The Effect of Nanodisc MSP Belt Proteins on the Incorporated Lipid Bilayer

Abstract

Nanodiscs are small discoidal lipid bilayers, whose size is governed by two membrane scaffold proteins (MSP). Developed by the Sligar Lab in the late 2000's, nanodiscs are a very useful model system due to the ability to control the size and composition of the lipid bilayer. Nanodiscs can be used to study protein-lipid interactions, membrane associated proteins and membrane-bound proteins. We have studied the effects of the MSPs on the lipid bilayer in both heterogeneous and homogeneous lipid environments over a range of temperatures. Using time-resolved emission spectra (TRES) of 7-nitro-2-1,3-benzoxadiazol-4-yl (NDB) head group labeled lipids, we have studied the relaxation of the lipid head groups. Using fluorescence anisotropy decay of the environmentally sensitive fluorescence probe Di-4-ANEPPDHQ, we have shown that lipid acyl chains are more constrained than those of liposomes or cells. The lateral pressure imparted by the belt protein could alter protein-lipid interactions and reduce movement of membrane bound proteins incorporated into nanodiscs.