101
|
Visco I, Chiantia S, Schwille P. Asymmetric supported lipid bilayer formation via methyl-β-cyclodextrin mediated lipid exchange: influence of asymmetry on lipid dynamics and phase behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7475-84. [PMID: 24885372 DOI: 10.1021/la500468r] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Supported lipid bilayers (SLBs) are broadly used as minimal membrane models and commonly produced by vesicle fusion (VF) on solid supports. Despite its advantages, VF does not allow the controlled formation of bilayers that mimic the leaflet asymmetry in lipid composition normally found in biological systems. Here we present a simple, quick, and versatile method to produce SLBs with a desired asymmetric lipid composition which is stable for ca. 4 h. We apply methyl-β-cyclodextrin mediated lipid exchange to SLBs formed by VF to enrich the upper leaflet of the bilayer with sphingomyelin. The bilayer asymmetry is assessed by fluorescence correlation spectroscopy, measuring the lipid mobility separately in each leaflet. To check the compatibility of the method with the most common protein reconstitution approaches, we report the production of asymmetric SLBs (aSLBs) in the presence of a glycosylphosphatidylinositol-anchored protein, reconstituted in the bilayer both, via direct protein insertion, and via proteoliposomes fusion. We finally apply aSLBs to study phase separation and transbilayer lipid movement of raft-mimicking lipid mixtures. The observed differences in terms of phase separation in symmetric and asymmetric SLBs with the same overall lipid composition provide further experimental evidence that the transversal lipid distribution affects the overall lipid miscibility and allow to temporally investigate leaflet mixing.
Collapse
Affiliation(s)
- Ilaria Visco
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry , Am Klopferspitz 18, 82152 Martinsried, Germany
| | | | | |
Collapse
|
102
|
Mishra S, Verhalen B, Stein RA, Wen PC, Tajkhorshid E, Mchaourab HS. Conformational dynamics of the nucleotide binding domains and the power stroke of a heterodimeric ABC transporter. eLife 2014; 3:e02740. [PMID: 24837547 PMCID: PMC4046567 DOI: 10.7554/elife.02740] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Multidrug ATP binding cassette (ABC) exporters are ubiquitous ABC transporters that extrude cytotoxic molecules across cell membranes. Despite recent progress in structure determination of these transporters, the conformational motion that transduces the energy of ATP hydrolysis to the work of substrate translocation remains undefined. Here, we have investigated the conformational cycle of BmrCD, a representative of the heterodimer family of ABC exporters that have an intrinsically impaired nucleotide binding site. We measured distances between pairs of spin labels monitoring the movement of the nucleotide binding (NBD) and transmembrane domains (TMD). The results expose previously unobserved structural intermediates of the NBDs arising from asymmetric configuration of catalytically inequivalent nucleotide binding sites. The two-state transition of the TMD, from an inward- to an outward-facing conformation, is driven exclusively by ATP hydrolysis. These findings provide direct evidence of divergence in the mechanism of ABC exporters.DOI: http://dx.doi.org/10.7554/eLife.02740.001.
Collapse
Affiliation(s)
- Smriti Mishra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Brandy Verhalen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Po-Chao Wen
- Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States
| | - Emad Tajkhorshid
- Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| |
Collapse
|
103
|
Kusters I, van Oijen AM, Driessen AJM. Membrane-on-a-chip: microstructured silicon/silicon-dioxide chips for high-throughput screening of membrane transport and viral membrane fusion. ACS NANO 2014; 8:3380-92. [PMID: 24601516 DOI: 10.1021/nn405884a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Screening of transport processes across biological membranes is hindered by the challenge to establish fragile supported lipid bilayers and the difficulty to determine at which side of the membrane reactants reside. Here, we present a method for the generation of suspended lipid bilayers with physiological relevant lipid compositions on microstructured Si/SiO2 chips that allow for high-throughput screening of both membrane transport and viral membrane fusion. Simultaneous observation of hundreds of single-membrane channels yields statistical information revealing population heterogeneities of the pore assembly and conductance of the bacterial toxin α-hemolysin (αHL). The influence of lipid composition and ionic strength on αHL pore formation was investigated at the single-channel level, resolving features of the pore-assembly pathway. Pore formation is inhibited by a specific antibody, demonstrating the applicability of the platform for drug screening of bacterial toxins and cell-penetrating agents. Furthermore, fusion of H3N2 influenza viruses with suspended lipid bilayers can be observed directly using a specialized chip architecture. The presented micropore arrays are compatible with fluorescence readout from below using an air objective, thus allowing high-throughput screening of membrane transport in multiwell formats in analogy to plate readers.
Collapse
Affiliation(s)
- Ilja Kusters
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 7, Groningen, The Netherlands
| | | | | |
Collapse
|
104
|
Mori T, Kamiya K, Tomita M, Yoshimura T, Tsumoto K. Incorporation of adenylate cyclase into membranes of giant liposomes using membrane fusion with recombinant baculovirus-budded virus particles. Biotechnol Lett 2014; 36:1253-61. [PMID: 24563316 DOI: 10.1007/s10529-014-1485-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/31/2014] [Indexed: 01/31/2023]
Abstract
Recombinant transmembrane adenylate cyclase (AC) was incorporated into membranes of giant liposomes using membrane fusion between liposomes and baculovirus-budded virus (BV). AC genes were constructed into transfer vectors in a form fused with fluorescent protein or polyhistidine at the C-terminus. The recombinant BVs were collected by ultracentrifugation and AC expression was verified using western blotting. The BVs and giant liposomes generated using gentle hydration were fused under acidic conditions; the incorporation of AC into giant liposomes was demonstrated by confocal laser scanning microscopy through the emission of fluorescence from their membranes. The AC-expressing BVs were also fused with liposomes containing the substrate (ATP) with/without a specific inhibitor (SQ 22536). An enzyme immunoassay on extracts of the sample demonstrated that cAMP was produced inside the liposomes. This procedure facilitates direct introduction of large transmembrane proteins into artificial membranes without solubilization.
Collapse
Affiliation(s)
- Takaaki Mori
- Molecular Bioengineering Laboratory, Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie, 514-8507, Japan,
| | | | | | | | | |
Collapse
|
105
|
King PH, Jones G, Morgan H, de Planque MRR, Zauner KP. Interdroplet bilayer arrays in millifluidic droplet traps from 3D-printed moulds. LAB ON A CHIP 2014; 14:722-9. [PMID: 24336841 DOI: 10.1039/c3lc51072g] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In droplet microfluidics, aqueous droplets are typically separated by an oil phase to ensure containment of molecules in individual droplets of nano-to-picoliter volume. An interesting variation of this method involves bringing two phospholipid-coated droplets into contact to form a lipid bilayer in-between the droplets. These interdroplet bilayers, created by manual pipetting of microliter droplets, have proved advantageous for the study of membrane transport phenomena, including ion channel electrophysiology. In this study, we adapted the droplet microfluidics methodology to achieve automated formation of interdroplet lipid bilayer arrays. We developed a 'millifluidic' chip for microliter droplet generation and droplet packing, which is cast from a 3D-printed mould. Droplets of 0.7-6.0 μL volume were packed as homogeneous or heterogeneous linear arrays of 2-9 droplets that were stable for at least six hours. The interdroplet bilayers had an area of up to 0.56 mm(2), or an equivalent diameter of up to 850 μm, as determined from capacitance measurements. We observed osmotic water transfer over the bilayers as well as sequential bilayer lysis by the pore-forming toxin melittin. These millifluidic interdroplet bilayer arrays combine the ease of electrical and optical access of manually pipetted microdroplets with the automation and reproducibility of microfluidic technologies. Moreover, the 3D-printing based fabrication strategy enables the rapid implementation of alternative channel geometries, e.g. branched arrays, with a design-to-device time of just 24-48 hours.
Collapse
Affiliation(s)
- Philip H King
- Electronics and Computer Science & Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
| | | | | | | | | |
Collapse
|
106
|
Itri R, Junqueira HC, Mertins O, Baptista MS. Membrane changes under oxidative stress: the impact of oxidized lipids. Biophys Rev 2014; 6:47-61. [PMID: 28509959 DOI: 10.1007/s12551-013-0128-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 12/03/2013] [Indexed: 12/11/2022] Open
Abstract
Studying photosensitized oxidation of unsaturated phospholipids is of importance for understanding the basic processes underlying photodynamic therapy, photoaging and many other biological dysfunctions. In this review we show that the giant unilamellar vesicle, when used as a simplified model of biological membranes, is a powerful tool to investigate how in situ photogenerated oxidative species impact the phospholipid bilayer. The extent of membrane damage can be modulated by choosing a specific photosensitizer (PS) which is activated by light irradiation and can react by either type I and or type II mechanism. We will show that type II PS generates only singlet oxygen which reacts to the phospholipid acyl double bond. The byproduct thus formed is a lipid hydroperoxide which accumulates in the membrane as a function of singlet oxygen production and induces an increase in its area without significantly affecting membrane permeability. The presence of a lipid hydroperoxide can also play an important role in the formation of the lipid domain for mimetic plasma membranes. Lipid hydroperoxides can be also transformed in shortened chain compounds, such as aldehydes and carboxylic acids, in the presence of a PS that reacts via the type I mechanism. The presence of such byproducts may form hydrophilic pores in the membrane for moderate oxidative stress or promote membrane disruption for massive oxidation. Our results provide a new tool to explore membrane response to an oxidative stress and may have implications in biological signaling of redox misbalance.
Collapse
Affiliation(s)
- Rosangela Itri
- Departamento de Física Aplicada, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil.
| | - Helena C Junqueira
- Departamento de Física Aplicada, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - Omar Mertins
- Departamento de Física Aplicada, Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - Maurício S Baptista
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| |
Collapse
|
107
|
Chiaruttini N, Letellier L, Viasnoff V. A novel method to couple electrophysiological measurements and fluorescence imaging of suspended lipid membranes: the example of T5 bacteriophage DNA ejection. PLoS One 2013; 8:e84376. [PMID: 24376806 PMCID: PMC3871697 DOI: 10.1371/journal.pone.0084376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 11/22/2013] [Indexed: 12/21/2022] Open
Abstract
We present an innovative method to couple electrophysiological measurements with fluorescence imaging of functionalized suspended bilayers. Our method combines several advantages: it is well suited to study transmembrane proteins that are difficult to incorporate in suspended bilayers, it allows single molecule resolution both in terms of electrophysiological measurements and fluorescence imaging, and it enables mechanical stimulations of the membrane. The approach comprises of two steps: first the reconstitution of membrane proteins in giant unilamellar vesicles; then the formation of a suspended bilayer spanning a 5 to 15 micron-wide aperture that can be visualized by high NA microscope objectives. We exemplified how the technique can be used to detect in real time the translocation of T5 DNA across the bilayer during its ejection from the bacteriophage capsid.
Collapse
Affiliation(s)
- Nicolas Chiaruttini
- ESPCI Paristech, CNRS, Paris, France
- Aurélien Roux Lab, Biochemistry Department, University of Geneva, Geneva, Switzerland
| | - Lucienne Letellier
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud-11, CNRS, Orsay, France
| | - Virgile Viasnoff
- ESPCI Paristech, CNRS, Paris, France
- Aurélien Roux Lab, Biochemistry Department, University of Geneva, Geneva, Switzerland
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud-11, CNRS, Orsay, France
- MechanoBiology Institute of Singapore, Singapore, Singapore
| |
Collapse
|
108
|
The biology of boundary conditions: cellular reconstitution in one, two, and three dimensions. Curr Opin Cell Biol 2013; 26:60-8. [PMID: 24529247 DOI: 10.1016/j.ceb.2013.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/10/2013] [Accepted: 10/15/2013] [Indexed: 01/16/2023]
Abstract
Reconstituting cellular behavior outside the complex environment of the cell allows the study of biological processes in simplified and controlled settings. Making the leap from cells to test tubes, however, carries the inevitable risk of removing too much context and therefore sacrificing the important biochemical, mechanical, or geometrical constraints that guide the system's behavior. In response to this challenge, reconstitution experiments have recently begun to focus not only on including the right molecules but also on faithfully recapitulating the constraints that are present within a cell. By setting the appropriate biological boundary conditions, these experiments are uncovering how dimensional constraints within the cellular environment guide biological processes.
Collapse
|
109
|
Hansen JS, Thompson JR, Hélix-Nielsen C, Malmstadt N. Lipid directed intrinsic membrane protein segregation. J Am Chem Soc 2013; 135:17294-7. [PMID: 24180248 DOI: 10.1021/ja409708e] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We demonstrate a new approach for direct reconstitution of membrane proteins during giant vesicle formation. We show that it is straightforward to create a tissue-like giant vesicle film swelled with membrane protein using aquaporin SoPIP2;1 as an illustration. These vesicles can also be easily harvested for individual study. By controlling the lipid composition we are able to direct the aquaporin into specific immiscible liquid domains in giant vesicles. The oligomeric α-helical protein cosegregates with the cholesterol-poor domains in phase separating ternary mixtures.
Collapse
Affiliation(s)
- Jesper S Hansen
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California , 925 Bloom Walk, Los Angeles, California 90089, United States
| | | | | | | |
Collapse
|
110
|
Liu YJ, Hansen GPR, Venancio-Marques A, Baigl D. Cell-free preparation of functional and triggerable giant proteoliposomes. Chembiochem 2013; 14:2243-7. [PMID: 24115581 DOI: 10.1002/cbic.201300501] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Indexed: 01/15/2023]
Abstract
Heat, we leak: We express a membrane protein outside well-defined giant liposomes obtained by gravity-transferred sucrose-in-oil droplets into a cell-free, reconstituted expression system. We show that the presence of the liposome is necessary during expression for efficient protein insertion into the membrane and that temperature can trigger the resulting membrane function.
Collapse
Affiliation(s)
- Yan-Jun Liu
- Department of Chemistry, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris (France) http://www.baigllab.com/; Université Pierre et Marie Curie Paris 6, 4 place Jussieu, 75005 Paris (France); UMR 8640, CNRS, 3 rue Michel-Ange, 75016 Paris (France)
| | | | | | | |
Collapse
|
111
|
Hughes LD, Boxer SG. DNA-based patterning of tethered membrane patches. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:12220-7. [PMID: 23992147 PMCID: PMC3815428 DOI: 10.1021/la402537p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Solid-supported lipid bilayers are useful model systems for mimicking cellular membranes; however, the interaction of the bilayer with the surface can disrupt the function of integral membrane proteins and impede topological transformations such as membrane fusion. As a result, a variety of tethered or cushioned lipid bilayer architectures have been described, which retain the proximity to the surface, enabling surface-sensitive techniques, but physically distance the bilayer from the surface. We have recently developed a method for spatially separating a lipid bilayer from a solid support using DNA lipids. In this system, a DNA strand is covalently attached to a glass slide or SiO2 wafer, and giant unilamellar vesicles (GUVs) displaying the complement rupture to form a planar lipid bilayer tethered above the surface. However, the location of the patch is random, determined by where the DNA-GUV initially binds to its complement. To allow greater versatility and control, we sought a way to pattern tethered membrane patches. We present a method for creating spatially distinct tethered membrane patches on a glass slide using microarray printing. Surface-reactive DNA sequences are spotted onto the slide, incubated to covalently link the DNA to the surface, and DNA-GUVs patches are formed selectively on the printed DNA. By interfacing the bilayers with microfluidic flow cells, materials can be added on top of or fused into the membrane to change the composition of the bilayers. With further development, this approach would enable rapid screening of different patches in protein binding assays and would enable interfacing patches with electrical detectors.
Collapse
Affiliation(s)
- Laura D. Hughes
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| |
Collapse
|