Abstract
Tomosyns are widely thought to attenuate membrane fusion by competing with synaptobrevin-2/VAMP2 for SNARE-complex assembly. Here, we present evidence against this scenario. In a novel mouse model, tomosyn-1/2 deficiency lowered the fusion barrier and enhanced the probability that synaptic vesicles fuse, resulting in stronger synapses with faster depression and slower recovery. While wild-type tomosyn-1m rescued these phenotypes, substitution of its SNARE motif with that of synaptobrevin-2/VAMP2 did not. Single-molecule force measurements indeed revealed that tomosyn’s SNARE motif cannot substitute synaptobrevin-2/VAMP2 to form template complexes with Munc18-1 and syntaxin-1, an essential intermediate for SNARE assembly. Instead, tomosyns extensively bind synaptobrevin-2/VAMP2-containing template complexes and prevent SNAP-25 association. Structure-function analyses indicate that the C-terminal polybasic region contributes to tomosyn’s inhibitory function. These results reveal that tomosyns regulate synaptic transmission by cooperating with synaptobrevin-2/VAMP2 to prevent SNAP-25 binding during SNARE assembly, thereby limiting initial synaptic strength and equalizing it during repetitive stimulation.
| Original language | English |
|---|---|
| Article number | 2652 |
| Pages (from-to) | 1-20 |
| Number of pages | 20 |
| Journal | Nature Communications |
| Volume | 15 |
| Early online date | 26 Mar 2024 |
| DOIs | |
| Publication status | Published - 2024 |
Bibliographical note
Publisher Copyright:© The Author(s) 2024.
Funding
We would like to thank Joke Wortel for animal breeding, Ingrid Saarloos for cloning, Robbert Zalm for producing viral particles, Lisa Laan and Desiree Schut for preparing glia cultures, and Joost Hoetjes for genotyping. We acknowledge Rien Dekker for high-pressure freeze electron microscopy. Furthermore, we would like to thank Vincent Huson for providing us with code and for assistance with fitting of hypertonic sucrose traces. We thank Niels Cornelisse, Ruud Toonen and Jacob Sørensen for their helpful discussion and comments on this work. This work is supported by the ZonMw-Veni program (09150161810052 to M.M.) from the Dutch Research Council (NWO), the ERC Advanced Grant (322966 to M.V.) of the European Union, the NWO Gravitation program grant BRAINSCAPES (NWO 024.004.012 to M.V.), the Horizon 2020 grant COSYN (RIA grant agreement no 610307, to M.V.), the Lundbeck Foundation Grant (R277-2018-802 to M.V.), the DFG (German Research Foundation) postdoctoral fellowship (DFG project number SU 1131/1-1 to A.S.) and the NIH grant R35 GM131714 to Y.Z.
| Funders | Funder number |
|---|---|
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
| Horizon 2020 | |
| South Carolina Rural Infrastructure Authority | 610307 |
| South Carolina Rural Infrastructure Authority | |
| European Research Council | 322966 |
| European Research Council | |
| Deutsche Forschungsgemeinschaft | SU 1131/1-1 |
| Deutsche Forschungsgemeinschaft | |
| Lundbeck Foundation | R277-2018-802 |
| Lundbeck Foundation | |
| European Commission | 024.004.012 |
| European Commission | |
| Vincent Huson | 09150161810052 |
| National Institutes of Health | R35 GM131714 |
| National Institutes of Health |