[Abstract Title]. - Society for Neuroscience

molecular determinants of this variability remain an open question that can now be addressed
using the methods we have developed.
Disclosures: P. Ariel , None; T.A. Ryan, None.
Poster
236. Neurotransmitter Release: Docking and Fusion
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 236.9/D9
Topic: B.06.a. Docking and fusion
Support: Deutsche Forschungsgemeinschaft (DFG) (SFB 530 and GRK1326) to D.B.
HOMFOR to D.B.
Title: Synaptobrevin II comprises a mechanism that stabilizes vesicles in the primed state
Authors: *M. BORISOVSKA 1 , D. BRUNS 2 ;
1 Oregon Hlth. Sci. Univ., Portland, OR; 2 Inst. for Physiol., Univ. of Saarland, Homburg,
Germany
Abstract: SNARE proteins play an essential role in multiple steps of regulated exocytosis. It is
believed that by binding one another, SNAREs mediate priming of vesicles and initiation of
membrane fusion. However little is known how structures outside the SNARE motif modulate
exocytosis. Here we investigate the impact of the membrane proximal region of Synaptobrevin II
on chromaffin granule exocytosis. For our experiments, we took advantage of double v-SNARE
deficient mice devoid of both synaptobrevin II and cellubrevin. The possibility to acutely express
the protein of interest on a genetic v-SNARE null background provides nearly ideal conditions
for a structure-function analysis. Whole-cell membrane capacitance measurements in
combination with flash-photolysis and calcium imaging allowed us to monitor exocytosis at a
millisecond time scale.
Amino acid insertions (1, 3 and 12 amino acids) between the SNARE motif and the tryptophanrich
region result in strong linker-length dependent reduction of vesicle priming as well as in
delayed stimulus-secretion coupling. These results are consistent with our previous observations
(Kesavan et al., 2007), but show stronger effects with respect to the linker length-dependent
attenuation suggesting a multifunctional role of juxtamembrane region of synaptobrevin II in
vesicle exocytosis. Moreover, we find that the increase in distance and flexibility between the
SNARE motif and the transmembrane anchor does not depend on the character of the inserted
amino acids. In addition, increase in distance or flexibility between the tryptophan residues and