title: Single-molecule force spectroscopy from nanodiscs: an assay to quantify folding, stability, and interactions of native membrane proteins.
abstract: Single-molecule force spectroscopy (SMFS) can quantify and localize inter- and intramolecular interactions that determine the folding, stability, and functional state of membrane proteins. To conduct SMFS the membranes embedding the membrane proteins must be imaged and localized in a rather time-consuming manner. Toward simplifying the investigation of membrane proteins by SMFS, we reconstituted the light-driven proton pump bacteriorhodopsin into lipid nanodiscs. The advantage of using nanodiscs is that membrane proteins can be handled like water-soluble proteins and characterized with similar ease. SMFS characterization of bacteriorhodopsin in native purple membranes and in nanodiscs reveals no significant alterations of structure, function, unfolding intermediates, and strengths of inter- and intramolecular interactions. This demonstrates that lipid nanodiscs provide a unique approach for in vitro studies of native membrane proteins using SMFS and open an avenue to characterize membrane proteins by a wide variety of SMFS approaches that have been established on water-soluble proteins.
authors.affiliation: Biosystems Science and Engineering (BSSE), ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Zocher
authors.forename: Christian
authors.initials: C
authors.lastname: Roos
authors.forename: Susanne
authors.initials: S
authors.lastname: Wegmann
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Bosshart
authors.forename: Volker
authors.initials: V
authors.lastname: Dötsch
authors.forename: Frank
authors.initials: F
authors.lastname: Bernhard
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Müller
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry*; D001665:Binding Sites; D008051:Lipid Bilayers / Q000737:chemistry*; D008422:Materials Testing; D008565:Membrane Proteins / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods*; D015336:Molecular Probe Techniques; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011485:Protein Binding
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins; D001436:Bacteriorhodopsins