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 #
5P01GM072694-12
Application #
9520220
Study Section
Special Emphasis Panel (ZRG1)
Project Start
Project End
Budget Start
2018-07-01
Budget End
2019-06-30
Support Year
12
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Virginia
Department
Type
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Yavuz, Halenur; Kattan, Iman; Hernandez, Javier M et al. (2018) Arrest of trans-SNARE zippering uncovers loosely and tightly docked intermediates in membrane fusion. J Biol Chem 293:8645-8655
Liang, Binyong; Tamm, Lukas K (2018) Solution NMR of SNAREs, complexin and ?-synuclein in association with membrane-mimetics. Prog Nucl Magn Reson Spectrosc 105:41-53
Hussain, Syed Saad; Harris, Megan T; Kreutzberger, Alex J B et al. (2018) Control of insulin granule formation and function by the ABC transporters ABCG1 and ABCA1 and by oxysterol binding protein OSBP. Mol Biol Cell 29:1238-1257
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Witkowska, Agata; Jablonski, Lukasz; Jahn, Reinhard (2018) A convenient protocol for generating giant unilamellar vesicles containing SNARE proteins using electroformation. Sci Rep 8:9422
Kiessling, Volker; Kreutzberger, Alex J B; Liang, Binyong et al. (2018) A molecular mechanism for calcium-mediated synaptotagmin-triggered exocytosis. Nat Struct Mol Biol 25:911-917
Nyenhuis, Sarah B; Cafiso, David S (2018) Choice of reconstitution protocol modulates the aggregation state of full-length membrane-reconstituted synaptotagmin-1. Protein Sci 27:1008-1012
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
Tamm, Lukas K (2017) Special Issue on Liposomes, Exosomes, and Virosomes. Biophys J 113:E1
Jakhanwal, Shrutee; Lee, Chung-Tien; Urlaub, Henning et al. (2017) An activated Q-SNARE/SM protein complex as a possible intermediate in SNARE assembly. EMBO J 36:1788-1802

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