Syntaxin-1A modulates vesicle fusion in mammalian neurons via juxtamembrane domain dependent palmitoylation of its transmembrane domain
- Charité - Universitätsmedizin Berlin, Germany
Abstract
SNAREs are undoubtedly one of the core elements of synaptic transmission. Contrary to the well characterized function of their SNARE domains bringing the plasma and vesicular membranes together, the level of contribution of their juxtamembrane domain (JMD) and the transmembrane domain (TMD) to the vesicle fusion is still under debate. To elucidate this issue, we analyzed three groups of STX1A mutations in cultured mouse hippocampal neurons: 1) elongation of STX1A's JMD by three amino acid insertions in the junction of SNARE-JMD or JMD-TMD; 2) charge reversal mutations in STX1A's JMD; and 3) palmitoylation deficiency mutations in STX1A's TMD. We found that both JMD elongations and charge reversal mutations have position dependent differential effects on Ca2+-evoked and spontaneous neurotransmitter release. Importantly, we show that STX1A's JMD regulates the palmitoylation of STX1A's TMD and loss of STX1A palmitoylation either through charge reversal mutation K260E or by loss of TMD cysteines inhibits spontaneous vesicle fusion. Interestingly, the retinal ribbon specific STX3B has a glutamate in the position corresponding to the K260E mutation in STX1A and mutating it with E259K acts as a molecular on-switch. Furthermore, palmitoylation of post-synaptic STX3A can be induced by the exchange of its JMD with STX1A's JMD together with the incorporation of two cysteines into its TMD. Forced palmitoylation of STX3A dramatically enhances spontaneous vesicle fusion suggesting that STX1A regulates spontaneous release through two distinct mechanisms: one through the C-terminal half of its SNARE domain and the other through the palmitoylation of its TMD.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting file; Source Data files that contain numerical data used to generate the figures have been provided for all figures. Source Data that contain the whole Western Blot images are provided Figures 3, 4, 6, and 8.
Article and author information
Author details
Christian Rosenmund
Funding
Deutsche Forschungsgemeinschaft (388271549)
- Christian Rosenmund
Deutsche Forschungsgemeinschaft (399894546)
- Christian Rosenmund
Deutsche Forschungsgemeinschaft (436260754)
- Christian Rosenmund
Deutsche Forschungsgemeinschaft (27800197)
- Christian Rosenmund
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All procedures for animal maintenance and experiments were in accordance with the regulations of and approved by the animal welfare committee of Charité-Universitätsmedizin and the Berlin state government Agency for Health and Social Services under license number T0220/09.
Copyright
© 2022, Vardar et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Syntaxin-1A modulates vesicle fusion in mammalian neurons via juxtamembrane domain dependent palmitoylation of its transmembrane domain
eLife 11:e78182.
https://doi.org/10.7554/eLife.78182
