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de la Mora E, Dezi M, Di Cicco A, Bigay J, Gautier R, Manzi J, Polidori J, Castaño-Díez D, Mesmin B, Antonny B, Lévy D. Nanoscale architecture of a VAP-A-OSBP tethering complex at membrane contact sites. Nat Commun 2021; 12:3459. [PMID: 34103503 PMCID: PMC8187361 DOI: 10.1038/s41467-021-23799-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 05/12/2021] [Indexed: 02/05/2023] Open
Abstract
Membrane contact sites (MCS) are subcellular regions where two organelles appose their membranes to exchange small molecules, including lipids. Structural information on how proteins form MCS is scarce. We designed an in vitro MCS with two membranes and a pair of tethering proteins suitable for cryo-tomography analysis. It includes VAP-A, an ER transmembrane protein interacting with a myriad of cytosolic proteins, and oxysterol-binding protein (OSBP), a lipid transfer protein that transports cholesterol from the ER to the trans Golgi network. We show that VAP-A is a highly flexible protein, allowing formation of MCS of variable intermembrane distance. The tethering part of OSBP contains a central, dimeric, and helical T-shape region. We propose that the molecular flexibility of VAP-A enables the recruitment of partners of different sizes within MCS of adjustable thickness, whereas the T geometry of the OSBP dimer facilitates the movement of the two lipid-transfer domains between membranes.
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Affiliation(s)
- Eugenio de la Mora
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Manuela Dezi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.
- Sorbonne Université, Paris, France.
| | - Aurélie Di Cicco
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Joëlle Bigay
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Romain Gautier
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - John Manzi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Joël Polidori
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | | | - Bruno Mesmin
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Bruno Antonny
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.
| | - Daniel Lévy
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.
- Sorbonne Université, Paris, France.
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Molbaek K, Tejada M, Ricke CH, Scharff-Poulsen P, Ellekvist P, Helix-Nielsen C, Kumar N, Klaerke DA, Pedersen PA. Purification and initial characterization of Plasmodium falciparum K + channels, PfKch1 and PfKch2 produced in Saccharomyces cerevisiae. Microb Cell Fact 2020; 19:183. [PMID: 32957994 PMCID: PMC7507820 DOI: 10.1186/s12934-020-01437-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/09/2020] [Indexed: 02/07/2023] Open
Abstract
Resistance towards known antimalarial drugs poses a significant problem, urging for novel drugs that target vital proteins in the malaria parasite Plasmodium falciparum. However, recombinant production of malaria proteins is notoriously difficult. To address this, we have investigated two putative K+ channels, PfKch1 and PfKch2, identified in the P. falciparum genome. We show that PfKch1 and PfKch2 and a C-terminally truncated version of PfKch1 (PfKch11−1094) could indeed be functionally expressed in vivo, since a K+-uptake deficient Saccharomyces cerevisiae strain was complemented by the P. falciparum cDNAs. PfKch11−1094-GFP and GFP-PfKch2 fusion proteins were overexpressed in yeast, purified and reconstituted in lipid bilayers to determine their electrophysiological activity. Single channel conductance amounted to 16 ± 1 pS for PfKch11−1094-GFP and 28 ± 2 pS for GFP-PfKch2. We predicted regulator of K+-conductance (RCK) domains in the C-terminals of both channels, and we accordingly measured channel activity in the presence of Ca2+.
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Affiliation(s)
- Karen Molbaek
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark.,Department of Biology, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Maria Tejada
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark
| | - Christina Hoeier Ricke
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark
| | - Peter Scharff-Poulsen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark
| | - Peter Ellekvist
- Medical Department, Herlev-Gentofte Hospital, Herlev, 2730, Denmark
| | - Claus Helix-Nielsen
- Aquaporin A/S, Kgs Lyngby, 2800, Denmark.,Department of Environmental Engineering, Technical University of Denmark, Kgs Lyngby, 2800, Denmark.,University of Maribor, Laboratory for Water Biophysics and Membrane Technology, Maribor, 2000, Slovenia
| | - Nirbhay Kumar
- Department of Global Health, Milken Institute School of Public Health, George Washington University, Washington DC, 20052-0066, USA
| | - Dan A Klaerke
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark.
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Cheng QD, Chen RQ, He J, Li DW, Yang F, Liu YM, Lu QQ, Dong C, Yin DC. Effect of the weather conditions during solution preparation on lysozyme crystallization. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717011086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Protein crystallization is a delicate process that is always sensitive to environmental factors. When the environmental factors are not well controlled or not controlled at all, identical crystallization droplets from the same mother liquid may yield different crystallization results. One environmental factor, the weather conditions during crystallization solution preparation, is not usually considered as a parameter for protein crystallization. In this paper, it is shown that the weather parameters during preparation of the crystallization experiment, including the ambient temperature, humidity, pressure and particulate matter in the air, can all affect the reproducibility of lysozyme crystallization. An identical lysozyme crystallization experiment was repeated for an entire year, and the weather conditions when each crystallization experiment was set up were recorded along with the crystallization results. Among the parameters recorded, the humidity during the experiment setup showed the strongest effect on lysozyme crystallization. On the basis of these results, it is suggested that the weather conditions during crystallization solution preparation should be considered as a potential factor that can influence protein crystallization.
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Abeyrathne PD, Grigorieff N. Expression, purification, and contaminant detection for structural studies of Ralstonia metallidurance ClC protein rm1. PLoS One 2017; 12:e0180163. [PMID: 28692650 PMCID: PMC5503242 DOI: 10.1371/journal.pone.0180163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/09/2017] [Indexed: 11/19/2022] Open
Abstract
Single-particle electron cryo-microscopy (cryo-EM) has become a popular method for high-resolution study of the structural and functional properties of proteins. However, sufficient expression and purification of membrane proteins holds many challenges. We describe methods to overcome these obstacles using ClC-rm1, a prokaryotic chloride channel (ClC) family protein from Ralstonia metallidurans, overexpressed in Escherichia coli (E. coli) BL21(DE3) strain. Mass spectrometry and electron microscopy analyses of purified samples revealed multiple contaminants that can obfuscate results of subsequent high-resolution structural analysis. Here we describe the systematic optimization of sample preparation procedures, including expression systems, solubilization techniques, purification protocols, and contamination detection. We found that expressing ClC-rm1 in E. coli BL21(DE3) and using n-dodecyl-β-D-maltopyranoside as a detergent for solubilization and purification steps resulted in the highest quality samples of those we tested. However, although protein yield, sample stability, and the resolution of structural detail were improved following these changes, we still detected contaminants including Acriflavine resistant protein AcrB. AcrB was particularly difficult to remove as it co-purified with ClC-rm1 due to four intrinsic histidine residues at its C-terminus that bind to affinity resins. We were able to obtain properly folded pure ClC-rm1 by adding eGFP to the C-terminus and overexpressing the protein in the ΔacrB variant of the JW0451-2 E. coli strain.
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Affiliation(s)
- Priyanka D. Abeyrathne
- Howard Hughes Medical Institute, Janelia Research Campus, Helix Drive, Ashburn, VA, United States of America
| | - Nikolaus Grigorieff
- Howard Hughes Medical Institute, Janelia Research Campus, Helix Drive, Ashburn, VA, United States of America
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Soranzo T, Martin DK, Lenormand JL, Watkins EB. Coupling neutron reflectivity with cell-free protein synthesis to probe membrane protein structure in supported bilayers. Sci Rep 2017; 7:3399. [PMID: 28611396 PMCID: PMC5469739 DOI: 10.1038/s41598-017-03472-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/16/2017] [Indexed: 01/01/2023] Open
Abstract
The structure of the p7 viroporin, an oligomeric membrane protein ion channel involved in the assembly and release of the hepatitis C virus, was determined from proteins expressed and inserted directly into supported model lipid membranes using cell-free protein expression. Cell-free protein expression allowed (i ) high protein concentration in the membrane, (ii ) control of the protein's isotopic constitution, and (iii ) control over the lipid environment available to the protein. Here, we used cell-free protein synthesis to directly incorporate the hepatitis C virus (HCV) p7 protein into supported lipid bilayers formed from physiologically relevant lipids (POPC or asolectin) for both direct structural measurements using neutron reflectivity (NR) and conductance measurements using electrical impedance spectroscopy (EIS). We report that HCV p7 from genotype 1a strain H77 adopts a conical shape within lipid bilayers and forms a viroporin upon oligomerization, confirmed by EIS conductance measurements. This combination of techniques represents a novel approach to the study of membrane proteins and, through the use of selective deuteration of particular amino acids to enhance neutron scattering contrast, has the promise to become a powerful tool for characterizing the protein conformation in physiologically relevant environments and for the development of biosensor applications.
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Affiliation(s)
- Thomas Soranzo
- Synthelis SAS, 5 avenue du Grand Sablon, 38700, La Tronche, France
- University Grenoble Alpes, TheREx, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Donald K Martin
- University Grenoble Alpes, SyNaBi, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Jean-Luc Lenormand
- University Grenoble Alpes, TheREx, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Erik B Watkins
- Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042, Grenoble, Cedex 9, France.
- MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
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6
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The lipidome associated with the γ-secretase complex is required for its integrity and activity. Biochem J 2016; 473:321-34. [PMID: 26811537 DOI: 10.1042/bj20150448] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
γ-Secretase is a multi-subunit membrane protease complex that catalyses the final intramembrane cleavage of the β-amyloid precursor protein (APP) during the neuronal production of amyloid-β peptides (Aβ), which are implicated as the causative agents of Alzheimer's disease (AD). In the present study, we report the reconstitution of a highly purified, active γ-secretase complex into proteoliposomes without exogenous lipids and provide the first direct evidence for the existence of a microenvironment of 53 molecular species from 11 major lipid classes specifically associated with the γ-secretase complex, including phosphatidylcholine and cholesterol. Importantly, we demonstrate that the pharmacological modulation of certain phospholipids abolishes both the integrity and the enzymatic activity of the intramembrane protease. Together, our findings highlight the importance of a specific lipid microenvironment for the structure and function of γ-secretase.
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Orwick‐Rydmark M, Arnold T, Linke D. The Use of Detergents to Purify Membrane Proteins. ACTA ACUST UNITED AC 2016; 84:4.8.1-4.8.35. [DOI: 10.1002/0471140864.ps0408s84] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
| | - Thomas Arnold
- Boehringer‐Ingelheim Veterinary Research Center Hannover Germany
| | - Dirk Linke
- University of Oslo, Department of Biosciences Oslo Norway
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Koudelka S, Mikulik R, Mašek J, Raška M, Turánek Knotigová P, Miller AD, Turánek J. Liposomal nanocarriers for plasminogen activators. J Control Release 2016; 227:45-57. [PMID: 26876783 DOI: 10.1016/j.jconrel.2016.02.019] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 02/09/2016] [Accepted: 02/10/2016] [Indexed: 12/18/2022]
Abstract
Several plasminogen activators (PAs) have been found effective in treating different thromboembolic diseases. However, administration of conventional thrombolytic therapy is limited by a low efficacy of present formulations of PAs. Conventional treatments using these therapeutic proteins are associated with several limitations including rapid inactivation and clearance, short half-life, bleeding complications or non-specific tissue targeting. Liposome-based formulations of PAs such as streptokinase, tissue-plasminogen activator and urokinase have been developed to improve the therapeutic efficacy of these proteins. Resulting liposomal formulations were found to preserve the original activity of PAs, promote their selective delivery and improve thrombus targeting. Therapeutic potential of these liposome-based PAs has been demonstrated successfully in various pre-clinical models in vivo. Reductions in unwanted side effects (e.g., hemorrhage or immunogenicity) as well as enhancements of efficacy and safety were achieved in comparison to currently existing treatment options based on conventional formulations of PAs. This review summarizes present achievements in: (i) preparation of liposome-based formulations of various PAs, (ii) development of PEGylated and targeted liposomal PAs, (iii) physico-chemical characterization of these developed systems, and (iv) testing of their thrombolytic efficacy. We also look to the future and the imminent arrival of theranostic liposomal formulations to move this field forward.
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Affiliation(s)
- Stepan Koudelka
- Department of Pharmacology and Immunotherapy, Veterinary Research Institute, Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic.
| | - Robert Mikulik
- International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic; Neurology Department of Masaryk University and St. Anne's University Hospital Brno, Czech Republic
| | - Josef Mašek
- Department of Pharmacology and Immunotherapy, Veterinary Research Institute, Brno, Czech Republic
| | - Milan Raška
- Department of Pharmacology and Immunotherapy, Veterinary Research Institute, Brno, Czech Republic; Department of Immunology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czech Republic
| | | | - Andrew D Miller
- Institute of Pharmaceutical Science, King's College London, United Kingdom and Global Acorn Ltd, London, United Kingdom
| | - Jaroslav Turánek
- Department of Pharmacology and Immunotherapy, Veterinary Research Institute, Brno, Czech Republic.
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9
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Textor M, Keller S. Calorimetric Quantification of Cyclodextrin-Mediated Detergent Extraction for Membrane-Protein Reconstitution. Methods Enzymol 2016; 567:129-56. [DOI: 10.1016/bs.mie.2015.07.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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10
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Tu Y, Peng F, Adawy A, Men Y, Abdelmohsen LKEA, Wilson DA. Mimicking the Cell: Bio-Inspired Functions of Supramolecular Assemblies. Chem Rev 2015; 116:2023-78. [DOI: 10.1021/acs.chemrev.5b00344] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Yingfeng Tu
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Fei Peng
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Alaa Adawy
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Yongjun Men
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Loai K. E. A. Abdelmohsen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Daniela A. Wilson
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
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11
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Two-Dimensional Crystallization Procedure, from Protein Expression to Sample Preparation. BIOMED RESEARCH INTERNATIONAL 2015; 2015:693869. [PMID: 26413539 PMCID: PMC4564634 DOI: 10.1155/2015/693869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 07/02/2015] [Indexed: 11/18/2022]
Abstract
Membrane proteins play important roles for living cells. Structural studies of membrane proteins provide deeper understanding of their mechanisms and further aid in drug design. As compared to other methods, electron microscopy is uniquely suitable for analysis of a broad range of specimens, from small proteins to large complexes. Of various electron microscopic methods, electron crystallography is particularly well-suited to study membrane proteins which are reconstituted into two-dimensional crystals in lipid environments. In this review, we discuss the steps and parameters for obtaining large and well-ordered two-dimensional crystals. A general description of the principle in each step is provided since this information can also be applied to other biochemical and biophysical methods. The examples are taken from our own studies and published results with related proteins. Our purpose is to give readers a more general idea of electron crystallography and to share our experiences in obtaining suitable crystals for data collection.
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12
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Panneels V, Wu W, Tsai CJ, Nogly P, Rheinberger J, Jaeger K, Cicchetti G, Gati C, Kick LM, Sala L, Capitani G, Milne C, Padeste C, Pedrini B, Li XD, Standfuss J, Abela R, Schertler G. Time-resolved structural studies with serial crystallography: A new light on retinal proteins. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2015; 2:041718. [PMID: 26798817 PMCID: PMC4711639 DOI: 10.1063/1.4922774] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/03/2015] [Indexed: 05/19/2023]
Abstract
Structural information of the different conformational states of the two prototypical light-sensitive membrane proteins, bacteriorhodopsin and rhodopsin, has been obtained in the past by X-ray cryo-crystallography and cryo-electron microscopy. However, these methods do not allow for the structure determination of most intermediate conformations. Recently, the potential of X-Ray Free Electron Lasers (X-FELs) for tracking the dynamics of light-triggered processes by pump-probe serial femtosecond crystallography has been demonstrated using 3D-micron-sized crystals. In addition, X-FELs provide new opportunities for protein 2D-crystal diffraction, which would allow to observe the course of conformational changes of membrane proteins in a close-to-physiological lipid bilayer environment. Here, we describe the strategies towards structural dynamic studies of retinal proteins at room temperature, using injector or fixed-target based serial femtosecond crystallography at X-FELs. Thanks to recent progress especially in sample delivery methods, serial crystallography is now also feasible at synchrotron X-ray sources, thus expanding the possibilities for time-resolved structure determination.
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Affiliation(s)
- Valérie Panneels
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Wenting Wu
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Ching-Ju Tsai
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Przemek Nogly
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Jan Rheinberger
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Kathrin Jaeger
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Gregor Cicchetti
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | | | - Leonhard M Kick
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Leonardo Sala
- Scientific Computing, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Guido Capitani
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Chris Milne
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Celestino Padeste
- Lab for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Bill Pedrini
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Xiao-Dan Li
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Jörg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Rafael Abela
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
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Astafyeva K, Urbach W, Garroum N, Taulier N, Thiam AR. Stability of C(12)E(j) Bilayers Probed with Adhesive Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6791-6796. [PMID: 26035626 DOI: 10.1021/acs.langmuir.5b00749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The stability of model surfactant bilayers from the poly(ethylene glycol) mono-n-dodecyl ether (C12Ej) family was probed. The surfactant bilayers were formed by the adhesion of emulsion droplets. We generated C12Ej bilayers by forming water-in-oil (w/o) emulsions with saline water droplets, covered by the surfactant, in a silicone and octane oil mixture. Using microfluidics, we studied the stability of those bilayers. C12E1 allowed only short-lived bilayers whereas C12E2 bilayers were stable over a wide range of oil mixtures. At high C12E2 concentration, a two-phase region was displayed in the phase diagram: bilayers formed by the adhesion of two water droplets and Janus-like particles consisting of adhering aqueous and amphiphilic droplets. C12E8 and C12E25 did not mediate bilayer formation and caused phase inversion leading to o/w emulsion. With intermediate C12E4 and C12E5 surfactants, both w/o and o/w emulsions were unstable. We provided the titration of the C12E2 bilayer with C12E4 and C12E5 to study and predict their stability behavior.
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Affiliation(s)
- Ksenia Astafyeva
- †Laboratoire de Physique Statistique, Ecole Normale Supérieure, Sorbonne Universités, UPMC Université, and Université Paris Diderot, CNRS, 24 rue Lhomond, F-75005 Paris, France
| | - Wladimir Urbach
- †Laboratoire de Physique Statistique, Ecole Normale Supérieure, Sorbonne Universités, UPMC Université, and Université Paris Diderot, CNRS, 24 rue Lhomond, F-75005 Paris, France
- ‡Université René Descartes, Paris, France
| | - Nabil Garroum
- †Laboratoire de Physique Statistique, Ecole Normale Supérieure, Sorbonne Universités, UPMC Université, and Université Paris Diderot, CNRS, 24 rue Lhomond, F-75005 Paris, France
| | - Nicolas Taulier
- §Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire d'Imagerie Biomédicale, INSERM, F-75006 Paris, France
| | - Abdou R Thiam
- †Laboratoire de Physique Statistique, Ecole Normale Supérieure, Sorbonne Universités, UPMC Université, and Université Paris Diderot, CNRS, 24 rue Lhomond, F-75005 Paris, France
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Textor M, Vargas C, Keller S. Calorimetric quantification of linked equilibria in cyclodextrin/lipid/detergent mixtures for membrane-protein reconstitution. Methods 2015; 76:183-193. [DOI: 10.1016/j.ymeth.2015.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 12/30/2014] [Accepted: 01/02/2015] [Indexed: 10/24/2022] Open
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15
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Lasala R, Coudray N, Abdine A, Zhang Z, Lopez-Redondo M, Kirshenbaum R, Alexopoulos J, Zolnai Z, Stokes DL, Ubarretxena-Belandia I. Sparse and incomplete factorial matrices to screen membrane protein 2D crystallization. J Struct Biol 2014; 189:123-34. [PMID: 25478971 DOI: 10.1016/j.jsb.2014.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 11/18/2014] [Accepted: 11/24/2014] [Indexed: 01/09/2023]
Abstract
Electron crystallography is well suited for studying the structure of membrane proteins in their native lipid bilayer environment. This technique relies on electron cryomicroscopy of two-dimensional (2D) crystals, grown generally by reconstitution of purified membrane proteins into proteoliposomes under conditions favoring the formation of well-ordered lattices. Growing these crystals presents one of the major hurdles in the application of this technique. To identify conditions favoring crystallization a wide range of factors that can lead to a vast matrix of possible reagent combinations must be screened. However, in 2D crystallization these factors have traditionally been surveyed in a relatively limited fashion. To address this problem we carried out a detailed analysis of published 2D crystallization conditions for 12 β-barrel and 138 α-helical membrane proteins. From this analysis we identified the most successful conditions and applied them in the design of new sparse and incomplete factorial matrices to screen membrane protein 2D crystallization. Using these matrices we have run 19 crystallization screens for 16 different membrane proteins totaling over 1300 individual crystallization conditions. Six membrane proteins have yielded diffracting 2D crystals suitable for structure determination, indicating that these new matrices show promise to accelerate the success rate of membrane protein 2D crystallization.
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Affiliation(s)
- R Lasala
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - N Coudray
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - A Abdine
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - Z Zhang
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - M Lopez-Redondo
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - R Kirshenbaum
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - J Alexopoulos
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Z Zolnai
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - D L Stokes
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA; Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - I Ubarretxena-Belandia
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA; Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA.
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16
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Surma MA, Szczepaniak A, Króliczewski J. Comparative studies on detergent-assisted apocytochrome b6 reconstitution into liposomal bilayers monitored by Zetasizer instruments. PLoS One 2014; 9:e111341. [PMID: 25423011 PMCID: PMC4244035 DOI: 10.1371/journal.pone.0111341] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 10/01/2014] [Indexed: 11/19/2022] Open
Abstract
The present paper is a systematic, comparative study on the reconstitution of an apocytochrome b6 purified from a heterologous system using a detergent-free method and reconstitution into liposomes performed using three different detergents: SDS, Triton X-100 and DM, and two methods of detergent removal by dialysis and using Bio-Beads. The product size, its distribution and zeta potential, and other parameters were monitored throughout the process. We found that zeta potential of proteoliposomes is correlated with reconstitution efficiency and, as such, can serve as a quick and convenient quality control for reconstitution experiments. We also advocate using detergent-free protein purification methods as they allow for an unfettered choice of detergent for reconstitution, which is the most crucial factor influencing the final product parameters.
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Affiliation(s)
- Michał A. Surma
- Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
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17
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Growth of large and highly ordered 2D crystals of a K⁺ channel, structural role of lipidic environment. Biophys J 2014; 105:398-408. [PMID: 23870261 DOI: 10.1016/j.bpj.2013.05.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 05/18/2013] [Accepted: 05/29/2013] [Indexed: 02/04/2023] Open
Abstract
2D crystallography has proven to be an excellent technique to determine the 3D structure of membrane proteins. Compared to 3D crystallography, it has the advantage of visualizing the protein in an environment closer to the native one. However, producing good 2D crystals is still a challenge and little statistical knowledge can be gained from literature. Here, we present a thorough screening of 2D crystallization conditions for a prokaryotic inwardly rectifying potassium channel (>130 different conditions). Key parameters leading to very large and well-organized 2D crystals are discussed. In addition, the problem of formation of multilayers during the growth of 2D crystals is also addressed. An intermediate resolution projection map of KirBac3.1 at 6 Å is presented, which sheds (to our knowledge) new light on the structure of this channel in a lipid environment.
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18
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Ferreira TM, Topgaard D, Ollila OHS. Molecular conformation and bilayer pores in a nonionic surfactant lamellar phase studied with 1H-13C solid-state NMR and molecular dynamics simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:461-469. [PMID: 24372090 DOI: 10.1021/la404684r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The structure of the lamellar phase of aqueous pentaethylene glycol mono-n-dodecyl ether (C12E5) surfactant at various temperatures and molar fractions is studied by using united atom molecular dynamics simulations and nuclear magnetic resonance measurements. Namely, the simulation model is used to interpret the magnitude and temperature dependence of experimental C-H order parameter profiles in terms of the molecular conformation and orientation. Our simulations suggest that the low order parameters that are generally measured in poly(ethylene oxide) surfactant bilayers are due to the presence of bilayer pores throughout the entire lamellar phase region.
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Affiliation(s)
- Tiago M Ferreira
- Division of Physical Chemistry, Centre for Chemistry and Chemical Engineering, Lund University , Lund, Sweden
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19
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Johnson MC, Schmidt-Krey I. Two-dimensional crystallization by dialysis for structural studies of membrane proteins by the cryo-EM method electron crystallography. Methods Cell Biol 2013; 113:325-37. [PMID: 23317909 DOI: 10.1016/b978-0-12-407239-8.00015-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Two-dimensional (2D) crystals of integral membrane proteins, comprising ordered protein reconstituted into a synthetic lipid bilayer, can be induced to form from detergent solubilized and purified membrane protein sources via the addition of exogenous lipid and the subsequent removal of the solubilizing detergent. This is most commonly accomplished by dialysis of a small volume of ternary protein-detergent-lipid mixture against a large volume of buffer, and can be carried out using common, easily available materials. Following successful crystallization, electron crystallographic data obtained by electron cryo-microscopy (cryo-EM) of vitrified 2D crystals can be used to determine the structure of the lipid bilayer-embedded integral membrane protein.
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Affiliation(s)
- Matthew C Johnson
- Georgia Institute of Technology, School of Biology, Atlanta, GA, USA
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20
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Johnson MC, Dreaden TM, Kim LY, Rudolph F, Barry BA, Schmidt-Krey I. Two-dimensional crystallization of membrane proteins by reconstitution through dialysis. Methods Mol Biol 2013; 955:31-58. [PMID: 23132054 DOI: 10.1007/978-1-62703-176-9_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Studies of membrane proteins by two-dimensional (2D) crystallization and electron crystallography have provided crucial information on the structure and function of a rapidly growing number of these intricate proteins within a close-to-native lipid bilayer. Here we provide protocols for planning and executing 2D crystallization trials by detergent removal through dialysis, including the preparation of phospholipids and the dialysis setup. General factors to be considered, such as the protein preparation, solubilizing detergent, lipid for reconstitution, and buffer conditions are discussed. Several 2D crystallization conditions are highlighted that have shown great promise to grow 2D crystals within a surprisingly short amount of time. Finally, conditions for optimizing order and size of 2D crystals are outlined.
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Affiliation(s)
- Matthew C Johnson
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA
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21
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Two-dimensional crystalline array formation of glucuronide transporter from Escherichia coli by the use of polystyrene beads for detergent removal. J Membr Biol 2012. [PMID: 23188061 DOI: 10.1007/s00232-012-9521-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
n-Dodecyl-β-D-maltoside solubilized glucuronide transporter (GusB), the product of gusB gene from Escherichia coli, was treated with Bio-Beads as an agent for removing the detergent from a micellar solution under suitable combination with dimyristoylphosphatidylcholine. Optimizing conditions led to a two-dimensional crystalline array formation of GusB. The crystalline arrays appear to have a hexagonal lattice with layer group P6, the unit cell dimensions of a = b = 13.8 nm and γ = 120°. Each stain-protruding periodic unit showed approximately 11.8 ± 0.3 nm in a diameter in the inverse Fourier-filtered image to have formed with pentameric GusB (5 × 49.7 kDa).
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22
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Rossi G, Fuchs PFJ, Barnoud J, Monticelli L. A coarse-grained MARTINI model of polyethylene glycol and of polyoxyethylene alkyl ether surfactants. J Phys Chem B 2012; 116:14353-62. [PMID: 23137188 DOI: 10.1021/jp3095165] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Nonionic surfactants are used for the isolation and purification of membrane proteins, as well as for the study of fundamental aspects of protein diffusion in membranes. Here we present a new coarse-grained model of polyethylene glycol (PEG) and of the family of polyoxyethylene alkyl ether (C(i)E(j)) surfactants. The model is compatible with the MARTINI coarse-grained force-field for lipids and proteins. We validate the model by comparing molecular dynamics simulations with experimental data. In particular, we show that the model reproduces the phase behavior of water-surfactant mixtures as a function of water concentration. We also simulate the self-assembly of two ternary mixtures that have been used for the experimental measure of protein diffusion coefficients. The first includes a cosurfactant that affects the curvature of the surfactant bilayers; the second is a mixture of C(i)E(j) surfactants, alkanes and water. In both cases, the results of self-assembly simulations are in agreement with experimental observations and pave the way to the use of the surfactant model in combination with MARTINI peptides and proteins.
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Affiliation(s)
- G Rossi
- INSERM, UMR-S665, Paris, F-75015, France.
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23
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Improvement of immunogenicity of meningococcal lipooligosaccharide by coformulation with lipidated transferrin-binding protein B in liposomes: implications for vaccine development. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:711-22. [PMID: 22441387 DOI: 10.1128/cvi.05683-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Among various meningococcal antigens, lipooligosaccharide (LOS) and recombinant lipidated transferrin-binding protein B (rlip-TbpB) are considered to be putative vaccine candidates against group B Neisseria meningitidis. In the present work, we report the development of a new liposome-based vaccine formulation containing both rlip-TbpB and L8 LOS. The endotoxic activity of the liposomal LOS was evaluated in vitro using the Limulus Amebocyte Lysate assay and compared to the endotoxic activity of free LOS. Above a 250:1 lipid/LOS molar ratio, liposomes were shown to effectively detoxify the LOS as the endotoxic activity of the LOS was reduced by more than 99%. Immunogenicity studies in rabbits showed that the presence of rlip-TbpB dramatically increased the immunogenicity of the LOS. While the formulation raised a strong anti-TbpB response, it elicited a higher anti-LOS IgG level than the liposomal LOS alone. Sera from rabbits immunized with rlip-TbpB/liposomal LOS displayed increased ability to recognize LOS on live bacteria expressing the L8 immunotype and increased anti-LOS-specific bactericidal activity compared to sera from rabbits immunized with liposomal LOS alone. Measurement of interleukin-8 (IL-8) produced by HEK293 cells transfected with Toll-like receptor (TLR) after stimulation with rlip-TbpB showed that the protein is a TLR2 agonist, which is in accordance with the structure of its lipid. Furthermore, an in vivo study demonstrated that the lipid moiety is not only required for its adjuvant effect but also has to be linked to the protein. Overall, the rlip-TbpB/LOS liposomal formulation was demonstrated to induce an effective anti-LOS response due to the adjuvant effect of rlip-TbpB on LOS.
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24
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Hassan HHAM, Soliman R. Synthesis and Antimicrobial Activity of Novel 3-Benzyloxy-4-Substituted-2- Azetidinones: Formation of a Hydrophobic Layer Via a Self-Organization Effect. PHOSPHORUS SULFUR 2011. [DOI: 10.1080/10426507.2011.553208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Hammed H. A. M. Hassan
- a Department of Chemistry, Faculty of Science , Alexandria University , Alexandria, Egypt
| | - Raafat Soliman
- b Department of Pharmaceutical Chemistry, Faculty of Pharmacy , Alexandria University , Alexandria, Egypt
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25
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Improved Technique for Reconstituting Incredibly High and Soluble Amounts of Tetrameric K+ Channel in Natural Membranes. J Membr Biol 2011; 241:141-4. [DOI: 10.1007/s00232-011-9370-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 05/02/2011] [Indexed: 10/18/2022]
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26
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Qin X, Liu M, Zhang X, Yang D. Proton NMR Based Investigation of the Effects of Temperature and NaCl on Micellar Properties of CHAPS. J Phys Chem B 2011; 115:1991-8. [DOI: 10.1021/jp108694v] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Xianguo Qin
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Maili Liu
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Xu Zhang
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Daiwen Yang
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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27
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Hassan HHAM. Synthesis and Antimicrobial Activity of Novel Types of Persulfide-Spacer α-O-glycosides: Formation of a Super Hydrophobic Layer via a Self-Organization Effect Through the Strong Hydrogen Bonding Interaction. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2011. [DOI: 10.1080/10601325.2011.544626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Takagi T, Takai K, Baba T, Kanamori T. Design and Characterization of Partially Fluorinated Lipid Liquid-Crystal Membranes as Biomaterials. J SYN ORG CHEM JPN 2010. [DOI: 10.5059/yukigoseikyokaishi.68.206] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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29
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30
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In Cubo Crystallization of Membrane Proteins. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/b978-0-12-381266-7.00009-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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31
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Streicher P, Nassoy P, Bärmann M, Dif A, Marchi-Artzner V, Brochard-Wyart F, Spatz J, Bassereau P. Integrin reconstituted in GUVs: a biomimetic system to study initial steps of cell spreading. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2291-300. [PMID: 19665445 DOI: 10.1016/j.bbamem.2009.07.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 07/10/2009] [Accepted: 07/27/2009] [Indexed: 10/20/2022]
Abstract
A novel in vitro membrane system mimicking the first steps of integrin-mediated cell spreading has been developed and characterized. We have reconstituted the transmembrane alpha(IIb)beta(3) integrin into giant unilamellar vesicles (GUVs). The reconstitution process has been validated by analyzing protein incorporation and biological activity by checking the specific interaction of GUVs containing integrin with quantum dots (QD) or surfaces coated with the integrin receptor tri-peptide RGD.(1) The spreading dynamics of integrin-functionalized GUVs onto fibrinogen-coated surfaces has been monitored by Reflection Interference Contrast Microscopy (RICM). Our results are quantitatively consistent with a theoretical model based on a dewetting process coupled to binder diffusion and provide a comprehensive description of the following sequence: i) nucleation and growth of adhesive patches coupled to the diffusion of the adhesive proteins to these adhesive zones ii) fusion of patches and formation of an adhesive ring iii) complete spreading of the GUV by dewetting of the central liquid film from the border to form an adhesive circular patch that is not significantly enriched in integrins, as compared to the unbound membrane. This finding is consistent with the recognized role of the actin cytoskeleton in stabilizing focal complexes and focal adhesions in a cell-extracellular matrix contact. These very large unilamellar integrin-containing vesicles provide a unique artificial system, which could be further developed towards realistic cell mimic and used to study the complexity of integrin-mediated cell spreading.
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Affiliation(s)
- Pia Streicher
- Institut Curie, Centre de Recherche, Université Pierre et Marie Curie, F-75248 Paris, France
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32
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Ma J, Xia D. The use of blue native PAGE in the evaluation of membrane protein aggregation states for crystallization. J Appl Crystallogr 2008; 41:1150-1160. [PMID: 19529836 DOI: 10.1107/s0021889808033797] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 10/16/2008] [Indexed: 02/08/2023] Open
Abstract
Crystallization has long been one of the bottlenecks in obtaining structural information at atomic resolution for membrane proteins. This is largely due to difficulties in obtaining high-quality protein samples. One frequently used indicator of protein quality for successful crystallization is the monodispersity of proteins in solution, which is conventionally obtained by size exclusion chromatography (SEC) or by dynamic light scattering (DLS). Although useful in evaluating the quality of soluble proteins, these methods are not always applicable to membrane proteins either because of the interference from detergent micelles or because of the requirement for large sample quantities. Here, the use of blue native polyacrylamide gel electrophoresis (BN-PAGE) to assess aggregation states of membrane protein samples is reported. A strong correlation is demonstrated between the monodispersity measured by BN-PAGE and the propensity for crystallization of a number of soluble and membrane protein complexes. Moreover, it is shown that there is a direct correspondence between the oligomeric states of proteins as measured by BN-PAGE and those obtained from their crystalline forms. When applied to a membrane protein with unknown structure, BN-PAGE was found to be useful and efficient for selecting well behaved proteins from various constructs and in screening detergents. Comparisons of BN-PAGE with DLS and SEC are provided.
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Affiliation(s)
- Jichun Ma
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Building 37, Room 2122C, Bethesda, MD 20892, USA
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33
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Mendes AA, Rodrigues DS, Filice M, Fernandez-Lafuente R, Guisan JM, Palomo JM. Regioselective monohydrolysis of per-O-acetylated-1-substituted-β-glucopyranosides catalyzed by immobilized lipases. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.08.099] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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34
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Soroka V, Kasper C, Poulsen FM. WITHDRAWN: Structural Biology of NCAM. Neurochem Res 2008. [PMID: 18758952 DOI: 10.1007/s11064-008-9837-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2008] [Indexed: 01/18/2023]
Affiliation(s)
- Vladislav Soroka
- Protein Laboratory, Institute of Neuroscience and Pharmacology, Panum Institute, Blegdamsvej 3 C, DK-2200, Copenhagen, Denmark,
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35
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Arnold T, Linke D. The Use of Detergents to Purify Membrane Proteins. ACTA ACUST UNITED AC 2008; Chapter 4:4.8.1-4.8.30. [DOI: 10.1002/0471140864.ps0408s53] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Thomas Arnold
- Max Planck Institute for Developmental Biology Tübingen Germany
| | - Dirk Linke
- Max Planck Institute for Developmental Biology Tübingen Germany
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36
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Liu LN, Aartsma TJ, Frese RN. Dimers of light-harvesting complex 2 from Rhodobacter sphaeroides characterized in reconstituted 2D crystals with atomic force microscopy. FEBS J 2008; 275:3157-66. [DOI: 10.1111/j.1742-4658.2008.06469.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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37
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Lee KE, Kim HM, Lee JO, Jeon H, Han SS. Regulation of CD40 reconstitution into a liposome using different ratios of solubilized LDAO to lipids. Colloids Surf B Biointerfaces 2007; 62:51-7. [PMID: 17981441 DOI: 10.1016/j.colsurfb.2007.09.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 09/17/2007] [Indexed: 11/20/2022]
Abstract
The integral membrane protein CD40 was found on the surface of B lymphocytes that interact with CD40L on T cells during the immune response. The hydrophobic transmembrane domains of membrane proteins can be stabilized in detergent or in lipid bilayers such as liposomes. Membrane proteins can be incorporated into the liposome in a similar fashion to the way they are handled in vivo. In this study, a large amount of full-sequence CD40 was produced using a bacterial system that contained a Mistic construct. The CD40 was then reconstituted into liposomes by detergent-mediated reconstitution. All stages in the process of liposome disruption with various detergent ratios were easily observed by monitoring the optical density. The structure of the liposome and the reconstitution of CD40 were confirmed by cryo-TEM. The results of the present study show that the detergent ratio had an effect on the structure of the liposome and the amount of CD40 that was reconstituted into the liposome.
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Affiliation(s)
- Kyung Eun Lee
- Laboratory of Cell Engineering and 3D Structure, School of Life Sciences and Biotechnology, Korea University, 1, 5-ka, Anam Dong, Sungbuk Ku, Seoul, Republic of Korea
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38
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Ahamed T, Esteban BNA, Ottens M, van Dedem GWK, van der Wielen LAM, Bisschops MAT, Lee A, Pham C, Thömmes J. Phase behavior of an intact monoclonal antibody. Biophys J 2007; 93:610-9. [PMID: 17449660 PMCID: PMC1896256 DOI: 10.1529/biophysj.106.098293] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding protein phase behavior is important for purification, storage, and stable formulation of protein drugs in the biopharmaceutical industry. Glycoproteins, such as monoclonal antibodies (MAbs) are the most abundant biopharmaceuticals and probably the most difficult to crystallize among water-soluble proteins. This study explores the possibility of correlating osmotic second virial coefficient (B(22)) with the phase behavior of an intact MAb, which has so far proved impossible to crystallize. The phase diagram of the MAb is presented as a function of the concentration of different classes of precipitants, i.e., NaCl, (NH4)2SO4, and polyethylene glycol. All these precipitants show a similar behavior of decreasing solubility with increasing precipitant concentration. B(22) values were also measured as a function of the concentration of the different precipitants by self-interaction chromatography and correlated with the phase diagrams. Correlating phase diagrams with B(22) data provides useful information not only for a fundamental understanding of the phase behavior of MAbs, but also for understanding the reason why certain proteins are extremely difficult to crystallize. The scaling of the phase diagram in B(22) units also supports the existence of a universal phase diagram of a complex glycoprotein when it is recast in a protein interaction parameter.
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Affiliation(s)
- Tangir Ahamed
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
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39
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Aich U, Loganathan D. Zeolite-catalyzed Helferich-type glycosylation of long-chain alcohols. Synthesis of acetylated alkyl 1,2-trans glycopyranosides and alkyl 1,2-cis C2-hydroxy-glycopyranosides. Carbohydr Res 2007; 342:704-9. [PMID: 17217935 DOI: 10.1016/j.carres.2006.12.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 12/11/2006] [Accepted: 12/17/2006] [Indexed: 11/28/2022]
Abstract
Zeolite-catalyzed glycosylation of long-chain alcohols, using the inexpensive and readily available peracetylated beta-D-gluco- and galactopyranoses as glycosyl donors under solvent free conditions, has been explored for the first time. Among the various forms (H-, Na-, Fe- and Zn) of beta zeolite examined as catalysts in the reaction of 1,2,3,4,6-penta-O-acetyl-beta-D-galactopyranose with cetyl alcohol, Fe-beta zeolite gave the maximum yield of 63% of cetyl 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside and cetyl 3,4,6-tri-O-acetyl-alpha-D-galactopyranoside. Fe-beta Zeolite-catalyzed glycosylation was found to be general affording the title compounds in each case in a moderate yield, but with a good stereoselectivity. The yield of synthetically valuable acetylated long-chain alkyl 1,2-cis C2-hydroxy-glycopyranosides obtained in the present single-step procedure is considerably higher than that of the previously reported multi-step method employing the Stork silicon tether approach.
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Affiliation(s)
- Udayanath Aich
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
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40
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Madden DR, Safferling M. Baculoviral expression of an integral membrane protein for structural studies. Methods Mol Biol 2007; 363:39-57. [PMID: 17272836 DOI: 10.1007/978-1-59745-209-0_3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The baculovirus system has proven successful for the expression of integral membrane proteins for structural studies. A recombinant baculovirus, in which the gene of interest is placed under the control of the late-stage polyhedrin promoter, serves as the starting point for viral expansion and protein expression studies. Using large-scale insect cell culture techniques together with a filter-binding assay for protein function, the conditions of expression, purification, and solubilization can be optimized. As applied to the glutamate receptor ion channel subunit GluR2, this approach yields milligram quantities of pure, active protein, which have been used for single-particle electron microscopic analysis of the receptor structure. Detergent exchange protocols are also discussed, as a prerequisite for two-dimensional crystallization trials.
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Affiliation(s)
- Dean R Madden
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH, USA
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Karlovská J, Williams AA, Macri RV, Gandour RD, Funari SS, Uhríková D, Balgavý P. Synchrotron SAX and WAX diffraction study of a hydrated very long-chain, dendritic amphiphile+DPPC mixture. Colloids Surf B Biointerfaces 2007; 54:160-4. [PMID: 17134885 DOI: 10.1016/j.colsurfb.2006.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 09/11/2006] [Accepted: 10/01/2006] [Indexed: 10/24/2022]
Abstract
The tri-headed anionic dendritic amphiphile, 4-(2-carboxyethyl)-4-[(icosyloxycarbonyl)amino]heptanedioic acid (3CCb20), forms mixed aggregates with dipalmitoylphosphatidylcholine (DPPC) in excess water at 3CCb20:DPPC = 0.91:1 molar ratio. On heating, these mixed aggregates transform into fluid bilayers stacked in the liquid crystalline lamellar L(alpha) phase at about 40 degrees C. This phase transition and the microstructure of 3CCb20 + DPPC aggregates were studied with small- and wide-angle synchrotron X-ray diffraction. The ability of 3CCb20 to solubilize solidlike lipid bilayers could contribute to the antimicrobial activities of 3CCb20, including its anti-HIV activity.
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Affiliation(s)
- Janka Karlovská
- Department of Physical Chemistry of Drugs, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia
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42
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Renault L, Chou HT, Chiu PL, Hill RM, Zeng X, Gipson B, Zhang ZY, Cheng A, Unger V, Stahlberg H. Milestones in electron crystallography. J Comput Aided Mol Des 2006; 20:519-27. [PMID: 17103018 PMCID: PMC2194810 DOI: 10.1007/s10822-006-9075-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 08/29/2006] [Indexed: 10/23/2022]
Abstract
Electron crystallography determines the structure of membrane embedded proteins in the two-dimensionally crystallized state by cryo-transmission electron microscopy imaging and computer structure reconstruction. Milestones on the path to the structure are high-level expression, purification of functional protein, reconstitution into two-dimensional lipid membrane crystals, high-resolution imaging, and structure determination by computer image processing. Here we review the current state of these methods. We also created an Internet information exchange platform for electron crystallography, where guidelines for imaging and data processing method are maintained. The server (http://2dx.org) provides the electron crystallography community with a central information exchange platform, which is structured in blog and Wiki form, allowing visitors to add comments or discussions. It currently offers a detailed step-by-step introduction to image processing with the MRC software program. The server is also a repository for the 2dx software package, a user-friendly image processing system for 2D membrane protein crystals.
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Affiliation(s)
- Ludovic Renault
- Molecular and Cellular Biology, College of Biological Sciences, University of California at Davis, Briggs Hall, 1 Shields Ave., Davis, CA 95616, USA
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43
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Pagan DL, Shiryayev A, Connor TP, Gunton JD. Simple model of membrane proteins including solvent. J Chem Phys 2006; 124:184904. [PMID: 16709136 DOI: 10.1063/1.2193511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report a numerical simulation for the phase diagram of a simple two-dimensional model, similar to the one proposed by Noro and Frenkel [J. Chem. Phys. 114, 2477 (2001)] for membrane proteins, but one that includes the role of the solvent. We first use Gibbs ensemble Monte Carlo simulations to determine the phase behavior of particles interacting via a square-well potential in two dimensions for various values of the interaction range. A phenomenological model for the solute-solvent interactions is then studied to understand how the fluid-fluid coexistence curve is modified by solute-solvent interactions. It is shown that such a model can yield systems with liquid-liquid phase separation curves that have both upper and lower critical points, as well as closed loop phase diagrams, as is the case with the corresponding three-dimensional model.
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Affiliation(s)
- D L Pagan
- Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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44
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Tsai CJ, Ziegler C. Structure Determination of Secondary Transport Proteins by Electron Crystallography: Two-Dimensional Crystallization of the Betaine Uptake System BetP. J Mol Microbiol Biotechnol 2006; 10:197-207. [PMID: 16645315 DOI: 10.1159/000091565] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Structure determination at high resolution is still a challenge for membrane proteins in general, but in particular for secondary transporters due to their highly dynamic nature. X-ray structures of ten secondary transporters have recently been determined, but a thorough understanding of transport mechanisms necessitates structures at different functional states. Electron cryo-microscopy of two-dimensional (2D) crystals offers an alternative to obtain structural information at intermediate resolution. Electron crystallography is a sophisticated way to study proteins in a natural membrane environment and to track conformational changes in situ. Furthermore, basic interactions between protein and lipids can be investigated. Projection and 3-dimensional maps of six secondary transporters from different families have been determined by electron crystallography of 2D crystals at a resolution of 8 A and better. In this review, we give an overview about the principles of 2D crystallization, in particular of secondary transporters, and summarize the important steps successfully applied to establish and improve the 2D crystallization of the high-affinity glycine betaine uptake system from Corynebacterium glutamicum, BetP.
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Affiliation(s)
- Ching-Ju Tsai
- Max Planck Institute of Biophysics Frankfurt, Department of Structural Biology, Frankfurt a. Main, Germany
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45
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Gudiksen KL, Gitlin I, Moustakas DT, Whitesides GM. Increasing the net charge and decreasing the hydrophobicity of bovine carbonic anhydrase decreases the rate of denaturation with sodium dodecyl sulfate. Biophys J 2006; 91:298-310. [PMID: 16617087 PMCID: PMC1479075 DOI: 10.1529/biophysj.106.081547] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This study compares the rate of denaturation with sodium dodecyl sulfate (SDS) of the individual rungs of protein charge ladders generated by acylation of the lysine epsilon-NH3+ groups of bovine carbonic anhydrase II (BCA). Each acylation decreases the number of positively charged groups, increases the net negative charge, and increases the hydrophobic surface area of BCA. This study reports the kinetics of denaturation in solutions containing SDS of the protein charge ladders generated with acetic and hexanoic anhydrides; plotting these rates of denaturation as a function of the number of modifications yields a U-shaped curve. The proteins with an intermediate number of modifications are the most stable to denaturation by SDS. There are four competing interactions-two resulting from the change in electrostatics and two resulting from the change in exposed hydrophobic surface area-that determine how a modification affects the stability of a rung of a charge ladder of BCA to denaturation with SDS. A model based on assumptions about how these interactions affect the folded and transition states has been developed and fits the experimental results. Modeling indicates that for each additional acylation, the magnitude of the change in the activation energy of denaturation (DeltaDeltaG(double dagger)) due to changes in the electrostatics is much larger than the change in DeltaDeltaG(double dagger) due to changes in the hydrophobicity, but the intermolecular and intramolecular electrostatic effects are opposite in sign. At the high numbers of acylations, hydrophobic interactions cause the hexanoyl-modified BCA to denature nearly three orders of magnitude more rapidly than the acetyl-modified BCA.
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Affiliation(s)
- Katherine L Gudiksen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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46
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Klammt C, Schwarz D, Fendler K, Haase W, Dötsch V, Bernhard F. Evaluation of detergents for the soluble expression of alpha-helical and beta-barrel-type integral membrane proteins by a preparative scale individual cell-free expression system. FEBS J 2006; 272:6024-38. [PMID: 16302967 DOI: 10.1111/j.1742-4658.2005.05002.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cell-free expression has become a highly promising tool for the fast and efficient production of integral membrane proteins. The proteins can be produced as precipitates that solubilize in mild detergents usually without any prior denaturation steps. Alternatively, membrane proteins can be synthesized in a soluble form by adding detergents to the cell-free system. However, the effects of a representative variety of detergents on the production, solubility and activity of a wider range of membrane proteins upon cell-free expression are currently unknown. We therefore analyzed the cell-free expression of three structurally very different membrane proteins, namely the bacterial alpha-helical multidrug transporter, EmrE, the beta-barrel nucleoside transporter, Tsx, and the porcine vasopressin receptor of the eukaryotic superfamily of G-protein coupled receptors. All three membrane proteins could be produced in amounts of several mg per one ml of reaction mixture. In general, the detergent 1-myristoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] was found to be most effective for the resolubilization of membrane protein precipitates, while long chain polyoxyethylene-alkyl-ethers proved to be most suitable for the soluble expression of all three types of membrane proteins. The yield of soluble expressed membrane protein remained relatively stable above a certain threshold concentration of the detergents. We report, for the first time, the high-level cell-free expression of a beta-barrel type membrane protein in a functional form. Structural and functional variations of the analyzed membrane proteins are evident that correspond with the mode of expression and that depend on the supplied detergent.
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Affiliation(s)
- Christian Klammt
- Centre for Biomolecular Magnetic Resonance, University of Frankfurt/Main, Institute for Biophysical Chemistry, Frankfurt/Main, Germany
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47
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Karlovská J, Uhríková D, Kucerka N, Teixeira J, Devínsky F, Lacko I, Balgavý P. Influence of N-dodecyl-N,N-dimethylamine N-oxide on the activity of sarcoplasmic reticulum Ca2+-transporting ATPase reconstituted into diacylphosphatidylcholine vesicles: Effects of bilayer physical parameters. Biophys Chem 2006; 119:69-77. [PMID: 16223561 DOI: 10.1016/j.bpc.2005.09.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 08/31/2005] [Accepted: 09/01/2005] [Indexed: 11/19/2022]
Abstract
Sarcoplasmic reticulum Ca-transporting ATPase (EC 3.6.1.38) was isolated from rabbit white muscle, purified and reconstituted into vesicles of synthetic diacylphosphatidylcholines with monounsaturated acyl chains using the cholate dilution method. In fluid bilayers at 37 degrees C, the specific activity of ATPase displays a maximum (31.5+/-0.8 IU/mg) for dioleoylphosphatidylcholine (diC18:1PC) and decreases progressively for both shorter and longer acyl chain lengths. Besides the hydrophobic mismatch between protein and lipid bilayer, changes in the bilayer hydration and lateral interactions detected by small angle neutron scattering (SANS) can contribute to this acyl chain length dependence. When reconstituted into dierucoylphosphatidylcholine (diC22:1PC), the zwitterionic surfactant N-dodecyl-N,N-dimethylamine N-oxide (C12NO) stimulates the ATPase activity from 14.2+/-0.6 to 32.5+/-0.8 IU/mg in the range of molar ratios C12NO:diC22:1PC=0/1.2. In dilauroylphosphatidylcholines (diC12:0PC) and diC18:1PC, the effect of C12NO is twofold-the ATPase activity is stimulated at low and inhibited at high C12NO concentrations. In diC18:1PC, it is observed an increase of activity induced by C12NO in the range of molar ratios C12NO:diC18:1PC< or =1.3 in bilayers, where the bilayer thickness estimated by SANS decreases by 0.4+/-0.1 nm. In this range, the 31P-NMR chemical shift anisotropy increases indicating an effect of C12NO on the orientation of the phosphatidylcholine dipole N(+)-P- accompanied by a variation of the local membrane dipole potential. A decrease of the ATPase activity is observed in the range of molar ratios C12NO:diC18:1PC=1.3/2.5, where mixed tubular micelles are detected by SANS in C12NO+diC18:1PC mixtures. It is concluded that besides hydrophobic thickness changes, the changes in dipole potential and curvature frustration of the bilayer could contribute as well to C12NO effects on Ca(2+)-ATPase activity.
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Affiliation(s)
- J Karlovská
- Faculty of Pharmacy, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia.
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48
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Vacha F, Bumba L, Kaftan D, Vacha M. Microscopy and single molecule detection in photosynthesis. Micron 2005; 36:483-502. [PMID: 15951188 DOI: 10.1016/j.micron.2005.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 04/18/2005] [Accepted: 04/19/2005] [Indexed: 11/30/2022]
Abstract
Progress in various fields of microscopy techniques brought up enormous possibilities to study the photosynthesis down to the level of individual pigment-protein complexes. The aim of this review is to present recent developments in the photosynthesis research obtained using such highly advanced techniques. Three areas of microscopy techniques covering optical microscopy, electron microscopy and scanning probe microscopy are reviewed. Whereas the electron microscopy and scanning probe microscopy are used in photosynthesis mainly for structural studies of photosynthetic pigment-protein complexes, the optical microscopy is used also for functional studies.
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Affiliation(s)
- Frantisek Vacha
- Institute of Physical Biology, University of South Bohemia, Budejovice, Czech Republic.
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49
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Scheuring S, Lévy D, Rigaud JL. Watching the components of photosynthetic bacterial membranes and their in situ organisation by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1712:109-27. [PMID: 15919049 DOI: 10.1016/j.bbamem.2005.04.005] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 04/04/2005] [Accepted: 04/15/2005] [Indexed: 11/18/2022]
Abstract
The atomic force microscope has developed into a powerful tool in structural biology allowing information to be acquired at submolecular resolution on the protruding structures of membrane proteins. It is now a complementary technique to X-ray crystallography and electron microscopy for structure determination of individual membrane proteins after extraction, purification and reconstitution into lipid bilayers. Moving on from the structures of individual components of biological membranes, atomic force microscopy has recently been demonstrated to be a unique tool to identify in situ the individual components of multi-protein assemblies and to study the supramolecular architecture of these components allowing the efficient performance of a complex biological function. Here, recent atomic force microscopy studies of native membranes of different photosynthetic bacteria with different polypeptide contents are reviewed. Technology, advantages, feasibilities, restrictions and limits of atomic force microscopy for the acquisition of highly resolved images of up to 10 A lateral resolution under native conditions are discussed. From a biological point of view, the new insights contributed by the images are analysed and discussed in the context of the strongly debated organisation of the interconnected network of membrane-associated chlorophyll-protein complexes composing the photosynthetic apparatus in different species of purple bacteria.
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Affiliation(s)
- Simon Scheuring
- Institut Curie, UMR-CNRS 168 and LRC-CEA 34V, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
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50
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Merino S, Domènech O, Montero MT, Hernández-Borrell J. Atomic force microscopy study of Escherichia coli lactose permease proteolipid sheets. Biosens Bioelectron 2005; 20:1843-6. [PMID: 15681202 DOI: 10.1016/j.bios.2004.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 05/03/2004] [Accepted: 05/05/2004] [Indexed: 11/27/2022]
Abstract
Proteolipid sheets (PLSs) obtained using the vesicle fusion technique on a convenient surface are the base to obtain transmembrane protein biosensors. In this preliminary work, we have screened several physicochemical conditions to optimize the visualization of proteolipid sheets formed between different phospholipid matrices and the membrane protein lactose permease (LacP) by atomic force microscopy (AFM). When LacP was reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes, the proteolipid sheets were densely packed with an upper layer that protruded from a background layer. Several lipid protein molar ratios (LPR) were screened. High resolution analysis of the upper layer revealed a quasi-crystalline arrangement formed by small entities that could be attributed to the protein. The approach described here may be suitable for the rational design of biosensors based in other transmembrane proteins.
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Affiliation(s)
- Sandra Merino
- Departament de Fisicoquímica, Universitat de Barcelona, 08028 Barcelona, Spain
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