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Ambrulevičius F, Valinčius G. Electrochemical impedance spectrum reveals structural details of distribution of pores and defects in supported phospholipid bilayers. Bioelectrochemistry 2022; 146:108092. [DOI: 10.1016/j.bioelechem.2022.108092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/23/2022] [Accepted: 02/26/2022] [Indexed: 11/15/2022]
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2
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Budvytyte R, Ambrulevičius F, Jankaityte E, Valincius G. Electrochemical Assessment of Dielectric Damage to Phospholipid Bilayers by Amyloid β-Oligomers. Bioelectrochemistry 2022; 145:108091. [DOI: 10.1016/j.bioelechem.2022.108091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/02/2022]
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3
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Penkauskas T, Ambrulevičius F, Valinčius G. Electrochemical Impedance Spectroscopy as a Convenient Tool to Characterize Tethered Bilayer Membranes. Methods Mol Biol 2022; 2402:31-59. [PMID: 34854034 DOI: 10.1007/978-1-0716-1843-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this paper, we describe the application of electrochemical impedance spectroscopy (EIS) to characterize process of formation and properties of solid-supported tethered bilayer membranes on solid conducting substrates. Along with the description of experimental procedures to prepare substrates and self-assembly of phospholipid bilayers onto gold-coated glass slides, we describe the detailed protocols of EIS measurements. We demonstrate the utility of EIS in the evaluation of the properties of both molecular anchor layers used to immobilize tBLMs as well as characterization of tBLMs. We show that the EIS methodology extends the applicability of this technique well beyond the mere evaluation of electric parameters. Specifically, we demonstrate how by using EIS one may evaluate both density and size of water-filled defects (ion-channels) in tBLMs, to determine the structural mode (homogeneous, heterogeneous, or clustered) of distribution of defects in tBLMs. Our methodology can be applied in both basic protein membrane interaction studies, as well as in the development of precision biosensoric systems with tBLMs as a sensing element.
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Affiliation(s)
- Tadas Penkauskas
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Filipas Ambrulevičius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Gintaras Valinčius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
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Guidelli R, Becucci L. Functional activity of peptide ion channels in tethered bilayer lipid membranes: Review. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rolando Guidelli
- Department of Chemistry University of Florence Sesto Fiorentino Firenze Italy
| | - Lucia Becucci
- Ministero dell'Istruzione Scuola Media “Guglielmo Marconi” San Giovanni Valdarno Arezzo Italy
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Birchenough HL, Jowitt TA. Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D): Preparing Functionalized Lipid Layers for the Study of Complex Protein-Ligand Interactions. Methods Mol Biol 2021; 2263:183-197. [PMID: 33877598 DOI: 10.1007/978-1-0716-1197-5_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Quartz crystal microbalance with dissipation monitoring (QCM-D) is one of the most widely used techniques for the deposition of lipid layers and provides a useful tool for protein-ligand analysis. By using functionalized lipids, for example, with nitrilotriacetic acid (NTA) or biotin, one can couple a molecule to the surface to investigate ligand interactions. Using lipid layers in this way allows for the analysis of complex binding events such as conformational changes, fibrillation, and hierarchical clustering on the surface, which is difficult to interpret with conventional surface sensor techniques. Deposition of lipids and subsequent molecular interactions are easily monitored using both the frequency and the dissipation, which have distinct features in bilayer formation and make QCM-D the ideal technique to use. Here we describe the formation of biotinylated lipid bilayers using two different types of lipids and the subsequent addition of avidin, which can then be used as a basis for linking biotinylated molecules to the surface. These protocols can be adapted to use other lipid moieties and linking chemistries.
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Affiliation(s)
- Holly L Birchenough
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Wellcome Trust Centre for Cell Matrix Research, University of Manchester, Manchester, UK
| | - Thomas A Jowitt
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
- Wellcome Trust Centre for Cell Matrix Research, University of Manchester, Manchester, UK.
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Raila T, Ambrulevičius F, Penkauskas T, Jankunec M, Meškauskas T, Vanderah DJ, Valincius G. Clusters of protein pores in phospholipid bilayer membranes can be identified and characterized by electrochemical impedance spectroscopy. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.137179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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8
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Electrochemical Biosensors Based on Membrane-Bound Enzymes in Biomimetic Configurations. SENSORS 2020; 20:s20123393. [PMID: 32560121 PMCID: PMC7349357 DOI: 10.3390/s20123393] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/12/2020] [Accepted: 06/14/2020] [Indexed: 02/07/2023]
Abstract
In nature, many enzymes are attached or inserted into the cell membrane, having hydrophobic subunits or lipid chains for this purpose. Their reconstitution on electrodes maintaining their natural structural characteristics allows for optimizing their electrocatalytic properties and stability. Different biomimetic strategies have been developed for modifying electrodes surfaces to accommodate membrane-bound enzymes, including the formation of self-assembled monolayers of hydrophobic compounds, lipid bilayers, or liposomes deposition. An overview of the different strategies used for the formation of biomimetic membranes, the reconstitution of membrane enzymes on electrodes, and their applications as biosensors is presented.
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Heinrich F, Kienzle PA, Hoogerheide DP, Lösche M. Information gain from isotopic contrast variation in neutron reflectometry on protein-membrane complex structures. J Appl Crystallogr 2020; 53:800-810. [PMID: 32684895 PMCID: PMC7312142 DOI: 10.1107/s1600576720005634] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/21/2020] [Indexed: 12/25/2022] Open
Abstract
A framework is applied to quantify information gain from neutron or X-ray reflectometry experiments [Treece, Kienzle, Hoogerheide, Majkrzak, Lösche & Heinrich (2019). J. Appl. Cryst. 52, 47-59], in an in-depth investigation into the design of scattering contrast in biological and soft-matter surface architectures. To focus the experimental design on regions of interest, the marginalization of the information gain with respect to a subset of model parameters describing the structure is implemented. Surface architectures of increasing complexity from a simple model system to a protein-lipid membrane complex are simulated. The information gain from virtual surface scattering experiments is quantified as a function of the scattering length density of molecular components of the architecture and the surrounding aqueous bulk solvent. It is concluded that the information gain is mostly determined by the local scattering contrast of a feature of interest with its immediate molecular environment, and experimental design should primarily focus on this region. The overall signal-to-noise ratio of the measured reflectivity modulates the information gain globally and is a second factor to be taken into consideration.
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Affiliation(s)
- Frank Heinrich
- Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-6102, USA
| | - Paul A. Kienzle
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-6102, USA
| | - David P. Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-6102, USA
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA
- Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-6102, USA
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA
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10
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Birchenough HL, Swann MJ, Zindy E, Day AJ, Jowitt TA. Enhanced avidin binding to lipid bilayers using PDP-PE lipids with PEG-biotin linkers. NANOSCALE ADVANCES 2020; 2:1625-1633. [PMID: 36132312 PMCID: PMC9417969 DOI: 10.1039/d0na00060d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/07/2020] [Indexed: 06/15/2023]
Abstract
Two of the most important aspects of lipid bilayers that have increased their popularity in the field of nanotechnology and biosensors are their fluid nature, which is highly beneficial in ensuring the spatial organization of attached molecules, and the relative ease in which they can be manipulated to change the surface chemistry. Here we have used two different types of functionalized lipids to study the interaction of avidin, which is a common approach to attach further ligands for study. We have tested the commonly used Biotinyl-Cap-PE lipids at different molar percentages and reveal that avidin is not evenly distributed, but forms what looks like clusters even at low percentage occupancy which hampers the level of avidin that can be associated with the surface. We have then successfully employed the novel strategy of using PDP-PE lipids which contain a reducible disulphide to which we added maleamide-PEG-biotin spacers of different lengths. There is a more even distribution of avidin on these layers and thereby increasing the amount and efficiency of avidin association. The reduced levels of avidin that was being associated with the Biotinyl-Cap-PE layers as compared to the PDP-PE lipids could be analysed with QCM-D and interferometry approaches, but it was only with SEEC microscopy that the reason for the reduced occupancy was resolved.
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Affiliation(s)
| | - Marcus J Swann
- Swann Scientific Consulting Ltd 110 Sandy Lane Lymm WA13 9HR UK
| | - Egor Zindy
- Wellcome Trust Centre for Cell-Matrix Research UK
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Electrochemical impedance of randomly distributed defects in tethered phospholipid bilayers: Finite element analysis. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2018.12.148] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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12
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Alghalayini A, Garcia A, Berry T, Cranfield CG. The Use of Tethered Bilayer Lipid Membranes to Identify the Mechanisms of Antimicrobial Peptide Interactions with Lipid Bilayers. Antibiotics (Basel) 2019; 8:antibiotics8010012. [PMID: 30704119 PMCID: PMC6466558 DOI: 10.3390/antibiotics8010012] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 01/29/2023] Open
Abstract
This review identifies the ways in which tethered bilayer lipid membranes (tBLMs) can be used for the identification of the actions of antimicrobials against lipid bilayers. Much of the new research in this area has originated, or included researchers from, the southern hemisphere, Australia and New Zealand in particular. More and more, tBLMs are replacing liposome release assays, black lipid membranes and patch-clamp electrophysiological techniques because they use fewer reagents, are able to obtain results far more quickly and can provide a uniformity of responses with fewer artefacts. In this work, we describe how tBLM technology can and has been used to identify the actions of numerous antimicrobial agents.
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Affiliation(s)
- Amani Alghalayini
- School of Life Science, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Alvaro Garcia
- School of Life Science, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Thomas Berry
- School of Life Science, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Charles G Cranfield
- School of Life Science, University of Technology Sydney, Ultimo, NSW 2007, Australia.
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Nikouee A, Uchida K, Moench I, Lopatin AN. Cholesterol Protects Against Acute Stress-Induced T-Tubule Remodeling in Mouse Ventricular Myocytes. Front Physiol 2018; 9:1516. [PMID: 30483142 PMCID: PMC6240595 DOI: 10.3389/fphys.2018.01516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/09/2018] [Indexed: 12/28/2022] Open
Abstract
Efficient excitation-contraction coupling in ventricular myocytes depends critically on the presence of the t-tubular network. It has been recently demonstrated that cholesterol, a major component of the lipid bilayer, plays an important role in long-term maintenance of the integrity of t-tubular system although mechanistic understanding of underlying processes is essentially lacking. Accordingly, in this study we investigated the contribution of membrane cholesterol to t-tubule remodeling in response to acute hyposmotic stress. Experiments were performed using isolated left ventricular cardiomyocytes from adult mice. Depletion and restoration of membrane cholesterol was achieved by applying methyl-β-cyclodextrin (MβCD) and water soluble cholesterol (WSC), respectively, and t-tubule remodeling in response to acute hyposmotic stress was assessed using fluorescent dextran trapping assay and by measuring t-tubule dependent IK1 tail current (IK1,tail). The amount of dextran trapped in t-tubules sealed in response to stress was significantly increased when compared to control cells, and reintroduction of cholesterol to cells treated with MβCD restored the amount of trapped dextran to control values. Alternatively, application of WSC to normal cells significantly reduced the amount of trapped dextran further suggesting the protective effect of cholesterol. Importantly, modulation of membrane cholesterol (without osmotic stress) led to significant changes in various parameters of IK1, tail strongly suggesting significant but essentially hidden remodeling of t-tubules prior to osmotic stress. Results of this study demonstrate that modulation of the level of membrane cholesterol has significant effects on the susceptibility of cardiac t-tubules to acute hyposmotic stress.
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Affiliation(s)
- Azadeh Nikouee
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Keita Uchida
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Ian Moench
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Anatoli N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
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Ragaliauskas T, Mickevicius M, Rakovska B, Penkauskas T, Vanderah DJ, Heinrich F, Valincius G. Fast formation of low-defect-density tethered bilayers by fusion of multilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:669-678. [PMID: 28088448 DOI: 10.1016/j.bbamem.2017.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/19/2016] [Accepted: 01/10/2017] [Indexed: 10/20/2022]
Abstract
A facile and reproducible preparation of surface-supported lipid bilayers is essential for fundamental membrane research and biotechnological applications. We demonstrate that multilamellar vesicles fuse to molecular-anchor-grafted surfaces yielding low-defect-density, tethered bilayer membranes. Continuous bilayers are formed within 10min, while the electrically insulating bilayers with <0.1μm-2 defect density can be accomplished within 60min. Surface plasmon resonance spectroscopy indicates that an amount of lipid material transferred from vesicles to a surface is inversely proportional to the density of an anchor, while the total amount of lipid that includes tethered and transferred lipid remains constant within 5% standard error. This attests for the formation of intact bilayers independent of the tethering agent density. Neutron reflectometry (NR) revealed the atomic level structural details of the tethered bilayer showing, among other things, that the total thickness of the hydrophobic slab of the construct was 3.2nm and that the molar fraction of cholesterol in lipid content is essentially the same as the molar fraction of cholesterol in the multilamellar liposomes. NR also indicated the formation of an overlayer with an effective thickness of 1.9nm. These overlayers may be easily removed by a single rinse of the tethered construct with 30% ethanol solution. Fast assembly and low residual defect density achievable within an hour of fusion makes our tethered bilayer methodology an attractive platform for biosensing of membrane damaging agents, such as pore forming toxins.
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Affiliation(s)
- Tadas Ragaliauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Mindaugas Mickevicius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Bozena Rakovska
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Tadas Penkauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - David J Vanderah
- Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
| | - Frank Heinrich
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Gintaras Valincius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania.
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Valiūnienė A, Petrulionienė T, Balevičiūtė I, Mikoliūnaitė L, Valinčius G. Formation of hybrid bilayers on silanized thin-film Ti electrode. Chem Phys Lipids 2016; 202:62-68. [PMID: 27964891 DOI: 10.1016/j.chemphyslip.2016.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/01/2016] [Accepted: 12/05/2016] [Indexed: 11/29/2022]
Abstract
Phospholipid bilayer membranes are essential elements of living organisms as they form boundaries between the intracellular cytoplasm and the extracellular environment, as well as organelles. In this work we report on our attempts to assemble artificial phospholipid bilayer model membranes on Ti surface. To provide hydrophobic cushion for phospholipids, the surface of a thin-film Ti electrode was initially functionalized with trichloro(octadecyl)silane (OTS). Increased hydrophobicity of the solid support allowed vesicle fusion and the formation of a hybrid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer, as probed by the electrochemical impedance spectroscopy (EIS), contact angle measurements (CA) also by the Fourier transform-infrared (FT-IR) spectroscopy, spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). Our study demonstrates the applicability of thin-film Ti electrodes for the formation of hybrid bilayer membranes. These membranes allow functional reconstitution of the pore-forming toxins and provide a bioanalytical platform for the detection of the activity of the cholesterol-dependent cytolysins.
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Affiliation(s)
- A Valiūnienė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania.
| | - T Petrulionienė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - I Balevičiūtė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - L Mikoliūnaitė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - G Valinčius
- Department of Chemistry and Bioengineering, Vilnius Gedimino Technical University, Sauletekio al. 11, LT-10223, Vilnius, Lithuania
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16
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Membrane Binding of HIV-1 Matrix Protein: Dependence on Bilayer Composition and Protein Lipidation. J Virol 2016; 90:4544-4555. [PMID: 26912608 DOI: 10.1128/jvi.02820-15] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/15/2016] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED By assembling in a protein lattice on the host's plasma membrane, the retroviral Gag polyprotein triggers formation of the viral protein/membrane shell. The MA domain of Gag employs multiple signals--electrostatic, hydrophobic, and lipid-specific-to bring the protein to the plasma membrane, thereby complementing protein-protein interactions, located in full-length Gag, in lattice formation. We report the interaction of myristoylated and unmyristoylated HIV-1 Gag MA domains with bilayers composed of purified lipid components to dissect these complex membrane signals and quantify their contributions to the overall interaction. Surface plasmon resonance on well-defined planar membrane models is used to quantify binding affinities and amounts of protein and yields free binding energy contributions, ΔG, of the various signals. Charge-charge interactions in the absence of the phosphatidylinositide PI(4,5)P2 attract the protein to acidic membrane surfaces, and myristoylation increases the affinity by a factor of 10; thus, our data do not provide evidence for a PI(4,5)P2 trigger of myristate exposure. Lipid-specific interactions with PI(4,5)P2, the major signal lipid in the inner plasma membrane, increase membrane attraction at a level similar to that of protein lipidation. While cholesterol does not directly engage in interactions, it augments protein affinity strongly by facilitating efficient myristate insertion and PI(4,5)P2 binding. We thus observe that the isolated MA protein, in the absence of protein-protein interaction conferred by the full-length Gag, binds the membrane with submicromolar affinities. IMPORTANCE Like other retroviral species, the Gag polyprotein of HIV-1 contains three major domains: the N-terminal, myristoylated MA domain that targets the protein to the plasma membrane of the host; a central capsid-forming domain; and the C-terminal, genome-binding nucleocapsid domain. These domains act in concert to condense Gag into a membrane-bounded protein lattice that recruits genomic RNA into the virus and forms the shell of a budding immature viral capsid. In binding studies of HIV-1 Gag MA to model membranes with well-controlled lipid composition, we dissect the multiple interactions of the MA domain with its target membrane. This results in a detailed understanding of the thermodynamic aspects that determine membrane association, preferential lipid recruitment to the viral shell, and those aspects of Gag assembly into the membrane-bound protein lattice that are determined by MA.
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Rakovska B, Ragaliauskas T, Mickevicius M, Jankunec M, Niaura G, Vanderah DJ, Valincius G. Structure and function of the membrane anchoring self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:846-857. [PMID: 25525904 DOI: 10.1021/la503715b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Structure of the self-assembled monolayers (SAMs) used to anchor phospholipid bilayers to surfaces affects the functional properties of the tethered bilayer membranes (tBLMs). SAMs of the same surface composition differing in the lateral distribution of the anchor molecule give rise to tBLMs of profoundly different defectiveness with residual conductance spanning 3 orders of magnitude. SAMs composed of anchors containing saturated alkyl chains, upon exposure to water (72 h), reconstruct to tightly packed clusters as deduced from reflection absorption infrared spectroscopy data and directly visualized by atomic force microscopy. The rearrangement into clusters results in an inability to establish highly insulating tBLMs on the same anchor layer. Unexpectedly, we also found that nanometer scale smooth gold film surfaces, populated predominantly with (111) facets, exhibit poor performance from the standpoint of the defectiveness of the anchored phospholipid bilayers, while corrugated (110) dominant surfaces produced SAMs with superior tethering quality. Although the detailed mechanism of cluster formation remains to be clarified, it appears that smooth surfaces favor lateral translocation of the molecular anchors, resulting in changes in functional properties of the SAMs. This work unequivocally establishes that conditions that favor cluster formation of the anchoring molecules in tBLM formation must be identified and avoided for the functional use of tBLMs in biomedical and diagnostic applications.
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Affiliation(s)
- Bozena Rakovska
- Institute of Biochemistry, Vilnius University , Mokslininku 12, Vilnius 08662, Lithuania
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18
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Valincius G, Mickevicius M. Tethered Phospholipid Bilayer Membranes. ADVANCES IN PLANAR LIPID BILAYERS AND LIPOSOMES 2015. [DOI: 10.1016/bs.adplan.2015.01.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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19
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Nanda H, Heinrich F, Lösche M. Membrane association of the PTEN tumor suppressor: neutron scattering and MD simulations reveal the structure of protein-membrane complexes. Methods 2014; 77-78:136-46. [PMID: 25461777 DOI: 10.1016/j.ymeth.2014.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 12/31/2022] Open
Abstract
Neutron reflection (NR) from planar interfaces is an emerging technology that provides unique and otherwise inaccessible structural information on disordered molecular systems such as membrane proteins associated with fluid bilayers, thus addressing one of the remaining challenges of structural biology. Although intrinsically a low-resolution technique, using structural information from crystallography or NMR allows the construction of NR models that describe the architecture of protein-membrane complexes at high resolution. In addition, a combination of these methods with molecular dynamics (MD) simulations has the potential to reveal the dynamics of protein interactions with the bilayer in atomistic detail. We review recent advances in this area by discussing the application of these techniques to the complex formed by the PTEN phosphatase with the plasma membrane. These studies provide insights in the cellular regulation of PTEN, its interaction with PI(4,5)P2 in the inner plasma membrane and the pathway by which its substrate, PI(3,4,5)P3, accesses the PTEN catalytic site.
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Affiliation(s)
- Hirsh Nanda
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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20
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Heinrich F, Lösche M. Zooming in on disordered systems: neutron reflection studies of proteins associated with fluid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:2341-9. [PMID: 24674984 PMCID: PMC4082750 DOI: 10.1016/j.bbamem.2014.03.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 11/23/2022]
Abstract
Neutron reflectometry (NR) is an emerging experimental technique for the structural characterization of proteins interacting with fluid bilayer membranes under conditions that mimic closely the cellular environment. Thus, cellular processes can be emulated in artificial systems and their molecular basis studied by adding cellular components one at a time in a well-controlled environment while the resulting structures, or structural changes in response to external cues, are monitored with neutron reflection. In recent years, sample environments, data collection strategies and data analysis were continuously refined. The combination of these improvements increases the information which can be obtained from NR to an extent that enables structural characterization of protein-membrane complexes at a length scale that exceeds the resolution of the measurement by far. Ultimately, the combination of NR with molecular dynamics (MD) simulations can be used to cross-validate the results of the two techniques and provide atomic-scale structural models. This review discusses these developments in detail and demonstrates how they provide new windows into relevant biomedical problems. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
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Affiliation(s)
- Frank Heinrich
- Physics Department, Carnegie Mellon University, Pittsburgh, PA, U.S.A.; NIST Center for Neutron Research, Gaithersburg, MD, U.S.A
| | - Mathias Lösche
- Physics Department, Carnegie Mellon University, Pittsburgh, PA, U.S.A.; NIST Center for Neutron Research, Gaithersburg, MD, U.S.A..
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Visco I, Chiantia S, Schwille P. Asymmetric supported lipid bilayer formation via methyl-β-cyclodextrin mediated lipid exchange: influence of asymmetry on lipid dynamics and phase behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7475-84. [PMID: 24885372 DOI: 10.1021/la500468r] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Supported lipid bilayers (SLBs) are broadly used as minimal membrane models and commonly produced by vesicle fusion (VF) on solid supports. Despite its advantages, VF does not allow the controlled formation of bilayers that mimic the leaflet asymmetry in lipid composition normally found in biological systems. Here we present a simple, quick, and versatile method to produce SLBs with a desired asymmetric lipid composition which is stable for ca. 4 h. We apply methyl-β-cyclodextrin mediated lipid exchange to SLBs formed by VF to enrich the upper leaflet of the bilayer with sphingomyelin. The bilayer asymmetry is assessed by fluorescence correlation spectroscopy, measuring the lipid mobility separately in each leaflet. To check the compatibility of the method with the most common protein reconstitution approaches, we report the production of asymmetric SLBs (aSLBs) in the presence of a glycosylphosphatidylinositol-anchored protein, reconstituted in the bilayer both, via direct protein insertion, and via proteoliposomes fusion. We finally apply aSLBs to study phase separation and transbilayer lipid movement of raft-mimicking lipid mixtures. The observed differences in terms of phase separation in symmetric and asymmetric SLBs with the same overall lipid composition provide further experimental evidence that the transversal lipid distribution affects the overall lipid miscibility and allow to temporally investigate leaflet mixing.
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Affiliation(s)
- Ilaria Visco
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
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22
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Ragaliauskas T, Mickevicius M, Budvytyte R, Niaura G, Carbonnier B, Valincius G. Adsorption of β-amyloid oligomers on octadecanethiol monolayers. J Colloid Interface Sci 2014; 425:159-67. [PMID: 24776678 DOI: 10.1016/j.jcis.2014.03.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/14/2014] [Accepted: 03/15/2014] [Indexed: 10/25/2022]
Abstract
HYPOTHESIS β-Amyloid oligomers of different aggregation and physiological functions exhibit distinct adsorption behavior allowing them to be discriminated in preparations. EXPERIMENTS Two forms of amyloid oligomers, small 1-4 nm and large 5-10nm were formulated using synthetic 42 amino acids β-amyloid peptide. Forms differ in their size and physiological function. A systematic study of adsorption of these amyloid species on self-assembled monolayers of octadecanethiol on gold was performed. Structural changes upon adsorption of oligomers were interrogated by the reflection absorption infrared spectroscopy. FINDINGS The amount of adsorbed peptide material, as detected by surface plasmon resonance spectroscopy, is similar in case of both small and large oligomers. However, adsorption of small oligomers leads to a transformation from beta sheet rich to beta sheet depleted secondary structure. These changes were accompanied by the unique morphology patterns detectable by atomic force microscopy (AFM), while the quartz microbalance with dissipation indicated a formation of a compact adsorbate layer in case of small oligomers. These effects may be integrated and utilized in bioanalytical systems for sensing and detection of Alzheimer's disease related peptide forms in artificial, and possibly, real preparations.
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Affiliation(s)
- Tadas Ragaliauskas
- Institute of Biochemistry, Vilnius University, Mokslininku 12, LT-08662 Vilnius, Lithuania.
| | - Mindaugas Mickevicius
- Institute of Biochemistry, Vilnius University, Mokslininku 12, LT-08662 Vilnius, Lithuania.
| | - Rima Budvytyte
- Institute of Biochemistry, Vilnius University, Mokslininku 12, LT-08662 Vilnius, Lithuania.
| | - Gediminas Niaura
- Institute of Biochemistry, Vilnius University, Mokslininku 12, LT-08662 Vilnius, Lithuania.
| | - Benjamin Carbonnier
- Institut de Chimie et des Matériaux Paris-Est, Université Paris-Est, 2 rue Henri Dunant, 94320 Thiais, France.
| | - Gintaras Valincius
- Institute of Biochemistry, Vilnius University, Mokslininku 12, LT-08662 Vilnius, Lithuania.
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Budvytyte R, Pleckaityte M, Zvirbliene A, Vanderah DJ, Valincius G. Reconstitution of cholesterol-dependent vaginolysin into tethered phospholipid bilayers: implications for bioanalysis. PLoS One 2013; 8:e82536. [PMID: 24349307 PMCID: PMC3862629 DOI: 10.1371/journal.pone.0082536] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/24/2013] [Indexed: 11/18/2022] Open
Abstract
Functional reconstitution of the cholesterol-dependent cytolysin vaginolysin (VLY) from Gardnerella vaginalis into artificial tethered bilayer membranes (tBLMs) has been accomplished. The reconstitution of VLY was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes of the EIS parameters of the tBLMs upon exposure to VLY solutions were consistent with the formation of water-filled pores in the membranes. It was found that reconstitution of VLY is a strictly cholesterol-dependent, irreversible process. At a constant cholesterol concentration reconstitution of VLY occurred in a concentration-dependent manner, thus allowing the monitoring of VLY concentration and activity in vitro and opening possibilities for tBLM utilization in bioanalysis. EIS methodology allowed us to detect VLY down to 0.5 nM (28 ng/mL) concentration. Inactivation of VLY by certain amino acid substitutions led to noticeably lesser tBLM damage. Pre-incubation of VLY with the neutralizing monoclonal antibody 9B4 inactivated the VLY membrane damage in a concentration-dependent manner, while the non-neutralizing antibody 21A5 exhibited no effect. These findings demonstrate the biological relevance of the interaction between VLY and the tBLM. The membrane-damaging interaction between VLY and tBLM was observed in the absence of the human CD59 receptor, known to strongly facilitate the hemolytic activity of VLY. Taken together, our study demonstrates the applicability of tBLMs as a bioanalytical platform for the detection of the activity of VLY and possibly other cholesterol-dependent cytolysins.
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Affiliation(s)
- Rima Budvytyte
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
- Bio Complexity Department, The Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark
| | - Milda Pleckaityte
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Aurelija Zvirbliene
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - David J. Vanderah
- Biomolecular Structure and Function Group, National Institute of Standards and Technology at Institute of Bioscience and Biotechnology Research, Rockville, Maryland, United States of America
| | - Gintaras Valincius
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
- * E-mail:
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