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Reconstitution of Detergent-Solubilized Membrane Proteins into Proteoliposomes and Nanodiscs for Functional and Structural Studies. Methods Mol Biol 2021; 2302:21-35. [PMID: 33877620 DOI: 10.1007/978-1-0716-1394-8_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Reconstitution of detergent-solubilized membrane proteins into phospholipid bilayers allows for functional and structural studies under close-to-native conditions that greatly support protein stability and function. Here we outline the detailed steps for membrane protein reconstitution to result in proteoliposomes and nanodiscs. Reconstitution can be achieved via a number of different strategies. The protocols for preparation of proteoliposomes use detergent removal via dialysis or via nonpolar polystyrene beads, or a mixture of the two methods. In this chapter, the protocols for nanodiscs apply polystyrene beads only. Proteoliposome preparation methods allow for substantial control of the lipid-to-protein ratio, from minimal amounts of phospholipid to high concentrations, type of phospholipid, and mixtures of phospholipids. In addition, dialysis affords a fairly large degree of control and variation of parameters such as rate of reconstitution, temperature, buffer conditions, and proteoliposome size. For the nanodisc approach, which is highly advantageous for ensuring equal access to both membrane sides of the protein as well as fast reconstitution of only a single membrane protein into a well-defined bilayer environment in each nanodisc, the protocols outline how a number of these parameters are more restricted in comparison to the proteoliposome protocols.
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2
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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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3
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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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4
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Cellular distribution of copper to superoxide dismutase involves scaffolding by membranes. Proc Natl Acad Sci U S A 2013; 110:20491-6. [PMID: 24297923 DOI: 10.1073/pnas.1309820110] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Efficient delivery of copper ions to specific intracellular targets requires copper chaperones that acquire metal cargo through unknown mechanisms. Here we demonstrate that the human and yeast copper chaperones (CCS) for superoxide dismutase 1 (SOD1), long thought to exclusively reside in the cytosol and mitochondrial intermembrane space, can engage negatively charged bilayers through a positively charged lipid-binding interface. The significance of this membrane-binding interface is established through SOD1 activity and genetic complementation studies in Saccharomyces cerevisiae, showing that recruitment of CCS to the membrane is required for activation of SOD1. Moreover, we show that a CCS:SOD1 complex binds to bilayers in vitro and that CCS can interact with human high affinity copper transporter 1. Shifting current paradigms, we propose that CCS-dependent copper acquisition and distribution largely occur at membrane interfaces and that this emerging role of the bilayer may reflect a general mechanistic aspect of cellular transition metal ion acquisition.
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5
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Dreaden TM, Metcalfe M, Kim LY, Johnson MC, Barry BA, Schmidt-Krey I. Screening for two-dimensional crystals by transmission electron microscopy of negatively stained samples. Methods Mol Biol 2013; 955:73-101. [PMID: 23132056 DOI: 10.1007/978-1-62703-176-9_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Structural studies of soluble and membrane proteins by electron crystallography include several critical steps. While the two-dimensional (2D) crystallization arguably may be described as the major bottleneck of electron crystallography, the screening by transmission electron microscopy (EM) to identify 2D crystals requires great care as well as practice. Both sample preparation and EM are skills that are relatively easily acquired, compared to the identification of the first ordered arrays. Added to this, membranes may have a variety of morphologies and sizes. Here we describe all steps involved in the screening for 2D crystals as well as the evaluation of samples.
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Affiliation(s)
- Tina M Dreaden
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
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6
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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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7
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Pope CR, Unger VM. Electron crystallography--the waking beauty of structural biology. Curr Opin Struct Biol 2012; 22:514-9. [PMID: 22525160 DOI: 10.1016/j.sbi.2012.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 12/24/2022]
Abstract
Since its debut in the mid 1970s, electron crystallography has been a valuable alternative in the structure determination of biological macromolecules. Its reliance on single-layered or double-layered two-dimensionally ordered arrays and the ability to obtain structural information from small and disordered crystals make this approach particularly useful for the study of membrane proteins in a lipid bilayer environment. Despite its unique advantages, technological hurdles have kept electron crystallography from reaching its full potential. Addressing the issues, recent initiatives developed high-throughput pipelines for crystallization and screening. Adding progress in automating data collection, image analysis and phase extension methods, electron crystallography is poised to raise its profile and may lead the way in exploring the structural biology of macromolecular complexes.
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Affiliation(s)
- Christopher R Pope
- Department of Molecular Biosciences, Northwestern University, 2205 Campus Drive, Evanston, IL 60208, USA
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8
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Zhao G, Johnson MC, Schnell JR, Kanaoka Y, Haase W, Irikura D, Lam BK, Schmidt-Krey I. Two-dimensional crystallization conditions of human leukotriene C4 synthase requiring adjustment of a particularly large combination of specific parameters. J Struct Biol 2009; 169:450-4. [PMID: 19903529 DOI: 10.1016/j.jsb.2009.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 11/03/2009] [Accepted: 11/05/2009] [Indexed: 11/29/2022]
Abstract
Human leukotriene C(4) synthase (LTC(4)S) forms highly ordered two-dimensional (2D) crystals under specific reconstitution conditions. It was found that control of a larger number of parameters than is usually observed for 2D crystallization of membrane proteins was necessary to induce crystal formation of LTC(4)S. Here, we describe the parameters that were optimized to yield large and well-ordered 2D crystals of LTC(4)S. Careful fractioning of eluates during the protein purification was essential for obtaining crystals. While the lipid-to-protein ratio was critical in obtaining order, four parameters were decisive in inducing growth of crystals that were up to several microns in size. To obtain a favorable diameter, salt, temperature, glycerol, and initial detergent concentration had to be controlled with great care. Interestingly, several crystal forms could be grown, namely the plane group symmetries of p2, p3, p312, and two different unit cell sizes of plane group symmetry p321.
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Affiliation(s)
- G Zhao
- Georgia Institute of Technology, School of Biology, School of Chemistry and Biochemistry, 310 Ferst Drive, Atlanta, GA 30332, USA
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9
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The role of lipids and salts in two-dimensional crystallization of the glycine–betaine transporter BetP from Corynebacterium glutamicum. J Struct Biol 2007; 160:275-86. [DOI: 10.1016/j.jsb.2007.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 09/06/2007] [Accepted: 09/12/2007] [Indexed: 11/21/2022]
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10
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Cheng A, Leung A, Fellmann D, Quispe J, Suloway C, Pulokas J, Abeyrathne PD, Lam JS, Carragher B, Potter CS. Towards automated screening of two-dimensional crystals. J Struct Biol 2007; 160:324-31. [PMID: 17977016 DOI: 10.1016/j.jsb.2007.09.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 09/10/2007] [Accepted: 09/11/2007] [Indexed: 12/01/2022]
Abstract
Screening trials to determine the presence of two-dimensional (2D) protein crystals suitable for three-dimensional structure determination using electron crystallography is a very labor-intensive process. Methods compatible with fully automated screening have been developed for the process of crystal production by dialysis and for producing negatively stained grids of the resulting trials. Further automation via robotic handling of the EM grids, and semi-automated transmission electron microscopic imaging and evaluation of the trial grids is also possible. We, and others, have developed working prototypes for several of these tools and tested and evaluated them in a simple screen of 24 crystallization conditions. While further development of these tools is certainly required for a turn-key system, the goal of fully automated screening appears to be within reach.
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Affiliation(s)
- Anchi Cheng
- The National Resource for Automated Molecular Microscopy, Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, CB-129, La Jolla, CA 92037, USA.
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11
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Schmidt-Krey I, Haase W, Mutucumarana V, Stafford DW, Kühlbrandt W. Two-dimensional crystallization of human vitamin K-dependent γ-glutamyl carboxylase. J Struct Biol 2007; 157:437-42. [PMID: 16979907 DOI: 10.1016/j.jsb.2006.08.002] [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: 06/15/2006] [Revised: 08/08/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
Planar-tubular two-dimensional (2D) crystals of human vitamin K-dependent gamma-glutamyl carboxylase grow in the presence of dimyristoyl phosphatidylcholine (DMPC). Surprisingly, these crystals form below the phase transition temperature of DMPC and at the unusually low molar lipid-to-protein (LPR) ratio of 1, while 2D crystals are conventionally grown above the phase transition temperature of the reconstituting lipid and significantly higher LPRs. The crystals are up to 0.75 microm in the shorter dimension of the planar tubes and at least 1 microm in length. Due to the planar-tubular nature of the crystals, two lattices are present. These are rotated by nearly 90 degrees in respect to each other. The ordered arrays exhibit p12(1) plane group symmetry with unit cell dimensions of a=83.7 A, b=76.6 A, gamma=91 degrees. Projection maps calculated from images of negatively stained and electron cryo-microscopy samples reveal the human vitamin K-dependent gamma-glutamyl carboxylase to be a monomer.
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Affiliation(s)
- Ingeborg Schmidt-Krey
- Georgia Institute of Technology, School of Biology, 310 Ferst Drive, Atlanta, GA 30332-0230, USA.
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12
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Signorell GA, Kaufmann TC, Kukulski W, Engel A, Rémigy HW. Controlled 2D crystallization of membrane proteins using methyl-β-cyclodextrin. J Struct Biol 2007; 157:321-8. [PMID: 16979348 DOI: 10.1016/j.jsb.2006.07.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 07/21/2006] [Accepted: 07/22/2006] [Indexed: 11/26/2022]
Abstract
High-resolution structural data of membrane proteins can be obtained by studying 2D crystals by electron crystallography. Finding the right conditions to produce these crystals is one of the major bottlenecks encountered in 2D crystallography. Many reviews address 2D crystallization techniques in attempts to provide guidelines for crystallographers. Several techniques including new approaches to remove detergent like the biobeads technique and the development of dedicated devices have been described (dialysis and dilution machines). In addition, 2D crystallization at interfaces has been studied, the most prominent method being the 2D crystallization at the lipid monolayer. A new approach based on detergent complexation by cyclodextrins is presented in this paper. To prove the ability of cyclodextrins to remove detergent from ternary mixtures (lipid, detergent and protein) in order to get 2D crystals, this method has been tested with OmpF, a typical beta-barrel protein, and with SoPIP2;1, a typical alpha-helical protein. Experiments over different time ranges were performed to analyze the kinetic effects of detergent removal with cyclodextrins on the formation of 2D crystals. The quality of the produced crystals was assessed with negative stain electron microscopy, cryo-electron microscopy and diffraction. Both proteins yielded crystals comparable in quality to previous crystallization reports.
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Affiliation(s)
- Gian A Signorell
- M. E. Müller Institute for Microscopy at the Biozentrum, University of Basel, Basel, Switzerland
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13
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Holm PJ, Bhakat P, Jegerschöld C, Gyobu N, Mitsuoka K, Fujiyoshi Y, Morgenstern R, Hebert H. Structural Basis for Detoxification and Oxidative Stress Protection in Membranes. J Mol Biol 2006; 360:934-45. [PMID: 16806268 DOI: 10.1016/j.jmb.2006.05.056] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 05/17/2006] [Accepted: 05/19/2006] [Indexed: 11/25/2022]
Abstract
Synthesis of mediators of fever, pain and inflammation as well as protection against reactive molecules and oxidative stress is a hallmark of the MAPEG superfamily (membrane associated proteins in eicosanoid and glutathione metabolism). The structure of a MAPEG member, rat microsomal glutathione transferase 1, at 3.2 A resolution, solved here in complex with glutathione by electron crystallography, defines the active site location and a cytosolic domain involved in enzyme activation. The glutathione binding site is found to be different from that of the canonical soluble glutathione transferases. The architecture of the homotrimer supports a catalytic mechanism involving subunit interactions and reveals both cytosolic and membraneous substrate entry sites, providing a rationale for the membrane location of the enzyme.
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Affiliation(s)
- Peter J Holm
- Department of Biosciences and Nutrition, Karolinska Institutet and School of Technology and Health, Royal Institute of Technology, SE-14157 Huddinge, Sweden
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14
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Huang X, Yan W, Gao D, Tong M, Tai HH, Zhan CG. Structural and functional characterization of human microsomal prostaglandin E synthase-1 by computational modeling and site-directed mutagenesis. Bioorg Med Chem 2006; 14:3553-62. [PMID: 16439136 DOI: 10.1016/j.bmc.2006.01.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 01/06/2006] [Accepted: 01/06/2006] [Indexed: 11/26/2022]
Abstract
Microsomal prostaglandin (PG) E synthase-1 (mPGES-1) has recently been recognized as a novel, promising drug target for inflammation-related diseases. Functional and pathological studies on this enzyme further stimulate to understand its structure and the structure-function relationships. Using an approach of the combined structure prediction, molecular docking, site-directed mutagenesis, and enzymatic activity assay, we have developed the first three-dimensional (3D) model of the substrate-binding domain (SBD) of mPGES-1 and its binding with substrates prostaglandin H2 (PGH2) and glutathione (GSH). In light of the 3D model, key amino acid residues have been identified for the substrate binding and the obtained experimental activity data have confirmed the computationally determined substrate-enzyme binding mode. Both the computational and experimental results show that Y130 plays a vital role in the binding with PGH2 and, probably, in the catalytic reaction process. R110 and T114 interact intensively with the carboxyl tail of PGH2, whereas Q36 and Q134 only enhance the PGH2-binding affinity. The modeled binding structure indicates that substrate PGH2 interacts with GSH through hydrogen binding between the peroxy group of PGH2 and the -SH group of GSH. The -SH group of GSH is expected to attack the peroxy group of PGH2, initializing the catalytic reaction transforming PGH2 to prostaglandin E2 (PGE2). The overall agreement between the calculated and experimental results demonstrates that the predicted 3D model could be valuable in future rational design of potent inhibitors of mPGES-1 as the next-generation inflammation-related therapeutic.
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Affiliation(s)
- Xiaoqin Huang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536, USA
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15
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Hebert H, Jegerschöld C, Bhakat P, Holm PJ. Two‐Dimensional Crystallization and Electron Crystallography of MAPEG Proteins. Methods Enzymol 2005; 401:161-8. [PMID: 16399385 DOI: 10.1016/s0076-6879(05)01010-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Members of the membrane-associated proteins in the eicosanoid and glutathione metabolism (MAPEG) superfamily have been subjected to two-dimensional crystallization experiments. A common denominator for successful attempts has been the use of a low lipid/protein ratio in the range of 1-9 (mol/mol). Electron crystallography demonstrated either hexagonal or orthorhombic packing of trimeric protein units. Three-dimensional structure analysis of the MAPEG member microsomal glutathione transferase 1 has shown that the monomer for this protein contains a left-handed bundle of four transmembrane helices. It is likely that this is a common structural motif for MAPEG proteins, because projection maps of all structurally characterized members are very similar.
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Affiliation(s)
- Hans Hebert
- Department of Biosciences at Novum, Karolinska Institute, Huddinge, Sweden
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16
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Busenlehner LS, Codreanu SG, Holm PJ, Bhakat P, Hebert H, Morgenstern R, Armstrong RN. Stress Sensor Triggers Conformational Response of the Integral Membrane Protein Microsomal Glutathione Transferase 1†. Biochemistry 2004; 43:11145-52. [PMID: 15366924 DOI: 10.1021/bi048716k] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microsomal glutathione (GSH) transferase 1 (MGST1) is a trimeric, integral membrane protein involved in cellular response to chemical or oxidative stress. The cytosolic domain of MGST1 harbors the GSH binding site and a cysteine residue (C49) that acts as a sensor of oxidative and chemical stress. Spatially resolved changes in the kinetics of backbone amide H/D exchange reveal that the binding of a single molecule of GSH/trimer induces a cooperative conformational transition involving movements of the transmembrane helices and a reordering of the cytosolic domain. Alkylation of the stress sensor preorganizes the helices and facilitates the cooperative transition resulting in catalytic activation.
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Affiliation(s)
- Laura S Busenlehner
- Department of Biochemistry, Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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17
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Holm PJ, Morgenstern R, Hebert H. The 3-D structure of microsomal glutathione transferase 1 at 6 A resolution as determined by electron crystallography of p22(1)2(1) crystals. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1594:276-85. [PMID: 11904223 DOI: 10.1016/s0167-4838(01)00311-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pure solubilised microsomal glutathione transferase 1 (MGST1) forms well-ordered two-dimensional (2-D) crystals of two different symmetries, one orthorhombic (p22(1)2(1)) and one hexagonal (p6), both diffracting electrons to a resolution beyond 3 A. A three-dimensional (3-D) map has previously been calculated to 6 A resolution from the hexagonal crystal form. From orthorhombic crystals we have now calculated a 6 A 3-D reconstruction displaying three repeats of four rod-like densities. These are inclined relative to the normal of the membrane plane and consistent with arising from a left-handed four-helix bundle fold. The rendered volume clearly displays the same structural features as the map previously calculated from the p6 crystal type including similar lengths and substructure of the helices, but several distinguishing features do exist. The helices are more tilted in the map calculated from the orthorhombic crystals indicating conformational flexibility. Density present on the cytosolic side is consistent with the location of the active site. In addition, the current map displays the noted similarity to subunit I of cytochrome c oxidase.
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Affiliation(s)
- Peter J Holm
- Karolinska Institutet, Center for Structural Biochemistry, Department of Biosciences at Novum, Huddinge, Sweden
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18
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Abstract
Two-dimensional crystallogenesis is a crucial step in the long road that leads to the determination of macromolecules structure via electron crystallography. The necessity of having large and highly ordered samples can hold back the resolution of structural works for a long time, and this, despite improvements made in electron microscopes or image processing. Today, finding good conditions for growing two-dimensional crystals still rely on either "biocrystallo-cooks" or on lucky ones. The present review presents the field by first describing the different crystals that one can encounter and the different crystallisation methods used. Then, the effects of different components (such as protein, lipids, detergent, buffer, and temperature) and the different methods (dialysis, hydrophobic adsorption) are discussed. This discussion is punctuated by correspondences made to the world of three-dimensional crystallogenesis. Finally, a guide for setting up 2D crystallogenesis experiments, built on the discussion mentioned before, is proposed to the reader. More than giving recipes, this review is meant to open up the discussions in this field.
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Affiliation(s)
- G Mosser
- LPCC, UMR168-CNRS, Institut Curie-Section de Recherche, 11 rue Pierre et Marie Curie, 75005 Paris, France.
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19
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Schmidt-Krey I, Mitsuoka K, Hirai T, Murata K, Cheng Y, Fujiyoshi Y, Morgenstern R, Hebert H. The three-dimensional map of microsomal glutathione transferase 1 at 6 A resolution. EMBO J 2000; 19:6311-6. [PMID: 11101503 PMCID: PMC305867 DOI: 10.1093/emboj/19.23.6311] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Microsomal glutathione transferase 1 (MGST1) is representative of a superfamily of membrane proteins where different members display distinct or overlapping physiological functions, including detoxication of reactive electrophiles (glutathione transferase), reduction of lipid hydroperoxides (glutathione peroxidase), and production of leukotrienes and prostaglandin E. It follows that members of this superfamily constitute important drug targets regarding asthma, inflammation and the febrile response. Here we propose that this superfamily consists of a new class of membrane proteins built on a common left-handed four-helix bundle motif within the membrane, as determined by electron crystallography of MGST1 at 6 A resolution. Based on the 3D map and biochemical data we discuss a model for the membrane topology. The 3D structure differs significantly from that of soluble glutathione transferases, which display overlapping substrate specificity with MGST1.
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Affiliation(s)
- I Schmidt-Krey
- Karolinska Institutet, Center for Structural Biochemistry, Department of Biosciences, Novum, S-141 57 Huddinge, Germany
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Rigaud J, Chami M, Lambert O, Levy D, Ranck J. Use of detergents in two-dimensional crystallization of membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1508:112-28. [PMID: 11090821 DOI: 10.1016/s0005-2736(00)00307-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Structure determination at high resolution is actually a difficult challenge for membrane proteins and the number of membrane proteins that have been crystallized is still small and far behind that of soluble proteins. Because of their amphiphilic character, membrane proteins need to be isolated, purified and crystallized in detergent solutions. This makes it difficult to grow the well-ordered three-dimensional crystals that are required for high resolution structure analysis by X-ray crystallography. In this difficult context, growing crystals confined to two dimensions (2D crystals) and their structural analysis by electron crystallography has opened a new way to solve the structure of membrane proteins. However, 2D crystallization is one of the major bottlenecks in the structural studies of membrane proteins. Advances in our understanding of the interaction between proteins, lipids and detergents as well as development and improvement of new strategies will facilitate the success rate of 2D crystallization. This review deals with the various available strategies for obtaining 2D crystals from detergent-solubilized intrinsic membrane proteins. It gives an overview of the methods that have been applied and gives details and suggestions of the physical processes leading to the formation of the ordered arrays which may be of help for getting more proteins crystallized in a form suitable for high resolution structural analysis by electron crystallography.
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Affiliation(s)
- J Rigaud
- Institut Curie, Section de Recherche, UMR-CNRS 168 and LRC-CEA 8, 11 rue Pierre et Marie Curie, 75231, Paris, France.
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Schmidt-Krey I, Murata K, Hirai T, Mitsuoka K, Cheng Y, Morgenstern R, Fujiyoshi Y, Hebert H. The projection structure of the membrane protein microsomal glutathione transferase at 3 A resolution as determined from two-dimensional hexagonal crystals. J Mol Biol 1999; 288:243-53. [PMID: 10329140 DOI: 10.1006/jmbi.1999.2683] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The formation of two-dimensional crystals of the membrane-bound enzyme microsomal glutathione transferase is sensitive to fractional changes in the lipid-to-protein ratio. Variation of this parameter results in crystal polymorphism. The projection structure of a p6 crystal form of the enzyme has been determined by the use of electron crystallography. The unit cell at 3 A resolution is comprised of two trimers. The hexagonal p6 and the orthorhombic p21212 crystal types have common elements in the packing arrangement which imply dominant crystal contacts. An overall structural similarity between the protein molecules in the two crystal forms is suggested by the projection maps. Furthermore, a comparison of the p6 and p21212 projection maps identifies additional corresponding protein densities which could not be assigned to the microsomal glutathione transferase trimer previously. Surprisingly, an ambiguity of the rotational orientation was found for trimers interspersed at certain positions within the crystal lattice.
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Affiliation(s)
- I Schmidt-Krey
- Center for Structural Biochemistry, Department of Biosciences, Karolinska Institutet, Huddinge, S-141 57, Sweden.
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Hasler L, Heymann JB, Engel A, Kistler J, Walz T. 2D crystallization of membrane proteins: rationales and examples. J Struct Biol 1998; 121:162-71. [PMID: 9615435 DOI: 10.1006/jsbi.1998.3960] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The difficulty in crystallizing channel proteins in three dimensions limits the use of X-ray crystallography in solving their structures. In contrast, the amphiphilic character of integral membrane proteins promotes their integration into artificial lipid bilayers. Protein-protein interactions may lead to ordering of the proteins within the lipid bilayer into two-dimensional crystals that are amenable to structural studies by electron crystallography and atomic force microscopy. While reconstitution of membrane proteins with lipids is readily achieved, the mechanisms for crystal formation during or after reconstitution are not well understood. The nature of the detergent and lipid as well as pH and counter-ions is known to influence the crystal type and quality. Protein-protein interactions may also promote crystal stacking and aggregation of the sheet-like crystals, posing problems in data collection. Although highly promising, the number of well-studied examples is still too small to draw conclusions that would be applicable to any membrane protein of interest. Here we discuss parameters influencing the outcome of two-dimensional crystallization trials using prominent examples of channel protein crystals and highlight areas where further improvements to crystallization protocols can be made.
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Affiliation(s)
- L Hasler
- Maurice E. Müller Institute for Microscopy, Biozentrum, University of Basel, Switzerland
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