Dresden 2017 – scientific programme
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BP: Fachverband Biologische Physik
BP 48: Membranes and Vesicles II
BP 48.7: Talk
Thursday, March 23, 2017, 11:45–12:00, HÜL 386
Lipid vesicle and SNARE-mediated membrane fusion studied by small-angle X-ray scattering — •Karlo Komorowski1,2, Annalena Salditt1, Yihui Xu1, Halenur Yavuz2, Reinhard Jahn2, and Tim Salditt1 — 1University of Göttingen, Institute for X-Ray Physics, Göttingen, Germany — 2Max-Planck-Institute for Biophysical Chemistry, Department of Neurobiology, Göttingen
Membrane fusion takes place in numerous physiological processes on the cellular and subcellular level as in the case of synaptic transmission. In order to release neurotransmitters into the synaptic cleft, fusion of synaptic vesicles with the presynaptic plasma membrane is mediated by the SNAREs synaptobrevin 2, syntaxin 1a and SNAP-25, initiating the merger by a zippering process of a four-helix bundle. Using mutants of synaptobrevin, a stable docking state between SNARE-liposomes can be arrested due to partial zippering of the SNARE complex. That way it is possible to overcome the short timescales in which the intermediates naturally occur. The biochemically well controlled systems are then suitable for steady state small-angle X-ray scattering (SAXS) experiments. Here we aim at the structure of the intermediates of the SNARE-mediated liposome fusion pathway, which can be partly arrested. In addition, we have performed protein-free vesicle fusion studies, aiming at an understanding of the role of inter-membrane potentials in docking and in fusion. Finally, we propose to enhance SAXS studies of vesicles by microfluidic sample environments, which allow the monitoring of different steps along the fusion pathway. In order to obtain structural parameters from the SAXS data, we make use of form and structure factor models of lipid bilayers.