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BP: Fachverband Biologische Physik
BP 21: Membranes and Vesicles II
BP 21.7: Talk
Tuesday, April 1, 2014, 15:30–15:45, ZEU 250
Asymmetric phospholipid: lipopolysaccharide bilayers; a Gram-negative bacterial outer membrane mimic — •Maximilian Skoda1, Luke Clifton1, Emma Daulton1, Arwel Hughes1, Anton Le Brun2, Jeremy Lakey3, and Stephen Holt2 — 1ISIS, STFC, Harwell, UK — 2Bragg Institute, ANSTO, Kirrawee DC,Australia — 3Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
The Gram-negative bacterial outer membrane (OM) is a complex and highly asymmetric biological barrier but the small size of bacteria has hindered advances in in-vivo examination of membrane dynamics. Thus, model OMs, amenable to physical study, are important sources of data. Here, we present data from asymmetric bilayers which emulate the OM and are formed by a simple two-step approach. LB deposition of phosphatidylcholine on an SiO2 surface formed the inner leaflet and Langmuir-Schaefer deposition of either Lipid A or Escherichia coli rough lipopolysaccharides (LPS) the outer one. The membranes were examined using neutron reflectometry (NR). NR data showed that in all cases the initial deposition asymmetry was mostly maintained for more than 16 h. This stability enabled the sizes of the headgroups and bilayer roughness of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and Lipid A, Rc- and Ra-LPS to be clearly resolved. This shows that rough LPS can be manipulated like phospholipids and used to fabricate advanced asymmetric bacterial membrane models using well-known bilayer deposition techniques. Such models will enable OM dynamics and interactions to be studied under in-vivo like conditions.