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Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion

In the neuron, neurotransmitter release is an essential function that must be both consistent and tightly regulated. The continuity of neurotransmitter release is dependent in large part on vesicle recycling. However, the protein factors that dictate the vesicle recycling pathway are elusive. Here,...

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Autores principales: Pierson, Josh, Shin, Yeon-Kyun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8712692/
https://www.ncbi.nlm.nih.gov/pubmed/34970598
http://dx.doi.org/10.3389/fmolb.2021.805000
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author Pierson, Josh
Shin, Yeon-Kyun
author_facet Pierson, Josh
Shin, Yeon-Kyun
author_sort Pierson, Josh
collection PubMed
description In the neuron, neurotransmitter release is an essential function that must be both consistent and tightly regulated. The continuity of neurotransmitter release is dependent in large part on vesicle recycling. However, the protein factors that dictate the vesicle recycling pathway are elusive. Here, we use a single vesicle-to-supported bilayer fusion assay to investigate complexin-1 (cpx1)’s influence on SNARE-dependent fusion pore expansion. With total internal reflection (TIR) microscopy using a 10 kDa polymer fluorescence probe, we are able to detect the presence of large fusion pores. With cpx1, however, we observe a significant increase of the probability of the formation of large fusion pores. The domain deletion analysis reveals that the SNARE-binding core domain of cpx1 is mainly responsible for its ability to promote the fusion pore expansion. In addition, the results show that cpx1 helps the pore to expand larger, which results in faster release of the polymer probe. Thus, the results demonstrate a reciprocal relationship between event duration and the size of the fusion pore. Based on the data, a hypothetical mechanistic model can be deduced. In this mechanistic model, the cpx1 binding stabilizes the four-helix bundle structure of the SNARE core throughout the fusion pore expansion, whereby the highly curved bilayer within the fusion pore is stabilized by the SNARE pins.
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spelling pubmed-87126922021-12-29 Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion Pierson, Josh Shin, Yeon-Kyun Front Mol Biosci Molecular Biosciences In the neuron, neurotransmitter release is an essential function that must be both consistent and tightly regulated. The continuity of neurotransmitter release is dependent in large part on vesicle recycling. However, the protein factors that dictate the vesicle recycling pathway are elusive. Here, we use a single vesicle-to-supported bilayer fusion assay to investigate complexin-1 (cpx1)’s influence on SNARE-dependent fusion pore expansion. With total internal reflection (TIR) microscopy using a 10 kDa polymer fluorescence probe, we are able to detect the presence of large fusion pores. With cpx1, however, we observe a significant increase of the probability of the formation of large fusion pores. The domain deletion analysis reveals that the SNARE-binding core domain of cpx1 is mainly responsible for its ability to promote the fusion pore expansion. In addition, the results show that cpx1 helps the pore to expand larger, which results in faster release of the polymer probe. Thus, the results demonstrate a reciprocal relationship between event duration and the size of the fusion pore. Based on the data, a hypothetical mechanistic model can be deduced. In this mechanistic model, the cpx1 binding stabilizes the four-helix bundle structure of the SNARE core throughout the fusion pore expansion, whereby the highly curved bilayer within the fusion pore is stabilized by the SNARE pins. Frontiers Media S.A. 2021-12-14 /pmc/articles/PMC8712692/ /pubmed/34970598 http://dx.doi.org/10.3389/fmolb.2021.805000 Text en Copyright © 2021 Pierson and Shin. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Molecular Biosciences
Pierson, Josh
Shin, Yeon-Kyun
Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title_full Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title_fullStr Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title_full_unstemmed Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title_short Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion
title_sort stabilization of the snare core by complexin-1 facilitates fusion pore expansion
topic Molecular Biosciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8712692/
https://www.ncbi.nlm.nih.gov/pubmed/34970598
http://dx.doi.org/10.3389/fmolb.2021.805000
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