title: The t-SNARE syntaxin is sufficient for spontaneous fusion of synaptic vesicles to planar membranes.
abstract: Vesicular trafficking and exocytosis are directed by the complementary interaction of membrane proteins that together form the SNARE complex. This complex is composed of proteins in the vesicle membrane (v-SNAREs) that intertwine with proteins of the target membrane (t-SNAREs). Here we show that modified synaptic vesicles (mSV), containing v-SNAREs, spontaneously fuse to planar membranes containing the t-SNARE, syntaxin 1A. Fusion was Ca(2+)-independent and did not occur with vesicles lacking v-SNAREs. Therefore, syntaxin alone forms a functional fusion complex with v-SNAREs. Our functional fusion assay uses synaptic vesicles that are modified, so each fusion event results in an observable transient current. The mSV do not fuse with protein-free membranes. Additionally, artificial vesicles lacking v-SNAREs do not fuse with membranes containing syntaxin. This technique can be adapted to measure fusion in other SNARE systems and should enable the identification of proteins critical to vesicle-membrane fusion. This will further our understanding of exocytosis and may improve targeting and delivery of therapeutic agents packaged in vesicles.
authors.affiliation: Department of Physiology, Wayne State University, School of Medicine, Detroit, MI 48201, USA. woodbury@med.wayne.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Woodbury
authors.forename: K
authors.initials: K
authors.lastname: Rognlien
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D050600:SNARE Proteins; D013572:Synaptic Vesicles / Q000502:physiology*; D050827:Syntaxin 1; D014101:Torpedo; D033921:Vesicular Transport Proteins
chemical_list: D000954:Antigens, Surface; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050600:SNARE Proteins; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins