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Goncharuk MV, Vasileva EV, Ananiev EA, Gorokhovatsky AY, Bocharov EV, Mineev KS, Goncharuk SA. Facade-Based Bicelles as a New Tool for Production of Active Membrane Proteins in a Cell-Free System. Int J Mol Sci 2023; 24:14864. [PMID: 37834312 PMCID: PMC10573531 DOI: 10.3390/ijms241914864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 09/18/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023] Open
Abstract
Integral membrane proteins are important components of a cell. Their structural and functional studies require production of milligram amounts of proteins, which nowadays is not a routine process. Cell-free protein synthesis is a prospective approach to resolve this task. However, there are few known membrane mimetics that can be used to synthesize active membrane proteins in high amounts. Here, we present the application of commercially available "Facade" detergents for the production of active rhodopsin. We show that the yield of active protein in lipid bicelles containing Facade-EM, Facade-TEM, and Facade-EPC is several times higher than in the case of conventional bicelles with CHAPS and DHPC and is comparable to the yield in the presence of lipid-protein nanodiscs. Moreover, the effects of the lipid-to-detergent ratio, concentration of detergent in the feeding mixture, and lipid composition of the bicelles on the total, soluble, and active protein yields are discussed. We show that Facade-based bicelles represent a prospective membrane mimetic, available for the production of membrane proteins in a cell-free system.
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Affiliation(s)
- Marina V. Goncharuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
| | - Ekaterina V. Vasileva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
| | - Egor A. Ananiev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
| | - Andrey Y. Gorokhovatsky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
| | - Eduard V. Bocharov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Konstantin S. Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
| | - Sergey A. Goncharuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow 117997, Russia; (M.V.G.); (A.Y.G.); (E.V.B.)
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
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2
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Stable Discoidal Bicelles: Formulation, Characterization, and Functions. Methods Mol Biol 2023; 2622:147-157. [PMID: 36781758 DOI: 10.1007/978-1-0716-2954-3_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Bicellar mixtures have been used as alignable membrane substrates under a magnetic field applicable for the structural characterization of membrane-associated proteins. Recently, it has shown that bicelles can serve as nanocarriers to effectively deliver hydrophobic therapeutic molecules to cancer cells with a three- to ten-fold enhancement compared to that of liposomes of a chemically identical composition. In this chapter, detailed preparation protocol, common structural characterization methods, the structural stability, the cellular uptake and a few unique functions of bicellar nanodiscs are discussed.
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3
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Patrick J, Alija MG, Liebau J, Pettersson P, Metola A, Mäler L. Dilute Bicelles for Glycosyltransferase Studies, Novel Bicelles with Phosphatidylinositol. J Phys Chem B 2022; 126:5655-5666. [PMID: 35880265 PMCID: PMC9358657 DOI: 10.1021/acs.jpcb.2c02327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Solution-state NMR can be used to study protein-lipid interactions, in particular, the effect that proteins have on lipids. One drawback is that only small assemblies can be studied, and therefore, fast-tumbling bicelles are commonly used. Bicelles contain a lipid bilayer that is solubilized by detergents. A complication is that they are only stable at high concentrations, exceeding the CMC of the detergent. This issue has previously been addressed by introducing a detergent (Cyclosfos-6) with a substantially lower CMC. Here, we developed a set of bicelles using this detergent for studies of membrane-associated mycobacterial proteins, for example, PimA, a key enzyme for bacterial growth. To mimic the lipid composition of mycobacterial membranes, PI, PG, and PC lipids were used. Diffusion NMR was used to characterize the bicelles, and spin relaxation was used to measure the dynamic properties of the lipids. The results suggest that bicelles are formed, although they are smaller than "conventional" bicelles. Moreover, we studied the effect of MTSL-labeled PimA on bicelles containing PI and PC. The paramagnetic label was shown to have a shallow location in the bicelle, affecting the glycerol backbone of the lipids. We foresee that these bicelles will be useful for detailed studies of protein-lipid interactions.
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Affiliation(s)
- Joan Patrick
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Mikel García Alija
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Jobst Liebau
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pontus Pettersson
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ane Metola
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
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4
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Ribić R, Manček-Keber M, Chain F, Sinnaeve D, Martins JC, Jerala R, Tomić S, Fehér K. Targeted Delivery of Adamantylated Peptidoglycan Immunomodulators in Lipid Nanocarriers: NMR Shows That Cargo Fragments Are Available on the Surface. J Phys Chem B 2020; 124:4132-4145. [PMID: 32283934 DOI: 10.1021/acs.jpcb.0c00029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We present an in-depth investigation of the membrane interactions of peptidoglycan (PGN)-based immune adjuvants designed for lipid-based delivery systems using NMR spectroscopy. The derivatives contain a cargo peptidoglycan (PGN) dipeptide fragment and an adamantyl group, which serves as an anchor to the lipid bilayer. Furthermore, derivatives with a mannose group that can actively target cell surface receptors on immune cells are also studied. We showed that the targeting mannose group and the cargo PGN fragment are both available on the lipid bilayer surface, thereby enabling interactions with cognate receptors. We found that the nonmannosylated compounds are incorporated stronger into the lipid assemblies than the mannosylated ones, but the latter compounds penetrate deeper in the bilayer. This might be explained by stronger electrostatic interactions available for zwitterionic nonmannosylated derivatives as opposed to the compounds in which the charged N-terminus is capped by mannose groups. The higher incorporation efficiency of the nonmannosylated compounds correlated with a larger relative enhancement in immune stimulation activities upon lipid incorporation compared to that of the derivatives with the mannose group. The chirality of the adamantyl group also influenced the incorporation efficiency, which in turn correlated with membrane-associated conformations that affect possible intermolecular interactions with lipid molecules. These findings will help in improving the development of PGN-based immune adjuvants suitable for delivery in lipid nanoparticles.
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Affiliation(s)
- Rosana Ribić
- University Center Varaždin, University North, Jurja Križanića 31b, HR-42 000 Varaždin, Croatia.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Mateja Manček-Keber
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Fernando Chain
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Davy Sinnaeve
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium.,Univ. Lille, Inserm, Institut Pasteur de Lille, CHU Lille, U1167 - Labex DISTALZ - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, F-59000 Lille, France.,CNRS, ERL9002 - Integrative Structural Biology, F-59000 Lille, France
| | - José C Martins
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Roman Jerala
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia
| | - Srđanka Tomić
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102A, HR-10 000 Zagreb, Croatia
| | - Krisztina Fehér
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Molecular Recognition and Interaction Research Group, Hungarian Academy of Sciences, Egyetem tér 1, H-4032 Debrecen, Hungary
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5
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de Souza RM, Ratochinski RH, Karttunen M, Dias LG. Self-Assembly of Phosphocholine Derivatives Using the ELBA Coarse-Grained Model: Micelles, Bicelles, and Reverse Micelles. J Chem Inf Model 2020; 60:522-536. [PMID: 31714768 DOI: 10.1021/acs.jcim.9b00790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ELBA coarse-grained force field was originally developed for lipids, and its water model is described as a single-site Lennard-Jones particle with electrostatics modeled by an embedded point-dipole, while other molecules in this force field have a three (or four)-to-one mapping scheme. Here, ELBA was applied to investigate the self-assembly processes of dodecyl-phosphocholine (DPC) micelle, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dihexaoyl-sn-glycero-3-phosphocholine (DPPC/DHPC) bicelles, and DPPC/cyclohexane/water reverse micelles through coarse-grained molecular dynamics (MD) simulations. New parameters were obtained using a simplex algorithm-based calibration procedure to determine the Lennard-Jones parameters for cyclohexane, dodecane, and cyclohexane-dodecane cross-interactions. Density, self-diffusion coefficient, surface tension, and mixture excess volume were found to be in fair agreement with experimental data. These new parameters were used in the simulations, and the obtained structures were analyzed for shape, size, volume, and surface area. Except for the shape of DPC micelles, all other properties match well with available experimental data and all-atom simulations. Remarkably, in agreement with experiments the rodlike shape of the DPPC reverse micelle is well described by ELBA, while all-atom data in the literature predicts a disclike shape. To further check the consistency of the force field in reproducing the correct shapes of reverse micelles, additional simulations were performed doubling the system size. Two distinct reverse micelles were obtained both presenting the rodlike shape and correct aggregation number.
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Affiliation(s)
- R M de Souza
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7
| | - R H Ratochinski
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
| | - Mikko Karttunen
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7.,Department of Applied Mathematics , The University of Western Ontario , London , Ontario , Canada N6A 5B7
| | - L G Dias
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
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6
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Taguchi S, Suga K, Hayashi K, Yoshimoto M, Okamoto Y, Nakamura H, Umakoshi H. Aggregation of chlorophyll a induced in self-assembled membranes composed of DMPC and DHPC. Colloids Surf B Biointerfaces 2019; 175:403-408. [DOI: 10.1016/j.colsurfb.2018.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/26/2018] [Accepted: 12/05/2018] [Indexed: 02/07/2023]
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7
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Systematic Characterization of DMPC/DHPC Self-Assemblies and Their Phase Behaviors in Aqueous Solution. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2040073] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Self-assemblies composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) form several kinds of structures, such as vesicle, micelle, and bicelle. Their morphological properties have been studied widely, but their interfacial membrane properties have not been adequately investigated. Herein, we report a systematic characterization of DMPC/DHPC assemblies at 20 °C. To investigate the phase behavior, optical density OD500, size (by dynamic light scattering), membrane fluidity 1/PDPH (using 1,6-diphenyl-1,3,5-hexatriene), and membrane polarity GP340 (using 6-dodecanoyl-N,N-dimethyl-2-naphthylamine) were measured as a function of molar ratio of DHPC (XDHPC). Based on structural properties (OD500 and size), large and small assemblies were categorized into Region (i) (XDHPC < 0.4) and Region (ii) (XDHPC ≥ 0.4), respectively. The DMPC/DHPC assemblies with 0.33 ≤ XDHPC ≤ 0.67 (Region (ii-1)) showed gel-phase-like interfacial membrane properties, whereas DHPC-rich assemblies (XDHPC ≥ 0.77) showed disordered membrane properties (Region (ii-2)). Considering the structural and interfacial membrane properties, the DMPC/DHPC assemblies in Regions (i), (ii-1), and (ii-2) can be determined to be vesicle, bicelle, and micelle, respectively.
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8
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Mortensen HG, Jensen GV, Hansen SK, Vosegaard T, Pedersen JS. Structure of Phospholipid Mixed Micelles (Bicelles) Studied by Small-Angle X-ray Scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:14597-14607. [PMID: 30383384 DOI: 10.1021/acs.langmuir.8b02704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Mixed phospholipid micelles (bicelles) are widely applied in nuclear magnetic resonance (NMR) studies of membrane proteins in solution, as they can solubilize these proteins and provide a membrane-like environment. In this work, the structure of bicelles of dihexanoyl phosphatidyl choline (DHPC) and dimyristoyl phosphatidyl choline (DMPC) at different ratios was determined by small-angle X-ray scattering (SAXS) at 37 °C. Samples with concentrations as applied for NMR measurements with 28 wt % lipids were diluted to avoid concentration effects in the SAXS data. The DMPC/DHPC ratio within the bicelles was kept constant by diluting with solutions of finite DHPC concentrations, where the concentration of free DHPC is the same as in the original solution. Absolute-scale modeling of the SAXS data using molecular and concentration constraints reveals a relatively complex set of morphologies of the lipid aggregates as a function of the molar ratio Q of DMPC to DHPC. At Q = 0 (pure DHPC lipids), oblate core-shell micelles are present. At Q = 0.5, the bicelles have a tablet-shaped core-shell cylindrical form with an ellipsoidal cross section. For Q = 1, 2, 3.2, and 4, the bicelles have a rectangular cuboidal structure with a core and a shell, for which the overall length and width increase with Q. At Q = ∞ (pure DMPC), there is coexistence between multilamellar structures and free bilayers. For Q = 1-4, the hydrocarbon core is relatively narrow and the headgroup thickness on the flat areas is larger than that of, respectively, pure DHPC and DMPC, suggesting some mixing of DHPC into these areas and staggering of the molecules. This is further supported by comparisons of the ratio of the areas of rim and flat parts and estimates of the composition of the flat areas.
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Affiliation(s)
- Henriette G Mortensen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , Gustav Wieds Vej 14 , 8000 Aarhus C , Denmark
| | - Grethe V Jensen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , Gustav Wieds Vej 14 , 8000 Aarhus C , Denmark
| | - Sara K Hansen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , Gustav Wieds Vej 14 , 8000 Aarhus C , Denmark
| | - Thomas Vosegaard
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , Gustav Wieds Vej 14 , 8000 Aarhus C , Denmark
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , Gustav Wieds Vej 14 , 8000 Aarhus C , Denmark
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9
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Bragin PE, Kuznetsov AS, Bocharova OV, Volynsky PE, Arseniev AS, Efremov RG, Mineev KS. Probing the effect of membrane contents on transmembrane protein-protein interaction using solution NMR and computer simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2486-2498. [PMID: 30279150 DOI: 10.1016/j.bbamem.2018.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/03/2018] [Accepted: 09/17/2018] [Indexed: 12/18/2022]
Abstract
The interaction between the secondary structure elements is the key process, determining the spatial structure and activity of a membrane protein. Transmembrane (TM) helix-helix interaction is known to be especially important for the function of so-called type I or bitopic membrane proteins. In the present work, we present the approach to study the helix-helix interaction in the TM domains of membrane proteins in various lipid environment using solution NMR spectroscopy and phospholipid bicelles. The technique is based on the ability of bicelles to form particles with the size, depending on the lipid/detergent ratio. To implement the approach, we report the experimental parameters of "ideal bicelle" models for four kinds of zwitterionic phospholipids, which can be also used in other structural studies. We show that size of bicelles and type of the rim-forming detergent do not affect substantially the spatial structure and stability of the model TM dimer. On the other hand, the effect of bilayer thickness on the free energy of the dimer is dramatic, while the structure of the protein is unchanged in various lipids with fatty chains having a length from 12 to 18 carbon atoms. The obtained data is analyzed using the computer simulations to find the physical origin of the observed effects.
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Affiliation(s)
- P E Bragin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Lomonosov Moscow State University, Leninskiye Gory, 1, Moscow 119991, Russian Federation
| | - A S Kuznetsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky per., 9, 141700 Dolgoprudnyi, Russian Federation; National Research University Higher School of Economics, Myasnitskaya ul. 20, 101000 Moscow, Russia
| | - O V Bocharova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky per., 9, 141700 Dolgoprudnyi, Russian Federation
| | - P E Volynsky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation
| | - A S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky per., 9, 141700 Dolgoprudnyi, Russian Federation
| | - R G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky per., 9, 141700 Dolgoprudnyi, Russian Federation; National Research University Higher School of Economics, Myasnitskaya ul. 20, 101000 Moscow, Russia
| | - K S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS, str. Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky per., 9, 141700 Dolgoprudnyi, Russian Federation.
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10
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Kot EF, Goncharuk SA, Arseniev AS, Mineev KS. Phase Transitions in Small Isotropic Bicelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3426-3437. [PMID: 29486112 DOI: 10.1021/acs.langmuir.7b03610] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Isotropic phospholipid bicelles are one of the most prospective membrane mimetics for the structural studies of membrane proteins in solution. Recent works provided an almost full set of data regarding the properties of isotropic bicelles; however, one major aspect of their behavior is still under consideration: the possible mixing between the lipid and detergent in the bilayer area. This problem may be resolved by studying the lipid phase transitions in bicelle particles. In the present work, we investigate two effects: phase transitions of bilayer lipids and temperature-induced growth of isotropic bicelles using the NMR spectroscopy. We propose an approach to study the phase transitions in isotropic bicelles based on the properties of 31P NMR spectra of bilayer-forming lipids. We show that phase transitions in small bicelles are "fractional", particles with the liquid-crystalline and gel bilayers coexist in solution at certain temperatures. We study the effects of lipid fatty chain type and demonstrate that the behavior of various lipids in bilayers is reproduced in the isotropic bicelles. We show that the temperature-induced growth of isotropic bicelles is not related directly to the phase transition but is the result of the reversible fusion of bicelle particles. In accordance with our data, rim detergents also have an impact on phase transitions: detergents that resist the temperature-induced growth provide the narrowest and most expressed transitions at higher temperatures. We demonstrate clearly that phase transitions take place even in the smallest bicelles that are applicable for structural studies of membrane proteins by solution NMR spectroscopy. This last finding, together with other data draws a thick line under the long-lasting argument about the relevance of small isotropic bicelles. We show with certainty that the small bicelles can reproduce the most fundamental property of lipid membranes: the ability to undergo phase transition.
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Affiliation(s)
- Erik F Kot
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10 , Moscow 117997 , Russian Federation
- Moscow Institute of Physics and Technology , Institutsky per., 9 , 141700 Dolgoprudnyi , Russian Federation
| | - Sergey A Goncharuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10 , Moscow 117997 , Russian Federation
- Lomonosov Moscow State University , Leninskiye Gory, 1 , Moscow 119991 , Russian Federation
| | - Alexander S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10 , Moscow 117997 , Russian Federation
- Moscow Institute of Physics and Technology , Institutsky per., 9 , 141700 Dolgoprudnyi , Russian Federation
| | - Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10 , Moscow 117997 , Russian Federation
- Moscow Institute of Physics and Technology , Institutsky per., 9 , 141700 Dolgoprudnyi , Russian Federation
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11
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Smrt ST, Draney AW, Singaram I, Lorieau JL. Structure and Dynamics of Membrane Proteins and Membrane Associated Proteins with Native Bicelles from Eukaryotic Tissues. Biochemistry 2017; 56:5318-5327. [PMID: 28915027 DOI: 10.1021/acs.biochem.7b00575] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Sean T. Smrt
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Adrian W. Draney
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Indira Singaram
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Justin L. Lorieau
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
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12
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Dos Santos Morais R, Delalande O, Pérez J, Mouret L, Bondon A, Martel A, Appavou MS, Le Rumeur E, Hubert JF, Combet S. Contrast-Matched Isotropic Bicelles: A Versatile Tool to Specifically Probe the Solution Structure of Peripheral Membrane Proteins Using SANS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6572-6580. [PMID: 28581294 DOI: 10.1021/acs.langmuir.7b01369] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Obtaining structural information on integral or peripheral membrane proteins is currently arduous due to the difficulty of their solubilization, purification, and crystallization (for X-ray crystallography (XRC) application). To overcome this challenge, bicelles are known to be a versatile tool for high-resolution structure determination, especially when using solution and/or solid state nuclear magnetic resonance (NMR) and, to a lesser extent, XRC. For proteins not compatible with these high-resolution methods, small-angle X-ray and neutron scattering (SAXS and SANS, respectively) are powerful alternatives to obtain structural information directly in solution. In particular, the SANS-based approach is a unique technique to obtain low-resolution structures of proteins in interactions with partners by contrast-matching the signal coming from the latter. In the present study, isotropic bicelles are used as a membrane mimic model for SANS-based structural studies of bound peripheral membrane proteins. We emphasize that the SANS signal coming from the deuterated isotropic bicelles can be contrast-matched in 100% D2O-based buffer, allowing us to separately and specifically focus on the signal coming from the protein in interaction with membrane lipids. We applied this method to the DYS-R11-15 protein, a fragment of the central domain of human dystrophin known to interact with lipids, and we were able to recover the signal from the protein alone. This approach gives rise to new perspectives to determine the solution structure of peripheral membrane proteins interacting with lipid membranes and might be extended to integral membrane proteins.
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Affiliation(s)
- Raphael Dos Santos Morais
- Université de Rennes 1 , F-35043 Rennes, France
- CNRS UMR 6290, Institut de Génétique et Développement de Rennes , F-35043 Rennes, France
- Laboratoire Léon-Brillouin, UMR 12 CEA-CNRS, Université Paris-Saclay, CEA-Saclay , Gif-sur-Yvette F-91191, France
- SWING Beamline, Synchrotron SOLEIL, L'Orme des Merisiers , BP48, Saint-Aubin, Gif-sur-Yvette F-91192, France
| | - Olivier Delalande
- Université de Rennes 1 , F-35043 Rennes, France
- CNRS UMR 6290, Institut de Génétique et Développement de Rennes , F-35043 Rennes, France
| | - Javier Pérez
- SWING Beamline, Synchrotron SOLEIL, L'Orme des Merisiers , BP48, Saint-Aubin, Gif-sur-Yvette F-91192, France
| | - Liza Mouret
- CNRS 6226, Institut des Sciences Chimiques de Rennes, PRISM , F-350043 Rennes, France
| | - Arnaud Bondon
- CNRS 6226, Institut des Sciences Chimiques de Rennes, PRISM , F-350043 Rennes, France
| | - Anne Martel
- Institut Laue-Langevin , F-38042 Grenoble, France
| | - Marie-Sousai Appavou
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH , Lichtenbergstr. 1, D-85748 Garching, Germany
| | - Elisabeth Le Rumeur
- Université de Rennes 1 , F-35043 Rennes, France
- CNRS UMR 6290, Institut de Génétique et Développement de Rennes , F-35043 Rennes, France
| | - Jean-François Hubert
- Université de Rennes 1 , F-35043 Rennes, France
- CNRS UMR 6290, Institut de Génétique et Développement de Rennes , F-35043 Rennes, France
| | - Sophie Combet
- Laboratoire Léon-Brillouin, UMR 12 CEA-CNRS, Université Paris-Saclay, CEA-Saclay , Gif-sur-Yvette F-91191, France
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13
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Liebau J, Ye W, Mäler L. Characterization of fast-tumbling isotropic bicelles by PFG diffusion NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:395-404. [PMID: 26662467 DOI: 10.1002/mrc.4399] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 11/12/2015] [Accepted: 11/17/2015] [Indexed: 06/05/2023]
Abstract
Small isotropic bicelles are versatile membrane mimetics, which, in contrast to micelles, provide a lipid bilayer and are at the same time suitable for solution-state NMR studies. The lipid composition of the bilayer is flexible allowing for incorporation of various head groups and acyl chain types. In bicelles, lipids are solubilized by detergents, which are localized in the rim of the disk-shaped lipid bilayer. Bicelles have been characterized by a broad array of biophysical methods, pulsed-field gradient NMR (PFG NMR) being one of them. PFG NMR can readily be used to measure diffusion coefficients of macromolecules. It is thus employed to characterize bicelle size and morphology. Even more importantly, PFG NMR can be used to study the degree of protein association to membranes. Here, we present the advances that have been made in producing small, fast-tumbling isotropic bicelles from a variety of lipids and detergents, together with insights on the morphology of such mixtures gained from PFG NMR. Furthermore, we review approaches to study protein-membrane interaction by PFG NMR. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Jobst Liebau
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Weihua Ye
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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14
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Liu Y, Xia Y, Rad AT, Aresh W, Nieh MP. Stable Discoidal Bicelles: A Platform of Lipid Nanocarriers for Cellular Delivery. Methods Mol Biol 2017; 1522:273-282. [PMID: 27837547 DOI: 10.1007/978-1-4939-6591-5_22] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Bicellar mixtures have been used as alignable membrane substrates for the structural characterization of membrane-associated proteins. Most recently, it has been shown that bicelles can serve as nanocarriers to effectively deliver hydrophobic molecules to cancer cells with a 3- to 10-fold enhancement compared to that of chemically identical liposomes. In this chapter, a detailed preparation protocol, common structural characterization methods, the structural stability and the cellular uptake of bicellar nanodisks are discussed.
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Affiliation(s)
- Ying Liu
- Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT, 06269, USA
| | - Yan Xia
- Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT, 06269, USA
| | - Armin Tahmasbi Rad
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, 06269, USA
| | - Wafa Aresh
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, 06269, USA
| | - Mu-Ping Nieh
- Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT, 06269, USA.
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, 06269, USA.
- Polymer Program, Institute of Materials Science, University of Connecticut, 97 North Eagleville Road, Unit 3136, Storrs, CT, 06269, USA.
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15
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Mineev KS, Nadezhdin KD, Goncharuk SA, Arseniev AS. Characterization of Small Isotropic Bicelles with Various Compositions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:6624-6637. [PMID: 27285636 DOI: 10.1021/acs.langmuir.6b00867] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
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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Affiliation(s)
- K S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10, Moscow, 117997 Russian Federation
| | - K D Nadezhdin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10, Moscow, 117997 Russian Federation
- Moscow Institute of Physics and Technology , Institutsky per., 9, 141700, Dolgoprudnyi, Russian Federation
| | - S A Goncharuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10, Moscow, 117997 Russian Federation
- Lomonosov Moscow State University , Leninskiye Gory, 1, Moscow, 119991, Russian Federation
| | - A S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences RAS , str. Miklukho-Maklaya 16/10, Moscow, 117997 Russian Federation
- Moscow Institute of Physics and Technology , Institutsky per., 9, 141700, Dolgoprudnyi, Russian Federation
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16
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Bian X, Lockless SW. Preparation To Minimize Buffer Mismatch in Isothermal Titration Calorimetry Experiments. Anal Chem 2016; 88:5549-53. [PMID: 27092566 DOI: 10.1021/acs.analchem.6b01319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
There is a growing need to study ligand binding to proteins in native or complex solution using isothermal titration calorimetry (ITC). For example, it is desirable to measure ligand binding to membrane proteins in more native lipid-like environments such as bicelles, where ligands can access both sides of the membrane in a homogeneous environment. A critical step to obtain high signal-to-noise is matching the reaction chamber solution to the ligand solution, typically through a final dialysis or gel filtration step. However, to obtain reproducible bicelles, the lipid concentrations must be carefully controlled which eliminates the use of dialysis that can disrupt these parameters. Here, we report and validate a rapid preparation ITC (RP-ITC) approach to measure ligand binding without the need for a dialysis step. This general approach is used to quantify ion binding to a K(+) channel embedded in bicelles and can be applied to complex, less defined systems.
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Affiliation(s)
- Xuelin Bian
- Department of Biology, Texas A&M University , 3474 TAMU, College Station, Texas 77843-3474, United States
| | - Steve W Lockless
- Department of Biology, Texas A&M University , 3474 TAMU, College Station, Texas 77843-3474, United States
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17
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Vestergaard M, Kraft JF, Vosegaard T, Thøgersen L, Schiøtt B. Bicelles and Other Membrane Mimics: Comparison of Structure, Properties, and Dynamics from MD Simulations. J Phys Chem B 2015; 119:15831-43. [PMID: 26610232 DOI: 10.1021/acs.jpcb.5b08463] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The increased interest in studying membrane proteins has led to the development of new membrane mimics such as bicelles and nanodiscs. However, only limited knowledge is available of how these membrane mimics are affected by embedded proteins and how well they mimic a lipid bilayer. Herein, we present molecular dynamics simulations to elucidate structural and dynamic properties of small bicelles and compare them to a large alignable bicelle, a small nanodisc, and a lipid bilayer. Properties such as lipid packing and properties related to embedding both an α-helical peptide and a transmembrane protein are investigated. The small bicelles are found to be very dynamic and mainly assume a prolate shape substantiating that small bicelles cannot be regarded as well-defined disclike structures. However, addition of a peptide results in an increased tendency to form disc-shaped bicelles. The small bicelles and the nanodiscs show increased peptide solvation and difference in peptide orientation compared to embedding in a bilayer. The large bicelle imitated a bilayer well with respect to both curvature and peptide solvation, although peripheral binding of short tailed lipids to the embedded proteins is observed, which could hinder ligand binding or multimer formation.
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Affiliation(s)
- Mikkel Vestergaard
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Johan F Kraft
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Thomas Vosegaard
- Danish Center for Ultrahigh-Field NMR Spectroscopy and Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Lea Thøgersen
- Center for Membrane Pumps in Cells and Disease (PUMPKIN), Bioinformatics Research Centre, Aarhus University , C.F. Møllers Alle 8, DK-8000 Aarhus C, Denmark
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
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18
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Analysing DHPC/DMPC bicelles by diffusion NMR and multivariate decomposition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2910-7. [DOI: 10.1016/j.bbamem.2015.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 08/06/2015] [Accepted: 09/01/2015] [Indexed: 12/16/2022]
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19
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Chen Q, Vishnivetskiy SA, Zhuang T, Cho MK, Thaker TM, Sanders CR, Gurevich VV, Iverson TM. The rhodopsin-arrestin-1 interaction in bicelles. Methods Mol Biol 2015; 1271:77-95. [PMID: 25697518 DOI: 10.1007/978-1-4939-2330-4_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
G-protein-coupled receptors (GPCRs) are essential mediators of information transfer in eukaryotic cells. Interactions between GPCRs and their binding partners modulate the signaling process. For example, the interaction between GPCR and cognate G protein initiates the signal, while the interaction with cognate arrestin terminates G-protein-mediated signaling. In visual signal transduction, arrestin-1 selectively binds to the phosphorylated light-activated GPCR rhodopsin to terminate rhodopsin signaling. Under physiological conditions, the rhodopsin-arrestin-1 interaction occurs in highly specialized disk membrane in which rhodopsin resides. This membrane is replaced with mimetics when working with purified proteins. While detergents are commonly used as membrane mimetics, most detergents denature arrestin-1, preventing biochemical studies of this interaction. In contrast, bicelles provide a suitable alternative medium. An advantage of bicelles is that they contain lipids, which have been shown to be necessary for normal rhodopsin-arrestin-1 interaction. Here we describe how to reconstitute rhodopsin into bicelles, and how bicelle properties affect the rhodopsin-arrestin-1 interaction.
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Affiliation(s)
- Qiuyan Chen
- Department of Pharmacology, Vanderbilt University Medical Center, 1211 Medical Center Drive, Nashville, TN, 37232-6600, USA
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20
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Bodor A, Kövér KE, Mäler L. Membrane interactions in small fast-tumbling bicelles as studied by 31P NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:760-6. [PMID: 25497765 DOI: 10.1016/j.bbamem.2014.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/11/2014] [Accepted: 12/01/2014] [Indexed: 01/02/2023]
Abstract
Small fast-tumbling bicelles are ideal for studies of membrane interactions at molecular level; they allow analysis of lipid properties using solution-state NMR. In the present study we used 31P NMR relaxation to obtain detailed information on lipid head-group dynamics. We explored the effect of two topologically different membrane-interacting peptides on bicelles containing either dimyristoylphosphocholine (DMPC), or a mixture of DMPC and dimyristoylphosphoglycerol (DMPG), and dihexanoylphosphocholine (DHPC). KALP21 is a model transmembrane peptide, designed to span a DMPC bilayer and dynorphin B is a membrane surface active neuropeptide. KALP21 causes significant increase in bicelle size, as evidenced by both dynamic light scattering and 31P T2 relaxation measurements. The effect of dynorphin B on bicelle size is more modest, although significant effects on T2 relaxation are observed at higher temperatures. A comparison of 31P T1 values for the lipids with and without the peptides showed that dynorphin B has a greater effect on lipid head-group dynamics than KALP21, especially at elevated temperatures. From the field-dependence of T1 relaxation data, a correlation time describing the overall lipid motion was derived. Results indicate that the positively charged dynorphin B decreases the mobility of the lipid molecules--in particular for the negatively charged DMPG--while KALP21 has a more modest influence. Our results demonstrate that while a transmembrane peptide has severe effects on overall bilayer properties, the surface bound peptide has a more dramatic effect in reducing lipid head-group mobility. These observations may be of general importance for understanding peptide-membrane interactions.
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Affiliation(s)
- Andrea Bodor
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary.
| | - Katalin E Kövér
- Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4032 Debrecen, Hungary
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm Sweden.
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21
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Draney AW, Smrt ST, Lorieau JL. Use of isotropically tumbling bicelles to measure curvature induced by membrane components. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11723-11733. [PMID: 25203267 DOI: 10.1021/la5030668] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Isotropically tumbling discoidal bicelles are a useful biophysical tool for the study of lipids and proteins by NMR, dynamic light scattering, and small-angle X-ray scattering. Isotropically tumbling bicelles present a low-curvature central region, typically enriched with DMPC in the lamellar state, and a highly curved detergent rim, typically composed of DHPC. In this report, we study the impact of the partitioning and induced curvature of a few molecules of a foreign lipid on the bicelle size, structure, and curvature. Previous approaches for studying curvature have focused on macroscopic and bulk properties of membrane curvature. In the approach presented here, we show that the conical shape of the DOPE lipid and the inverted-conical shape of the DPC lipid induce measurable curvature changes in the bicelle size. Bicelles with an average of 1.8 molecules of DOPE have marked increases in the size of bicelles, consistent with negative membrane curvature in the central region of the bicelle. With bicelle curvature models, radii of curvature on the order of -100 Å and below are measured, with a greater degree of curvature observed in the more pliable Lα state above the phase-transition temperature of DMPC. Bicelles with an average of 1.8 molecules of DPC are reduced in size, consistent with positive membrane curvature in the rim, and at higher temperatures, DPC is distributed in the central region to form mixed-micelle structures. We use translational and rotational diffusion measurements by NMR, size-exclusion chromatography, and structural models to quantitate changes in bicelle size, curvature, and lipid dynamics.
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Affiliation(s)
- Adrian W Draney
- Department of Chemistry, University of Illinois at Chicago , Chicago Illinois 60607, United States
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