular Chemistry, Georg August University Göttingen, Tammannstraße 2, 37077 Göttingen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Höbartner
authors.affiliation: 1] Research Group Biomolecular Spectroscopy and Single-Molecule Detection, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany [2] Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, University of Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany.
authors.forename: Peter Jomo
authors.initials: PJ
authors.lastname: Walla
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry; D002264:Carboxylic Acids; D002413:Cations, Divalent; D002784:Cholesterol / Q000737:chemistry; D005456:Fluorescent Dyes; D015870:Gene Expression; D008856:Microscopy, Fluorescence; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D017729:Presynaptic Terminals / Q000737:chemistry* / Q000378:metabolism; D011510:Proteolipids / Q000737:chemistry; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D050600:SNARE Proteins / Q000737:chemistry* / Q000378:metabolism; D013572:Synaptic Vesicles / Q000737:chemistry* / Q000378:metabolism; D050863:Synaptotagmin I / Q000737:chemistry* / Q000378:metabolism; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D002413:Cations, Divalent; D005456:Fluorescent Dyes; D009841:Oligonucleotides; C436864:Oregon Green 488 carboxylic acid; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D011510:Proteolipids; D011994:Recombinant Proteins; D050600:SNARE Proteins; D050863:Synaptotagmin I; C494312:Syt1 protein, rat; D053835:Unilamellar Liposomes; C020485:proteoliposomes; C094877:dioleoyl phosphatidylethanolamine; C042511:1,2-dioleoylphosphatidylserine; D002784:Cholesterol; D002118:Calcium