Regensburg 2019 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
BP: Fachverband Biologische Physik
BP 2: Membranes and vesicles I (joint session BP/CPP)
BP 2.7: Vortrag
Montag, 1. April 2019, 11:45–12:00, H10
Lipid membrane fusion in proteoliposomes and multilamellar stacks studied by X-ray scattering — •Kilian Frank1, Karlo Komorowski1, Veronica Chappa2, Max Scheu1, Marcus Müller2, and Tim Salditt1 — 1Georg-August-Universität, Institute for X-ray Physics, Friedrich-Hund-Platz 1, 37077 Göttingen — 2Georg-August-Universität, Institute for Theoretical Physics, Friedrich-Hund-Platz 1, 37077 Göttingen
Intermediate structures of membrane fusion, e.g. during release of neurotransmitter at the synapse, are difficult to resolve at the molecular level, especially in the close-to-physiological regime with SNARE fusion proteins. To provide structural information, we combine two X-ray scattering approaches: First, SAXS on proteoliposomes (PL) with reconstituted SNAREs serves to identify changes in PL size and radial density profile upon fusion in a hydrated environment. We present a simulation framework based on 3D-FFT to estimate how well size and shape changes (homogeneous swelling of an ensemble, thermal fluctuations, and strong equilibrium defomations) are detected in PL-SAXS. Second, GISAXS on solid-supported multilamellar membrane stacks at controlled humidity and salt concentration allows to characterize the energy of fusion stalk formation, prior to crystallization to a stalk phase with rhombohedral symmetry. Here we find that CaCl2, in contrast to other salts, facilitates stalk phase formation, also cooperatively in fusiogenic lipid mixtures. By combining both methods, we lay the foundation for a quantitative X-ray analysis of the membrane fusion process with natural proteins or artificial peptides.