A coiled coil trigger site is essential for rapid binding of synaptobrevin to the SNARE acceptor complex

TY - JOUR

T1 - A coiled coil trigger site is essential for rapid binding of synaptobrevin to the SNARE acceptor complex

AU - Wiederhold, Katrin

AU - Kloepper, Tobias H

AU - Walter, Alexander M

AU - Stein, Alexander

AU - Kienle, Nickias

AU - Sørensen, Jakob B

AU - Fasshauer, Dirk

N1 - Keywords: Amino Acid Motifs; Animals; Binding Sites; Calcium; Calorimetry; Chromaffin Cells; Dimerization; Electrophysiology; Liposomes; Mice; Neurotransmitter Agents; Point Mutation; Protein Structure, Tertiary; R-SNARE Proteins; Rats; SNARE Proteins

PY - 2010/7/9

Y1 - 2010/7/9

N2 - Exocytosis from synaptic vesicles is driven by stepwise formation of a tight α-helical complex between the fusing membranes. The complex is composed of the three SNAREs: synaptobrevin 2, SNAP-25, and syntaxin 1a. An important step in complex formation is fast binding of vesicular synaptobrevin to the preformed syntaxin 1·SNAP-25 dimer. Exactly how this step relates to neurotransmitter release is not well understood. Here, we combined different approaches to gain insights into this reaction. Using computational methods, we identified a stretch in synaptobrevin 2 that may function as a coiled coil "trigger site." This site is also present in many synaptobrevin homologs functioning in other trafficking steps. Point mutations in this stretch inhibited binding to the syntaxin 1·SNAP-25 dimer and slowed fusion of liposomes. Moreover, the point mutations severely inhibited secretion from chromaffin cells. Altogether, this demonstrates that the trigger site in synaptobrevin is crucial for productive SNARE zippering.

AB - Exocytosis from synaptic vesicles is driven by stepwise formation of a tight α-helical complex between the fusing membranes. The complex is composed of the three SNAREs: synaptobrevin 2, SNAP-25, and syntaxin 1a. An important step in complex formation is fast binding of vesicular synaptobrevin to the preformed syntaxin 1·SNAP-25 dimer. Exactly how this step relates to neurotransmitter release is not well understood. Here, we combined different approaches to gain insights into this reaction. Using computational methods, we identified a stretch in synaptobrevin 2 that may function as a coiled coil "trigger site." This site is also present in many synaptobrevin homologs functioning in other trafficking steps. Point mutations in this stretch inhibited binding to the syntaxin 1·SNAP-25 dimer and slowed fusion of liposomes. Moreover, the point mutations severely inhibited secretion from chromaffin cells. Altogether, this demonstrates that the trigger site in synaptobrevin is crucial for productive SNARE zippering.

U2 - 10.1074/jbc.M110.105148

DO - 10.1074/jbc.M110.105148

M3 - Journal article

C2 - 20406821

SN - 0021-9258

VL - 285

SP - 21549

EP - 21559

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 28

ER -