title: Nanodiscs and SILAC-based mass spectrometry to identify a membrane protein interactome.
abstract: Integral membrane proteins are challenging to work with biochemically given their insoluble nature; the nanodisc circumvents the difficulty by stabilizing them in small patches of lipid bilayer. Here, we show that nanodiscs combined with SILAC-based quantitative proteomics can be used to identify the soluble interacting partners of virtually any membrane protein. As a proof of principle, we applied the method to the bacterial SecYEG protein-conducting channel, the maltose transporter MalFGK(2) and the membrane integrase YidC. In contrast to the detergent micelles, which tend to destabilize interactions, the nanodisc was able to capture out of a complex whole cell extract the proteins SecA, Syd, and MalE with a high degree of confidence and specificity. The method was sensitive enough to isolate these interactors as a function of the lipid composition in the disc and the culture conditions. In agreement with a previous photo-cross linking analysis, YidC did not show any high-affinity interactions with cytosolic or periplasmic proteins. These three examples illustrate the utility of nanoscale lipid bilayers to identify the soluble peripheral partners of  proteins intergrated in the lipid bilayer.
authors: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors: Xiao X
authors: XX
authors: Zhang
authors: Catherine S
authors: CS
authors: Chan
authors: Huan
authors: H
authors: Bao
authors: Yuan
authors: Y
authors: Fang
authors: Leonard J
authors: LJ
authors: Foster
authors: Franck
authors: F
authors: Duong
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D049329:Nanostructures / Q000737:chemistry*; D020543:Proteome / Q000737:chemistry / Q000378:metabolism; D040901:Proteomics / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D008055:Lipids; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D020543:Proteome