1
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Liu TT, Huang SH, Chao L. Rapid Enrichment of a Native Multipass Transmembrane Protein via Cell Membrane Electrophoresis through Buffer pH and Ionic Strength Adjustment. J Am Chem Soc 2024; 146:11634-11647. [PMID: 38628144 PMCID: PMC11066866 DOI: 10.1021/jacs.3c13579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 05/02/2024]
Abstract
Supported membrane electrophoresis is a promising technique for collecting membrane proteins in native bilayer environments. However, the slow mobility of typical transmembrane proteins has impeded the technique's advancement. Here, we successfully applied cell membrane electrophoresis to rapidly enrich a 12-transmembrane helix protein, glucose transporter 1 with antibodies (GLUT1 complex), by tuning the buffer pH and ionic strength. The identified conditions allowed the separation of the GLUT1 complex and a lipid probe, Fast-DiO, within a native-like environment in a few minutes. A force model was developed to account for distinct electric and drag forces acting on the transmembrane and aqueous-exposed portion of a transmembrane protein as well as the electroosmotic force. This model not only elucidates the impact of size and charge properties of transmembrane proteins but also highlights the influence of pH and ionic strength on the driving forces and, consequently, electrophoretic mobility. Model predictions align well with experimentally measured electrophoretic mobilities of the GLUT1 complex and Fast-DiO at various pH and ionic strengths as well as with several lipid probes, lipid-anchored proteins, and reconstituted membrane proteins from previous studies. Force analyses revealed the substantial membrane drag of the GLUT1 complex, significantly slowing down electrophoretic mobility. Besides, the counterbalance of similar magnitudes of electroosmotic and electric forces results in a small net driving force and, consequently, reduced mobility under typical neutral pH conditions. Our results further highlight how the size and charge properties of transmembrane proteins influence the suitable range of operating conditions for effective movement, providing potential applications for concentrating and isolating membrane proteins within this platform.
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Affiliation(s)
- Tzu-Tzu Liu
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
| | - Sin-Han Huang
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
| | - Ling Chao
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
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2
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Zhang Y, Su H, Wang W, Dong M, Han X. Phospholipid Epitaxial Assembly Behavior on a Hydrophobic Highly Ordered Pyrolytic Graphite Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1439-1446. [PMID: 38163753 DOI: 10.1021/acs.langmuir.3c03145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Supported lipid bilayers (SLBs) are excellent models of cell membranes. However, most SLBs exist in the form of phospholipid molecules standing on a substrate, making it difficult to have a side view of the phospholipid membranes. In this study, the phospholipid striped lamella with the arrangement of their alkane tails lying on highly ordered pyrolytic graphite (HOPG) was constructed by a spin coating method. Atomic force microscopy and molecular dynamics simulations are utilized to study the self-assembly of phospholipids on HOPG. Results show that various phospholipids with different packing parameters and electrical property are able to epitaxially adsorb on HOPG. 0.1 mg/mL Plasm PC (0.1 mg/mL) could form a striped monolayer with a width of 5.93 ± 0.21 nm and form relatively stable four striped layers with the concentration increasing to 1 mg/mL. The width of the DOPS multilayer is more than that of electroneutral lipids due to the static electrical repulsion force. This universal strategy sheds light on direct observation of the membrane structure from the side view and modification of 2D materials with amphiphilic biomolecules.
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Affiliation(s)
- Ying Zhang
- College of Materials and Chemical Engineering, Heilongjiang Institute of Technology, Harbin 150050, China
- State Key Laboratory of Urban Water Resource and Environment School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus 8000C, Denmark
| | - Hui Su
- College of Materials and Chemical Engineering, Heilongjiang Institute of Technology, Harbin 150050, China
| | - Wei Wang
- College of Materials and Chemical Engineering, Heilongjiang Institute of Technology, Harbin 150050, China
| | - Mingdong Dong
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus 8000C, Denmark
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
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3
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Henning P, Köster T, Haack F, Burrage K, Uhrmacher AM. Implications of different membrane compartmentalization models in particle-based in silico studies. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221177. [PMID: 37416823 PMCID: PMC10320350 DOI: 10.1098/rsos.221177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 06/12/2023] [Indexed: 07/08/2023]
Abstract
Studying membrane dynamics is important to understand the cellular response to environmental stimuli. A decisive spatial characteristic of the plasma membrane is its compartmental structure created by the actin-based membrane-skeleton (fences) and anchored transmembrane proteins (pickets). Particle-based reaction-diffusion simulation of the membrane offers a suitable temporal and spatial resolution to analyse its spatially heterogeneous and stochastic dynamics. Fences have been modelled via hop probabilities, potentials or explicit picket fences. Our study analyses the different approaches' constraints and their impact on simulation results and performance. Each of the methods comes with its own constraints; the picket fences require small timesteps, potential fences might induce a bias in diffusion in crowded systems, and probabilistic fences, in addition to carefully scaling the probability with the timesteps, induce higher computational costs for each propagation step.
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Affiliation(s)
- Philipp Henning
- Institute for Visual and Analytic Computing, University of Rostock, Rostock, Germany
| | - Till Köster
- Institute for Visual and Analytic Computing, University of Rostock, Rostock, Germany
| | - Fiete Haack
- Institute for Visual and Analytic Computing, University of Rostock, Rostock, Germany
| | - Kevin Burrage
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
- Visiting Professor, Department of Computer Science, University of Oxford, Oxford, UK
| | - Adelinde M. Uhrmacher
- Institute for Visual and Analytic Computing, University of Rostock, Rostock, Germany
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4
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Meredith SA, Kusunoki Y, Connell SD, Morigaki K, Evans SD, Adams PG. Self-Quenching Behavior of a Fluorescent Probe Incorporated within Lipid Membranes Explored Using Electrophoresis and Fluorescence Lifetime Imaging Microscopy. J Phys Chem B 2023; 127:1715-1727. [PMID: 36802586 PMCID: PMC9986866 DOI: 10.1021/acs.jpcb.2c07652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Fluorescent probes are useful in biophysics research to assess the spatial distribution, mobility, and interactions of biomolecules. However, fluorophores can undergo "self-quenching" of their fluorescence intensity at high concentrations. A greater understanding of concentration-quenching effects is important for avoiding artifacts in fluorescence images and relevant to energy transfer processes in photosynthesis. Here, we show that an electrophoresis technique can be used to control the migration of charged fluorophores associated with supported lipid bilayers (SLBs) and that quenching effects can be quantified with fluorescence lifetime imaging microscopy (FLIM). Confined SLBs containing controlled quantities of lipid-linked Texas Red (TR) fluorophores were generated within 100 × 100 μm corral regions on glass substrates. Application of an electric field in-plane with the lipid bilayer induced the migration of negatively charged TR-lipid molecules toward the positive electrode and created a lateral concentration gradient across each corral. The self-quenching of TR was directly observed in FLIM images as a correlation of high concentrations of fluorophores to reductions in their fluorescence lifetime. By varying the initial concentration of TR fluorophores incorporated into the SLBs from 0.3% to 0.8% (mol/mol), the maximum concentration of fluorophores reached during electrophoresis could be modulated from 2% up to 7% (mol/mol), leading to the reduction of fluorescence lifetime down to 30% and quenching of the fluorescence intensity down to 10% of their original levels. As part of this work, we demonstrated a method for converting fluorescence intensity profiles into molecular concentration profiles by correcting for quenching effects. The calculated concentration profiles have a good fit to an exponential growth function, suggesting that TR-lipids can diffuse freely even at high concentrations. Overall, these findings prove that electrophoresis is effective at producing microscale concentration gradients of a molecule-of-interest and that FLIM is an excellent approach to interrogate dynamic changes to molecular interactions via their photophysical state.
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Affiliation(s)
- Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Yuka Kusunoki
- Graduate School of Agricultural Science, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501, Japan
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501, Japan
| | - Stephen D Evans
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
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5
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Chen R, Chen X, Liu H, Fang L, Chen B, Luan T. Developing a robust method integrating with selective membrane-based preconcentration and signal amplification for field virus detection. Anal Chim Acta 2022; 1229:340360. [PMID: 36156222 DOI: 10.1016/j.aca.2022.340360] [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: 05/27/2022] [Revised: 08/29/2022] [Accepted: 09/02/2022] [Indexed: 11/01/2022]
Abstract
Infectious diseases caused by viruses have attracted global concern owing to their rapid spread and catastrophic consequences. Therefore, developing fast and reliable on-site virus detection methods is essential for the prevention and treatment of virus-related diseases. In this study, immunoassays on a membrane, combining virus preconcentration with nanoparticle-based signal amplification, were used to realize the rapid and accurate visual detection of viruses. The biotin-streptavidin scaffolds for target virus preconcentration were established on a membrane, and subsequently a Zika aptamer (Apt) immobilized on the membrane recognized and captured the nonstructural protein 1 of Zika virus (ZIKV-NS1). The probe for detection was synthesized by conjugating the Zika Apt with a high level of horseradish peroxidase on gold nanoparticles. The ZIKV-loaded membrane was incubated with the probes, and the viral signal was amplified as the signal of horseradish peroxidase. In the presence of 3,3,5',5'-tetramethyl benzidine and hydrogen peroxide, the green color of the probe-coated membrane indicated the level of ZIKV-NS1. Our developed method could reach a detection limit of 5 ng mL-1, and the whole procedure could be completed within 1 h. Analyses of rabbit serum and environmental water samples demonstrated that an immunoassay-based approach on the membrane could accurately determine the level of ZIKV-NS1 against the complicated matrix. Our results suggest that this virus detection method has a high potential for application in clinical and environmental settings.
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Affiliation(s)
- Ruohong Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Xingni Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Hongtao Liu
- Instrumental Analysis & Research Center, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Ling Fang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China; Instrumental Analysis & Research Center, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Baowei Chen
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510276, China.
| | - Tiangang Luan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China; Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, 510006, China; School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, 510006, China.
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6
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Huang SH, Huang BC, Chao L. Development of Cell Membrane Electrophoresis to Measure the Diffusivity of a Native Transmembrane Protein. Anal Chem 2022; 94:4531-4537. [PMID: 35230091 DOI: 10.1021/acs.analchem.2c00211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The lateral diffusion of transmembrane proteins in cell membranes is an important process that controls the dynamics and functions of the cell membrane. Several fluorescence-based techniques have been developed to study the diffusivities of transmembrane proteins. However, it is challenging to measure the diffusivity of a transmembrane protein with slow diffusion because of the photobleaching effect caused by long exposure times or multiple exposures to light. In this study, we developed a cell membrane electrophoresis platform to measure diffusivity. We deposited cell membrane vesicles derived from HeLa cells to form supported cell membrane patches. We demonstrated that the electrophoresis platform can be used to drive the movement of not only a lipid probe but also a native transmembrane protein, GLUT1. The movements were halted by the boundaries of the membrane patches and the concentration profiles reached steady states when the diffusion mass flux was balanced with the electrical mass flux. We used the Nernst-Planck equation as the mass balance equation to describe the steady concentration profiles and fitted these equations to our data to obtain the diffusivities. The obtained diffusivities were comparable to those obtained by fluorescence recovery after photobleaching, suggesting the validity of this new method of diffusivity measurement. Only a single snapshot is required for the diffusivity measurement, addressing the problems associated with photobleaching and allowing researchers to measure the diffusivity of transmembrane proteins with slow diffusion.
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Affiliation(s)
- Sin-Han Huang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Bo-Chuan Huang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Ling Chao
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
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7
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Lee D, Jung WH, Lee S, Yu ES, Lee T, Kim JH, Song HS, Lee KH, Lee S, Han SK, Choi MC, Ahn DJ, Ryu YS, Kim C. Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer. Nat Commun 2021; 12:3741. [PMID: 34145296 PMCID: PMC8213817 DOI: 10.1038/s41467-021-24122-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 06/03/2021] [Indexed: 11/09/2022] Open
Abstract
Despite technological advances in biomolecule detections, evaluation of molecular interactions via potentiometric devices under ion-enriched solutions has remained a long-standing problem. To avoid severe performance degradation of bioelectronics by ionic screening effects, we cover probe surfaces of field effect transistors with a single film of the supported lipid bilayer, and realize respectable potentiometric signals from receptor-ligand bindings irrespective of ionic strength of bulky solutions by placing an ion-free water layer underneath the supported lipid bilayer. High-energy X-ray reflectometry together with the circuit analysis and molecular dynamics simulation discovered biochemical findings that effective electrical signals dominantly originated from the sub-nanoscale conformational change of lipids in the course of receptor-ligand bindings. Beyond thorough analysis on the underlying mechanism at the molecular level, the proposed supported lipid bilayer-field effect transistor platform ensures the world-record level of sensitivity in molecular detection with excellent reproducibility regardless of molecular charges and environmental ionic conditions.
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Affiliation(s)
- Donggeun Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea.,Department of Electrical & Electronic Engineering, Yonsei University, Seoul, Republic of Korea
| | - Woo Hyuk Jung
- Department of Chemical and Biological Engineering, Korea University, Seoul, Republic of Korea
| | - Suho Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Eui-Sang Yu
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Taikjin Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Jae Hun Kim
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Hyun Seok Song
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Kwan Hyi Lee
- Center for Biomaterials, Korea Institute of Science and Technology, Seoul, Republic of Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Seok Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Sang-Kook Han
- Department of Electrical & Electronic Engineering, Yonsei University, Seoul, Republic of Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dong June Ahn
- Department of Chemical and Biological Engineering, Korea University, Seoul, Republic of Korea. .,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.
| | - Yong-Sang Ryu
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea. .,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.
| | - Chulki Kim
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea.
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8
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Sabirovas T, Valiūnienė A, Valincius G. Hybrid bilayer membranes on metallurgical polished aluminum. Sci Rep 2021; 11:9648. [PMID: 33958658 PMCID: PMC8102548 DOI: 10.1038/s41598-021-89150-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/15/2021] [Indexed: 11/09/2022] Open
Abstract
In this work we describe the functionalization of metallurgically polished aluminum surfaces yielding biomimetic electrodes suitable for probing protein/phospholipid interactions. The functionalization involves two simple steps: silanization of the aluminum and subsequent fusion of multilamellar vesicles which leads to the formation of a hybrid bilayer lipid membrane (hBLM). The vesicle fusion was followed in real-time by fast Fourier transform electrochemical impedance spectroscopy (FFT EIS). The impedance-derived complex capacitance of the hBLMs was approximately 0.61 µF cm−2, a value typical for intact phospholipid bilayers. We found that the hBLMs can be readily disrupted if exposed to > 400 nM solutions of the pore-forming peptide melittin. However, the presence of cholesterol at 40% (mol) in hBLMs exhibited an inhibitory effect on the membrane-damaging capacity of the peptide. The melittin-membrane interaction was concentration dependent decreasing with concentration. The hBLMs on Al surface can be regenerated multiple times, retaining their dielectric and functional properties essentially intact.
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Affiliation(s)
- Tomas Sabirovas
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio ave. 7, 10257, Vilnius, Lithuania
| | - Aušra Valiūnienė
- Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, 03225, Vilnius, Lithuania.
| | - Gintaras Valincius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio ave. 7, 10257, Vilnius, Lithuania
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9
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Zhang Y, Li Q, Dong M, Han X. Effect of cholesterol on the fluidity of supported lipid bilayers. Colloids Surf B Biointerfaces 2020; 196:111353. [DOI: 10.1016/j.colsurfb.2020.111353] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 01/12/2023]
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10
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Electromigration of cell surface macromolecules in DC electric fields during cell polarization and galvanotaxis. J Theor Biol 2019; 478:58-73. [DOI: 10.1016/j.jtbi.2019.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 12/14/2022]
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11
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Bi H, Wang X, Han X, Voïtchovsky K. Impact of Electric Fields on the Nanoscale Behavior of Lipid Monolayers at the Surface of Graphite in Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9561-9571. [PMID: 30028144 DOI: 10.1021/acs.langmuir.8b01631] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The nanoscale organization and dynamics of lipid molecules in self-assembled membranes is central to the biological function of cells and in the technological development of synthetic lipid structures as well as in devices such as biosensors. Here, we explore the nanoscale molecular arrangement and dynamics of lipids assembled in monolayers at the surface of highly ordered pyrolytic graphite (HOPG), in different ionic solutions, and under electrical potentials. Using a combination of atomic force microscopy and fluorescence recovery after photobleaching, we show that HOPG is able to support fully formed and fluid lipid membranes, but mesoscale order and corrugations can be observed depending on the type of the lipid considered (1,2-dioleoyl- sn-glycero-3-phosphocholine, 1,2-dioleoyl- sn-glycero-3-phospho-l-serine (DOPS), and 1,2-dioleoyl-3-trimethylammoniumpropane) and the ion present (Na+, Ca2+, Cl-). Interfacial solvation forces and ion-specific effects dominate over the electrostatic changes induced by moderate electric fields (±1.0 V vs Ag/AgCl reference electrode) with particularly marked effects in the presence of calcium, and for DOPS. Our results provide insights into the interplay between the molecular, ionic, and electrostatic interactions and the formation of dynamical ordered structures in fluid lipid membranes.
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Affiliation(s)
- Hongmei Bi
- College of Science , Heilongjiang Bayi Agricultural University , Daqing 163319 , China
| | - Xuejing Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering , Harbin Institute of Technology , Harbin 150001 , China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering , Harbin Institute of Technology , Harbin 150001 , China
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12
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Bao P, Cartron ML, Sheikh KH, Johnson BRG, Hunter CN, Evans SD. Controlling transmembrane protein concentration and orientation in supported lipid bilayers. Chem Commun (Camb) 2018; 53:4250-4253. [PMID: 28361139 DOI: 10.1039/c7cc01023k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The trans-membrane protein - proteorhodopsin (pR) has been incorporated into supported lipid bilayers (SLB). In-plane electric fields have been used to manipulate the orientation and concentration of these proteins, within the SLB, through electrophoresis leading to a 25-fold increase concentration of pR.
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Affiliation(s)
- P Bao
- School of Physics & Astronomy, University of Leeds, LS2 9JT, UK.
| | - M L Cartron
- Department of Molecular Biology & Biotechnology, University of Sheffield, S10 2TH, UK
| | - K H Sheikh
- School of Biomedical Science, University of Leeds, LS2 9JT, UK
| | - B R G Johnson
- School of Physics & Astronomy, University of Leeds, LS2 9JT, UK.
| | - C N Hunter
- Department of Molecular Biology & Biotechnology, University of Sheffield, S10 2TH, UK
| | - S D Evans
- School of Physics & Astronomy, University of Leeds, LS2 9JT, UK.
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13
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Abstract
Endogenous electric fields (EFs) are involved in developmental regulation and wound healing. Although the phenomenon is known for more than a century, it is not clear how cells perceive the external EF. Membrane proteins, responding to electrophoretic and electroosmotic forces, have long been proposed as the sensing molecules. However, specific charge modification of surface proteins did not change cell migration motility nor directionality in EFs. Moreover, symmetric alternating current (AC) EF directs cell migration in a frequency-dependent manner. Due to their charge and ability to coalesce, glycolipids are therefore the likely primary EF sensor driving polarization of membrane proteins and intracellular signaling. We demonstrate that detergent-resistant membrane nanodomains, also known as lipid rafts, are the primary response element in EF sensing. The clustering and activation of caveolin and signaling proteins further stabilize raft structure and feed-forward downstream signaling events, such as rho and PI3K activation. Theoretical modeling supports the experimental results and predicts AC frequency-dependent cell and raft migration. Our results establish a fundamental mechanism for cell electrosensing and provide a role in lipid raft mechanotransduction.
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14
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Harb F, Giudici-Orticoni MT, Guiral M, Tinland B. Electrophoretic mobility of a monotopic membrane protein inserted into the top of supported lipid bilayers. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:127. [PMID: 28012146 DOI: 10.1140/epje/i2016-16127-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/22/2016] [Indexed: 06/06/2023]
Abstract
We have studied the translational migration of a monotopic membrane protein, the bacterial sulfide quinone reductase (SQR) in supported n-bilayers ([Formula: see text]) under the influence of an electric field parallel to the membrane plane. The direction of the migration changes when the charge of the protein changes its sign. Measuring mobilities at different pH enables us to gain experimental physico-chemical data on SQR as its isoelectric point and its estimated oligomeric state (at least trimeric) when inserted in a lipid membrane. Consequently, in addition to the migration study of membrane proteins in a lipid environment, this experimental system, previously used with a transmembrane protein, is thus suitable to define membrane protein properties in conditions approaching the native ones (in the absence of detergent).
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Affiliation(s)
- Frédéric Harb
- Doctoral school for Science and Technology, platform for research in Nanosciences and Nanotechnology, Lebanese University, Campus Pierre Gemayel, BP 90239, Fanar-Metn, Lebanon
- Aix-Marseille Univ, CINaM-CNRS, UMR7325, 13288, Marseille, France
| | | | - Marianne Guiral
- Aix Marseille Univ, CNRS, BIP UMR 7281, 13402, Marseille, France
| | - Bernard Tinland
- Aix-Marseille Univ, CINaM-CNRS, UMR7325, 13288, Marseille, France.
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15
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Ryu YS, Wittenberg NJ, Suh JH, Lee SW, Sohn Y, Oh SH, Parikh AN, Lee SD. Continuity of Monolayer-Bilayer Junctions for Localization of Lipid Raft Microdomains in Model Membranes. Sci Rep 2016; 6:26823. [PMID: 27230411 PMCID: PMC4882513 DOI: 10.1038/srep26823] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/09/2016] [Indexed: 11/16/2022] Open
Abstract
We show that the selective localization of cholesterol-rich domains and associated ganglioside receptors prefer to occur in the monolayer across continuous monolayer-bilayer junctions (MBJs) in supported lipid membranes. For the MBJs, glass substrates were patterned with poly(dimethylsiloxane) (PDMS) oligomers by thermally-assisted contact printing, leaving behind 3 nm-thick PDMS patterns. The hydrophobicity of the transferred PDMS patterns was precisely tuned by the stamping temperature. Lipid monolayers were formed on the PDMS patterned surface while lipid bilayers were on the bare glass surface. Due to the continuity of the lipid membranes over the MBJs, essentially free diffusion of lipids was allowed between the monolayer on the PDMS surface and the upper leaflet of the bilayer on the glass substrate. The preferential localization of sphingomyelin, ganglioside GM1 and cholesterol in the monolayer region enabled to develop raft microdomains through coarsening of nanorafts. Our methodology provides a simple and effective scheme of non-disruptive manipulation of the chemical landscape associated with lipid phase separations, which leads to more sophisticated applications in biosensors and as cell culture substrates.
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Affiliation(s)
- Yong-Sang Ryu
- School of Electrical Engineering #032, Seoul National University, Kwanak P.O. Box 34, Seoul 151-600 Korea
| | - Nathan J. Wittenberg
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Jeng-Hun Suh
- School of Electrical Engineering #032, Seoul National University, Kwanak P.O. Box 34, Seoul 151-600 Korea
| | - Sang-Wook Lee
- School of Electrical Engineering #032, Seoul National University, Kwanak P.O. Box 34, Seoul 151-600 Korea
| | - Youngjoo Sohn
- Department of Anatomy, College of Korean Medicine, Institute of Oriental Medicine, Kyung Hee University, Seoul 130-701, Korea
| | - Sang-Hyun Oh
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Atul N. Parikh
- Departments of Biomedical Engineering and Chemical Engineering & Materials Science, University of California, Davis, California 95616, USA
| | - Sin-Doo Lee
- School of Electrical Engineering #032, Seoul National University, Kwanak P.O. Box 34, Seoul 151-600 Korea
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16
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Wang X, Zhang Y, Bi H, Han X. Supported lipid bilayer membrane arrays on micro-patterned ITO electrodes. RSC Adv 2016. [DOI: 10.1039/c6ra10294h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lipid bilayer arrays were formed on micropatterned ITO electrodes. With this bilayer array platform both the fluorescence microscopy and electrochemical detection can be realized to explore the biophysical properties of cell membrane.
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Affiliation(s)
- Xuejing Wang
- State Key Laboratory of Urban Water Resource and Environment
- School of Chemistry and Chemical Engineering
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Ying Zhang
- State Key Laboratory of Urban Water Resource and Environment
- School of Chemistry and Chemical Engineering
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Hongmei Bi
- State Key Laboratory of Urban Water Resource and Environment
- School of Chemistry and Chemical Engineering
- Harbin Institute of Technology
- Harbin 150001
- China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment
- School of Chemistry and Chemical Engineering
- Harbin Institute of Technology
- Harbin 150001
- China
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17
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Liu C, Huang D, Yang T, Cremer PS. Simultaneous Detection of Multiple Proteins that Bind to the Identical Ligand in Supported Lipid Bilayers. Anal Chem 2015; 87:7163-70. [DOI: 10.1021/acs.analchem.5b00999] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Chunming Liu
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Da Huang
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Tinglu Yang
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
- Department
of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Paul S. Cremer
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
- Department
of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Department
of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802, United States
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18
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Krabbenborg SO, van Weerd J, Karperien M, Jonkheijm P, Huskens J. Locked-in biomimetic surface gradients that are tunable in size, density and functionalization. Chemphyschem 2014; 15:3460-5. [PMID: 25115904 DOI: 10.1002/cphc.201402509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Indexed: 11/09/2022]
Abstract
Tuneable and stable surface-chemical gradients in supported lipid bilayers (SLBs) hold great promise for a range of applications in biological sensing and screening. Yet, until now, no method has been reported that provides temporal control of SLB gradients. Herein we report on the development of locked-in SLB gradients that can be tuned in space, time and density by applying a process to control lipid phase behaviour, electric field and temperature. Stable gradients of charged Texas-Red-, serine- or biotin-terminated lipids have been prepared. For example, the Texas-Red surface density was varied from 0 to 2 mol %, while the length was varied between several tens to several hundreds of microns. At room temperature the gradients are shown to be stable up to 24 h, while at 60 °C the gradients could be erased in 30 min. Covalent and non-covalent chemical modification of the gradients is demonstrated, for example, by FITC, hexahistidine-tagged proteins, and SAv/biotin. The amenability to various (bio)chemistries paves the way for novel SLB-based gradients, useful in sensing, high-throughput screening and for understanding dynamic biological processes.
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Affiliation(s)
- Sven O Krabbenborg
- Molecular NanoFabrication Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (The Netherlands)
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19
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Liu C, Huang D, Yang T, Cremer PS. Monitoring phosphatidic acid formation in intact phosphatidylcholine bilayers upon phospholipase D catalysis. Anal Chem 2014; 86:1753-9. [PMID: 24456402 PMCID: PMC3983022 DOI: 10.1021/ac403580r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 01/15/2014] [Indexed: 12/25/2022]
Abstract
We have monitored the production of the negatively charged lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidic acid acid (POPA), in supported lipid bilayers via the enzymatic hydrolysis of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (PC), a zwitterionic lipid. Experiments were performed with phospholipase D (PLD) in a Ca(2+) dependent fashion. The strategy for doing this involved using membrane-bound streptavidin as a biomarker for the charge on the membrane. The focusing position of streptavidin in electrophoretic-electroosmotic focusing (EEF) experiments was monitored via a fluorescent tag on this protein. The negative charge increased during these experiments due to the formation of POPA lipids. This caused the focusing position of streptavidin to migrate toward the negatively charged electrode. With the use of a calibration curve, the amount of POPA generated during this assay could be read out from the intact membrane, an objective that has been otherwise difficult to achieve because of the lack of unique chromophores on PA lipids. On the basis of these results, other enzymatic reactions involving the change in membrane charge could also be monitored in a similar way. This would include phosphorylation, dephosphorylation, lipid biosynthesis, and additional phospholipase reactions.
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Affiliation(s)
- Chunming Liu
- Department
of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843, United States
| | - Da Huang
- Department
of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843, United States
| | - Tinglu Yang
- Department
of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843, United States
| | - Paul S. Cremer
- Department
of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843, United States
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20
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van Weerd J, Krabbenborg SO, Eijkel J, Karperien M, Huskens J, Jonkheijm P. On-chip electrophoresis in supported lipid bilayer membranes achieved using low potentials. J Am Chem Soc 2014; 136:100-3. [PMID: 24345193 PMCID: PMC3901391 DOI: 10.1021/ja411287u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Indexed: 01/10/2023]
Abstract
A micro supported lipid bilayer (SLB) electrophoresis method was developed, which functions at low potentials and appreciable operating times. To this end, (hydroxymethyl)-ferrocene (FcCH2OH) was employed to provide an electrochemical reaction at the anode and cathode at low applied potential to avoid electrolysis of water. The addition of FcCH2OH did not alter the SLB characteristics or affect biomolecule function, and pH and temperature variations and bubble formation were eliminated. Applying potentials of 0.25-1.2 V during flow gave homogeneous electrical fields and a fast, reversible, and strong build-up of a charged dye-modified lipid in the direction of the oppositely charged electrode. Moreover, streptavidin mobility could be modulated. This method paves the way for further development of analytical devices.
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Affiliation(s)
- Jasper van Weerd
- Molecular nanoFabrication group and BIOS lab-on-a-chip
group, MESA Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Developmental
Bioengineering, MIRA Biomedical Technology and Technical Medicine, University of Twente,
P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Sven O. Krabbenborg
- Molecular nanoFabrication group and BIOS lab-on-a-chip
group, MESA Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jan Eijkel
- Molecular nanoFabrication group and BIOS lab-on-a-chip
group, MESA Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Marcel Karperien
- Developmental
Bioengineering, MIRA Biomedical Technology and Technical Medicine, University of Twente,
P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jurriaan Huskens
- Molecular nanoFabrication group and BIOS lab-on-a-chip
group, MESA Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Pascal Jonkheijm
- Molecular nanoFabrication group and BIOS lab-on-a-chip
group, MESA Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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21
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Abstract
While electrophoresis in lipid bilayers has been performed since the 1970s, the technique has until now been unable to accurately measure the charge on lipids and proteins within the membrane based on drift velocity measurements. Part of the problem is caused by the use of the Einstein-Smoluchowski equation to estimate the electrophoretic mobility of such species. The source of the error arises from the fact that a lipid headgroup is typically smaller than the Debye length of the adjacent aqueous solution in most electrophoresis experiments. Instead, the Henry equation can more accurately predict the electrophoretic mobility at sufficient ionic strength. This was done for three dye-labeled lipids with different sized head groups and a charge on each lipid of -1. Also, the charge was measured as a function of pH for two titratable lipids that were fluorescently labeled. Finally, it was shown that the Henry equation also has difficulties measuring the correct lipid charge at salt concentrations below 5 mM, where electroosmotic forces are more significant.
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Affiliation(s)
- Matthew F Poyton
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Penn State University , State College, Pennsylvania 16802, United States
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22
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Harb F, Tinland B. Electric migration of α-hemolysin in supported n-bilayers: a model for transmembrane protein microelectrophoresis. Electrophoresis 2013; 34:3054-63. [PMID: 23925931 DOI: 10.1002/elps.201300202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 06/26/2013] [Accepted: 07/12/2013] [Indexed: 11/06/2022]
Abstract
Proteome analysis involves separating proteins as a preliminary step toward their characterization. This paper reports on the translational migration of a model transmembrane protein (α-hemolysin) in supported n-bilayers (n, the number of bilayers, varies from 1 to around 500 bilayers) when an electric field parallel to the membrane plane is applied. The migration changes in direction as the charge on the protein changes its sign. Its electrophoretic mobility is shown to depend on size and charge. The electrophoretic mobility varies as 1/R(2), with R the equivalent geometric radius of the embedded part of the protein. Measuring mobilities at differing pH in our system enables us to determine the pI and the charge of the protein. Establishing all these variations points to the feasibility of electrophoretic transport of a charged object in this medium and is a first step toward electrophoretic separation of membrane proteins in n-bilayer systems.
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Affiliation(s)
- Frédéric Harb
- Aix-Marseille Université, CINaM, CNRS, Marseille, France
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23
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Zhang Y, Wang L, Wang X, Qi G, Han X. Forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces. Chemistry 2013; 19:9059-63. [PMID: 23695862 DOI: 10.1002/chem.201204419] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/25/2013] [Indexed: 11/11/2022]
Abstract
A novel method of forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces is introduced. Polyelectrolyte films were fabricated by the layer-by-layer technique on a silicon oxide surface modified with a 3-aminopropyltriethoxysilane (APTES) monolayer. The surface pK(a) value of the APTES monolayer was determined by cyclic voltammetry to be approximately 5.61, on the basis of which a pH value of 2.0 was chosen for layer-by-layer assembly. Micropatterned polyelectrolyte films were obtained by deep-UV (254 nm) photolysis though a mask. Absorbed fluorescent latex beads were used to visualize the patterned surfaces. Lipid bilayer arrays were fabricated on the micropatterned surfaces by immersing the patterned substrates into a solution containing egg phosphatidylcholine vesicles. Fluorescence recovery after photobleaching studies yielded a lateral diffusion coefficient for probe molecules of 1.31±0.17 μm(2) s(-1) in the bilayer region, and migration of the lipid NBD PE in bilayer lipid membrane arrays was observed in an electric field.
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Affiliation(s)
- Ying Zhang
- School of Chemical Engineering and Technology, Harbin Institute of Technology, No. 92, West Da-Zhi Street, Harbin, 150001, P.R. China
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24
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Bao P, Cheetham MR, Roth JS, Blakeston AC, Bushby RJ, Evans SD. On-Chip Alternating Current Electrophoresis in Supported Lipid Bilayer Membranes. Anal Chem 2012; 84:10702-7. [DOI: 10.1021/ac302446w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peng Bao
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Matthew R. Cheetham
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Johannes S. Roth
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Anita C. Blakeston
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Richard J. Bushby
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Stephen D. Evans
- School of Physics and
Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
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25
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Lipid Bilayer Membrane Arrays: Fabrication and Applications. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2012; 131:121-52. [DOI: 10.1007/10_2012_135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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26
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Nanofabrication for the analysis and manipulation of membranes. Ann Biomed Eng 2011; 40:1356-66. [PMID: 22143598 DOI: 10.1007/s10439-011-0479-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 11/23/2011] [Indexed: 12/21/2022]
Abstract
Recent advancements and applications of nanofabrication have enabled the characterization and control of biological membranes at submicron scales. This review focuses on the application of nanofabrication towards the nanoscale observing, patterning, sorting, and concentrating membrane components. Membranes on living cells are a necessary component of many fundamental cellular processes that naturally incorporate nanoscale rearrangement of the membrane lipids and proteins. Nanofabrication has advanced these understandings, for example, by providing 30 nm resolution of membrane proteins with metal-enhanced fluorescence at the tip of a scanning probe on fixed cells. Naturally diffusing single molecules at high concentrations on live cells have been observed at 60 nm resolution by confining the fluorescence excitation light through nanoscale metallic apertures. The lateral reorganization on the plasma membrane during membrane-mediated signaling processes has been examined in response to nanoscale variations in the patterning and mobility of the signal-triggering molecules. Further, membrane components have been separated, concentrated, and extracted through on-chip electrophoretic and microfluidic methods. Nanofabrication provides numerous methods for examining and manipulating membranes for both greater understandings of membrane processes as well as for the application of membranes to other biophysical methods.
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27
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Han X, Qi G, Xu X, Wang L. Formation of Lipid Bilayer Microarrays on Photo-Oxidized Polystyrene Surfaces. Chemistry 2011; 17:14741-4. [DOI: 10.1002/chem.201102941] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Indexed: 11/12/2022]
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28
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Liu C, Monson CF, Yang T, Pace H, Cremer PS. Protein separation by electrophoretic-electroosmotic focusing on supported lipid bilayers. Anal Chem 2011; 83:7876-80. [PMID: 21958061 PMCID: PMC3198849 DOI: 10.1021/ac201768k] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
An electrophoretic-electroosmotic focusing (EEF) method was developed and used to separate membrane-bound proteins and charged lipids based on their charge-to-size ratio from an initially homogeneous mixture. EEF uses opposing electrophoretic and electroosmotic forces to focus and separate proteins and lipids into narrow bands on supported lipid bilayers (SLBs). Membrane-associated species were focused into specific positions within the SLB in a highly repeatable fashion. The steady-state focusing positions of the proteins could be predicted and controlled by tuning experimental conditions, such as buffer pH, ionic strength, electric field, and temperature. Careful tuning of the variables should enable one to separate mixtures of membrane proteins with only subtle differences. The EEF technique was found to be an effective way to separate protein mixtures with low initial concentrations, and it overcame diffusive peak broadening to allow four bands to be separated simultaneously within a 380 μm wide isolated supported membrane patch.
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Affiliation(s)
- Chunming Liu
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843
| | | | - Tinglu Yang
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843
| | - Hudson Pace
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843
| | - Paul S. Cremer
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, TX 77843
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29
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Cheetham MR, Bramble JP, McMillan DGG, Krzeminski L, Han X, Johnson BRG, Bushby RJ, Olmsted PD, Jeuken LJC, Marritt SJ, Butt JN, Evans SD. Concentrating Membrane Proteins Using Asymmetric Traps and AC Electric Fields. J Am Chem Soc 2011; 133:6521-4. [DOI: 10.1021/ja2007615] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew R. Cheetham
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Jonathan P. Bramble
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Duncan G. G. McMillan
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, U.K
- Centre for Molecular Nanoscience, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Lukasz Krzeminski
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Centre for Molecular Nanoscience, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Xiaojun Han
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | | | - Richard J. Bushby
- Centre for Molecular Nanoscience, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Peter D. Olmsted
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Lars J. C. Jeuken
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, U.K
- Centre for Molecular Nanoscience, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Sophie J. Marritt
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Julea N. Butt
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Stephen D. Evans
- School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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30
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Monson CF, Pace HP, Liu C, Cremer PS. Supported bilayer electrophoresis under controlled buffer conditions. Anal Chem 2011; 83:2090-6. [PMID: 21319743 DOI: 10.1021/ac1028819] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A pH controlled flow cell device was constructed to allow electrophoretic movement of charged lipids and membrane associated proteins in supported phospholipid bilayers. The device isolated electrolysis products near the electrodes from the electrophoresis process within the bilayer. This allowed the pH over the bilayer region to remain within ±0.2 pH units or better over many hours at salt concentrations up to 10 mM. Using this setup, it was found that the electrophoretic mobility of a dye conjugated lipid (Texas Red 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE)) was essentially constant between pH 3.3 and 9.3. In contrast, streptavidin, which was bound to biotinylated lipids, shifted from migrating cathodically at acidic pH values to migrating anodically under basic conditions. This shift was due to the modulation of the net charge on the protein, which changed the electrophoretic forces experienced by the macromolecule. The addition of a polyethylene glycol (PEG) cushion beneath the bilayer or the increase in the ionic strength of the buffer solution resulted in a decrease of the electroosmotic force experienced by the streptavidin with little effect on the Texas Red-DHPE. As such, it was possible in part to control the electrophoretic and electroosmotic contributions to streptavidin independently of one another.
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Affiliation(s)
- Christopher F Monson
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
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31
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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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