Format

Send to

Choose Destination
Mol Biol Cell. 2008 Mar;19(3):776-84. Epub 2007 Dec 19.

A novel site of action for alpha-SNAP in the SNARE conformational cycle controlling membrane fusion.

Author information

1
Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.

Abstract

Regulated exocytosis in neurons and neuroendocrine cells requires the formation of a stable soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex consisting of synaptobrevin-2/vesicle-associated membrane protein 2, synaptosome-associated protein of 25 kDa (SNAP-25), and syntaxin 1. This complex is subsequently disassembled by the concerted action of alpha-SNAP and the ATPases associated with different cellular activities-ATPase N-ethylmaleimide-sensitive factor (NSF). We report that NSF inhibition causes accumulation of alpha-SNAP in clusters on plasma membranes. Clustering is mediated by the binding of alpha-SNAP to uncomplexed syntaxin, because cleavage of syntaxin with botulinum neurotoxin C1 or competition by using antibodies against syntaxin SNARE motif abolishes clustering. Binding of alpha-SNAP potently inhibits Ca(2+)-dependent exocytosis of secretory granules and SNARE-mediated liposome fusion. Membrane clustering and inhibition of both exocytosis and liposome fusion are counteracted by NSF but not when an alpha-SNAP mutant defective in NSF activation is used. We conclude that alpha-SNAP inhibits exocytosis by binding to the syntaxin SNARE motif and in turn prevents SNARE assembly, revealing an unexpected site of action for alpha-SNAP in the SNARE cycle that drives exocytotic membrane fusion.

PMID:
18094056
PMCID:
PMC2262999
DOI:
10.1091/mbc.e07-05-0498
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center