Curved Lipid Interfaces Studied with Grazing Incident SANS

Abstract

Curved cell membranes are important for the function of the cell, both for compartmentalization in organelles within the cell, as well as for cellular mitosis. It has also been shown that the curvature of a lipid membrane can affect the concentration of membrane bound proteins. In this project we have used semiconductor nanowires in order to study the effect of curvature on phospholipid bilayers and membrane proteins. We have previously demonstrated the formation of a supported phospholipid bilayer on nano wires via vesicle fusion, which can be used as a proxy to curved membranes. Based on fluorescence recovery after photobleaching, FRAP, measurement, the phospholipid bilayers were found to follow the contours of the nano wires as continuous and fluid, locally curved bilayers. However these data do not reveal the coverage, composition and the dimensions of the bilayer. In this project we aim to revel this using grazing incident small angle neutron scattering (GISANS). For this purpose we have performed GISANS experiments at the KSW-1 at FRM II (Germany), VSANS at NIST (USA) and SANS2D at ISIS (UK) with phospholipid covered nanowires. The nanowires were covered with a phospholipid bilayer obtained from deposition from vesicular dispersion of mixture of 20mol% DOPE in DOPC. In these experiments we have successfully shown the formation of a lipid bilayer and the subsequent binding of membrane protein. These results shows that nanowire supported lipid bilayer is an excellent way to study biding membrane protein to curved lipid interfaces.