Modifying styrene-maleic acid co-polymer for studying lipid nanodiscs

Abstract

Recently, styrene-maleic acid copolymer lipid nanodiscs have become an increasingly popular tool for the study of membrane proteins. In the work we report here, we have developed a novel method for the efficient preparation of labeled nanodiscs, under chemically mild conditions, by modification of the hydrolyzed styrene-maleic acid copolymer. This protocol is designed to be easily accessible to biochemistry laboratories. We use this procedure to prepare various fluorescent nanodiscs labeled with different fluorophores. By studying the development of Förster resonance energy transfer, we demonstrate the rapid exchange of co-polymer between nanodiscs. This demonstration, in conjunction of previous work, indicates that the lipid nanodiscs prepared using this polymer are very dynamic structures with rapid exchange of the different components.

Macrodiscs Comprising SMALPs for Oriented Sample Solid-State NMR Spectroscopy of Membrane Proteins

“…Following the initial incorporation of PagP and bacteriorhodopsin into SMA nanodiscs (11), a variety of membrane proteins have been studied using similar preparations (12,15,16). Further development has led to similar polymers with greater pH stability and decreased susceptibility to divalent metal cations, among other favorable properties (17)(18)(19)(20)(21)(22).…”

Adsorption of a styrene maleic acid (SMA) copolymer-stabilized phospholipid nanodisc on a solid-supported planar lipid bilayer

“…Exchange of polymers in addition to lipids is not unexpected. Recent studies have shown by fluorescently labelling SMA polymers, that in addition to the now-accepted lipid exchange between nanodiscs in solution [39] , [40] , there is also exchange of polymers between nanodiscs [51] . Furthermore, Langmuir balance and molecular dynamics studies of nanodisc self-assembly have demonstrated that nanodiscs form via an initial adsorption of polymers to the bilayer surface, prior to embedding into the hydrophobic core and subsequent solubilization [27] , [52] .…”

Single molecule binding of a ligand to a G-protein-coupled receptor in real time using fluorescence correlation spectroscopy, rendered possible by nano-encapsulation in styrene maleic acid lipid particles

“…For example, styrene-co-maleimide (SMI) is positively-charged and retains functionality at acidic pH, in contrast to the negative charge and alkaline working range of SMA; 28 styrene maleimide quarternary ammonium (SMA-QA) forms relatively large nanodiscs (∼30 nm diameter) that remain stable between pH 2.5-pH 10; 29 diisobutylene-co-maleic acid (DIBMA) in which the styrene aromatic ring of SMA is replaced by the aliphatic diisobutylene thereby changing how the polymer interacts with the lipid in the nanoparticles 30 and thiolated SMA (SMA-SH) which can be derivatised or immobilised via the introduced thiol. 43 All of these 'second generation' polymers generate lipid nanoparticles in the complete absence of detergent so preserve the native lipid in close association with the membrane protein. This is particularly important for GPCRs, as it has been shown that they can be regulated by the juxtaposition of specific membrane lipids.…”