251
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Kumar M, Habel JEO, Shen YX, Meier WP, Walz T. High-density reconstitution of functional water channels into vesicular and planar block copolymer membranes. J Am Chem Soc 2012; 134:18631-7. [PMID: 23082933 PMCID: PMC3497857 DOI: 10.1021/ja304721r] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The exquisite selectivity and unique transport properties
of membrane
proteins can be harnessed for a variety of engineering and biomedical
applications if suitable membranes can be produced. Amphiphilic block
copolymers (BCPs), developed as stable lipid analogs, form membranes
that functionally incorporate membrane proteins and are ideal for
such applications. While high protein density and planar membrane
morphology are most desirable, BCP–membrane protein aggregates
have so far been limited to low protein densities in either vesicular
or bilayer morphologies. Here, we used dialysis to reproducibly form
planar and vesicular BCP membranes with a high density of reconstituted
aquaporin-0 (AQP0) water channels. We show that AQP0 retains its biological
activity when incorporated at high density in BCP membranes, and that
the morphology of the BCP–protein aggregates can be controlled
by adjusting the amount of incorporated AQP0. We also show that BCPs
can be used to form two-dimensional crystals of AQP0.
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Affiliation(s)
- Manish Kumar
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, United States.
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252
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Doumiati S, Haupt K, Rossi C. Autophosphorylation activation and inhibition by curcumin of the epidermal growth factor receptor reconstituted in liposomes. J Mol Recognit 2012; 25:623-9. [DOI: 10.1002/jmr.2194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Samah Doumiati
- UMR 6022 CNRS; Université de Technologie de Compiègne; BP 20529, 60205; Compiègne Cedex; France
| | - Karsten Haupt
- UMR 6022 CNRS; Université de Technologie de Compiègne; BP 20529, 60205; Compiègne Cedex; France
| | - Claire Rossi
- UMR 6022 CNRS; Université de Technologie de Compiègne; BP 20529, 60205; Compiègne Cedex; France
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253
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Schaap IAT, Eghiaian F, des Georges A, Veigel C. Effect of envelope proteins on the mechanical properties of influenza virus. J Biol Chem 2012; 287:41078-88. [PMID: 23048030 DOI: 10.1074/jbc.m112.412726] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The envelope of the influenza virus undergoes extensive structural change during the viral life cycle. However, it is unknown how lipid and protein components of the viral envelope contribute to its mechanical properties. Using atomic force microscopy, here we show that the lipid envelope of spherical influenza virions is ∼10 times softer (∼0.05 nanonewton nm(-1)) than a viral protein-capsid coat and sustains deformations of one-third of the virion's diameter. Compared with phosphatidylcholine liposomes, it is twice as stiff, due to membrane-attached protein components. We found that virus indentation resulted in a biphasic force-indentation response. We propose that the first phase, including a stepwise reduction in stiffness at ∼10-nm indentation and ∼100 piconewtons of force, is due to mobilization of membrane proteins by the indenting atomic force microscope tip, consistent with the glycoprotein ectodomains protruding ∼13 nm from the bilayer surface. This phase was obliterated for bromelain-treated virions with the ectodomains removed. Following pH 5 treatment, virions were as soft as pure liposomes, consistent with reinforcing proteins detaching from the lipid bilayer. We propose that the soft, pH-dependent mechanical properties of the envelope are critical for the pH-regulated life cycle and support the persistence of the virus inside and outside the host.
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Affiliation(s)
- Iwan A T Schaap
- National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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254
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Haferkamp I, Linka N. Functional expression and characterisation of membrane transport proteins. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:675-90. [PMID: 22639981 DOI: 10.1111/j.1438-8677.2012.00591.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Membrane transporters set the framework organising the complexity of plant metabolism in cells, tissues and organisms. Their substrate specificity and controlled activity in different cells is a crucial part for plant metabolism to run pathways in concert. Transport proteins catalyse the uptake and exchange of ions, substrates, intermediates, products and cofactors across membranes. Given the large number of metabolites, a wide spectrum of transporters is required. The vast majority of in silico annotated membrane transporters in plant genomes, however, has not yet been functionally characterised. Hence, to understand the metabolic network as a whole, it is important to understand how transporters connect and control the metabolic pathways of plant cells. Heterologous expression and in vitro activity studies of recombinant transport proteins have highly improved their functional analysis in the last two decades. This review provides a comprehensive overview of the recent advances in membrane protein expression and functional characterisation using various host systems and transport assays.
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Affiliation(s)
- I Haferkamp
- Plant Physiology, Technical University of Kaiserslautern, Kaiserslautern, Germany Plant Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - N Linka
- Plant Physiology, Technical University of Kaiserslautern, Kaiserslautern, Germany Plant Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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255
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Functional reconstitution and characterization of the Arabidopsis Mg2+ transporter AtMRS2-10 in proteoliposomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2202-8. [DOI: 10.1016/j.bbamem.2012.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 04/05/2012] [Accepted: 04/19/2012] [Indexed: 11/24/2022]
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256
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Sferdean FC, Weis RM, Thompson LK. Ligand affinity and kinase activity are independent of bacterial chemotaxis receptor concentration: insight into signaling mechanisms. Biochemistry 2012; 51:6920-31. [PMID: 22870954 DOI: 10.1021/bi3007466] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Binding of attractant to bacterial chemotaxis receptors initiates a transmembrane signal that inhibits the kinase CheA bound ~300 Å distant at the other end of the receptor. Chemoreceptors form large clusters in many bacterial species, and the extent of clustering has been reported to vary with signaling state. To test whether ligand binding regulates kinase activity by modulating a clustering equilibrium, we measured the effects of two-dimensional receptor concentration on kinase activity in proteoliposomes containing the purified Escherichia coli serine receptor reconstituted into vesicles over a range of lipid:protein molar ratios. The IC(50) of kinase inhibition was unchanged despite a 10-fold change in receptor concentration. Such a change in concentration would have produced a measurable shift in the IC(50) if receptor clustering were involved in kinase regulation, based on a simple model in which the receptor oligomerization and ligand binding equilibria are coupled. These results indicate that the primary signal, ligand control of kinase activity, does not involve a change in receptor oligomerization state. In combination with previous work on cytoplasmic fragments assembled on vesicle surfaces [Besschetnova, T. Y., et al. (2008) Proc. Natl. Acad. Sci. U.S.A.105, 12289-12294], this suggests that binding of ligand to chemotaxis receptors inhibits the kinase by inducing a conformational change that expands the membrane area occupied by the receptor cytoplasmic domain, without changing the number of associated receptors in the signaling complex.
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Affiliation(s)
- Fe C Sferdean
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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257
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Althoff T, Davies KM, Schulze S, Joos F, Kühlbrandt W. GRecon: a method for the lipid reconstitution of membrane proteins. Angew Chem Int Ed Engl 2012; 51:8343-7. [PMID: 22821803 PMCID: PMC3494379 DOI: 10.1002/anie.201202094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Indexed: 11/30/2022]
Affiliation(s)
- Thorsten Althoff
- Max-Planck-Institut für Biophysik, Strukturbiologie, Max-von-Laue-Strasse 3, 60438 Frankfurt, Germany
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258
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Althoff T, Davies KM, Schulze S, Joos F, Kühlbrandt W. GRecon: A Method for the Lipid Reconstitution of Membrane Proteins. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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259
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Teboul D, Beaufils S, Taveau JC, Iatmanen-Harbi S, Renault A, Venien-Bryan C, Vie V, Lacapere JJ. Mouse TSPO in a lipid environment interacting with a functionalized monolayer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2791-800. [PMID: 22771765 DOI: 10.1016/j.bbamem.2012.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 06/11/2012] [Accepted: 06/26/2012] [Indexed: 12/28/2022]
Abstract
Translocator protein TSPO is a membrane protein highly conserved in evolution which does not belong to any structural known family. TSPO is involved in physiological functions among which transport of molecules such as cholesterol to form steroids and bile salts in mammalian cells. Membrane protein structure determination remains a difficult task and needs concomitant approaches (for instance X-ray- or Electron-crystallography and NMR). Electron microscopy and two-dimensional crystallization under functionalized monolayers have been successfully developed for recombinant tagged proteins. The difficulty comes from the detergent carried by membrane proteins that disrupt the lipid monolayer. We identified the best conditions for injecting the histidine tagged recombinant TSPO in detergent in the subphase and to keep the protein stable. Reconstituted recombinant protein into a lipid bilayer favors its adsorption to functionalized monolayers and limits the disruption of the monolayer by reducing the amount of detergent. Finally, we obtained the first transmission electron microscopy images of recombinant mouse TSPO negatively stained bound to the lipid monolayer after injection into the subphase of pre-reconstituted TSPO in lipids. Image analysis reveals that circular objects could correspond to an association of at least four monomers of mouse TSPO. The different amino acid compositions and the location of the polyhistidine tag between bacterial and mouse TSPO could account for the formation of dimer versus tetramer, respectively. The difference in the loop between the first and second putative transmembrane domain may contribute to distinct monomer interaction, this is supported by differences in ligand binding parameters and biological functions of both proteins.
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260
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Morigaki K, Kimura S, Okada K, Kawasaki T, Kawasaki K. Formation of substrate-supported membranes from mixtures of long- and short-chain phospholipids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9649-9655. [PMID: 22591412 DOI: 10.1021/la300696z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We studied the formation of substrate-supported planar phospholipid bilayers (SPBs) on glass and silica from mixtures of long- and short-chain phospholipids to assess the effects of detergent additives on SPB formation. 1,2-Hexyanoyl-sn-glycero-3-phosphocholine (DHPC-C6) and 1,2-heptanoyl-sn-glycero-3-phosphocholine (DHPC-C7) were chosen as short-chain phospholipids. 1-Palmitoyl-2-oleol-sn-glycero-3-phosphocholine (POPC) was used as a model long-chain phospholipid. Kinetic studies by quartz crystal microbalance with dissipation monitoring (QCM-D) showed that the presence of short-chain phospholipids significantly accelerated the formation of SPBs. Rapid rinsing with a buffer solution did not change the adsorbed mass on the surface if POPC/DHPC-C6 mixtures were used below the critical micelle concentration (cmc) of DHPC-C6, indicating that an SPB composed of POPC molecules remained on the surface. Fluorescence microscopy observation showed homogeneous SPBs, and the fluorescence recovery after photobleaching (FRAP) measurements gave a diffusion coefficient comparable to that for SPBs formed from POPC vesicles. However, mixtures of POPC/DHPC-C7 resulted in a smaller mass of lipid adsorption on the substrate. FRAP measurements also yielded significantly smaller diffusion coefficients, suggesting the presence of defects. The different behaviors for DHPC-C6 and DHPC-C7 point to the dual roles of detergents to enhance the formation of SPBs and to destabilize them, depending on their structures and aggregation properties.
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Affiliation(s)
- Kenichi Morigaki
- Research Center for Environmental Genomics, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501 Japan.
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261
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Hernandez JM, Stein A, Behrmann E, Riedel D, Cypionka A, Farsi Z, Walla PJ, Raunser S, Jahn R. Membrane fusion intermediates via directional and full assembly of the SNARE complex. Science 2012; 336:1581-4. [PMID: 22653732 PMCID: PMC3677693 DOI: 10.1126/science.1221976] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cellular membrane fusion is thought to proceed through intermediates including docking of apposed lipid bilayers, merging of proximal leaflets to form a hemifusion diaphragm, and fusion pore opening. A membrane-bridging four-helix complex of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediates fusion. However, how assembly of the SNARE complex generates docking and other fusion intermediates is unknown. Using a cell-free reaction, we identified intermediates visually and then arrested the SNARE fusion machinery when fusion was about to begin. Partial and directional assembly of SNAREs tightly docked bilayers, but efficient fusion and an extended form of hemifusion required assembly beyond the core complex to the membrane-connecting linkers. We propose that straining of lipids at the edges of an extended docking zone initiates fusion.
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Affiliation(s)
- Javier M. Hernandez
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Alexander Stein
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Elmar Behrmann
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Dietmar Riedel
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Anna Cypionka
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
- AG Biomolecular Spectroscopy and Single-Molecule Detection, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Zohreh Farsi
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Peter J. Walla
- AG Biomolecular Spectroscopy and Single-Molecule Detection, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, Technical University of Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany
| | - Stefan Raunser
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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262
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Anwar K, Klemm RW, Condon A, Severin KN, Zhang M, Ghirlando R, Hu J, Rapoport TA, Prinz WA. The dynamin-like GTPase Sey1p mediates homotypic ER fusion in S. cerevisiae. ACTA ACUST UNITED AC 2012; 197:209-17. [PMID: 22508509 PMCID: PMC3328390 DOI: 10.1083/jcb.201111115] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Budding yeast Sey1p functions analogously to mammalian atlastins in mediating ER fusion through a mechanism that is redundant with a second, ER SNARE-mediated fusion mechanism. The endoplasmic reticulum (ER) forms a network of tubules and sheets that requires homotypic membrane fusion to be maintained. In metazoans, this process is mediated by dynamin-like guanosine triphosphatases (GTPases) called atlastins (ATLs), which are also required to maintain ER morphology. Previous work suggested that the dynamin-like GTPase Sey1p was needed to maintain ER morphology in Saccharomyces cerevisiae. In this paper, we demonstrate that Sey1p, like ATLs, mediates homotypic ER fusion. The absence of Sey1p resulted in the ER undergoing delayed fusion in vivo and proteoliposomes containing purified Sey1p fused in a GTP-dependent manner in vitro. Sey1p could be partially replaced by ATL1 in vivo. Like ATL1, Sey1p underwent GTP-dependent dimerization. We found that the residual ER–ER fusion that occurred in cells lacking Sey1p required the ER SNARE Ufe1p. Collectively, our results show that Sey1p and its homologues function analogously to ATLs in mediating ER fusion. They also indicate that S. cerevisiae has an alternative fusion mechanism that requires ER SNAREs.
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Affiliation(s)
- Kamran Anwar
- Laboratory of Molecular and Cell Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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263
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Curnow P, Senior L, Knight MJ, Thamatrakoln K, Hildebrand M, Booth PJ. Expression, purification, and reconstitution of a diatom silicon transporter. Biochemistry 2012; 51:3776-85. [PMID: 22530967 DOI: 10.1021/bi3000484] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis and manipulation of silicon materials on the nanoscale are core themes in nanotechnology research. Inspiration is increasingly being taken from the natural world because the biological mineralization of silicon results in precisely controlled, complex silica structures with dimensions from the millimeter to the nanometer. One fascinating example of silicon biomineralization occurs in the diatoms, unicellular algae that sheath themselves in an ornate silica-based cell wall. To harvest silicon from the environment, diatoms have developed a unique family of integral membrane proteins that bind to a soluble form of silica, silicic acid, and transport it across the cell membrane to the cell interior. These are the first proteins shown to directly interact with silicon, but the current understanding of these specific silicon transport proteins is limited by the lack of in vitro studies of structure and function. We report here the recombinant expression, purification, and reconstitution of a silicon transporter from the model diatom Thalassiosira pseudonana. After using GFP fusions to optimize expression and purification protocols, a His(10)-tagged construct was expressed in Saccharomyces cerevisiae, solubilized in the detergent Fos-choline-12, and purified by affinity chromatography. Size-exclusion chromatography and particle sizing by dynamic light scattering showed that the protein was purified as a homotetramer, although nonspecific oligomerization occurred at high protein concentrations. Circular dichroism measurements confirmed sequence-based predictions that silicon transporters are α-helical membrane proteins. Silicic acid transport could be established in reconstituted proteoliposomes, and silicon uptake was found to be dependent upon an applied sodium gradient. Transport data across different substrate concentrations were best fit to the sigmoidal Hill equation, with a K(0.5) of 19.4 ± 1.3 μM and a cooperativity coefficient of 1.6. Sodium binding was noncooperative with a K(m)(app) of 1.7 ± 1.0 mM, suggesting a transport silicic acid:Na(+) stoichiometry of 2:1. These results provide the basis for a full understanding of both silicon transport in the diatom and protein-silicon interactions in general.
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Affiliation(s)
- Paul Curnow
- School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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264
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Barbosa-Barros L, Rodríguez G, Barba C, Cócera M, Rubio L, Estelrich J, López-Iglesias C, de la Maza A, López O. Bicelles: lipid nanostructured platforms with potential dermal applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:807-818. [PMID: 22114051 DOI: 10.1002/smll.201101545] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/26/2011] [Indexed: 05/31/2023]
Abstract
Bicelles emerge as promising membrane models, and because of their attractive combination of lipid composition, small size and morphological versatility, they become new targets in skin research. Bicelles are able to modify skin biophysical parameters and modulate the skin's barrier function, acting to enhance drug penetration. Because of their nanostructured assemblies, bicelles have the ability to penetrate through the narrow intercellular spaces of the stratum corneum of the skin to reinforce its lipid lamellae. The bicelle structure also allows for the incorporation of different molecules that can be carried through the skin layers. All of these characteristics can be modulated by varying the lipid composition and experimental conditions. The remarkable versatility of bicelles is their most important characteristic, which makes their use possible in various fields. This system represents a platform for dermal applications. In this review, an overview of the main properties of bicelles and their effects on the skin are presented.
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Affiliation(s)
- Lucyanna Barbosa-Barros
- Dept. of Chemical Technology and Surfactants, Institut de Química Avançada de Catalunya-I.Q.A.C., Consejo Superior de Investigaciones Científicas-C.S.I.C., C/Jordi Girona 18-26, 08034 Barcelona, Spain.
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265
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Verchère A, Broutin I, Picard M. Photo-induced proton gradients for the in vitro investigation of bacterial efflux pumps. Sci Rep 2012; 2:306. [PMID: 22400101 PMCID: PMC3296093 DOI: 10.1038/srep00306] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/16/2012] [Indexed: 12/04/2022] Open
Abstract
We describe an original activity assay for membrane transport that uses the proton motive force-dependent efflux pump MexAB from Pseudomonas aeruginosa. This pump is co-reconstituted into proteoliposomes together with bacteriorhodopsin (BR), a light-activated proton pump. In this system, upon illumination with visible light, the photo-induced proton gradient created by the BR is shown to be coupled to the active transport of substrates through the pump.
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Affiliation(s)
- Alice Verchère
- Laboratoire de Cristallographie et RMN Biologiques (CNRS UMR8015), Faculté de Pharmacie, Université Paris Descartes , Sorbonne Paris Cité, 4 Avenue de l'Observatoire, 75006 Paris, France
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266
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Kimura T, Yeliseev AA, Vukoti K, Rhodes SD, Cheng K, Rice KC, Gawrisch K. Recombinant cannabinoid type 2 receptor in liposome model activates g protein in response to anionic lipid constituents. J Biol Chem 2012; 287:4076-87. [PMID: 22134924 PMCID: PMC3281699 DOI: 10.1074/jbc.m111.268425] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 11/29/2011] [Indexed: 11/06/2022] Open
Abstract
Human cannabinoid type 2 (CB(2)) receptor expressed in Escherichia coli was purified and successfully reconstituted in the functional form into lipid bilayers composed of POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and cholesteryl hemisuccinate (CHS). Reconstitution was performed by detergent removal from the protein/lipid/detergent mixed micelles either on an adsorbent column, or by rapid dilution to below the critical micelle concentration of detergent followed by removal of detergent monomers on a concentrator. Proteoliposomes prepared at a protein/phospholipid/CHS molar ratio of 1/620-650/210-220 are free of detergent as shown by (1)H NMR, have a homogeneous protein/lipid ratio shown by isopycnic gradient ultracentrifugation, and are small in size with a mean diameter of 150-200 nm as measured by dynamic light scattering. Functional integrity of the reconstituted receptor was confirmed by quantitative binding of (2)H-labeled agonist CP-55,940-d(6) measured by (2)H magic angle spinning NMR, as well as by activation of G protein. The efficiency of G protein activation by agonist-bound CB(2) receptor was affected by negative electric surface potentials of proteoliposomes controlled by the content of anionic CHS or POPS. The activation was highest at an anionic lipid content of about 50 mol %. There was no correlation between the efficiency of G protein activation and an increase of hydrocarbon chain order induced by CHS or cholesterol. The results suggest the importance of anionic lipids in regulating signal transduction by CB(2) receptor and other class A GPCR. The successful reconstitution of milligram quantities of pure, functional CB(2) receptor enables a wide variety of structural studies.
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Affiliation(s)
- Tomohiro Kimura
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | | | - Krishna Vukoti
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | - Steven D. Rhodes
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
| | - Kejun Cheng
- the Chemical Biology Research Branch, NIDA and NIAAA, National Institutes of Health, Bethesda, Maryland 20852
| | - Kenner C. Rice
- the Chemical Biology Research Branch, NIDA and NIAAA, National Institutes of Health, Bethesda, Maryland 20852
| | - Klaus Gawrisch
- From the Laboratory of Membrane Biochemistry and Biophysics, NIAAA, and
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267
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Türck M, Bierbaum G. Purification and activity testing of the full-length YycFGHI proteins of Staphylococcus aureus. PLoS One 2012; 7:e30403. [PMID: 22276191 PMCID: PMC3262814 DOI: 10.1371/journal.pone.0030403] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/20/2011] [Indexed: 11/19/2022] Open
Abstract
Background The YycFG two-component regulatory system (TCS) of Staphylococcus aureus represents the only essential TCS that is almost ubiquitously distributed in Gram-positive bacteria with a low G+C-content. YycG (WalK/VicK) is a sensor histidine-kinase and YycF (WalR/VicR) is the cognate response regulator. Both proteins play an important role in the biosynthesis of the cell envelope and mutations in these proteins have been involved in development of vancomycin and daptomycin resistance. Methodology/Principal Findings Here we present high yield expression and purification of the full-length YycG and YycF proteins as well as of the auxiliary proteins YycH and YycI of Staphylococcus aureus. Activity tests of the YycG kinase and a mutated version, that harbours an Y306N exchange in its cytoplasmic PAS domain, in a detergent-micelle-model and a phosholipid-liposome-model showed kinase activity (autophosphorylation and phosphoryl group transfer to YycF) only in the presence of elevated concentrations of alkali salts. A direct comparison of the activity of the kinases in the liposome-model indicated a higher activity of the mutated YycG kinase. Further experiments indicated that YycG responds to fluidity changes in its microenvironment. Conclusions/Significance The combination of high yield expression, purification and activity testing of membrane and membrane-associated proteins provides an excellent experimental basis for further protein-protein interaction studies and for identification of all signals received by the YycFGHI system.
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Affiliation(s)
- Michael Türck
- Institute of Medical Microbiology, Immunology and Parasitology (IMMIP), University of Bonn, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology (IMMIP), University of Bonn, Bonn, Germany
- * E-mail:
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268
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Harsman A, Bartsch P, Hemmis B, Krüger V, Wagner R. Exploring protein import pores of cellular organelles at the single molecule level using the planar lipid bilayer technique. Eur J Cell Biol 2012; 90:721-30. [PMID: 21684628 DOI: 10.1016/j.ejcb.2011.04.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Proteins of living cells carry out their specialized functions within various subcellular membranes or aqueous spaces. Approximately half of all the proteins of a typical cell are transported into or across membranes. Targeting and transport to their correct subcellular destinations are essential steps in protein biosynthesis. In eukaryotic cells secretory proteins are transported into the endoplasmic reticulum before they are transported in vesicles to the plasma membrane. Virtually all proteins of the endosymbiotic organelles, chloroplasts and mitochondria, are synthesized on cytosolic ribosomes and posttranslationally imported. Genetic and biochemical techniques led to rather detailed knowledge on the subunit composition of the various protein transport complexes which carry out the membrane transport of the preproteins. Conclusive concepts on targeting and cytosolic transport of polypeptides emerged, while still few details on the molecular nature and mechanisms of the channel moieties of protein translocation complexes have been achieved. In this paper we will describe the history of how the individual subunits forming the channel pores of the chloroplast, mitochondrial and endoplasmic reticulum protein import machineries were identified and characterized by single channel electrophysiological techniques in planar bilayers. We will also highlight recent developments in the exploration of the molecular properties of protein translocating channels and the regulation of the diverse protein translocation systems using the planar bilayer technique.
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Affiliation(s)
- Anke Harsman
- University of Osnabrück, Faculty of Biology and Chemistry, Department of Biophysics, Barbarastr. 13, 49076 Osnabrück, Germany
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269
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Bending Rigidities of Lipid Bilayers. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/b978-0-12-396533-2.00006-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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270
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Abstract
Although cell-free expression is a relative newcomer to the biochemical toolbox, it has already been reviewed extensively, even in the more specialized cases such as membrane protein expression, nanolipoprotein particles, and applications to crystallography and nuclear magnetic resonance (NMR). Solid-state NMR is also a newcomer to the structural biology toolbox, with its own specificities in terms of sample preparation. Cell-free expression and solid-state NMR are a promising combination that has already proven useful for the structural study of membrane proteins in their native environment, the hydrated lipid bilayer. We describe below several protocols for preparing MscL, a mechanosensitive membrane channel, using cell-free expression destined for a solid-state NMR study. These protocols are flexible and can easily be applied to other membrane proteins, with minor adjustments.
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Affiliation(s)
- Alaa Abdine
- CNRS and Université Paris Diderot, IBPC, Paris, France
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271
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Carnarius C, Kreir M, Krick M, Methfessel C, Moehrle V, Valerius O, Brüggemann A, Steinem C, Fertig N. Green fluorescent protein changes the conductance of connexin 43 (Cx43) hemichannels reconstituted in planar lipid bilayers. J Biol Chem 2011; 287:2877-86. [PMID: 22139870 DOI: 10.1074/jbc.m111.319871] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In mammalian tissues, connexin 43 (Cx43) is the most prominent member of the connexin family. In a single lipid bilayer, six connexin subunits assemble into a hemichannel (connexon). Direct communication of apposing cells is realized by two adjacent hemichannels, which can form gap junction channels. Here, we established an expression system in Pichia pastoris to recombinantly produce and purify Cx43 as well as Cx43 fused to green fluorescent protein (GFP). Proteins were isolated from crude cell membrane fractions via affinity chromatography. Cx43 and Cx43-GFP hemichannels were reconstituted in giant unilamellar vesicles as proven by fluorescence microscopy, and their electrophysiological behavior was analyzed on the single channel level by planar patch clamping. Cx43 and Cx43-GFP both showed an ohmic behavior and a voltage-dependent open probability. Cx43 hemichannels exhibited one major mean conductance of 224 ± 26 picosiemens (pS). In addition, a subconductance state at 124 ± 5 pS was identified. In contrast, the analysis of Cx43-GFP single channels revealed 10 distinct conductance states in the range of 15 to 250 pS, with a larger open probability at 0 mV as compared with Cx43, which suggests that intermolecular interactions between the GFP molecules alter the electrophysiology of the protein.
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Affiliation(s)
- Christian Carnarius
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
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272
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Siegel A, Kimble-Hill A, Garg S, Jordan R, Naumann C. Native ligands change integrin sequestering but not oligomerization in raft-mimicking lipid mixtures. Biophys J 2011; 101:1642-50. [PMID: 21961590 PMCID: PMC3183796 DOI: 10.1016/j.bpj.2011.08.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 08/17/2011] [Accepted: 08/30/2011] [Indexed: 11/16/2022] Open
Abstract
Distinct lipid environments, including lipid rafts, are increasingly recognized as a crucial factor affecting membrane protein function in plasma membranes. Unfortunately, an understanding of their role in membrane protein activation and oligomerization has remained elusive due to the challenge of characterizing these often small and transient plasma membrane heterogeneities in live cells. To address this difficulty, we present an experimental model membrane platform based on polymer-supported lipid bilayers containing stable raft-mimicking domains (type I) and homogeneous cholesterol-lipid mixtures (type II) into which transmembrane proteins are incorporated (α(v)β(3) and α(5)β(1) integrins). These flexible lipid platforms enable the use of confocal fluorescence spectroscopy, including the photon counting histogram method, in tandem with epifluorescence microscopy to quantitatively probe the effect of the binding of native ligands from the extracellular matrix ligands (vitronectin and fibronectin for α(v)β(3) and α(5)β(1), respectively) on domain-specific protein sequestration and on protein oligomerization state. We found that both α(v)β(3) and α(5)β(1) sequester preferentially to nonraft domains in the absence of extracellular matrix ligands, but upon ligand addition, α(v)β(3) sequesters strongly into raft-like domains and α(5)β(1) loses preference for either raft-like or nonraft-like domains. A corresponding photon counting histogram analysis showed that integrins exist predominantly in a monomeric state. No change was detected in oligomerization state upon ligand binding in either type I or type II bilayers, but a moderate increase in oligomerization state was observed for increasing concentrations of cholesterol. The combined findings suggest a mechanism in which changes in integrin sequestering are caused by ligand-induced changes in integrin conformation and/or dynamics that affect integrin-lipid interactions without altering the integrin oligomerization state.
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Affiliation(s)
- Amanda P. Siegel
- Department of Chemistry and Chemical Biology, Indiana University Purdue University, Indianapolis, Indiana
| | - Ann Kimble-Hill
- Department of Chemistry and Chemical Biology, Indiana University Purdue University, Indianapolis, Indiana
| | - Sumit Garg
- Department of Chemistry and Chemical Biology, Indiana University Purdue University, Indianapolis, Indiana
| | - Rainer Jordan
- Department Chemie, Technische Universität Dresden, Dresden, Germany
| | - Christoph A. Naumann
- Department of Chemistry and Chemical Biology, Indiana University Purdue University, Indianapolis, Indiana
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273
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Monitoring the active transport of efflux pumps after their reconstitution into proteoliposomes: caveats and keys. Anal Biochem 2011; 420:194-6. [PMID: 22019764 DOI: 10.1016/j.ab.2011.09.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/20/2011] [Accepted: 09/26/2011] [Indexed: 11/23/2022]
Abstract
There is an acute need for a functional assay allowing the investigation of efflux pumps. A dedicated procedure was previously developed, but although it was unambiguous, it suffered from a lack of reproducibility. We describe an optimization of the procedure that makes the assay much more robust.
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274
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Warschawski DE, Arnold AA, Beaugrand M, Gravel A, Chartrand É, Marcotte I. Choosing membrane mimetics for NMR structural studies of transmembrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1957-74. [DOI: 10.1016/j.bbamem.2011.03.016] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 12/11/2022]
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275
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Petrova I, Kurashov V, Semenov A, Mamedov M. Manganese-depleted/reconstituted photosystem II core complexes in solution and liposomes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2011; 104:372-6. [DOI: 10.1016/j.jphotobiol.2011.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 02/28/2011] [Accepted: 03/05/2011] [Indexed: 11/26/2022]
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276
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Desrosiers DC, Anand A, Luthra A, Dunham-Ems SM, LeDoyt M, Cummings MAD, Eshghi A, Cameron CE, Cruz AR, Salazar JC, Caimano MJ, Radolf JD. TP0326, a Treponema pallidum β-barrel assembly machinery A (BamA) orthologue and rare outer membrane protein. Mol Microbiol 2011; 80:1496-515. [PMID: 21488980 PMCID: PMC3115443 DOI: 10.1111/j.1365-2958.2011.07662.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Definitive identification of Treponema pallidum rare outer membrane proteins (OMPs) has long eluded researchers. TP0326, the sole protein in T. pallidum with sequence homology to a Gram-negative OMP, belongs to the BamA family of proteins essential for OM biogenesis. Structural modelling predicted that five polypeptide transport-associated (POTRA) domains comprise the N-terminus of TP0326, while the C-terminus forms an 18-stranded amphipathic β-barrel. Circular dichroism, heat modifiability by SDS-PAGE, Triton X-114 phase partitioning and liposome incorporation supported these topological predictions and confirmed that the β-barrel is responsible for the native protein's amphiphilicity. Expression analyses revealed that native TP0326 is expressed at low abundance, while a protease-surface accessibility assay confirmed surface exposure. Size-exclusion chromatography and blue native polyacrylamide gel electrophoresis revealed a modular Bam complex in T. pallidum larger than that of Escherichia coli. Non-orthologous ancillary factors and self-association of TP0326 via its β-barrel may both contribute to the Bam complex. T. pallidum-infected rabbits mount a vigorous antibody response to both POTRA and β-barrel portions of TP0326, whereas humans with secondary syphilis respond predominantly to POTRA. The syphilis spirochaete appears to have devised a stratagem for harnessing the Bam pathway while satisfying its need to limit surface antigenicity.
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Affiliation(s)
- Daniel C. Desrosiers
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Arvind Anand
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Amit Luthra
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Star M Dunham-Ems
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Morgan LeDoyt
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Michael A. D. Cummings
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Azad Eshghi
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Caroline E. Cameron
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Adriana R. Cruz
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
| | - Juan C. Salazar
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
- Department of Pediatrics, Connecticut Children's Medical Center, Division of Pediatric Infectious Diseases, Hartford, CT 06106
| | - Melissa J. Caimano
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - Justin D. Radolf
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06030
- Department of Pediatrics, Connecticut Children's Medical Center, Division of Pediatric Infectious Diseases, Hartford, CT 06106
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277
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Optimized purification of a heterodimeric ABC transporter in a highly stable form amenable to 2-D crystallization. PLoS One 2011; 6:e19677. [PMID: 21602923 PMCID: PMC3094339 DOI: 10.1371/journal.pone.0019677] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 04/06/2011] [Indexed: 12/24/2022] Open
Abstract
Optimized protocols for achieving high-yield expression, purification and reconstitution of membrane proteins are required to study their structure and function. We previously reported high-level expression in Escherichia coli of active BmrC and BmrD proteins from Bacillus subtilis, previously named YheI and YheH. These proteins are half-transporters which belong to the ABC (ATP-Binding Cassette) superfamily and associate in vivo to form a functional transporter able to efflux drugs. In this report, high-yield purification and functional reconstitution were achieved for the heterodimer BmrC/BmrD. In contrast to other detergents more efficient for solubilizing the transporter, dodecyl-ß-D-maltoside (DDM) maintained it in a drug-sensitive and vanadate-sensitive ATPase-competent state after purification by affinity chromatography. High amounts of pure proteins were obtained which were shown either by analytical ultracentrifugation or gel filtration to form a monodisperse heterodimer in solution, which was notably stable for more than one month at 4°C. Functional reconstitution using different lipid compositions induced an 8-fold increase of the ATPase activity (kcat∼5 s−1). We further validated that the quality of the purified BmrC/BmrD heterodimer is suitable for structural analyses, as its reconstitution at high protein densities led to the formation of 2-D crystals. Electron microscopy of negatively stained crystals allowed the calculation of a projection map at 20 Å resolution revealing that BmrC/BmrD might assemble into oligomers in a lipidic environment.
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278
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Moss TJ, Daga A, McNew JA. Fusing a lasting relationship between ER tubules. Trends Cell Biol 2011; 21:416-23. [PMID: 21550242 DOI: 10.1016/j.tcb.2011.03.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 03/31/2011] [Accepted: 03/31/2011] [Indexed: 11/18/2022]
Abstract
Atlastin is an integral membrane GTPase localized to the endoplasmic reticulum (ER). In vitro and in vivo analyses indicate that atlastin is a membrane fusogen capable of driving membrane fusion, suggesting a role in ER structure and maintenance. Interestingly, mutations in the human atlastin-1 gene, SPG3A, cause a form of autosomal dominant hereditary spastic paraplegia (HSP). The etiology of HSP is unclear, but two predominant forms of the disorder are caused by mutant proteins that affect ER structure, formation and maintenance in motor neurons. In this review, we describe the current knowledge about the molecular mechanism of atlastin function and its potential role in HSP. Greater understanding of the function of atlastin and associated proteins should provide important insight into normal ER biogenesis and maintenance, as well as the pathology of disease.
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Affiliation(s)
- Tyler J Moss
- Department of Biochemistry and Cell Biology, Rice University, MS601, Houston, TX 77005, USA
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279
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Hua D, Kuang L, Liang H. Self-Directed Reconstitution of Proteorhodopsin with Amphiphilic Block Copolymers Induces the Formation of Hierarchically Ordered Proteopolymer Membrane Arrays. J Am Chem Soc 2011; 133:2354-7. [DOI: 10.1021/ja109796x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daoben Hua
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Liangju Kuang
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Hongjun Liang
- Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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280
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Demarche S, Sugihara K, Zambelli T, Tiefenauer L, Vörös J. Techniques for recording reconstituted ion channels. Analyst 2011; 136:1077-89. [PMID: 21267480 DOI: 10.1039/c0an00828a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review describes and discusses techniques useful for monitoring the activity of protein ion channels in vitro. In the first section the biological importance and the classification of ion channels are outlined in order to justify the strong motivation for dealing with this important class of membrane proteins. The expression, reconstitution and integration of recombinant proteins into lipid bilayers are crucial steps to obtain consistent data when working with ion channels. In the second section recording techniques used in research are presented. Since this review focuses on analytical systems bearing reconstituted ion channels the industrial most important patch-clamp techniques of cells are only briefly mentioned. In section three, artificial systems developed in the last decades are described while the emerging technologies using nanostructured supports or microfluidic systems are presented in section four. Finally, the remaining challenges of membrane protein analysis and its potential applications are briefly outlined.
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Affiliation(s)
- Sophie Demarche
- Biomolecular Research, Paul Scherrer Institut (PSI), CH-5232 Villigen, Switzerland
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281
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Faxén K, Andersen JL, Gourdon P, Fedosova N, Morth JP, Nissen P, Møller JV. Characterization of a Listeria monocytogenes Ca(2+) pump: a SERCA-type ATPase with only one Ca(2+)-binding site. J Biol Chem 2011; 286:1609-17. [PMID: 21047776 PMCID: PMC3020769 DOI: 10.1074/jbc.m110.176784] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 10/21/2010] [Indexed: 11/06/2022] Open
Abstract
We have characterized a putative Ca(2+)-ATPase from the pathogenic bacterium Listeria monocytogenes with the locus tag lmo0841. The purified and detergent-solubilized protein, which we have named Listeria monocytogenes Ca(2+)-ATPase 1 (LMCA1), performs a Ca(2+)-dependent ATP hydrolysis and actively transports Ca(2+) after reconstitution in dioleoylphosphatidyl-choline vesicles. Despite a high sequence similarity to the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1a) and plasma membrane Ca(2+)-ATPase (PMCA), LMCA1 exhibits important biochemical differences such as a low Ca(2+) affinity (K(0.5) ∼80 μm) and a high pH optimum (pH ∼9). Mutational studies indicate that the unusually high pH optimum can be partially ascribed to the presence of an arginine residue (Arg-795), corresponding in sequence alignments to the Glu-908 position at Ca(2+) binding site I of rabbit SERCA1a, but probably with an exposed position in LMCA1. The arginine is characteristic of a large group of putative bacterial Ca(2+)-ATPases. Moreover, we demonstrate that H(+) is countertransported with a transport stoichiometry of 1 Ca(2+) out and 1 H(+) in per ATP hydrolyzed. The ATPase may serve an important function by removing Ca(2+) from the microorganism in environmental conditions when e.g. stressed by high Ca(2+) and alkaline pH.
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Affiliation(s)
- Kristina Faxén
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | | | - Pontus Gourdon
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Natalya Fedosova
- Physiology and Biophysics, Ole Worms Allé 6, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000, Aarhus, Denmark
| | - Jens Preben Morth
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Poul Nissen
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Jesper Vuust Møller
- Physiology and Biophysics, Ole Worms Allé 6, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000, Aarhus, Denmark
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282
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Menon I, Huber T, Sanyal S, Banerjee S, Barré P, Canis S, Warren JD, Hwa J, Sakmar TP, Menon AK. Opsin is a phospholipid flippase. Curr Biol 2011; 21:149-53. [PMID: 21236677 DOI: 10.1016/j.cub.2010.12.031] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 11/17/2010] [Accepted: 12/14/2010] [Indexed: 11/19/2022]
Abstract
Polar lipids must flip-flop rapidly across biological membranes to sustain cellular life [1, 2], but flipping is energetically costly [3] and its intrinsic rate is low. To overcome this problem, cells have membrane proteins that function as lipid transporters (flippases) to accelerate flipping to a physiologically relevant rate. Flippases that operate at the plasma membrane of eukaryotes, coupling ATP hydrolysis to unidirectional lipid flipping, have been defined at a molecular level [2]. On the other hand, ATP-independent bidirectional flippases that translocate lipids in biogenic compartments, e.g., the endoplasmic reticulum, and specialized membranes, e.g., photoreceptor discs [4, 5], have not been identified even though their activity has been recognized for more than 30 years [1]. Here, we demonstrate that opsin is the ATP-independent phospholipid flippase of photoreceptor discs. We show that reconstitution of opsin into large unilamellar vesicles promotes rapid (τ<10 s) flipping of phospholipid probes across the vesicle membrane. This is the first molecular identification of an ATP-independent phospholipid flippase in any system. It reveals an unexpected activity for opsin and, in conjunction with recently available structural information on this G protein-coupled receptor [6, 7], significantly advances our understanding of the mechanism of ATP-independent lipid flip-flop.
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Affiliation(s)
- Indu Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
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283
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Vecino AJ, de la Arada I, Segura RL, Goñi FM, de la Cruz F, Arrondo JLR, Alkorta I. Membrane insertion stabilizes the structure of TrwB, the R388 conjugative plasmid coupling protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1032-9. [PMID: 21211515 DOI: 10.1016/j.bbamem.2010.12.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 12/23/2010] [Accepted: 12/25/2010] [Indexed: 11/30/2022]
Abstract
TrwB is an integral membrane protein that plays a crucial role in the conjugative process of plasmid R388. We have recently shown [Vecino et al., Biochim. Biophys. Acta 1798(11), 2160-2169 (2010)] that TrwB can be reconstituted into liposomes, and that bilayer incorporation increases its affinity for nucleotides and its specificity for ATP. In the present contribution we examine the structural effects of membrane insertion on TrwB, by comparing the protein in reconstituted form and in the form of protein/lipid/detergent mixed micelles. TrwB was reconstituted in PE:PG:CL (76.3:19.6:4.1mol ratio) with a final 99:1 lipid:protein mol ratio. This lipid mixture is intended to mimic the bacterial inner membrane composition, and allows a more efficient reconstitution than other lipid mixtures tested. The studies have been carried out mainly using infrared spectroscopy, because this technique provides simultaneously information on both the lipid and protein membrane components. Membrane reconstitution of TrwB is accompanied by a decrease in β-sheet contents and an increase in β-strand structures, probably related to protein-protein contacts in the bilayer. The predominant α-helical component remains unchanged. The bilayer-embedded protein becomes thermally more stable, and also more resistant to trypsin digestion. The properties of the bilayer lipids are also modified in the presence of TrwB, the phospholipid acyl chains are slightly ordered, and the phosphate groups at the interface become more accessible to water. In addition, we observe that the protein thermal denaturation affects the lipid thermal transition profile.
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Affiliation(s)
- Ana J Vecino
- Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
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284
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Nam J, Beales PA, Vanderlick TK. Giant phospholipid/block copolymer hybrid vesicles: mixing behavior and domain formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1-6. [PMID: 21133340 DOI: 10.1021/la103428g] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Lipids and block copolymers can be individually assembled into unsupported, spherical membranes (liposomes or polymersomes), each having their own particular benefits and limitations. Here we demonstrate the preparation of microscale, hybrid "lipopolymersomes" composed of the common lipid POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine) and the commercially available copolymer PBd-b-PEO (polybutadiene-b-poly(ethylene oxide)) with the goal of incorporating the advantageous qualities of the unitary systems into mixed-membrane capsules. We investigate the lipopolymersomes using confocal fluorescence microscopy and demonstrate that these hybrid membranes are well mixed on nanoscopic length scales within the permittable compositional windows for hybrid vesicle formation. We measure the intramembrane dynamics and mechanical properties of these hybrid membranes by fluorescence recovery after photobleaching (FRAP) and micropipet aspiration, respectively. For the first time, we demonstrate the demixing of lipid-rich and polymer-rich membrane domains within the same vesicle membrane. This is achieved by the biotinylation of one of the constituent species and cross linking with the protein NeutrAvidin. The resultant domain patterning is dependent upon which component carries the biotin functionality: cross linking of the copolymer species results in domains that ripen into a single, large, copolymer-rich island, and cross linking of the lipids yields many small, "spot-like", lipid-rich domains within a copolymer-rich matrix. We discuss these morphological differences in terms of the fluidity and mechanical properties of the membrane phases and the possible resultant interdomain interactions within the membrane. These heterogeneous hybrid lipopolymersomes could find applications in fields such as targeted delivery, controlled release, and environmental detection assays where these capsules possess the characteristics of biocompatible lipid membranes combined with enhanced mechanical strength and stability from the copolymer matrix.
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Affiliation(s)
- Jin Nam
- Chemical & Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States
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285
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Mašek J, Bartheldyová E, Korvasová Z, Škrabalová M, Koudelka Š, Kulich P, Kratochvílová I, Miller AD, Ledvina M, Raška M, Turánek J. Immobilization of histidine-tagged proteins on monodisperse metallochelation liposomes: Preparation and study of their structure. Anal Biochem 2011; 408:95-104. [DOI: 10.1016/j.ab.2010.08.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/02/2010] [Accepted: 08/16/2010] [Indexed: 12/22/2022]
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286
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Lin WC, Yu CH, Triffo S, Groves JT. Supported Membrane Formation, Characterization, Functionalization, and Patterning for Application in Biological Science and Technology. ACTA ACUST UNITED AC 2010; 2:235-69. [DOI: 10.1002/9780470559277.ch100131] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Wan-Chen Lin
- Howard Hughes Medical Institute, Department of Chemistry, University of California; Berkeley California
| | - Cheng-Han Yu
- Research Center of Excellence in Mechanobiology; National University of Singapore Singapore
| | - Sara Triffo
- Howard Hughes Medical Institute, Department of Chemistry, University of California; Berkeley California
| | - Jay T. Groves
- Howard Hughes Medical Institute, Department of Chemistry, University of California; Berkeley California
- Research Center of Excellence in Mechanobiology; National University of Singapore Singapore
- Physical Biosciences Division, Lawrence Berkeley National Laboratory; Berkeley California
- Materials Sciences Division, Lawrence Berkeley National Laboratory; Berkeley California
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287
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Ji H, Coleman J, Yang R, Melia TJ, Rothman JE, Tareste D. Protein determinants of SNARE-mediated lipid mixing. Biophys J 2010; 99:553-60. [PMID: 20643074 DOI: 10.1016/j.bpj.2010.04.060] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 04/19/2010] [Accepted: 04/26/2010] [Indexed: 01/14/2023] Open
Abstract
Soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE)-mediated lipid mixing can be efficiently recapitulated in vitro by the incorporation of purified vesicle membrane (-v) SNARE and target membrane (t-) SNARE proteins into separate liposome populations. Despite the strong correlation between the observed activities in this system and the known SNARE physiology, some recent works have suggested that SNARE-mediated lipid mixing may be limited to circumstances where membrane defects arise from artifactual reconstitution conditions (such as nonphysiological high-protein concentrations or unrealistically small liposome populations). Here, we show that the previously published strategies used to reconstitute SNAREs into liposomes do not significantly affect either the physical parameters of the proteoliposomes or the ability of SNAREs to drive lipid mixing in vitro. The surface density of SNARE proteins turns out to be the most critical parameter, which controls both the rate and the extent of SNARE-mediated liposome fusion. In addition, the specific activity of the t-SNARE complex is significantly influenced by expression and reconstitution protocols, such that we only observe optimal lipid mixing when the t-SNARE proteins are coexpressed before purification.
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Affiliation(s)
- Hong Ji
- Department of Cell Biology, School of Medicine, Yale University, New Haven, Connecticut, USA
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288
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Ménager C, Guemghar D, Cabuil V, Lesieur S. Interaction of n-octyl β,D-glucopyranoside with giant magnetic-fluid-loaded phosphatidylcholine vesicles: direct visualization of membrane curvature fluctuations as a function of surfactant partitioning between water and lipid bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:15453-15463. [PMID: 20825201 DOI: 10.1021/la102532h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The present study deals with the morphological modifications of giant dioleoyl phosphatidylcholine vesicles (DOPC GUVs) induced by the nonionic surfactant n-octyl β,D-glucopyranoside at sublytic levels, i.e., in the first steps of the vesicle-to-micelle transition process, when surfactant inserts into the vesicle bilayer without disruption. Experimental conditions were perfected to exactly control the surfactant bilayer composition of the vesicles, in line with former work focused on the mechanical properties of the membrane of magnetic-fluid-loaded DOPC GUVs submitted to a magnetic field. The purpose here was to systematically examine, in the absence of any external mechanical constraint, the dynamics of giant vesicle shape and membrane deformations as a function of surfactant partitioning between the aqueous phase and the lipid membrane, beforehand established by turbidity measurements from small unilamellar vesicles.
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Affiliation(s)
- Christine Ménager
- UPMC Univ Paris 06, UMR 7195 PECSA, Physicochimie des Electrolytes, Colloïdes, Sciences Analytiques, F-75005 Paris France
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289
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Kataoka-Hamai C, Higuchi M, Iwai H, Miyahara Y. Detergent-mediated formation of polymer-supported phospholipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:14600-14605. [PMID: 20726608 DOI: 10.1021/la102151p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Supported phospholipid bilayers can be formed by established methods such as vesicle fusion and the Langmuir-Blodgett (LB) technique. However, challenges remain in regards to creating supported bilayers from various lipid compositions, using various support surfaces, and incorporating membrane proteins. Here we report a detergent removal method as an alternative means of supported bilayer formation. The process consists of three steps: (1) incubation of phospholipid-poly(ethylene glycol) (PEG)-grafted glass with lipid-detergent micelles; (2) detergent removal by washing the surface with vesicles; and (3) incubation with the vesicles to complete lipid adsorption. These procedures yielded fluid planar bilayers of zwitterionic lipids. Because fluid structures were not obtained by vesicle fusion, the detergent seemed necessary to produce the polymer-supported bilayers. While anionic phospholipids inhibited the attachment of fluid bilayers in the absence of calcium ions, supported bilayers with almost full mobility were obtained from lipid mixtures containing 10-20 mol % anionic lipids in the presence of calcium ions. The incorporation of the anionic lipids in the bulk-facing leaflet was demonstrated by the binding of dye-labeled annexin V.
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Affiliation(s)
- Chiho Kataoka-Hamai
- Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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290
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Lactose permease lipid selectivity using Förster resonance energy transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1707-13. [DOI: 10.1016/j.bbamem.2010.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 05/09/2010] [Accepted: 05/12/2010] [Indexed: 11/23/2022]
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291
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Debnath DK, Otzen DE. Cell-free synthesis and folding of transmembrane OmpA reveals higher order structures and premature truncations. Biophys Chem 2010; 152:80-8. [PMID: 20813447 DOI: 10.1016/j.bpc.2010.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/04/2010] [Accepted: 08/08/2010] [Indexed: 01/23/2023]
Abstract
We use a cell-free transcription-translation system to monitor the effect of different lipids on the synthesis and folding of the transmembrane domain of the outer membrane protein OmpA from E. coli under physiological conditions. Folding is consistent with previous observations made in vitro at high pH. Synthesis and folding yields are optimal in phosphocholine lipids, particularly in short chain lipids and small vesicles, while lipid rafts do not promote folding compared to the folding in the absence of lipids. Truncated species are observed during translation in the presence of the periplasmic chaperone Skp, which likely binds to the newly synthesized polypeptide chain during cell-free translation and thus prematurely terminate polypeptide chain synthesis. In contrast, folded and unfolded dimers of OmpA correlate negatively with folding yields. This suggests that dimer formation competes with folding and insertion of monomeric OmpA, though folded dimers slowly appear to convert to folded monomers.
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Affiliation(s)
- Dilip K Debnath
- Center for insoluble protein structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C., Denmark
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292
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Reconstitution in liposome bilayers enhances nucleotide binding affinity and ATP-specificity of TrwB conjugative coupling protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2160-9. [PMID: 20647001 DOI: 10.1016/j.bbamem.2010.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/04/2010] [Accepted: 07/07/2010] [Indexed: 11/24/2022]
Abstract
Bacterial conjugative systems code for an essential membrane protein that couples the relaxosome to the DNA transport apparatus, called type IV coupling protein (T4CP). TrwB is the T4CP of the conjugative plasmid R388. In earlier work we found that this protein, purified in the presence of detergents, binds preferentially purine nucleotides trisphosphate. In contrast a soluble truncated mutant TrwBΔN70 binds uniformly all nucleotides tested. In this work, TrwB has been successfully reconstituted into liposomes. The non-membranous portion of the protein is almost exclusively oriented towards the outside of the vesicles. Functional analysis of TrwB proteoliposomes demonstrates that when the protein is inserted into the lipid bilayer the affinity for adenine and guanine nucleotides is enhanced as compared to that of the protein purified in detergent or to the soluble deletion mutant, TrwBΔN70. The protein specificity for adenine nucleotides is also increased. No ATPase activity has been found in TrwB reconstituted in proteoliposomes. This result suggests that the N-terminal transmembrane segment of this T4CP interferes with its ATPase activity and can be taken to imply that the TrwB transmembrane domain plays a regulatory role in its biological activity.
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293
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Picas L, Carretero-Genevrier A, Montero MT, Vázquez-Ibar J, Seantier B, Milhiet PE, Hernández-Borrell J. Preferential insertion of lactose permease in phospholipid domains: AFM observations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1014-9. [DOI: 10.1016/j.bbamem.2010.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/01/2010] [Accepted: 01/11/2010] [Indexed: 11/29/2022]
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294
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Yoshiura C, Kofuku Y, Ueda T, Mase Y, Yokogawa M, Osawa M, Terashima Y, Matsushima K, Shimada I. NMR Analyses of the Interaction between CCR5 and Its Ligand Using Functional Reconstitution of CCR5 in Lipid Bilayers. J Am Chem Soc 2010; 132:6768-77. [DOI: 10.1021/ja100830f] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Chie Yoshiura
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Yutaka Kofuku
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Takumi Ueda
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Yoko Mase
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Yuya Terashima
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Kouji Matsushima
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Effector Cell Institute, Inc., Tokyo 150-0036, Japan, and Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Aomi 2-41-6, Koto-ku, Tokyo 135-0064, Japan
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295
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Kim C, Vink M, Hu M, Love J, Stokes DL, Ubarretxena-Belandia I. An automated pipeline to screen membrane protein 2D crystallization. ACTA ACUST UNITED AC 2010; 11:155-66. [PMID: 20349145 DOI: 10.1007/s10969-010-9088-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 03/11/2010] [Indexed: 12/21/2022]
Abstract
Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified membrane proteins, the detergent in a protein-lipid-detergent ternary mixture must be removed, generally by dialysis, under conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices. To identify these conditions a wide range of parameters such as pH, lipid composition, lipid-to-protein ratio, ionic strength and ligands must be screened in a procedure involving four steps: crystallization, specimen preparation for electron microscopy, image acquisition, and evaluation. Traditionally, these steps have been carried out manually and, as a result, the scope of 2D crystallization trials has been limited. We have therefore developed an automated pipeline to screen the formation of 2D crystals. We employed a 96-well dialysis block for reconstitution of the target protein over a wide range of conditions designed to promote crystallization. A 96-position magnetic platform and a liquid handling robot were used to prepare negatively stained specimens in parallel. Robotic grid insertion into the electron microscope and computerized image acquisition ensures rapid evaluation of the crystallization screen. To date, 38 2D crystallization screens have been conducted for 15 different membrane proteins, totaling over 3000 individual crystallization experiments. Three of these proteins have yielded diffracting 2D crystals. Our automated pipeline outperforms traditional 2D crystallization methods in terms of throughput and reproducibility.
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Affiliation(s)
- Changki Kim
- The New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
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296
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Walde P, Cosentino K, Engel H, Stano P. Giant Vesicles: Preparations and Applications. Chembiochem 2010; 11:848-65. [DOI: 10.1002/cbic.201000010] [Citation(s) in RCA: 556] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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297
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298
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Holzer M, Momm J, Schubert R. Lipid transfer mediated by a recombinant pro-sterol carrier protein 2 for the accurate preparation of asymmetrical membrane vesicles requires a narrow vesicle size distribution: a free-flow electrophoresis study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4142-4151. [PMID: 20095535 DOI: 10.1021/la903386d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We applied protein-mediated lipid transfer using recombinant His-tagged pro-sterol carrier protein 2 (pro-SCP2) to prepare asymmetrical membrane vesicles (AMV) featuring an unequal transmembrane distribution of the negative phospholipid egg-phosphatidylglycerol (EPG). Pure egg-phosphatidylcholine (EPC) vesicles were used as the acceptor and EPC:EPG 90:10 mol % vesicles as the donor populations. The changes in surface charge during EPG transfer were used to quantify the degree of asymmetry by free-flow electrophoresis (FFE). The relative deflection in FFE correlated with EPG content in the outer monolayer (x(EPG)). The initial transfer rates and first order rate constants for the transfer process were determined. The addition of pro-SCP2 at a molar protein-to-lipid ratio R(P/L) of (15-20) x 10(-5) accelerated the EPG transfer to half-times of between 2 and 3 h. Thus, the transmembrane redistribution of EPG by flip-flop, which reduces the degree of asymmetry and occurs at half-times of tens of hours, was minimized during the transfer process. We investigated the influence of membrane curvature on the transfer rate using 50 and 100 nm vesicles with very low size distribution widths (RSD of 13-17%). Transfer occurred with a 55.7% higher initial rate between the smaller vesicles. The use of equally sized acceptor and donor populations of such narrow size distributions was shown to be important for the preparation of AMV with a uniform degree of asymmetry. Under these conditions, AMV were obtained after less than 3 h by preparative FFE separation. In the case of the acceptor vesicles, EPG transfer increased x(EPG) to 3 mol %, whereas it was reduced to 6 mol % in the donor vesicles.
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Affiliation(s)
- Martin Holzer
- Department of Pharmaceutical Technology and Biopharmacy, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany.
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299
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Vuong N, Baenziger JE, Johnston LJ. Preparation of reconstituted acetylcholine receptor membranes suitable for AFM imaging of lipid–protein interactions. Chem Phys Lipids 2010; 163:117-26. [DOI: 10.1016/j.chemphyslip.2009.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 09/04/2009] [Accepted: 09/24/2009] [Indexed: 12/20/2022]
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300
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Picas L, Montero MT, Morros A, Vázquez-Ibar J, Hernández-Borrell J. Evidence of phosphatidylethanolamine and phosphatidylglycerol presence at the annular region of lactose permease of Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:291-6. [DOI: 10.1016/j.bbamem.2009.06.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 06/15/2009] [Accepted: 06/29/2009] [Indexed: 10/20/2022]
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