1
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Ayscough SE, Clifton LA, Skoda MWA, Titmuss S. Suspended phospholipid bilayers: A new biological membrane mimetic. J Colloid Interface Sci 2023; 633:1002-1011. [PMID: 36516676 DOI: 10.1016/j.jcis.2022.11.148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/04/2022]
Abstract
HYPOTHESIS The attractive interaction between a cationic surfactant monolayer at the air-water interface and vesicles, incorporating anionic lipids, is sufficient to drive the adsorption and deformation of the vesicles. Osmotic rupture of the vesicles produces a continuous lipid bilayer beneath the monolayer. EXPERIMENTAL Specular neutron reflectivity has been measured from the surface of a purpose-built laminar flow trough, which allows for rapid adsorption of vesicles, the changes in salt concentration required for osmotic rupture of the adsorbed vesicles into a bilayer, and for neutron contrast variation of the sub-phase without disturbing the monolayer. FINDINGS The neutron reflectivity profiles measured after vesicle addition are consistent with the adsorption and flattening of the vesicles beneath the monolayer. An increase in the buffer salt concentration results in further flattening and fusion of the adsorbed vesicles, which are ruptured by a subsequent decrease in the salt concentration. This process results in a continuous, high coverage, bilayer suspended 11 Åbeneath the monolayer. As the bilayer is not constrained by a solid substrate, this new mimetic is well-suited to studying the structure of lipid bilayers that include transmembrane proteins.
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Affiliation(s)
- Sophie E Ayscough
- School of Physics & Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - Luke A Clifton
- ISIS Neutron & Muon Source, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0XX, UK
| | - Maximilian W A Skoda
- ISIS Neutron & Muon Source, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0XX, UK
| | - Simon Titmuss
- School of Physics & Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK.
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2
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Pusterla J, Scoppola E, Appel C, Mukhina T, Shen C, Brezesinski G, Schneck E. Characterization of lipid bilayers adsorbed to functionalized air/water interfaces. NANOSCALE 2022; 14:15048-15059. [PMID: 36200471 DOI: 10.1039/d2nr03334h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Lipid bilayers immobilized in planar geometries, such as solid-supported or "floating" bilayers, have enabled detailed studies of biological membranes with numerous experimental techniques, notably X-ray and neutron reflectometry. However, the presence of a solid support also has disadvantages as it complicates the use of spectroscopic techniques as well as surface rheological measurements that would require surface deformations. Here, in order to overcome these limitations, we investigate lipid bilayers adsorbed to inherently soft and experimentally well accessible air/water interfaces that are functionalized with Langmuir monolayers of amphiphiles. The bilayers are characterized with ellipsometry, X-ray scattering, and X-ray fluorescence. Grazing-incidence X-ray diffraction reveals that lipid bilayers in a chain-ordered state can have significantly different structural features than regular Langmuir monolayers of the same composition. Our results suggest that bilayers at air/water interfaces may be well suited for fundamental studies in the field of membrane biophysics.
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Affiliation(s)
- Julio Pusterla
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Ernesto Scoppola
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Christian Appel
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Tetiana Mukhina
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Chen Shen
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gerald Brezesinski
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
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3
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Hall SCL, Tognoloni C, Campbell RA, Richens J, O'Shea P, Terry AE, Price GJ, Dafforn TR, Edler KJ, Arnold T. The interaction of styrene maleic acid copolymers with phospholipids in Langmuir monolayers, vesicles and nanodiscs; a structural study. J Colloid Interface Sci 2022; 625:220-236. [PMID: 35716617 DOI: 10.1016/j.jcis.2022.03.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 10/31/2022]
Abstract
HYPOTHESIS Self-assembly of amphipathic styrene maleic acid copolymers with phospholipids in aqueous solution results in the formation of 'nanodiscs' containing a planar segment of phospholipid bilayer encapsulated by a polymer belt. Recently, studies have reported that lipids rapidly exchange between both nanodiscs in solution and external sources of lipids. Outstanding questions remain regarding details of polymer-lipid interactions, factors influencing lipid exchange and structural effects of such exchange processes. Here, the dynamic behaviour of nanodiscs is investigated, specifically the role of membrane charge and polymer chemistry. EXPERIMENTS Two model systems are investigated: fluorescently labelled phospholipid vesicles, and Langmuir monolayers of phospholipids. Using fluorescence spectroscopy and time-resolved neutron reflectometry, the membrane potential, monolayer structure and composition are monitored with respect to time upon polymer and nanodisc interactions. FINDINGS In the presence of external lipids, polymer chains embed throughout lipid membranes, the extent of which is governed by the net membrane charge. Nanodiscs stabilised by three different polymers will all exchange lipids and polymer with monolayers to differing extents, related to the properties of the stabilising polymer belt. These results demonstrate the dynamic nature of nanodiscs which interact with the local environment and are likely to deposit both lipids and polymer at all stages of use.
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Affiliation(s)
- Stephen C L Hall
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK; Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 ODE, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK.
| | - Cecilia Tognoloni
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Richard A Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, UK
| | - Joanna Richens
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Paul O'Shea
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK; Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YG, UK
| | - Ann E Terry
- MAX IV Laboratory, Lund University, SE-221 00 Lund, Sweden
| | - Gareth J Price
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Tim R Dafforn
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Karen J Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Thomas Arnold
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK; Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; European Spallation Source ERIC, P.O Box 176, SE-221 00 Lund, Sweden
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4
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Hall SCL, Clifton LA, Tognoloni C, Morrison KA, Knowles TJ, Kinane CJ, Dafforn TR, Edler KJ, Arnold T. Adsorption of a styrene maleic acid (SMA) copolymer-stabilized phospholipid nanodisc on a solid-supported planar lipid bilayer. J Colloid Interface Sci 2020; 574:272-284. [PMID: 32330753 PMCID: PMC7276985 DOI: 10.1016/j.jcis.2020.04.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/12/2022]
Abstract
Over recent years, there has been a rapid development of membrane-mimetic systems to encapsulate and stabilize planar segments of phospholipid bilayers in solution. One such system has been the use of amphipathic copolymers to solubilize lipid bilayers into nanodiscs. The attractiveness of this system, in part, stems from the capability of these polymers to solubilize membrane proteins directly from the host cell membrane. The assumption has been that the native lipid annulus remains intact, with nanodiscs providing a snapshot of the lipid environment. Recent studies have provided evidence that phospholipids can exchange from the nanodiscs with either lipids at interfaces, or with other nanodiscs in bulk solution. Here we investigate kinetics of lipid exchange between three recently studied polymer-stabilized nanodiscs and supported lipid bilayers at the silicon-water interface. We show that lipid and polymer exchange occurs in all nanodiscs tested, although the rate and extent differs between different nanodisc types. Furthermore, we observe adsorption of nanodiscs to the supported lipid bilayer for one nanodisc system which used a polymer made using reversible addition-fragmentation chain transfer polymerization. These results have important implications in applications of polymer-stabilized nanodiscs, such as in the fabrication of solid-supported films containing membrane proteins.
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Affiliation(s)
- Stephen C L Hall
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK; Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 ODE, UK
| | - Luke A Clifton
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Cecilia Tognoloni
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Kerrie A Morrison
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Timothy J Knowles
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Christian J Kinane
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Tim R Dafforn
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Karen J Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Thomas Arnold
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 ODE, UK; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK; Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK; European Spallation Source ERIC, P.O Box 176, SE-221 00 Lund, Sweden.
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5
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Clifton LA, Campbell RA, Sebastiani F, Campos-Terán J, Gonzalez-Martinez JF, Björklund S, Sotres J, Cárdenas M. Design and use of model membranes to study biomolecular interactions using complementary surface-sensitive techniques. Adv Colloid Interface Sci 2020; 277:102118. [PMID: 32044469 DOI: 10.1016/j.cis.2020.102118] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/24/2020] [Accepted: 01/29/2020] [Indexed: 01/07/2023]
Abstract
Cellular membranes are complex structures and simplified analogues in the form of model membranes or biomembranes are used as platforms to understand fundamental properties of the membrane itself as well as interactions with various biomolecules such as drugs, peptides and proteins. Model membranes at the air-liquid and solid-liquid interfaces can be studied using a range of complementary surface-sensitive techniques to give a detailed picture of both the structure and physicochemical properties of the membrane and its resulting interactions. In this review, we will present the main planar model membranes used in the field to date with a focus on monolayers at the air-liquid interface, supported lipid bilayers at the solid-liquid interface and advanced membrane models such as tethered and floating membranes. We will then briefly present the principles as well as the main type of information on molecular interactions at model membranes accessible using a Langmuir trough, quartz crystal microbalance with dissipation monitoring, ellipsometry, atomic force microscopy, Brewster angle microscopy, Infrared spectroscopy, and neutron and X-ray reflectometry. A consistent example for following biomolecular interactions at model membranes is used across many of the techniques in terms of the well-studied antimicrobial peptide Melittin. The overall objective is to establish an understanding of the information accessible from each technique, their respective advantages and limitations, and their complementarity.
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Affiliation(s)
- Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, United Kingdom
| | - Richard A Campbell
- Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Federica Sebastiani
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - José Campos-Terán
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Unidad Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, Delegación Cuajimalpa de Morelos, 05348, Mexico; Lund Institute of advanced Neutron and X-ray Science, Lund University, Scheelevägen 19, 223 70 Lund, Sweden
| | - Juan F Gonzalez-Martinez
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Sebastian Björklund
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Javier Sotres
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Marité Cárdenas
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden.
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6
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Braun L, Uhlig M, von Klitzing R, Campbell RA. Polymers and surfactants at fluid interfaces studied with specular neutron reflectometry. Adv Colloid Interface Sci 2017; 247:130-148. [PMID: 28822539 DOI: 10.1016/j.cis.2017.07.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/08/2017] [Indexed: 01/18/2023]
Abstract
This review addresses the advances made with specular neutron reflectometry in studies of aqueous mixtures of polymers and surfactants at fluid interfaces during the last decade (or so). The increase in neutron flux due to improvements in instrumentation has led to routine measurements at the air/water interface that are faster and involve samples with lower isotopic contrast than in previous experiments. One can now resolve the surface excess of a single deuterated component on the second time scale and the composition of a mixture on the minute time scale, and information about adsorption processes and dynamic rheology can also be accessed. Research areas addressed include the types of formed equilibrium surface structures, the link to foam film stability and the range of non-equilibrium effects that dominate the behavior of oppositely charged polyelectrolyte/surfactant mixtures, macroscopic film formation in like-charged polymer/surfactant mixtures, and the properties of mixtures of bio-polymers with surfactants and lipids.
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7
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Browning KL, Lind TK, Maric S, Malekkhaiat-Häffner S, Fredrikson GN, Bengtsson E, Malmsten M, Cárdenas M. Human Lipoproteins at Model Cell Membranes: Effect of Lipoprotein Class on Lipid Exchange. Sci Rep 2017; 7:7478. [PMID: 28785025 PMCID: PMC5547137 DOI: 10.1038/s41598-017-07505-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/29/2017] [Indexed: 01/19/2023] Open
Abstract
High and low density lipoproteins (HDL and LDL) are thought to play vital roles in the onset and development of atherosclerosis; the biggest killer in the western world. Key issues of initial lipoprotein (LP) interactions at cellular membranes need to be addressed including LP deposition and lipid exchange. Here we present a protocol for monitoring the in situ kinetics of lipoprotein deposition and lipid exchange/removal at model cellular membranes using the non-invasive, surface sensitive methods of neutron reflection and quartz crystal microbalance with dissipation. For neutron reflection, lipid exchange and lipid removal can be distinguished thanks to the combined use of hydrogenated and tail-deuterated lipids. Both HDL and LDL remove lipids from the bilayer and deposit hydrogenated material into the lipid bilayer, however, the extent of removal and exchange depends on LP type. These results support the notion of HDL acting as the ‘good’ cholesterol, removing lipid material from lipid-loaded cells, whereas LDL acts as the ‘bad’ cholesterol, depositing lipid material into the vascular wall.
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Affiliation(s)
- K L Browning
- Department of Pharmacy, Uppsala University, Uppsala, Sweden
| | - T K Lind
- Department of Biomedical Sciences and Biofilms, Malmö University, Malmö, Sweden
| | - S Maric
- Department of Biomedical Sciences and Biofilms, Malmö University, Malmö, Sweden
| | | | - G N Fredrikson
- Department of Clinical Sciences, Malmö, Lund University, Malmö, Sweden
| | - E Bengtsson
- Department of Clinical Sciences, Malmö, Lund University, Malmö, Sweden
| | - M Malmsten
- Department of Pharmacy, Uppsala University, Uppsala, Sweden. .,Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark.
| | - M Cárdenas
- Department of Biomedical Sciences and Biofilms, Malmö University, Malmö, Sweden.
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8
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Abstract
Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Stephen G Sligar
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
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9
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Hazell G, Arnold T, Barker RD, Clifton LA, Steinke NJ, Tognoloni C, Edler KJ. Evidence of Lipid Exchange in Styrene Maleic Acid Lipid Particle (SMALP) Nanodisc Systems. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11845-11853. [PMID: 27739678 DOI: 10.1021/acs.langmuir.6b02927] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Styrene-alt-maleic acid lipid particles (SMALPs) are self-assembled discoidal structures composed of a polymer belt and a segment of lipid bilayer, which are capable of encapsulating membrane proteins directly from the cell membrane. Here we present evidence of the exchange of lipids between such "nanodiscs" and lipid monolayers adsorbed at either solid-liquid or air-liquid interfaces. This behavior has important implications for the potential uses of nanodiscs.
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Affiliation(s)
- Gavin Hazell
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Thomas Arnold
- Diamond Light Source, Harwell Science and Innovation Campus , Didcot, OX11 ODE, United Kingdom
| | - Robert D Barker
- School of Science and Engineering, University of Dundee , Dundee, DD1 4HN, United Kingdom
| | - Luke A Clifton
- ISIS Spallation Neutron Source, STFC, Harwell Science and Innovation Campus, Didcot, OX11 OQX, United Kingdom
| | - Nina-Juliane Steinke
- ISIS Spallation Neutron Source, STFC, Harwell Science and Innovation Campus, Didcot, OX11 OQX, United Kingdom
| | - Cecilia Tognoloni
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Karen J Edler
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
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10
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Campbell RA, Tummino A, Noskov BA, Varga I. Polyelectrolyte/surfactant films spread from neutral aggregates. SOFT MATTER 2016; 12:5304-12. [PMID: 27221521 DOI: 10.1039/c6sm00637j] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We describe a new methodology to prepare loaded polyelectrolyte/surfactant films at the air/water interface by exploiting Marangoni spreading resulting from the dynamic dissociation of hydrophobic neutral aggregates dispensed from an aqueous dispersion. The system studied is mixtures of poly(sodium styrene sulfonate) with dodecyl trimethylammonium bromide. Our approach results in the interfacial confinement of more than one third of the macromolecules in the system even though they are not even surface-active without the surfactant. The interfacial stoichiometry of the films was resolved during measurements of surface pressure isotherms in situ for the first time using a new implementation of neutron reflectometry. The interfacial coverage is determined by the minimum surface area reached when the films are compressed beyond a single complete surface layer. The films exhibit linear ripples on a length scale of hundreds of micrometers during the squeezing out of material, after which they behave as perfectly insoluble membranes with consistent stoichiometric charge binding. We discuss our findings in terms of scope for the preparation of loaded membranes for encapsulation applications and in deposition-based technologies.
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Affiliation(s)
- Richard A Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38.042 Grenoble Cedex 9, France.
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11
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Akkaladevi N, Mukherjee S, Katayama H, Janowiak B, Patel D, Gogol EP, Pentelute BL, Collier RJ, Fisher MT. Following Natures Lead: On the Construction of Membrane-Inserted Toxins in Lipid Bilayer Nanodiscs. J Membr Biol 2015; 248:595-607. [PMID: 25578459 PMCID: PMC4580227 DOI: 10.1007/s00232-014-9768-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 12/22/2014] [Indexed: 11/27/2022]
Abstract
Bacterial toxin or viral entry into the cell often requires cell surface binding and endocytosis. The endosomal acidification induces a limited unfolding/refolding and membrane insertion reaction of the soluble toxins or viral proteins into their translocation competent or membrane inserted states. At the molecular level, the specific orientation and immobilization of the pre-transitioned toxin on the cell surface is often an important prerequisite prior to cell entry. We propose that structures of some toxin membrane insertion complexes may be observed through procedures where one rationally immobilizes the soluble toxin so that potential unfolding ↔ refolding transitions that occur prior to membrane insertion orientate away from the immobilization surface in the presence of lipid micelle pre-nanodisc structures. As a specific example, the immobilized prepore form of the anthrax toxin pore translocon or protective antigen can be transitioned, inserted into a model lipid membrane (nanodiscs), and released from the immobilized support in its membrane solubilized form. This particular strategy, although unconventional, is a useful procedure for generating pure membrane-inserted toxins in nanodiscs for electron microscopy structural analysis. In addition, generating a similar immobilized platform on label-free biosensor surfaces allows one to observe the kinetics of these acid-induced membrane insertion transitions. These platforms can facilitate the rational design of inhibitors that specifically target the toxin membrane insertion transitions that occur during endosomal acidification. This approach may lead to a new class of direct anti-toxin inhibitors.
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Affiliation(s)
- Narahari Akkaladevi
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Srayanta Mukherjee
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Hiroo Katayama
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Blythe Janowiak
- Department of Biology, Saint Louis University, St. Louis, MO 63101, USA
| | - Deepa Patel
- Department of Microbiology and Molecular Genetics, Harvard University, Boston, MA, USA
| | - Edward P. Gogol
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Bradley L. Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02193, USA
| | - R. John Collier
- Department of Microbiology and Molecular Genetics, Harvard University, Boston, MA, USA
| | - Mark T. Fisher
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
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12
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Maric S, Thygesen MB, Schiller J, Marek M, Moulin M, Haertlein M, Forsyth VT, Bogdanov M, Dowhan W, Arleth L, Pomorski TG. Biosynthetic preparation of selectively deuterated phosphatidylcholine in genetically modified Escherichia coli. Appl Microbiol Biotechnol 2015; 99:241-54. [PMID: 25301578 PMCID: PMC4289089 DOI: 10.1007/s00253-014-6082-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/28/2014] [Accepted: 09/09/2014] [Indexed: 01/07/2023]
Abstract
Phosphatidylcholine (PC) is a major component of eukaryotic cell membranes and one of the most commonly used phospholipids for reconstitution of membrane proteins into carrier systems such as lipid vesicles, micelles and nanodiscs. Selectively deuterated versions of this lipid have many applications, especially in structural studies using techniques such as NMR, neutron reflectivity and small-angle neutron scattering. Here we present a comprehensive study of selective deuteration of phosphatidylcholine through biosynthesis in a genetically modified strain of Escherichia coli. By carefully tuning the deuteration level in E. coli growth media and varying the deuteration of supplemented carbon sources, we show that it is possible to achieve a controlled deuteration for three distinct parts of the PC lipid molecule, namely the (a) lipid head group, (b) glycerol backbone and (c) fatty acyl tail. This biosynthetic approach paves the way for the synthesis of specifically deuterated, physiologically relevant phospholipid species which remain difficult to obtain through standard chemical synthesis.
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Affiliation(s)
- Selma Maric
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Center for Membrane Pumps in Cells and Disease, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Mikkel B. Thygesen
- CARB Centre, Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Jürgen Schiller
- Institut für Medizinische Physik und Biophysik, Medizinische Fakultät, Universität Leipzig, Härtelstrasse 16-18, 04107 Leipzig, Germany
| | - Magdalena Marek
- Center for Membrane Pumps in Cells and Disease, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Martine Moulin
- Life Sciences Group, Institut Laue Langevin, 6 rue Jules Horowitz, CEDEX 9, BP156, 38042 Grenoble, France
- Faculty of Natural Sciences & Institute for Science and Technology in Medicine, Keele University, Staffordshire ST5 5BG, UK
| | - Michael Haertlein
- Life Sciences Group, Institut Laue Langevin, 6 rue Jules Horowitz, CEDEX 9, BP156, 38042 Grenoble, France
| | - V. Trevor Forsyth
- Life Sciences Group, Institut Laue Langevin, 6 rue Jules Horowitz, CEDEX 9, BP156, 38042 Grenoble, France
- Faculty of Natural Sciences & Institute for Science and Technology in Medicine, Keele University, Staffordshire ST5 5BG, UK
| | - Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, TX 77030, USA
| | - William Dowhan
- Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, TX 77030, USA
| | - Lise Arleth
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Thomas Günther Pomorski
- Center for Membrane Pumps in Cells and Disease, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
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13
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Yeliseev AA. Methods for recombinant expression and functional characterization of human cannabinoid receptor CB2. Comput Struct Biotechnol J 2013; 6:e201303011. [PMID: 24688719 PMCID: PMC3962128 DOI: 10.5936/csbj.201303011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/08/2013] [Accepted: 08/10/2013] [Indexed: 12/22/2022] Open
Abstract
Cannabinoid receptor CB2 is a seven transmembrane-domain integral membrane protein that belongs to a large superfamily of G protein-coupled receptors (GPCR). CB2 is a part of the endocannabinoid system that plays vital role in regulation of immune response, inflammation, pain sensitivity, obesity and other physiological responses. Information about the structure and mechanisms of functioning of this receptor in cell membranes is essential for the rational development of specific pharmaceuticals. Here we review the methodology for recombinant expression, purification, stabilization and biochemical characterization of CB2 suitable for preparation of multi-milligram quantities of functionally active receptor. The biotechnological protocols include expression of the recombinant CB2 in E. coli cells as a fusion with the maltose binding protein, stabilization with a high affinity ligand and a derivative of cholesterol in detergent micelles, efficient purification by tandem affinity chromatography, and reconstitution of the receptor into lipid bilayers. The purified recombinant CB2 receptor is amenable to functional and structural studies including nuclear magnetic resonance spectroscopy and a wide range of biochemical and biophysical techniques.
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Affiliation(s)
- Alexei A Yeliseev
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Bethesda, MD 20892, USA
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14
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Wadsäter M, Barker R, Mortensen K, Feidenhans'l R, Cárdenas M. Effect of phospholipid composition and phase on nanodisc films at the solid-liquid interface as studied by neutron reflectivity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2871-2880. [PMID: 23373466 DOI: 10.1021/la3024698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nanodiscs are disc-like self-assembled structures formed by phospholipids and amphipatic proteins. The proteins wrap like a belt around the hydrophobic part of the lipids, basically producing nanometer-sized patches of lipid bilayers. The bilayer in the nanodisc constitutes a native-like model of the cell membrane and can act as a nanometer-sized container for functional single membrane proteins. In this study, we present a general nanodisc-based system, intended for structural and functional studies of membrane proteins. In this method, the nanodiscs are aligned at a solid surface, providing the ability to determine the average structure of the film along an axis perpendicular to the interface as measured by neutron reflectivity. The nanodisc film was optimized in terms of nanodisc coverage, reduced film roughness, and stability for time-consuming studies. This was achieved by a systematic variation of the lipid phase, charge, and length of lipid tails. Herein, we show that, although all studied nanodiscs align with their lipid bilayer parallel to the interface, gel-phase DMPC nanodiscs form the most suitable film for future membrane protein studies since they yield a dense irreversibly adsorbed film with low roughness and high stability over time. This may be explained by the appropriate matching between the thickness of the hydrophobic lipid core of gel phase DMPC and the height of the belt protein. Moreover, once formed the gel-phase DMPC nanodiscs film can be heated up to melt the lipid bilayer, thus providing a more biologically friendly environment for membrane proteins.
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Affiliation(s)
- Maria Wadsäter
- Nano-Science Center and Institute of Chemistry, University of Copenhagen, Copenhagen, Denmark
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15
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Abstract
Studying the structure of protein-lipid complexes, be they in vesicles, planar bilayers, monolayers, or nanodiscs, poses two particular challenges. Firstly such complexes are often dynamic. Secondly we need to resolve the lipid and protein structures within the complex. Neutron scattering is well placed to help in both respects since it deals with molecules in large, complex, dynamic structures and can easily differentiate between different molecular species. This comes from the great penetrating power of neutrons and their sensitivity to the difference between hydrogen (H) and deuterium (D). Both membrane proteins and lipids can be produced with varying degrees of deuteration, thus allowing us to dissect complexes with great accuracy. Two main scattering techniques are immediately applicable to the study of protein-lipid interactions. Neutron reflection exploits the constructive interference, which occurs when neutrons are reflected from different points in a layer. An everyday example is the rainbow of colors reflected from an oil film on water, which result from varying film thickness and the angle of reflection. Neutrons because of their short wavelengths (4-15 Å) and H/D sensitivity can, in reflectometry mode, provide accurate cross sections of lipid monolayers and bilayers. Small-angle neutron scattering (SANS) can resolve the structures of protein-lipid complexes if they are present as homogeneous dispersions. This is easiest with detergent micelles, but increasingly methods are being developed whereby vesicles, nanodiscs, etc., can be resolved. Again the ability to deuterate proteins and lipids enables SANS to resolve the inner structure of big, dynamic, lipid-protein complexes. The recent introduction of advanced neutron beam lines means that the technique is now within the grasp of a broad cross section of researchers.
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16
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Wadsäter M, Laursen T, Singha A, Hatzakis NS, Stamou D, Barker R, Mortensen K, Feidenhans'l R, Møller BL, Cárdenas M. Monitoring shifts in the conformation equilibrium of the membrane protein cytochrome P450 reductase (POR) in nanodiscs. J Biol Chem 2012; 287:34596-603. [PMID: 22891242 PMCID: PMC3464565 DOI: 10.1074/jbc.m112.400085] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/09/2012] [Indexed: 11/06/2022] Open
Abstract
Nanodiscs are self-assembled ∼50-nm(2) patches of lipid bilayers stabilized by amphipathic belt proteins. We demonstrate that a well ordered dense film of nanodiscs serves for non-destructive, label-free studies of isolated membrane proteins in a native like environment using neutron reflectometry (NR). This method exceeds studies of membrane proteins in vesicle or supported lipid bilayer because membrane proteins can be selectively adsorbed with controlled orientation. As a proof of concept, the mechanism of action of the membrane-anchored cytochrome P450 reductase (POR) is studied here. This enzyme is responsible for catalyzing the transfer of electrons from NADPH to cytochrome P450s and thus is a key enzyme in the biosynthesis of numerous primary and secondary metabolites in plants. Neutron reflectometry shows a coexistence of two different POR conformations, a compact and an extended form with a thickness of 44 and 79 Å, respectively. Upon complete reduction by NADPH, the conformational equilibrium shifts toward the compact form protecting the reduced FMN cofactor from engaging in unspecific electron transfer reaction.
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Affiliation(s)
- Maria Wadsäter
- From the Nano-Science Center and Institute of Chemistry, Faculty of Science, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Tomas Laursen
- the Plant Biochemistry Laboratory, Department of Plant and Environmental Science, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Aparajita Singha
- the Bio-Nanotechnology Laboratory, Department of Neuroscience and Pharmacology, Nano-Science Center, Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Nikos S. Hatzakis
- the Bio-Nanotechnology Laboratory, Department of Chemistry, Department of Neuroscience and Pharmacology, Nano-Science Center, Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Dimitrios Stamou
- the Bio-Nanotechnology Laboratory, Department of Chemistry, Department of Neuroscience and Pharmacology, Nano-Science Center, Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Robert Barker
- the Institut Laue Langevin, 6 rue Jules Horowitz – BP 156, 38042 Grenoble Cedex 9, France, and
| | - Kell Mortensen
- the Nano-Science Center and Niels Bohr Institute, Universitetsparken 5, 2200 Copenhagen, Denmark
| | - Robert Feidenhans'l
- the Nano-Science Center and Niels Bohr Institute, Universitetsparken 5, 2200 Copenhagen, Denmark
| | - Birger Lindberg Møller
- the Plant Biochemistry Laboratory, Department of Plant and Environmental Science, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Marité Cárdenas
- From the Nano-Science Center and Institute of Chemistry, Faculty of Science, University of Copenhagen, DK-2200 Copenhagen, Denmark
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