UNC-18 and tomosyn antagonistically control synaptic vesicle priming downstream of UNC-13 in Caenorhabditis elegans

Seungmee Park, Na Ryum Bin, Bin Yu, Raymond Wong, Ewa Sitarska, Kyoko Sugita, Ke Ma, Junjie Xu, Chi Wei Tien, Arash Algouneh, Ekaterina Turlova, Siyan Wang, Pranay Siriya, Waleed Shahid, Lorraine Kalia, Zhong Ping Feng, Philippe P. Monnier, Hong Shuo Sun, Mei Zhen, Shangbang GaoJose Rizo-Rey, Shuzo Sugita

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Munc18-1/UNC-18 is believed to prime SNARE-mediated membrane fusion, yet the underlying mechanisms remain enigmatic. Here, we examine how potential gain-of-function mutations of Munc18-1/UNC-18 affect locomotory behavior and synaptic transmission, and how Munc18-1-mediated priming is related to Munc13-1/UNC-13 and Tomosyn/TOM-1, positive and negative SNARE regulators, respectively. We show that a Munc18-1(P335A)/UNC-18(P334A) mutation leads to significantly increased locomotory activity and acetylcholine release in Caenorhabditis elegans, as well as enhanced synaptic neurotransmission in cultured mammalian neurons. Importantly, similar to tom-1 null mutants, unc-18(P334A) mutants partially bypass the requirement of UNC-13. Moreover, unc-18(P334A) and tom-1 null mutations confer a strong synergy in suppressing the phenotypes of unc-13 mutants. Through biochemical experiments, we demonstrate that Munc18-1(P335A) exhibits enhanced activity in SNARE complex formation as well as in binding to the preformed SNARE complex, and partially bypasses the Munc13-1 requirement in liposome fusion assays. Our results indicate that Munc18-1/UNC-18 primes vesicle fusion downstream of Munc13-1/ UNC-13 by templating SNARE complex assembly and acts antagonistically with Tomosyn/TOM-1.

Original languageEnglish (US)
Pages (from-to)8797-8815
Number of pages19
JournalJournal of Neuroscience
Issue number36
StatePublished - Sep 6 2017


  • C.elegans
  • Exocytosis
  • Membrane fusion
  • Munc18
  • Synapse

ASJC Scopus subject areas

  • Neuroscience(all)


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