title: A molecular toggle after exocytosis sequesters the presynaptic syntaxin1a molecules involved in prior vesicle fusion.
abstract: Neuronal synapses are among the most scrutinized of cellular systems, serving as a model for all membrane trafficking studies. Despite this, synaptic biology has proven difficult to interrogate directly in situ due to the small size and dynamic nature of central synapses and the molecules within them. Here we determine the spatial and temporal interaction status of presynaptic proteins, imaging large cohorts of single molecules inside active synapses. Measuring rapid interaction dynamics during synaptic depolarization identified the small number of syntaxin1a and munc18-1 protein molecules required to support synaptic vesicle exocytosis. After vesicle fusion and subsequent SNARE complex disassembly, a prompt switch in syntaxin1a and munc18-1-binding mode, regulated by charge alteration on the syntaxin1a N-terminal, sequesters monomeric syntaxin1a from other disassembled fusion complex components, preventing ectopic SNARE complex formation, readying the synapse for subsequent rounds of neurotransmission.
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Kavanagh
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org [3] Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
authors.forename: Annya M
authors.initials: AM
authors.lastname: Smyth
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Kirsty J
authors.initials: KJ
authors.lastname: Martin
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Alison
authors.initials: A
authors.lastname: Dun
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Euan R
authors.initials: ER
authors.lastname: Brown
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gordon
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Smillie
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, 161 Cathedral Street, Glasgow G4 0RE, UK.
authors.forename: Luke H
authors.initials: LH
authors.lastname: Chamberlain
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Rhodri S
authors.initials: RS
authors.lastname: Wilson
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Weiping
authors.initials: W
authors.lastname: Lu
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cousin
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Colin
authors.initials: C
authors.lastname: Rickman
authors.affiliation: 1] Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Edinburgh EH14 4AS, UK [2] Edinburgh Super-Resolution Imaging Consortium, www.esric.org.
authors.forename: Rory R
authors.initials: RR
authors.lastname: Duncan
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D019274:Botulinum Toxins, Type A / Q000494:pharmacology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004622:Embryo, Mammalian; D005089:Exocytosis / Q000235:genetics*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008561:Membrane Fusion; D057054:Molecular Imaging; D051938:Munc18 Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D061251:Primary Cell Culture; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D050827:Syntaxin 1 / Q000235:genetics / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D051938:Munc18 Proteins; D050600:SNARE Proteins; D050827:Syntaxin 1; D000097573:Red Fluorescent Protein; C497939:Stxbp1 protein, rat; C485184:enhanced green fluorescent protein; C096324:botulinum toxin type C