Modified lipid and protein dynamics in nanodiscs

Abstract

For membrane protein studies, nanodiscs have been shown to hold great potential in terms of preparing soluble samples while maintaining a lipid environment. Here, we describe the differences in lipid order and protein dynamics in MSP1 nanodiscs compared to lamellar preparations by solid-state NMR. For DMPC, an increase of the dipolar C-H lipid acyl chain order parameters in nanodiscs is observed in both gel- and liquid crystalline phases. Incorporating proteorhodopsin in these nanodiscs resulted in a significantly longer rotating frame spin-lattice relaxation time for (13)C leerzeichen and better cross polarisation efficiency due to restricted protein dynamics. A comparison of (13)C-(13)C correlation spectra revealed no structural differences. The incorporation of proteorhodopsin into nanodiscs has been optimised with respect to detergent and to protein/scaffold protein/lipid stoichiometries. Its functional state was probed by time-resolved optical spectroscopy revealing only minor differences between lamellar and nanodisc preparations. Our observations show remarkable dynamic effects between membrane proteins, lipids and scaffold protein. The potential use of nanodiscs for solid-state NMR applications is discussed.

Physicochemical Factors Controlling the Activity and Energy Coupling of an Ionic Strength-gated ATP-binding Cassette (ABC) Transporter

“…It has been argued that the lateral tension exerted by the membrane lipids onto a membrane protein is different in nanodiscs and lamellar vesicular membrane systems. In fact, there is evidence that the lipid acyl chains are stretched (and as a corollary, the bilayer thickness is increased) in the nanodiscs as compared with vesicular membranes (39). We propose that conformational transitions associated with OpuA-mediated transport are facilitated in the nanodiscs as compared with the proteoliposomes, which may relate to a different lipid order and consequently a different lateral pressure (profile).…”

An Annular Lipid Belt Is Essential for Allosteric Coupling and Viral Inhibition of the Antigen Translocation Complex TAP (Transporter Associated with Antigen Processing)

“…In addition, in nanodiscs the number of lipids and protein subunits is well defined. The limited number of lipids in nanodiscs mimics molecular crowding as recently observed by solidstate NMR, which shows a reduced dynamic of proteorhodopsin in nanodiscs compared with lamellar preparations (31). Therefore, nanodiscs display a more native-like environment compared with liposomes.…”

“…Nanodiscs provide several key advantages (29) as follows: (i) small size compared with liposomes (30,31); (ii) stoichiometry and composition of membrane proteins and lipids can be controlled precisely (28); (iii) substrate, ligand, and protein interactions can be studied in a close-to-native lipid environment with access to both sides of the membrane protein complex (32)(33)(34)(35)(36). Here, we demonstrate that TAP reconstituted in nanodiscs displays an allosteric coupling between peptide binding and ATP hydrolysis.…”

Artificial membranes for membrane protein purification, functionality and structure studies

“…MSP plays a similar scaffolding role to Apolipoprotein A-I around the phospholipid bilayer containing the membrane protein of interest [36]. Nanodiscs are made by mixing bicelles containing the protein of interest with MSP followed by slow detergent removal through techniques such as dialysis or BioBeads [38]. Several sizes of MSPs have been engineered to adapt to different membrane protein structures and shapes [39][40][41][42].…”