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Updated: Apr 11, 2026

In Vivo Single-Molecule Tracking at the Drosophila Presynaptic Motor Nerve Terminal
Published on: January 14, 2018
Syntaxin opening by the MUN domain underlies the function of Munc13 in synaptic-vesicle priming
Xiaoyu Yang1, Shen Wang1, Yi Sheng1
1Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.
Abstract:
UNC-13-Munc13s have a central function in synaptic-vesicle priming through their MUN domains. However, it is unclear whether this function arises from the ability of the MUN domain to mediate the transition from the Munc18-1-closed syntaxin-1 complex to the SNARE complex in vitro. The crystal structure of the rat Munc13-1 MUN domain now reveals an elongated, arch-shaped architecture formed by α-helical bundles, with a highly conserved hydrophobic pocket in the middle. Mutation of two residues (NF) in this pocket abolishes the stimulation caused by the Munc13-1 MUN domain on SNARE-complex assembly and on SNARE-dependent proteoliposome fusion in vitro. Moreover, the same mutation in UNC-13 abrogates synaptic-vesicle priming in Caenorhabditis elegans neuromuscular junctions. These results support the notion that orchestration of syntaxin-1 opening and SNARE-complex assembly underlies the central role of UNC-13-Munc13s in synaptic-vesicle priming.
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