Membrane bridging by Munc13-1 is crucial for neurotransmitter release

• Published in: eLife 2019-02, Vol.8
• Main Authors: Quade, Bradley, Camacho, Marcial, Zhao, Xiaowei, Orlando, Marta, Trimbuch, Thorsten, Xu, Junjie, Li, Wei, Nicastro, Daniela, Rosenmund, Christian, Rizo, Josep
• Format: Article
• Language: English
• Subjects: Animals; Bridges (Structures); Calcium; Cell Membrane - metabolism; Cells, Cultured; Cytoplasmic Vesicles - metabolism; Exocytosis; Intracellular Membranes - metabolism; Liposomes; membrane bridging; Membranes; Mice; Munc13; Mutation; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Neurological research; Neurons; Neurons - metabolism; Neuroscience; Neurotransmitter Agents - metabolism; Neurotransmitter release; Neurotransmitters; Plasma; Plasma membranes; Rats; reconstitution; Structural Biology and Molecular Biophysics; synaptic vesicle docking; synaptic vesicle fusion
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.42806

Munc13-1 plays a crucial role in neurotransmitter release. We recently proposed that the C-terminal region encompassing the C , C B, MUN and C C domains of Munc13-1 (C C BMUNC C) bridges the synaptic vesicle and plasma membranes through interactions involving the C C domain and the C -C B region. However, the physiological relevance of this model has not been demonstrated. Here we show that C C BMUNC C bridges membranes through opposite ends of its elongated structure. Mutations in putative membrane-binding sites of the C C domain disrupt the ability of C C BMUNC C to bridge liposomes and to mediate liposome fusion in vitro. These mutations lead to corresponding disruptive effects on synaptic vesicle docking, priming, and Ca -triggered neurotransmitter release in mouse neurons. Remarkably, these effects include an almost complete abrogation of release by a single residue substitution in this 200 kDa protein. These results show that bridging the synaptic vesicle and plasma membranes is a central function of Munc13-1.