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BP: Fachverband Biologische Physik
BP 16: Membranes and Vesicles II
BP 16.1: Talk
Wednesday, March 20, 2024, 09:30–09:45, H 0112
Structural changes in lipid monolayers induced by synapsin and vesicles investigated by X-ray reflectivity and GID — Hendrik Bruns1, •Titus Czajka1, Charlotte Neuhaus1, Christian Hoffmann2, Dragomir Milovanovic2, and Tim Salditt1 — 1Institut für Röntgenphysik, Georg-August-Universität Göttingen, Germany — 2Laboratory of Molecular Neuroscience, DZNE, Berlin, Germany
Neurotransmitter release happens upon fusion of synaptic vesicles (SVs) carrying the neurotransmitter with the presynaptic membrane. SVs act as the trafficking organelles and are clustered in pools to facilitate the rapid release of neurotransmitters into the synaptic cleft. While the process of SV fusion mediated by SNARE complexes is well understood, the influence of the vesicle pool and its mediating protein, synapsin, on the membrane-vesicle interaction is less clear. To this end, we have carried out X-ray reflectivity (XRR) and grazing incidence diffraction (GID) experiments on lipid monolayers at controlled surface pressures in a Langmuir trough at ID10 (ESRF). Interaction between monolayer and SVs is measured in the monolayer plane by GID measurements, allowing the measurement of lipid molecule tilt angles. Density profiles modelled to fit the XRR data additionally reveal changes in the structure along the third dimension. We hypothesise that synapsin protein has a stiffening influence on the monolayer and also strengthens the interaction between monolayer and SVs, thus highlighting the importance of the protein not only to the clustering of SVs but potentially to the docking process as well.
Keywords: synaptic vesicle; synapsin; X-ray reflectivity; lipid monolayer; Langmuir Trough