Interfacial structure and protein incorporation in sparsely tethered phospholipid membranes : Data

Abstract for the Article:

We describe herein a cell membrane mimicking system designed for bioanalytical applications. Our tethered bilayer lipid membrane (tBLM) is based on mixed self-assembled monolayers (SAMs) on gold terminated by linear hydrophobic tethers. Based on the previous studies, the latter are either randomly distributed over the SAM surface or phase-segregated into nanoclusters of at least 40 molecules. We have prepared and analyzed a series of tBLMs covering a range of conditions in terms of membrane phase (gel vs. fluid phases), type of substrate attachment (floating vs. tethered) and electrostatics (zwitterionic PC and negatively charged PG lipids). We studied the interfacial tBLM structure by employing neutron reflectometry (NR). In all cases, the NR analysis revealed formation of high coverage tBLMs where the lipid bilayer was separated from the SAM by a highly hydrated interlayer of 5-6 Å. Notably, the 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) tBLM on a substrate presenting nanoscale tether clusters had a larger solution interlayer thickness around 12 Å. We relate this structural feature of the tBLM to the structural mismatch between the tether clusters and the kink in the oleoyl leg of the SOPC lipid. Further on, as a proof of concept we have successfully reconstituted the deuterated outer membrane protein F (OmpF) from E. coli into our tBLM system and confirmed the protein insertion by NR. Thus, the presented cell membrane mimicking platform is promising for quantitative studies of lipid and protein structures and interactions taking place at the cell membrane.

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The Neutron Reflectometry data and data analysis scripts for the rascal software are found. As is the qaurtz crystal microbalance data.