Autoinhibition of munc18-1 modulates synaptobrevin binding and helps to enable munc13-dependent regulation of membrane fusion

Ewa Sitarska, Junjie Xu, Seungmee Park, Xiaoxia Liu, Bradley Quade, Karolina Stepien, Kyoko Sugita, Chad A Brautigam, Shuzo Sugita, Jose Rizo-Rey

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Munc18-1 orchestrates SNARE complex assembly together with Munc13-1 to mediate neurotransmitter release. Munc18-1 binds to synaptobrevin, but the relevance of this interaction and its relation to Munc13 function are unclear. NMR experiments now show that Munc18-1 binds specifically and non-specifically to synaptobrevin. Specific binding is inhibited by a L348R mutation in Munc18-1 and enhanced by a D326K mutation designed to disrupt the ‘furled conformation’ of a Munc18-1 loop. Correspondingly, the activity of Munc18-1 in reconstitution assays that require Munc18-1 and Munc13-1 for membrane fusion is stimulated by the D326K mutation and inhibited by the L348R mutation. Moreover, the D326K mutation allows Munc13-1-independent fusion and leads to a gain-of-function in rescue experiments in Caenorhabditis elegans unc-18 nulls. Together with previous studies, our data support a model whereby Munc18-1 acts as a template for SNARE complex assembly, and autoinhibition of synaptobrevin binding contributes to enabling regulation of neurotransmitter release by Munc13-1.

Original languageEnglish (US)
Article numbere24278
JournaleLife
Volume6
DOIs
StatePublished - May 6 2017

Fingerprint

Vesicle-Associated Membrane Protein 1
R-SNARE Proteins
Membrane Fusion
Fusion reactions
Membranes
Mutation
Neurotransmitter Agents
SNARE Proteins
Conformations
Assays
Experiments
Nuclear magnetic resonance
Caenorhabditis elegans

ASJC Scopus subject areas

  • Neuroscience(all)
  • Medicine(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)

Cite this

Autoinhibition of munc18-1 modulates synaptobrevin binding and helps to enable munc13-dependent regulation of membrane fusion. / Sitarska, Ewa; Xu, Junjie; Park, Seungmee; Liu, Xiaoxia; Quade, Bradley; Stepien, Karolina; Sugita, Kyoko; Brautigam, Chad A; Sugita, Shuzo; Rizo-Rey, Jose.

In: eLife, Vol. 6, e24278, 06.05.2017.

Research output: Contribution to journalArticle

Sitarska, Ewa ; Xu, Junjie ; Park, Seungmee ; Liu, Xiaoxia ; Quade, Bradley ; Stepien, Karolina ; Sugita, Kyoko ; Brautigam, Chad A ; Sugita, Shuzo ; Rizo-Rey, Jose. / Autoinhibition of munc18-1 modulates synaptobrevin binding and helps to enable munc13-dependent regulation of membrane fusion. In: eLife. 2017 ; Vol. 6.
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