The overall goal of this program project is to elucidate the precise molecular mechanism and regulation of the fusion machine that drives exocytosis for the controlled release of neurotransmitter at nerve terminals. The assembly of SNARE molecules residing in the synaptic vesicle and presynaptic plasma membrane takes center stage and provides the driving energy for this process. Even though we know the structure of the fully assembled cis-SNARE complex after fusion in atomic detail and have detailed conformational models for several of the SNAREs before fusion, we do not precisely know how (i) they are conditioned with regulatory proteins such as Munc18 and Munc13 to form an active acceptor complex on the plasma membrane, (ii) how this acceptor SNARE complex engages with the synaptic vesicle SNARE upon encounter, and (iii) how this high-energy trans-SNARE complex is ultimately triggered by the synaptic vesicle protein synaptotagmin and calcium to proceed to full assembly and fusion. Three projects led by three expert leaders in the biochemistry, structural biology, and biophysics of neuronal exocytotic membrane fusion are designed to jointly unravel the precise molecular interactions that drive the neuronal fusion machine through the vesicle docking, priming, and fusion steps with the highest possible structural and time resolution. The team will seek to define the structures and configurations of the active presynaptic acceptor SNARE complex and the fusion-restricted trans-SNARE complex between two membranes, and the team will strive to uncover the molecular mechanism, by which calcium-synaptotagmin engages with the membranes and/or complex to release their fusion-restriction. To achieve this goal the team will use a unique combination of approaches ranging from highly innovative biochemical procedures to reconstitute the relevant proteins, EPR, DEER, and NMR spectroscopy to characterize the pertinent structures in membrane environments, and FLIC and single vesicle TIRF microscopy to measure membrane topology and read out fusion on the millisecond timescale.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
2P01GM072694-11A1
Application #
9209669
Study Section
Special Emphasis Panel (ZRG1)
Project Start
Project End
Budget Start
2016-09-01
Budget End
2017-08-31
Support Year
11
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Virginia
Department
Type
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
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Kreutzberger, Alex J B; Kiessling, Volker; Liang, Binyong et al. (2017) Asymmetric Phosphatidylethanolamine Distribution Controls Fusion Pore Lifetime and Probability. Biophys J 113:1912-1915
Katti, Sachin; Nyenhuis, Sarah B; Her, Bin et al. (2017) Non-Native Metal Ion Reveals the Role of Electrostatics in Synaptotagmin 1-Membrane Interactions. Biochemistry 56:3283-3295
Kreutzberger, Alex J B; Kiessling, Volker; Liang, Binyong et al. (2017) Reconstitution of calcium-mediated exocytosis of dense-core vesicles. Sci Adv 3:e1603208
Zdanowicz, Rafal; Kreutzberger, Alex; Liang, Binyong et al. (2017) Complexin Binding to Membranes and Acceptor t-SNAREs Explains Its Clamping Effect on Fusion. Biophys J 113:1235-1250
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Kreutzberger, Alex J B; Liang, Binyong; Kiessling, Volker et al. (2016) Assembly and Comparison of Plasma Membrane SNARE Acceptor Complexes. Biophys J 110:2147-50
Liang, Binyong; Tamm, Lukas K (2016) NMR as a tool to investigate the structure, dynamics and function of membrane proteins. Nat Struct Mol Biol 23:468-74
Dawidowski, Damian; Cafiso, David S (2016) Munc18-1 and the Syntaxin-1 N Terminus Regulate Open-Closed States in a t-SNARE Complex. Structure 24:392-400
Milovanovic, Dragomir; Platen, Mitja; Junius, Meike et al. (2016) Calcium Promotes the Formation of Syntaxin 1 Mesoscale Domains through Phosphatidylinositol 4,5-Bisphosphate. J Biol Chem 291:7868-76

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