title: Functional synergy between the Munc13 C-terminal C1 and C2 domains.
abstract: Neurotransmitter release requires SNARE complexes to bring membranes together, NSF-SNAPs to recycle the SNAREs, Munc18-1 and Munc13s to orchestrate SNARE complex assembly, and Synaptotagmin-1 to trigger fast Ca(2+)-dependent membrane fusion. However, it is unclear whether Munc13s function upstream and/or downstream of SNARE complex assembly, and how the actions of their multiple domains are integrated. Reconstitution, liposome-clustering and electrophysiological experiments now reveal a functional synergy between the C1, C2B and C2C domains of Munc13-1, indicating that these domains help bridging the vesicle and plasma membranes to facilitate stimulation of SNARE complex assembly by the Munc13-1 MUN domain. Our reconstitution data also suggest that Munc18-1, Munc13-1, NSF, αSNAP and the SNAREs are critical to form a 'primed' state that does not fuse but is ready for fast fusion upon Ca(2+) influx. Overall, our results support a model whereby the multiple domains of Munc13s cooperate to coordinate synaptic vesicle docking, priming and fusion.
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Alpay Burak
authors.initials: AB
authors.lastname: Seven
authors.affiliation: Department of Neurophysiology, NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Marcial
authors.initials: M
authors.lastname: Camacho
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Victoria
authors.initials: V
authors.lastname: Esser
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Junjie
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Neurophysiology, NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Trimbuch
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Bradley
authors.initials: B
authors.lastname: Quade
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Lijing
authors.initials: L
authors.lastname: Su
authors.affiliation: Key Laboratory of Molecular Biophysics of the Ministry of Education, Huazhong University of Science and Technology, Wuhan, China.|College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Cong
authors.identifier: 0000-0002-7814-0500
authors.initials: C
authors.lastname: Ma
authors.affiliation: Department of Neurophysiology, NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rosenmund
authors.affiliation: Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.|Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.
authors.forename: Josep
authors.identifier: 0000-0003-1773-8311
authors.initials: J
authors.lastname: Rizo
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D000072417:Protein Domains; D055503:Protein Multimerization; D051381:Rats; D050600:SNARE Proteins / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; D050600:SNARE Proteins; C103912:Unc13a protein, rat
keywords: C2 domain; Munc13; Munc18; biophysics; membrane fusion; mouse; neuroscience; neurotransmitter release; reconstitution; structural biology