1
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Influence of Phase Transitions on Diffusive Molecular Transport Across Biological Membranes. Angew Chem Int Ed Engl 2022; 61:e202205608. [DOI: 10.1002/anie.202205608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Indexed: 11/07/2022]
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2
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Wu T, Wilhelm MJ, Ma J, Li Y, Wu Y, Dai HL. Influence of Phase Transitions on Diffusive Molecular Transport Across Biological Membranes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tong Wu
- Temple University Department of Chemistry UNITED STATES
| | - Michael J. Wilhelm
- Temple University Department of Chemistry 1901 N. 13th Street 19122 Philadelphia UNITED STATES
| | - Jianqiang Ma
- Temple University Department of Chemistry UNITED STATES
| | - Yujie Li
- Temple University Department of Chemistry UNITED STATES
| | - Yuhao Wu
- Temple University Department of Chemistry UNITED STATES
| | - Hai-Lung Dai
- Temple University Department of Chemistry UNITED STATES
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3
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Martinez WE, Arenas JE, Mok L, Wong NY, Lozano MM, Lin WC, Gutierrez MG, Sierra Chavera R, McGivern JG. Bioelectronic Measurement of Target Engagement to a Membrane-Bound Transporter. SLAS DISCOVERY 2021; 26:1004-1013. [PMID: 33980065 DOI: 10.1177/24725552211013067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ability to detect and characterize drug binding to a target protein is of high priority in drug discovery research. However, there are inherent challenges when the target of interest is an integral membrane protein (IMP). Assuming successful purification of the IMP, traditional approaches for measuring binding such as surface plasmon resonance (SPR) and fluorescence resonance energy transfer (FRET) have been proven valuable. However, the mass dependence of SPR signals may preclude the detection of binding events when the ligand has a significantly smaller mass than the target protein. In FRET-based experiments, protein labeling through modification may inadvertently alter protein dynamics. Graphene Bio-Electronic Sensing Technology (GBEST) aims to overcome these challenges. Label-free characterization takes place in a microfluidic chamber wherein a fluid lipid membrane is reconstituted directly above the GBEST sensor surface. By leveraging the high conductivity, sensitivity, and electrical properties of monolayer graphene, minute changes in electrostatic charges arising from the binding and unbinding of a ligand to a native IMP target can be detected in real time and in a mass-independent manner. Using crude membrane fractions prepared from cells overexpressing monocarboxylate transporter 1 (MCT1), we demonstrate the ability to (1) form a fluid lipid bilayer enriched with MCT1 directly on top of the GBEST sensor and (2) obtain kinetic binding data for an anti-MCT1 antibody. Further development of this novel technology will enable characterization of target engagement by both low- and high-molecular-weight drug candidates to native IMP targets in a physiologically relevant membrane environment.
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Affiliation(s)
- William E Martinez
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Avalor Therapeutics, Seattle, WA, USA
| | - Jaime E Arenas
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA
| | - Leo Mok
- Discovery Technologies, Amgen Research, South San Francisco, CA, USA
| | - Ngo Yin Wong
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Ximedica, LLC, San Francisco, CA, USA
| | - Monica M Lozano
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Profusa, Inc., Emeryville, CA, USA
| | - Wan-Chen Lin
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Imgenix Corp., Paoli, PA, USA
| | - M Gertrude Gutierrez
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Pharmaceutical Science & Technology, AstraZeneca, South San Francisco, CA, USA
| | - Rodrigo Sierra Chavera
- Research and Development, Nanotech Biomachines, Inc., Richmond, CA, USA.,Sierra Intelligence, Bahrain
| | - Joseph G McGivern
- Discovery Technologies, Amgen Research, South San Francisco, CA, USA.,Denali Therapeutics, South San Francisco, CA, USA
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4
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Understanding the formation of supported lipid bilayers via vesicle fusion—A case that exemplifies the need for the complementary method approach (Review). Biointerphases 2016; 11:020801. [DOI: 10.1116/1.4944830] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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5
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Lind TK, Wacklin H, Schiller J, Moulin M, Haertlein M, Pomorski TG, Cárdenas M. Formation and Characterization of Supported Lipid Bilayers Composed of Hydrogenated and Deuterated Escherichia coli Lipids. PLoS One 2015; 10:e0144671. [PMID: 26658241 PMCID: PMC4676697 DOI: 10.1371/journal.pone.0144671] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/20/2015] [Indexed: 01/26/2023] Open
Abstract
Supported lipid bilayers are widely used for sensing and deciphering biomolecular interactions with model cell membranes. In this paper, we present a method to form supported lipid bilayers from total lipid extracts of Escherichia coli by vesicle fusion. We show the validity of this method for different types of extracts including those from deuterated biomass using a combination of complementary surface sensitive techniques; quartz crystal microbalance, neutron reflection and atomic force microscopy. We find that the head group composition of the deuterated and the hydrogenated lipid extracts is similar (approximately 75% phosphatidylethanolamine, 13% phosphatidylglycerol and 12% cardiolipin) and that both samples can be used to reconstitute high-coverage supported lipid bilayers with a total thickness of 41 ± 3 Å, common for fluid membranes. The formation of supported lipid bilayers composed of natural extracts of Escherichia coli allow for following biomolecular interactions, thus advancing the field towards bacterial-specific membrane biomimics.
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Affiliation(s)
- Tania Kjellerup Lind
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
- European Spallation Source ESS AB, Lund, Sweden
| | - Hanna Wacklin
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
- European Spallation Source ESS AB, Lund, Sweden
| | - Jürgen Schiller
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Martine Moulin
- Institut Laue-Langevin, Life Science Group, Grenoble, France
| | | | - Thomas Günther Pomorski
- Centre for Membrane Pumps in Cells and Disease—PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marité Cárdenas
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
- Malmoe University, Department of Biomedical Sciences, Health & Society, 20500 Malmoe, Sweden
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6
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Taylor GJ, Sarles SA. Heating-enabled formation of droplet interface bilayers using Escherichia coli total lipid extract. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:325-37. [PMID: 25514167 DOI: 10.1021/la503471m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Droplet interface bilayers (DIBs) serve as a convenient platform to study interactions between synthetic lipid membranes and proteins. However, a majority of DIBs have been assembled using a single lipid type, diphytanoylphosphatidylcholine (DPhPC). The work described herein establishes a new method to assemble DIBs using total lipid extract from Escherichia coli (eTLE); it is found that incubating oil-submerged aqueous droplets containing eTLE liposomes at a temperature above the gel-fluid phase transition temperature (Tg) promotes monolayer self-assembly that does not occur below Tg. Once monolayers are properly assembled via heating, droplets can be directly connected or cooled below Tg and then connected to initiate bilayer formation. This outcome contrasts immediate droplet coalescence observed upon contact between nonheated eTLE-infused droplets. Specific capacitance measurements confirm that the interface between droplets containing eTLE lipids is a lipid bilayer with thickness of 29.6 Å at 25 °C in hexadecane. We observe that bilayers formed from eTLE or DPhPC survive cooling and heating between 25 and 50 °C and demonstrate gigaohm (GΩ) membrane resistances at all temperatures tested. Additionally, we study the insertion of alamethicin peptides into both eTLE and DPhPC membranes to understand how lipid composition, temperature, and membrane phase influence ion channel formation. Like in DPhPC bilayers, alamethicin peptides in eTLE exhibit discrete, voltage-dependent gating characterized by multiple open channel conductance levels, though at significantly lower applied voltages. Cyclic voltammetry measurements of macroscopic channel currents confirm that the voltage-dependent conductance of alamethicin channels in eTLE bilayers occurs at lower voltages than in DPhPC bilayers at equivalent peptide concentrations. This result suggests that eTLE membranes, via composition, fluidity, or the presence of subdomains, offer an environment that enhances alamethicin insertion. For both membrane compositions, increasing temperature reduces the lifetimes of single channel gating events and increases the voltage required to cause an exponential increase in channel current. However, the fact that alamethicin insertion in eTLE exhibits significantly greater sensitivity to temperature changes through its Tg suggests that membrane phase plays an important role in channel formation. These effects are much less severe in DPhPC, where heating from 25 to 50 °C does not induce a phase change. The described technique for heating-assisted monolayer formation permits the use of other high transition temperature lipids in aqueous droplets for DIB formation, thereby increasing the types of lipids that can be considered for assembling model membranes.
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Affiliation(s)
- Graham J Taylor
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
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7
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Lind TK, Cárdenas M, Wacklin HP. Formation of Supported Lipid Bilayers by Vesicle Fusion: Effect of Deposition Temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7259-63. [PMID: 24932971 DOI: 10.1021/la500897x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- Tania Kjellerup Lind
- Nano-Science
Center and Institute of Chemistry, Copenhagen University, Copenhagen, Denmark
- European Spallation
Source ESS AB, Lund, Sweden
| | - Marité Cárdenas
- Nano-Science
Center and Institute of Chemistry, Copenhagen University, Copenhagen, Denmark
- Malmoe University, Health & Society, 20506 Malmoe, Sweden
| | - Hanna Pauliina Wacklin
- Nano-Science
Center and Institute of Chemistry, Copenhagen University, Copenhagen, Denmark
- European Spallation
Source ESS AB, Lund, Sweden
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8
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Lopes SC, Neves CS, Eaton P, Gameiro P. Improved model systems for bacterial membranes from differing species: Theimportance of varying composition in PE/PG/cardiolipin ternary mixtures. Mol Membr Biol 2012; 29:207-17. [DOI: 10.3109/09687688.2012.700491] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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9
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Abstract
Monoglyceride esters of fatty acids occur naturally and encompass a broad spectrum of antimicrobial activity. Monocaprylate is generally regarded as safe (GRAS) and can function both as an emulsifier and as a preservative in food. However, knowledge about its mode of action is lacking. The aim of this study was therefore to elucidate the mechanism behind monocaprylate's antimicrobial effect. The cause of cell death in Escherichia coli, Staphylococcus xylosus, and Zygosaccharomyces bailii was investigated by examining monocaprylate's effect on cell structure, membrane integrity, and its interaction with model membranes. Changes in cell structure were visible by atomic force microscopy (AFM), and propidium iodide staining showed membrane disruption, indicating the membrane as a site of action. This indication was confirmed by measuring calcein leakage from membrane vesicles exposed to monocaprylate. AFM imaging of supported lipid bilayers visualized the integration of monocaprylate into the liquid disordered, and not the solid ordered, phase of the membrane. The integration of monocaprylate was confirmed by quartz crystal microbalance measurements, showing an abrupt increase in mass and hydration of the membrane after exposure to monocaprylate above a threshold concentration. We hypothesize that monocaprylate destabilizes membranes by increasing membrane fluidity and the number of phase boundary defects. The sensitivity of cells to monocaprylate will therefore depend on the lipid composition, fluidity, and curvature of the membrane.
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10
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Gröger T, Nathoo S, Ku T, Sikora C, Turner RJ, Prenner EJ. Real-time imaging of lipid domains and distinct coexisting membrane protein clusters. Chem Phys Lipids 2011; 165:216-24. [PMID: 22227110 DOI: 10.1016/j.chemphyslip.2011.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 12/15/2011] [Accepted: 12/19/2011] [Indexed: 12/20/2022]
Abstract
A detailed understanding of biomembrane architecture is still a challenging task. Many in vitro studies have shown lipid domains but much less information is known about the lateral organization of membrane proteins because their hydrophobic nature limits the use of many experimental methods. We examined lipid domain formation in biomimetic Escherichia coli membranes composed of phosphatidylethanolamine and phosphatidylglycerol in the absence and presence of 1% and 5% (mol/mol) membrane multidrug resistance protein, EmrE. Monolayer isotherms demonstrated protein insertion into the lipid monolayer. Subsequently, Brewster angle microscopy was applied to image domains in lipid matrices and lipid-protein mixtures. The images showed a concentration dependent impact of the protein on lipid domain size and shape and more interestingly distinct coexisting protein clusters. Whereas lipid domains varied in size (14-47μm), protein clusters exhibited a narrow size distribution (2.6-4.8μm) suggesting a non-random process of cluster formation. A 3-D display clearly indicates that these proteins clusters protrude from the membrane plane. These data demonstrate distinct co-existing lipid domains and membrane protein clusters as the monofilm is being compressed and illustrate the significant mutual impact of lipid-protein interactions on lateral membrane architecture.
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Affiliation(s)
- Thomas Gröger
- Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherbeg, Germany
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11
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Zhong J. From simple to complex: investigating the effects of lipid composition and phase on the membrane interactions of biomolecules using in situ atomic force microscopy. Integr Biol (Camb) 2011; 3:632-44. [DOI: 10.1039/c0ib00157k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Lopes S, Neves CS, Eaton P, Gameiro P. Cardiolipin, a key component to mimic the E. coli bacterial membrane in model systems revealed by dynamic light scattering and steady-state fluorescence anisotropy. Anal Bioanal Chem 2010; 398:1357-66. [PMID: 20680614 DOI: 10.1007/s00216-010-4028-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 07/11/2010] [Accepted: 07/12/2010] [Indexed: 12/01/2022]
Abstract
The phase transition temperatures of several lipidic systems were determined using two different techniques: dynamic light scattering (DLS) and steady-state fluorescence anisotropy, using two fluorescent probes that report different membrane regions (TMA-DPH and DPH). Atomic force microscopy (AFM) was used as a complementary technique to characterize different lipid model systems under study. The systems were chosen due to the increased interest in bacterial membrane studies due to the problem of antibiotic drug resistance. The simpler models studied comprised of mixtures of POPE and POPG lipids, which form a commonly used model system for Escherichia coli membranes. Given the important role of cardiolipin (CL) in natural membranes, a ternary model system, POPE/POPG/CL, was then considered. The results obtained in these mimetic systems were compared with those obtained for the natural systems E. coli polar and total lipid extract. DLS and fluorescence anisotropy are not commonly used to study lipid phase transitions, but it was shown that they can give useful information about the thermotropic behaviors of model systems for bacterial membranes. These two techniques provided very similar results, validating their use as methods to measure phase transitions in lipid model systems. The temperature transitions obtained from these two very different techniques and the AFM results clearly show that cardiolipin is a fundamental component to mimic bacteria membranes. The results suggest that the less commonly used ternary system is a considerably better mimic for natural E. coli membranes than binary lipid mixture.
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Affiliation(s)
- S Lopes
- Requimte, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
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13
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The role of calcium ions in the interactions of PrP106-126 amide with model membranes. Colloids Surf B Biointerfaces 2010; 77:40-6. [DOI: 10.1016/j.colsurfb.2010.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 12/30/2009] [Accepted: 01/03/2010] [Indexed: 11/24/2022]
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14
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Lateral heterogeneities in supported bilayers from pure and mixed phosphatidylethanolamine demonstrating hydrogen bonding capacity. Biointerphases 2010; 3:96-104. [PMID: 20408706 DOI: 10.1116/1.3040158] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The phase behavior and lateral organization of saturated phosphatidylethanolamine (PE) and phosphatidylcholine (PC) bilayers were investigated using atomic force microscopy (AFM) and force-volume (FV) imaging for both pure and two component mixed layers. The results demonstrated the existence of unexpected segregated domains in pure PE membranes at temperatures well below the transition temperature (T(m)) of the component phospholipid. These domains were of low mechanical stability and lacked the capacity for hydrogen bonding between lipid headgroups. Temperature dependent studies for different PC/PE ratios using AFM also demonstrated the mixing of these phospholipid bilayers to exhibit only a single gel to liquid transition temperature. Further work performed using FV imaging and chemically modified probes established that no lipid segregation exists at the PC/PE ratios investigated.
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15
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AFM study of the interaction of cytochrome P450 2C9 with phospholipid bilayers. Chem Phys Lipids 2010; 163:182-9. [DOI: 10.1016/j.chemphyslip.2009.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 08/07/2009] [Accepted: 11/09/2009] [Indexed: 11/18/2022]
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16
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Domenech O, Francius G, Tulkens PM, Van Bambeke F, Dufrêne Y, Mingeot-Leclercq MP. Interactions of oritavancin, a new lipoglycopeptide derived from vancomycin, with phospholipid bilayers: Effect on membrane permeability and nanoscale lipid membrane organization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1832-40. [DOI: 10.1016/j.bbamem.2009.05.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/25/2009] [Accepted: 05/05/2009] [Indexed: 11/25/2022]
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17
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The interactions between phosphatidylglycerol and phosphatidylethanolamines in model bacterial membranes. Colloids Surf B Biointerfaces 2009; 72:32-9. [DOI: 10.1016/j.colsurfb.2009.03.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 03/08/2009] [Accepted: 03/17/2009] [Indexed: 11/24/2022]
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18
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Chalmeau J, Dagkessamanskaia A, Le Grimellec C, Francois JM, Sternick J, Vieu C. Contribution to the elucidation of the structure of the bacterial flagellum nano-motor through AFM imaging of the M-Ring. Ultramicroscopy 2009; 109:845-53. [DOI: 10.1016/j.ultramic.2009.03.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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19
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Boumann HA, Stroeve P, Longo ML, Poolman B, Kuiper JM, Hopmans EC, Jetten MS, Sinninghe Damsté JS, Schouten S. Biophysical properties of membrane lipids of anammox bacteria: II. Impact of temperature and bacteriohopanoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1452-7. [DOI: 10.1016/j.bbamem.2009.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2008] [Revised: 03/31/2009] [Accepted: 04/08/2009] [Indexed: 10/20/2022]
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20
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Erickson B, DiMaggio S, Mullen DG, Kelly CV, Leroueil PR, Berry SA, Baker JR, Orr BG, Banaszak Holl MM. Interactions of poly(amidoamine) dendrimers with Survanta lung surfactant: the importance of lipid domains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11003-11008. [PMID: 18763817 PMCID: PMC2917325 DOI: 10.1021/la801497d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The interaction of generation 5 (G5) and 7 (G7) poly(amidoamine) (PAMAM) dendrimers with mica-supported Survanta bilayers is studied with atomic force microscopy (AFM). In these experiments, Survanta forms distinct gel and fluid domains with differing lipid composition. Nanoscale defects are induced by the PAMAM dendrimers. The positively charged dendrimers remove lipid from the fluid domains at a significantly greater rate than for the gel domains. Dendrimer accumulation on lipid edges and terraces preceding lipid removal has been directly imaged. Immediately following lipid removal, the mica surface is clean, indicating that lipid defects are not induced by dendrimers binding to the mica substrate and displacing the lipid.
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Affiliation(s)
| | | | | | | | | | | | | | - Bradford G. Orr
- To whom correspondence should be addressed. Phone: 734-936-3609(B.G.O);734-763-2283(M.M.B.H.). (B.G.O.); (M.M.B.H.)
| | - Mark M. Banaszak Holl
- To whom correspondence should be addressed. Phone: 734-936-3609(B.G.O);734-763-2283(M.M.B.H.). (B.G.O.); (M.M.B.H.)
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Domènech O, Redondo L, Picas L, Morros A, Montero MT, Hernández-Borrell J. Atomic force microscopy characterization of supported planar bilayers that mimic the mitochondrial inner membrane. J Mol Recognit 2008; 20:546-53. [PMID: 17907278 DOI: 10.1002/jmr.849] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this study we examined the properties of supported planar bilayers (SPBs) formed from phospholipid components that comprise the mitochondrial inner membrane. We used 1-palmitoyl-2-oleoyl-sn-glycero- 3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and cardiolipin (CL). Liposomes of binary POPE:POPC (1:1, mol:mol) and ternary (POPE:POPC:CL (0.5:0.3:0.2, mol:mol:mol) composition were used in the formation of SPBs on mica. The characterization of the SPBs was carried out below (4 degrees C) and above (24 and 37 degrees C) the phase transition temperature (Tm) of the mixtures in solution. We observed: (i) that the thickness of the bilayers, calculated from a cross-sectional analysis, decreased as the visualization temperature increased; (ii) the existence of laterally segregated domains that respond to temperature in SPBs of POPE:POPC:CL; (iii) a decrease in height and an increase in roughness (Ra) of SPBs after cytochrome c (cyt c) injection at room temperature. To obtain further insight into the nature of the interaction between cyt c and the bilayers, the competition between 8-anilino-1-naphthalene sulfonate (ANS) and the protein for the same binding sites in liposomes was monitored by fluorescence. The results confirm the existence of preferential interaction of cyt c with CL containing liposomes. Taking these results and those of previous papers published by the group, we discuss the preferential adsorption of cyt c in CL domains. This provides support for the relevance of these phospholipids as a proton trap in the oxidative phosphorylation process that occurs in the energy transducing membranes.
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Affiliation(s)
- Oscar Domènech
- Departament de Química-Física, Facultat de Química, Universitat de Barcelona 08028-Barcelona Spain
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22
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Topography and functional information of plasma membrane. ACTA ACUST UNITED AC 2008; 51:95-103. [DOI: 10.1007/s11427-008-0007-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 11/11/2007] [Indexed: 11/26/2022]
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23
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Montero MT, Pijoan M, Merino-Montero S, Vinuesa T, Hernández-Borrell J. Interfacial membrane effects of fluoroquinolones as revealed by a combination of fluorescence binding experiments and atomic force microscopy observations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7574-8. [PMID: 16922535 DOI: 10.1021/la060633c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
6-Fluoroquinolones are useful antimicrobial agents against gram-positive and gram-negative bacteria and some mycobacterial species as well. Although the diffusion through porins in gram-negative bacteria is well established, other mechanisms such as the hydrophobic pathway through the apolar regions of the bilayer and the self-promoted pathway appear to be relevant or concomitant with the hydrophilic pathway in many cases. This article discusses the interaction of ciprofloxacin (CPX) and two new synthesized compounds (M3CPX and M4CPX)-with a methyl group attached at the N3 and N4 positions of the piperazynil ring of the CPX-with liposomes and supported planar bilayers (SPBs) of Escherichia coli. Binding experiments using ANS revealed that the three compounds interact electrostatically with the bilayer. The variations in the electrostatic surface potential, which is always positive, were higher for M3CPX than for CPX or M4CPX. Related to that, the SPBs of E. coli were more affected by M3CPX than by the other two compounds, as judged by the analysis of the atomic force microcopy (AFM) images. The in situ injection of the three 6-fluoroquinolones (6-FQs) induced different changes in height, roughness (Ra), and area covered by the SPBs.
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Affiliation(s)
- M Teresa Montero
- Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, E-08028 Barcelona, Spain
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24
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Domènech O, Morros A, Cabañas ME, Teresa Montero M, Hernández-Borrell J. Supported planar bilayers from hexagonal phases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:100-6. [PMID: 16860290 DOI: 10.1016/j.bbamem.2006.06.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 06/02/2006] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
In this work the presence of inverted hexagonal phases H(II) of 1-palmitoy-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and cardiolipin (CL) (0.8:0.2, mol/mol) in the presence of Ca(2+) were observed via (31)P-NMR spectroscopy. When suspensions of the same composition were extended onto mica, H(II) phases transformed into structures which features are those of supported planar bilayers (SPBs). When characterized by atomic force microscopy (AFM), the SPBs revealed the existence of two laterally segregated domains (the interdomain height being approximately 1 nm). Cytochrome c (cyt c), which binds preferentially to acidic phospholipids like CL, was used to demonstrate the nature of the domains. We used 1-anilinonaphtalen-8-sulfonate (ANS) to demonstrate that in the presence of cyt c, the fluorescence of ANS decreased significantly in lamellar phases. Conversely, the ANS binding to H(II) phases was negligible. When cyt c was injected into AFM fluid imaging cells, where SPBs of POPE:CL had previously formed poorly defined structures, protein aggregates ( approximately 100 nm diameter) were ostensibly observed only on the upper domains, which suggests not only that they are mainly formed by CL, but also provides evidence of bilayer formation from H(II) phases. Furthermore, a model for the nanostructure of the SPBs is herein proposed.
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Affiliation(s)
- Oscar Domènech
- Departament de Química-Física, Facultat de Química, Spain
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Domènech O, Sanz F, Montero MT, Hernández-Borrell J. Thermodynamic and structural study of the main phospholipid components comprising the mitochondrial inner membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:213-21. [PMID: 16556434 DOI: 10.1016/j.bbamem.2006.02.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 01/24/2006] [Accepted: 02/07/2006] [Indexed: 11/26/2022]
Abstract
Cardiolipin (CL) is a phospholipid found in the energy-transducing membranes of bacteria and mitochondria and it is thought to be involved in relevant biological processes as apoptosis. In this work, the mixing properties of CL and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocoline (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) at the air-water interface, have been examined using the thermodynamic framework analysis of compression isotherms. Accordingly, the values of the Gibbs energy of mixing, the more stable monolayers assayed were: POPC:CL (0.6:0.4, mol:mol) and POPE:CL (0.8:0.2, mol:mol). The results reflect that attractive forces are the greatest contributors to the total interaction in these compositions. Supported planar bilayers (SPBs) with such compositions were examined using atomic force microscopy (AFM) at different temperatures. With the POPC:CL mixture, rounded and featureless SPBs were obtained at 4 degrees C and 24 degrees C. In contrast, the extension of the POPE:CL mixture revealed the existence of different lipid domains at 24 degrees C and 37 degrees C. Three lipid domains coexisted which can be distinguished by measuring the step height difference between the uncovered mica and the bilayer. While the low and intermediate domains were temperature dependent, the high domain was composition dependent. When cytochrome c (cyt c) was injected into the fluid cell, the protein showed a preferential adsorption onto the high domain of the POPC:CL. These results suggest that the high domain is mainly formed by CL.
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Affiliation(s)
- Oscar Domènech
- Departament de Química Física, U.B. 08028-Barcelona, Spain
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