Munc18-1 induces conformational changes of syntaxin-1 in multiple intermediates for SNARE assembly

Title
Munc18-1 induces conformational changes of syntaxin-1 in multiple intermediates for SNARE assembly
Authors
정철현이상화신종혁정영훈손혜진신재열권대혁신연균
Keywords
SNARE; Munc18-1; syntaxin-1; single molecule FRET
Issue Date
2020-07
Publisher
Scientific Reports
Citation
VOL 10, 11623
Abstract
In neuronal exocytosis, SNARE assembly into a stable four-helix bundle drives membrane fusion. Previous studies have revealed that the SM protein Munc18-1 plays a critical role for precise SNARE assembly with the help of Munc13-1, but the underlying mechanism remains unclear. Here, we used single-molecule FRET assays with a nanodisc membrane reconstitution system to investigate the conformational dynamics of SNARE/Munc18-1 complexes in multiple intermediate steps towards the SNARE complex. We found that single Munc18-1 proteins induce the closed conformation of syntaxin-1 not only in the free syntaxin-1 but also in the t-SNARE (syntaxin-1/SNAP-25) complex. These results implicate that Munc18-1 may act as a gatekeeper for both binary and ternary SNARE complex formation by locking the syntaxin-1 in a cleft of Munc18-1. Furthermore, the kinetic analysis of the opening/closing transition reveals that the closed syntaxin-1 in the syntaxin-1/SNAP-25/Munc18-1 complex is less stable than that in the closed syntaxin-1/Munc18-1 complex, which is manifested by the infrequent closing transition, indicating that the conformational equilibrium of the ternary complex is biased toward the open conformation of syntaxin-1 compared with the binary complex.
URI
http://pubs.kist.re.kr/handle/201004/71939
ISSN
2045-2322
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KIST Publication > Article
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