1
|
Darren Tan CW, Forsthuber A, Ehmoser EK. Functional proteoliposome-like structure derived from simultaneous evisceration and enucleation of T-lymphoblastoid A3R5.7 cells: A top-down story. Exp Cell Res 2021; 400:112487. [PMID: 33476652 DOI: 10.1016/j.yexcr.2021.112487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/08/2021] [Accepted: 01/10/2021] [Indexed: 10/22/2022]
Abstract
Structurally-reduced cells and cell-derived structures are powerful tools for membrane studies. Using this approach, we probed whether a cell, without its nucleus and cytoplasm, is still capable of undergoing CD4-mediated membrane fusion. For this, we needed a cell-derived structure, akin to a giant liposome functionalised with CD4 and chemokine receptors. We present a method for the simultaneous removal of cytoplasmic and nuclear material from cells presenting CD4, CCR5, and CXCR4, using Colcemid treatment followed by hypotonic cytolysis, and then enriched using preparative flow cytometry. We show that the resultant cell membrane remains intact, retains presentation of CD4, CCR5, and CXCR4, and is still capable of CD4-mediated membrane fusion with a target cell. Finally, we detail how this protocol was developed, as well as how such samples should be handled for storage and assays. We envision the use of such systems for host-pathogen interaction studies, and the development of targeted delivery vehicles.
Collapse
Affiliation(s)
- Cherng-Wen Darren Tan
- University of Natural Resources and Life Sciences Vienna, Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, Muthgasse 11, 1190, Vienna, Austria.
| | - Andreas Forsthuber
- University of Natural Resources and Life Sciences Vienna, Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, Muthgasse 11, 1190, Vienna, Austria
| | - Eva-Kathrin Ehmoser
- University of Natural Resources and Life Sciences Vienna, Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, Muthgasse 11, 1190, Vienna, Austria
| |
Collapse
|
2
|
Calmet P, Cullin C, Cortès S, Vang M, Caudy N, Baccouch R, Dessolin J, Maamar NT, Lecomte S, Tillier B, Alves ID. Cholesterol impacts chemokine CCR5 receptor ligand-binding activity. FEBS J 2019; 287:2367-2385. [PMID: 31738467 DOI: 10.1111/febs.15145] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/27/2019] [Accepted: 11/16/2019] [Indexed: 01/03/2023]
Abstract
The chemokine CCR5 receptor is target of maraviroc, a negative allosteric modulator of CCR5 that blocks the HIV protein gp120 from associating with the receptor, thereby inhibiting virus cellular entry. As noted with other G-protein-coupled receptor family members, the role of the lipid environment in CCR5 signaling remains obscure and very modestly investigated. Controversial literature on the impact of cholesterol (Chol) depletion in HIV infection and CCR5 signaling, including the hypothesis that Chol depletion could inhibit HIV infection, lead us to focus on the understanding of Chol impact in the first stages of receptor activation. To address this aim, the approach chosen was to employ reconstituted model lipid systems of controlled lipid composition containing CCR5 from two distinct expression systems: Pichia pastoris and cell-free expression. The characterization of receptor/ligand interaction in terms of total binding or competition binding assays was independently performed by plasmon waveguide resonance and fluorescence anisotropy, respectively. Maraviroc, a potent receptor antagonist, was the ligand investigated. Additionally, coarse-grained molecular dynamics simulation was employed to investigate Chol impact in the receptor-conformational flexibility and dynamics. Results obtained with receptor produced by different expression systems and using different biophysical approaches clearly demonstrate a considerable impact of Chol in the binding affinity of maraviroc to the receptor and receptor-conformational dynamics. Chol considerably decreases maraviroc binding affinity to the CCR5 receptor. The mechanisms by which this effect occurs seem to involve the adoption of distinct receptor-conformational states with restrained structural dynamics and helical motions in the presence of Chol.
Collapse
Affiliation(s)
- Pierre Calmet
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | | | - Maylou Vang
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Nada Caudy
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Rim Baccouch
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Jean Dessolin
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | - Sophie Lecomte
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | - Isabel D Alves
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| |
Collapse
|
3
|
Kuzmina A, Vaknin K, Gdalevsky G, Vyazmensky M, Marks RS, Taube R, Engel S. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes. PLoS One 2015; 10:e0144043. [PMID: 26629902 PMCID: PMC4667905 DOI: 10.1371/journal.pone.0144043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 11/12/2015] [Indexed: 12/15/2022] Open
Abstract
Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env) gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4) mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential.
Collapse
Affiliation(s)
- Alona Kuzmina
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Karin Vaknin
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Garik Gdalevsky
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Maria Vyazmensky
- National Institute for Biotechnology in the Negev, Beer-Sheva, Israel
| | - Robert S. Marks
- National Institute for Biotechnology in the Negev, Beer-Sheva, Israel
- The Department of Biotechnology Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ran Taube
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- * E-mail: (SE); (RT)
| | - Stanislav Engel
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- National Institute for Biotechnology in the Negev, Beer-Sheva, Israel
- The Department of Biotechnology Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| |
Collapse
|
4
|
Su Z, Shi Y, Xiao Y, Sun M, Ping Q, Zong L, Li S, Niu J, Huang A, You W, Chen Y, Chen X, Fei J, Tian J. Effect of octreotide surface density on receptor-mediated endocytosis in vitro and anticancer efficacy of modified nanocarrier in vivo after optimization. Int J Pharm 2013; 447:281-92. [DOI: 10.1016/j.ijpharm.2013.01.068] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/14/2013] [Accepted: 01/30/2013] [Indexed: 02/07/2023]
|
5
|
Goncalves J, Eilers M, South K, Opefi CA, Laissue P, Reeves PJ, Smith SO. Magic angle spinning nuclear magnetic resonance spectroscopy of G protein-coupled receptors. Methods Enzymol 2013; 522:365-89. [PMID: 23374193 DOI: 10.1016/b978-0-12-407865-9.00017-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of membrane receptors and mediate a diversity of cellular processes. These receptors have a common seven-transmembrane helix structure, yet have evolved to respond to literally thousands of different ligands. In this chapter, we describe the use of magic angle spinning solid-state NMR spectroscopy for characterizing the structure and dynamics of GPCRs. Solid-state NMR spectroscopy is well suited for structural measurements in both detergent micelles and membrane bilayer environments. We first outline the methods for large-scale production of stable, functional receptors containing (13)C- and (15)N-labeled amino acids. The expression methods make use of eukaryotic HEK293S cell lines that produce correctly folded, fully functional receptors. We subsequently describe the basic methods used for magic angle spinning solid-state NMR measurements of chemical shifts and dipolar couplings, which reveal detailed information on GPCR structure and dynamics.
Collapse
Affiliation(s)
- Joseph Goncalves
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA
| | | | | | | | | | | | | |
Collapse
|
6
|
Zhukovsky MA, Lee PH, Ott A, Helms V. Putative cholesterol-binding sites in human immunodeficiency virus (HIV) coreceptors CXCR4 and CCR5. Proteins 2012; 81:555-67. [DOI: 10.1002/prot.24211] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/31/2012] [Accepted: 10/11/2012] [Indexed: 11/08/2022]
|
7
|
Bronshtein T, Toledano N, Danino D, Pollack S, Machluf M. Cell derived liposomes expressing CCR5 as a new targeted drug-delivery system for HIV infected cells. J Control Release 2011; 151:139-48. [DOI: 10.1016/j.jconrel.2011.02.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 01/17/2011] [Accepted: 02/22/2011] [Indexed: 10/18/2022]
|
8
|
Gao T, Blanchette CD, He W, Bourguet F, Ly S, Katzen F, Kudlicki WA, Henderson PT, Laurence TA, Huser T, Coleman MA. Characterizing diffusion dynamics of a membrane protein associated with nanolipoproteins using fluorescence correlation spectroscopy. Protein Sci 2011; 20:437-47. [PMID: 21280134 PMCID: PMC3048428 DOI: 10.1002/pro.577] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 11/29/2010] [Accepted: 12/01/2010] [Indexed: 01/28/2023]
Abstract
Nanolipoprotein particles (NLPs) represent a unique nanometer-sized scaffold for supporting membrane proteins (MP). Characterization of their dynamic shape and association with MP in solution remains a challenge. Here, we present a rapid method of analysis by fluorescence correlation spectroscopy (FCS) to characterize bacteriorhodopsin (bR), a membrane protein capable of forming a NLP complex. By selectively labeling individual components of NLPs during cell-free synthesis, FCS enabled us to measure specific NLP diffusion times and infer size information for different NLP species. The resulting bR-loaded NLPs were shown to be dynamically discoidal in solution with a mean diameter of 7.8 nm. The insertion rate of bR in the complex was ∼55% based on a fit model incorporating two separate diffusion properties to best approximate the FCS data. More importantly, based on these data, we infer that membrane protein associated NLPs are thermodynamically constrained as discs in solution, while empty NLPs appear to be less constrained and dynamically spherical.
Collapse
Affiliation(s)
- Tingjuan Gao
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
| | - Craig D Blanchette
- Lawrence Livermore National Laboratory, Physics and Life SciencesLivermore, California 94550
| | - Wei He
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
| | - Feliza Bourguet
- Lawrence Livermore National Laboratory, Physics and Life SciencesLivermore, California 94550
| | - Sonny Ly
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
| | | | | | - Paul T Henderson
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
| | - Ted A Laurence
- Lawrence Livermore National Laboratory, Physics and Life SciencesLivermore, California 94550
| | - Thomas Huser
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
| | - Matthew A Coleman
- NSF Center for Biophotonics Science and Technology, School of Medicine, University of California DavisSacramento, California 95817
- Lawrence Livermore National Laboratory, Physics and Life SciencesLivermore, California 94550
| |
Collapse
|
9
|
Zhukovsky MA, Basmaciogullari S, Pacheco B, Wang L, Madani N, Haim H, Sodroski J. Thermal stability of the human immunodeficiency virus type 1 (HIV-1) receptors, CD4 and CXCR4, reconstituted in proteoliposomes. PLoS One 2010; 5:e13249. [PMID: 20967243 PMCID: PMC2954141 DOI: 10.1371/journal.pone.0013249] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 09/13/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The entry of human immunodeficiency virus (HIV-1) into host cells involves the interaction of the viral exterior envelope glycoprotein, gp120, and receptors on the target cell. The HIV-1 receptors are CD4 and one of two chemokine receptors, CCR5 or CXCR4. METHODOLOGY/PRINCIPAL FINDINGS We created proteoliposomes that contain CD4, the primary HIV-1 receptor, and one of the coreceptors, CXCR4. Antibodies against CD4 and CXCR4 specifically bound the proteoliposomes. CXCL12, the natural ligand for CXCR4, and the small-molecule CXCR4 antagonist, AMD3100, bound the proteoliposomes with affinities close to those associated with the binding of these molecules to cells expressing CXCR4 and CD4. The HIV-1 gp120 exterior envelope glycoprotein bound tightly to proteoliposomes expressing only CD4 and, in the presence of soluble CD4, bound weakly to proteoliposomes expressing only CXCR4. The thermal stability of CD4 and CXCR4 inserted into liposomes was examined. Thermal denaturation of CXCR4 followed second-order kinetics, with an activation energy (E(a)) of 269 kJ/mol (64.3 kcal/mol) and an inactivation temperature (T(i)) of 56°C. Thermal inactivation of CD4 exhibited a reaction order of 1.3, an E(a) of 278 kJ/mol (66.5 kcal/mol), and a T(i) of 52.2°C. The second-order denaturation kinetics of CXCR4 is unusual among G protein-coupled receptors, and may result from dimeric interactions between CXCR4 molecules. CONCLUSIONS/SIGNIFICANCE Our studies with proteoliposomes containing the native HIV-1 receptors allowed an examination of the binding of biologically important ligands and revealed the higher-order denaturation kinetics of these receptors. CD4/CXCR4-proteoliposomes may be useful for the study of virus-target cell interactions and for the identification of inhibitors.
Collapse
Affiliation(s)
- Mikhail A. Zhukovsky
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Structural Dynamics of (Bio)chemical Systems, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stéphane Basmaciogullari
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Beatriz Pacheco
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Liping Wang
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Navid Madani
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Hillel Haim
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joseph Sodroski
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| |
Collapse
|
10
|
Reconstitution in liposome bilayers enhances nucleotide binding affinity and ATP-specificity of TrwB conjugative coupling protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2160-9. [PMID: 20647001 DOI: 10.1016/j.bbamem.2010.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/04/2010] [Accepted: 07/07/2010] [Indexed: 11/24/2022]
Abstract
Bacterial conjugative systems code for an essential membrane protein that couples the relaxosome to the DNA transport apparatus, called type IV coupling protein (T4CP). TrwB is the T4CP of the conjugative plasmid R388. In earlier work we found that this protein, purified in the presence of detergents, binds preferentially purine nucleotides trisphosphate. In contrast a soluble truncated mutant TrwBΔN70 binds uniformly all nucleotides tested. In this work, TrwB has been successfully reconstituted into liposomes. The non-membranous portion of the protein is almost exclusively oriented towards the outside of the vesicles. Functional analysis of TrwB proteoliposomes demonstrates that when the protein is inserted into the lipid bilayer the affinity for adenine and guanine nucleotides is enhanced as compared to that of the protein purified in detergent or to the soluble deletion mutant, TrwBΔN70. The protein specificity for adenine nucleotides is also increased. No ATPase activity has been found in TrwB reconstituted in proteoliposomes. This result suggests that the N-terminal transmembrane segment of this T4CP interferes with its ATPase activity and can be taken to imply that the TrwB transmembrane domain plays a regulatory role in its biological activity.
Collapse
|
11
|
Leitz AJ, Bayburt TH, Barnakov AN, Springer BA, Sligar SG. Functional reconstitution of β2-adrenergic receptors utilizing self-assembling Nanodisc technology. Biotechniques 2006; 40:601-2, 604, 606, passim. [PMID: 16708760 DOI: 10.2144/000112169] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Integral membrane G protein-coupled receptors (GPCRs) compose the single most prolific class of drug targets, yet significant functional and structural questions remain unanswered for this superfamily. A primary reason for this gap in understanding arises from the difficulty of forming soluble, monodisperse receptor membrane preparations that maintain the trans-membrane signaling activity of the receptor and provide robust biophysical and biochemical assay systems. Here we report a technique for self-assembling functional 2-adrenergic receptor (β2AR) into a nanoscale phospholipid bilayer system (Nanodisc) that is highly soluble in aqueous solution. The approximately 10-nm nanobilayer particles contain β2AR in a native-like phospholipid bilayer domain of approximately 100 phospholipid molecules circumferentially bound by a membrane scaffold protein (MSP). The resulting construct allows for access to the physiologically intracellular and extracellular faces of the receptor and thus allows unrestricted access of antagonists, agonists, and G proteins. These Nanodisc-solubilized GPCRs can be directly purified by normal chromatographic procedures. We define the resultant Nanodisc-embedded monomeric β2AR by antagonist and agonist binding isotherms and demonstrate faithful G protein coupling.
Collapse
Affiliation(s)
- Andrew J Leitz
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| | | | | | | | | |
Collapse
|
12
|
Zipeto D, Matucci A, Ripamonti C, Scarlatti G, Rossolillo P, Turci M, Sartoris S, Tridente G, Bertazzoni U. Induction of human immunodeficiency virus neutralizing antibodies using fusion complexes. Microbes Infect 2006; 8:1424-33. [PMID: 16702010 DOI: 10.1016/j.micinf.2006.03.001] [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: 01/20/2005] [Revised: 05/12/2005] [Accepted: 05/12/2005] [Indexed: 11/21/2022]
Abstract
Human immunodeficiency virus-1 (HIV-1) infects cells by membrane fusion that is mediated by the envelope proteins gp120/gp41 and the cellular receptors CD4 and CCR5. During this process, some conserved viral epitopes are temporarily exposed and may induce a neutralizing antibody response when fixed in the fusogenic conformation. These transient structures are conserved and may be effective antigens for use in an anti-HIV-1 vaccine. In this study we tested different conditions of preparation of fusion complexes inducing neutralizing antibodies against both R5 and X4 tropic HIV-1 strains. Cell lines expressing HIV-1 gp120/gp41 and CD4-CCR5 were prepared and conditions for producing fusion complexes were tested. Complexes produced at different temperature and fixative combinations were used to immunize mice. Results indicated that (a) fusion complexes prepared at either 21 degrees C, 30 degrees C or 37 degrees C were immunogenic and induced neutralizing antibodies against both R5 and X4 HIV-1 heterologous isolates; (b) after extensive purification of antibodies there was no cytotoxic effect; (c) complexes prepared at 37 degrees C were more immunogenic and induced higher titers of neutralizing antibodies than complexes prepared at either 21 degrees C or 30 degrees C; (d) the fixative used did not affect the titer of neutralizing antibodies except for glutaraldehyde which was ineffective; (e) the neutralizing activity was retained after CD4-CCR5 antibody removal. The production of higher titers of neutralizing antibody with fusion complexes prepared at 37 degrees C, as compared to lower temperatures, may be related to the induction of antibodies against many different conformation intermediates that subsequently act synergistically at different steps in the fusion process.
Collapse
Affiliation(s)
- Donato Zipeto
- Laboratory of Molecular Virology, Department of Mother and Child, Biology and Genetics, Section of Biology and Genetics, University of Verona, Strada le Grazie n. 8, 37134 Verona, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Yokogawa M, Takeuchi K, Shimada I. Bead-linked Proteoliposomes: A Reconstitution Method for NMR Analyses of Membrane Protein−Ligand Interactions. J Am Chem Soc 2005; 127:12021-7. [PMID: 16117542 DOI: 10.1021/ja0511772] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structural information about the interactions between membrane proteins and their ligands provides insights into the membrane protein functions. A variety of surfactants have been used for structural analyses of membrane proteins, and in some cases, they yielded successful results. However, the use of surfactants frequently increases the conformational instability of membrane proteins and distorts their normal function. Here, we propose a new strategy of membrane protein reconstitution into lipid bilayers on affinity beads, which maintains the native conformation and function of the protein for NMR studies. The reconstituted membrane proteins are suitable for NMR analyses of interactions, by using the transferred cross-saturation method. The strategy was successfully applied to the interaction between a potassium ion channel, KcsA, and a pore-blocker, agitoxin2 (AgTx2). This strategy would be useful for analyzing the interactions between various membrane proteins and their ligands.
Collapse
Affiliation(s)
- Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | | | | |
Collapse
|
14
|
Luca S, Heise H, Lange A, Baldus M. Investigation of Ligand-Receptor Systems by High-Resolution Solid-State NMR: Recent Progress and Perspectives. Arch Pharm (Weinheim) 2005; 338:217-28. [PMID: 15938000 DOI: 10.1002/ardp.200400991] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Solid-state Nuclear Magnetic Resonance (NMR) provides a general method to study molecular structure and dynamics in a non-crystalline and insoluble environment. We discuss the latest methodological progress to construct 3D molecular structures from solid-state NMR data obtained under magic-angle-spinning conditions. As shown for the neurotensin/NTS-1 system, these methods can be readily applied to the investigation of ligand-binding to G-protein coupled receptors.
Collapse
Affiliation(s)
- Sorin Luca
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
15
|
Yoshino T, Takahashi M, Takeyama H, Okamura Y, Kato F, Matsunaga T. Assembly of G protein-coupled receptors onto nanosized bacterial magnetic particles using Mms16 as an anchor molecule. Appl Environ Microbiol 2004; 70:2880-5. [PMID: 15128546 PMCID: PMC404404 DOI: 10.1128/aem.70.5.2880-2885.2004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) play a central role in a wide range of biological processes and are prime targets for drug discovery. GPCRs have large hydrophobic domains, and therefore purification of GPCRs from cells is frequently time-consuming and typically results in loss of native conformation. In this work, GPCRs have been successfully assembled into the lipid membrane of nanosized bacterial magnetic particles (BMPs) produced by the magnetic bacterium Magnetospirillum magneticum AMB-1. A BMP-specific protein, Mms16, was used as an anchor molecule, and localization of heterologous Mms16 on BMPs was confirmed by luciferase fusion studies. Stable luminescence was obtained from BMPs bearing Mms16 fused with luciferase at the C-terminal region. D1 dopamine receptor (D1R), a GPCR, was also efficiently assembled onto BMPs by using Mms16 as an anchor molecule. D1R-BMP complexes were simply extracted by magnetic separation from ruptured AMB-1 transformants. After washing, the complexes were ready to use for analysis. This system conveniently refines the native conformation of GPCRs without the need for detergent solubilization, purification, and reconstitution after cell disruption.
Collapse
Affiliation(s)
- Tomoko Yoshino
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | | | | | | | | | | |
Collapse
|
16
|
Abstract
Tissue factor (TF), the physiological trigger of the blood clotting cascade, is also the active ingredient in thromboplastin preparations which are widely used in clotting assays such as the prothrombin time (PT) test. A type I integral membrane protein, TF must be incorporated into suitable phospholipid membranes for full procoagulant activity. Several methods exist for incorporating TF into phospholipid vesicles, typically employing the formation of mixed micelles containing detergent, phospholipid and TF, followed by detergent removal or dilution below the critical micelle concentration (CMC). These methods have certain drawbacks: they may take several days to complete, employ expensive detergents, are difficult to scale up, and do not always result in complete detergent removal. In this study we have investigated the use of a variety of detergents [Triton X-100, octaethylene glycol monododecyl ether (C(12)E(8)), cholate, deoxycholate, and n-octyl-beta-D-glucopyranoside], and the use of adsorbent beads (Bio-Beads SM-2) for removing detergent, in processes to incorporate TF into proteoliposomes with high specific activity in coagulation assays. The method we have developed is rapid and readily scalable, yielding thromboplastin preparations with specific activities in plasma clotting assays that are at least as high as those made with detergent dialysis.
Collapse
Affiliation(s)
- S A Smith
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | |
Collapse
|
17
|
Literature Alerts. J Microencapsul 2003. [DOI: 10.3109/02652040309178081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|