Speaker
Description
All biological plasma membranes are intrinsically asymmetric in their lipid composition across the two leaflets, a feature believed to be essential for maintaining membrane integrity and enabling efficient cellular signaling.$^1$
In this work, joint small-angle X-ray and neutron scattering (SAXS/SANS) experiments are used to resolve leaflet-specific structural properties of 100 nm large unilamellar vesicles and proteoliposomes. Specifically, we are focusing on the outer membrane phospholipase A (OmpLA) from Gram-negative bacteria as a prototypical $\beta$-barrel integral protein and its effect on asymmetric lipid bilayers. Both symmetric and asymmetric membranes are prepared with and without reconstituted OmpLA across a range of lipid compositions and protein concentrations using established protocols.$^2$
To resolve the individual membrane leaflets we apply contrast variation in SANS experiments using chain deuterated lipids and different D$_2$O/H$_2$O ratios. We provide first insights from a newly developed analysis platform SAS-MoCa which applies Bayesian inference to combine the SAXS/SANS data with complementary molecular dynamics simulations and $^2$H-NMR experiments.
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Schütz, G. J., Pabst, G. (2023). The asymmetric plasma membrane—A composite material combining different functionalities? BioEssays, 45, e2300116.
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Doktorova, M., Heberle, F.A., Eicher, B. et al. (2018) Preparation of asymmetric phospholipid vesicles for use as cell membrane models. Nat Protoc 13, 2086–2101.