title: Juxtamembrane tryptophans of synaptobrevin 2 control the process of membrane fusion.
abstract: Synaptobrevin 2 (Syb2), syntaxin (Sx1A), and SNAP-25, generate a force to induce fusion pore formation. The v-SNARE, Syb2, is anchored to the vesicle membrane by a single transmembrane domain. Here we show that 2 tryptophans (W89/W90) located in the juxtamembrane domain of Syb2, which stabilize the transmembrane (TM) domain position, control the ratio of spontaneous vs. stimulated membrane fusion events in chromaffin cells. Changing the 2 hydrophobic tryptophans to neutral alanines promotes spontaneous membrane fusion, faster transmitter release kinetics and complete release from individual vesicles. The results indicate that the two tryptophans act as a fusion clamp making fusion stimulus-dependent.
authors.affiliation: School of Applied & Engineering Physics, Cornell University, Ithaca, NY 14853, USA. fangqinghua@gmail.com
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Fang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Manfred
authors.initials: M
authors.lastname: Lindau
mesh_terms: D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005089:Exocytosis; D057927:Hydrophobic and Hydrophilic Interactions; D008561:Membrane Fusion; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D018408:Patch-Clamp Techniques; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*; D050988:Vesicle-Associated Membrane Protein 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051040:Vesicle-Associated Membrane Protein 3 / Q000235:genetics / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D011994:Recombinant Proteins; D050988:Vesicle-Associated Membrane Protein 2; D051040:Vesicle-Associated Membrane Protein 3; C494808:vesicle-associated membrane protein 2, mouse; C494953:vesicle-associated membrane protein 3, mouse; D014364:Tryptophan; D000409:Alanine