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Syntaxin clusters at secretory granules in a munc18-bound conformation

Syntaxin (stx)-1 is an integral plasma membrane protein that is crucial for two distinct steps of regulated exocytosis, docking of secretory granules at the plasma membrane and membrane fusion. During docking, stx1 clusters at the granule docking site, together with the S/M protein munc18. Here we d...

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Autores principales: Yin, Peng, Gandasi, Nikhil R., Arora, Swati, Omar-Hmeadi, Muhmmad, Saras, Jan, Barg, Sebastian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249827/
https://www.ncbi.nlm.nih.gov/pubmed/30156474
http://dx.doi.org/10.1091/mbc.E17-09-0541
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author Yin, Peng
Gandasi, Nikhil R.
Arora, Swati
Omar-Hmeadi, Muhmmad
Saras, Jan
Barg, Sebastian
author_facet Yin, Peng
Gandasi, Nikhil R.
Arora, Swati
Omar-Hmeadi, Muhmmad
Saras, Jan
Barg, Sebastian
author_sort Yin, Peng
collection PubMed
description Syntaxin (stx)-1 is an integral plasma membrane protein that is crucial for two distinct steps of regulated exocytosis, docking of secretory granules at the plasma membrane and membrane fusion. During docking, stx1 clusters at the granule docking site, together with the S/M protein munc18. Here we determined features of stx1 that contribute to its clustering at granules. In live insulin-secreting cells, stx1 and stx3 (but not stx4 or stx11) accumulated at docked granules, and stx1 (but not stx4) rescued docking in cells expressing botulinum neurotoxin-C. Using a series of stx1 deletion mutants and stx1/4 chimeras, we found that all four helical domains (Ha, Hb, Hc, SNARE) and the short N-terminal peptide contribute to recruitment to granules. However, only the Hc domain confers specificity, and it must be derived from stx1 for recruitment to occur. Point mutations in the Hc or the N-terminal peptide designed to interfere with binding to munc18-1 prevent stx1 from clustering at granules, and a mutant munc18 deficient in binding to stx1 does not cluster at granules. We conclude that stx1 is recruited to the docking site in a munc18-1–bound conformation, providing a rationale for the requirement for both proteins for granule docking.
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spelling pubmed-62498272019-01-16 Syntaxin clusters at secretory granules in a munc18-bound conformation Yin, Peng Gandasi, Nikhil R. Arora, Swati Omar-Hmeadi, Muhmmad Saras, Jan Barg, Sebastian Mol Biol Cell Articles Syntaxin (stx)-1 is an integral plasma membrane protein that is crucial for two distinct steps of regulated exocytosis, docking of secretory granules at the plasma membrane and membrane fusion. During docking, stx1 clusters at the granule docking site, together with the S/M protein munc18. Here we determined features of stx1 that contribute to its clustering at granules. In live insulin-secreting cells, stx1 and stx3 (but not stx4 or stx11) accumulated at docked granules, and stx1 (but not stx4) rescued docking in cells expressing botulinum neurotoxin-C. Using a series of stx1 deletion mutants and stx1/4 chimeras, we found that all four helical domains (Ha, Hb, Hc, SNARE) and the short N-terminal peptide contribute to recruitment to granules. However, only the Hc domain confers specificity, and it must be derived from stx1 for recruitment to occur. Point mutations in the Hc or the N-terminal peptide designed to interfere with binding to munc18-1 prevent stx1 from clustering at granules, and a mutant munc18 deficient in binding to stx1 does not cluster at granules. We conclude that stx1 is recruited to the docking site in a munc18-1–bound conformation, providing a rationale for the requirement for both proteins for granule docking. The American Society for Cell Biology 2018-11-01 /pmc/articles/PMC6249827/ /pubmed/30156474 http://dx.doi.org/10.1091/mbc.E17-09-0541 Text en © 2018 Yin et al. “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology. http://creativecommons.org/licenses/by-nc-sa/3.0 This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License.
spellingShingle Articles
Yin, Peng
Gandasi, Nikhil R.
Arora, Swati
Omar-Hmeadi, Muhmmad
Saras, Jan
Barg, Sebastian
Syntaxin clusters at secretory granules in a munc18-bound conformation
title Syntaxin clusters at secretory granules in a munc18-bound conformation
title_full Syntaxin clusters at secretory granules in a munc18-bound conformation
title_fullStr Syntaxin clusters at secretory granules in a munc18-bound conformation
title_full_unstemmed Syntaxin clusters at secretory granules in a munc18-bound conformation
title_short Syntaxin clusters at secretory granules in a munc18-bound conformation
title_sort syntaxin clusters at secretory granules in a munc18-bound conformation
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249827/
https://www.ncbi.nlm.nih.gov/pubmed/30156474
http://dx.doi.org/10.1091/mbc.E17-09-0541
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