Abstract
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 language | English (US) |
---|---|
Pages (from-to) | 8797-8815 |
Number of pages | 19 |
Journal | Journal of Neuroscience |
Volume | 37 |
Issue number | 36 |
DOIs | |
State | Published - Sep 6 2017 |
Keywords
- C.elegans
- Exocytosis
- Membrane fusion
- Munc18
- SNARE
- Synapse
ASJC Scopus subject areas
- General Neuroscience