Comparative EPR studies on lipid bilayer properties in nanodiscs and liposomes

Stępień, Piotr; Polit, Agnieszka; Wiśniewska-Becker, Anna

doi:10.1016/j.bbamem.2014.10.004

Cited by 48 publications

(55 citation statements)

References 41 publications

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“…Thus, different state of lipids is observed in LPNs in comparison to various bicelles. This is in agreement with the observation that in LPNs lipids are packed tightly and are less mobile than in fluid liposomes 19,20,64 . On the other hand it was shown that LPNs experience phase transitions at temperatures, close to the critical temperatures found for lipid bilayers 63 .…”

Section: Use Of Other Lipids For Bicelle Formationsupporting

confidence: 91%

Characterization of Small Isotropic Bicelles with Various Compositions

et al. 2016

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Structural studies of membrane proteins are of great importance and interest, with solution and solid state NMR spectroscopy being very promising tools for that task. However, such investigations are hindered by a number of obstacles, and in the first place by the fact that membrane proteins need an adequate environment that models the cell membrane. One of the most widely used and prospective membrane mimetics is isotropic bicelles. While large anisotropic bicelles are well-studied, the field of small bicelles contains a lot of "white spots". The present work reports the radii of particles and concentration of the detergents in the monomeric state in solutions of isotropic bicelles, formed by 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO), and sodium cholate, as a function of lipid/detergent ratio and temperature. These parameters were measured using (1)H NMR diffusion spectroscopy for the bicelles composed of lipids with saturated fatty chains of different length and lipids, containing unsaturated fatty acid residue. The influence of a model transmembrane protein (membrane domain of rat TrkA) on the properties of bicelles and the effect of the bicelle size and composition on the properties of the transmembrane protein were investigated with heteronuclear NMR and nuclear Overhauser effect spectroscopy. We show that isotropic bicelles that are applicable for solution NMR spectroscopy behave as predicted by the theoretical models and are likely to be bicelles rather than mixed micelles. Using the obtained data, we propose a simple approach to control the size of bicelles at low concentrations. On the basis of our results, we compared different rim-forming agents and selected CHAPS as a detergent of choice for structural studies in bicelles, if the deuteration of the detergent is not required.

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Section: Use Of Other Lipids For Bicelle Formationsupporting

confidence: 91%

Characterization of Small Isotropic Bicelles with Various Compositions

et al. 2016

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“…Various biophysical methods have been used to study lipid-cholesterol interactions, including electron spin resonance (ESR) (Cheng et al, 2014; Delmelle et al, 1980; Hubbell and McConnell, 1971; Lai and Freed, 2014; Manukovsky et al, 2013; Semer and Gelerinter, 1979; Stepien et al, 2015; Vitiello et al, 2015; Williams et al, 2013), Raman (Lippert and Peticolas, 1971; Mendelsohn, 1972; Tantipolphan et al, 2006), Fourier transform infrared (FT-IR) (Umemura et al, 1980), fluorescence spectroscopy (Xu and London, 2000; Yasuda et al, 2015a), atomic force microscopy (AFM), multidimensional NMR spectroscopy (Holland and Alam, 2006; Leftin et al, 2013; Leftin et al, 2014a; Warschawski and Devaux, 2005), solid-state 2 H nuclear magnetic resonance (NMR) (Bartels et al, 2008; Brown, 1990; Bunge et al, 2008; Martinez et al, 2004; Martinez et al, 2002; Matsumori et al, 2012; Stockton et al, 1976; Vogel et al, 2016; Weisz et al, 1992; Yasuda et al, 2015a), and neutron diffraction methods (Armstrong et al, 2014; Toppozini et al, 2014). However, a thorough understanding of the physical basis for these observations in relation to the intricate lipid compositions of many biological membranes to some extent remains an enigma (Feigenson, 2015; McConnell, 2005; Meinhardt et al, 2013; Sodt et al, 2014; Stanich et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Cholesterol-induced suppression of membrane elastic fluctuations at the atomistic level

Molugu

Brown

2016

Chemistry and Physics of Lipids

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Applications of solid-state NMR spectroscopy for investigating the influences of lipid-cholesterol interactions on membrane fluctuations are reviewed in this paper. Emphasis is placed on understanding the energy landscapes and fluctuations at an emergent atomistic level. Solid-state 2H NMR spectroscopy directly measures residual quadrupolar couplings (RQCs) due to individual C–2H labeled segments of the lipid molecules. Moreover, residual dipolar couplings (RDCs) of 13C–1H bonds are obtained in separated local-field NMR spectroscopy. The distributions of RQC or RDC values give nearly complete profiles of the order parameters as a function of acyl segment position. Measured equilibrium properties of glycerophospholipids and sphingolipids including their binary and tertiary mixtures with cholesterol show unequal mixing associated with liquid-ordered domains. The entropic loss upon addition of cholesterol to sphingolipids is less than for glycerophospholipids and may drive the formation of lipid rafts. In addition relaxation time measurements enable one to study the molecular dynamics over a wide time-scale range. For 2H NMR the experimental spin-lattice (R1Z) relaxation rates follow a theoretical square-law dependence on segmental order parameters (SCD) due to collective slow dynamics over mesoscopic length scales. The functional dependence for the liquid-crystalline lipid membranes is indicative of viscoelastic properties as they emerge from atomistic-level interactions. A striking decrease in square-law slope upon addition of cholesterol denotes stiffening relative to the pure lipid bilayers that is diminished in the case of lanosterol. Measured equilibrium properties and relaxation rates infer opposite influences of cholesterol and detergents on collective dynamics and elasticity at an atomistic scale that potentially affects lipid raft formation in cellular membranes.

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“…EPR spin probes can be attached to different positions of lipid molecules to report the mobility of the probe and the polarity of its nano-environment. Systematic EPR studies with spin-labeled lipids revealed characteristic fluidity and polarity profiles across liposomal membranes of defined lipid compositions (McConnell and Hubbell, 1971;Marsh, 2001;Subczynski et al, 2010;Stepien et al, 2015). Thus, a biological membrane exhibits not just a single, bulk fluidity and its properties are not sufficiently described by a single number.…”

Section: What Is Membrane Fluidity and How To Measure It?mentioning

confidence: 99%

Control of membrane fluidity: the OLE pathway in focus

Ballweg

Ernst

2016

Biological Chemistry

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Abstract:The maintenance of a fluid lipid bilayer is key for membrane integrity and cell viability. We are only beginning to understand how eukaryotic cells sense and maintain the characteristic lipid compositions and bulk membrane properties of their organelles. One of the key factors determining membrane fluidity and phase behavior is the proportion of saturated and unsaturated acyl chains in membrane lipids. Saccharomyces cerevisiae is an ideal model organism to study the regulation of the lipid acyl chain composition via the OLE pathway. The OLE pathway comprises all steps involved in the regulated mobilization of the transcription factors Mga2 and Spt23 from the endoplasmic reticulum (ER), which then drive the expression of OLE1 in the nucleus. OLE1 encodes for the essential Δ9-fatty acid desaturase Ole1 and is crucial for de novo biosynthesis of unsaturated fatty acids (UFAs) that are used as lipid building blocks. This review summarizes our current knowledge of the OLE pathway, the best-characterized, eukaryotic senseand-control system regulating membrane lipid saturation, and identifies open questions to indicate future directions.

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Comparative EPR studies on lipid bilayer properties in nanodiscs and liposomes

Cited by 48 publications

References 41 publications

Characterization of Small Isotropic Bicelles with Various Compositions

Characterization of Small Isotropic Bicelles with Various Compositions

Cholesterol-induced suppression of membrane elastic fluctuations at the atomistic level

Control of membrane fluidity: the OLE pathway in focus

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