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Zhu Y, Peng BJ, Kumar S, Stover L, Chang JY, Lyu J, Zhang T, Schrecke S, Azizov D, Russell DH, Fang L, Laganowsky A. Polyamine detergents tailored for native mass spectrometry studies of membrane proteins. Nat Commun 2023; 14:5676. [PMID: 37709761 PMCID: PMC10502129 DOI: 10.1038/s41467-023-41429-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023] Open
Abstract
Native mass spectrometry (MS) is a powerful technique for interrogating membrane protein complexes and their interactions with other molecules. A key aspect of the technique is the ability to preserve native-like structures and noncovalent interactions, which can be challenging depending on the choice of detergent. Different strategies have been employed to reduce charge on protein complexes to minimize activation and preserve non-covalent interactions. Here, we report the synthesis of a class of polyamine detergents tailored for native MS studies of membrane proteins. These detergents, a series of spermine covalently attached to various alkyl tails, are exceptional charge-reducing molecules, exhibiting a ten-fold enhanced potency over spermine. Addition of polyamine detergents to proteins solubilized in maltoside detergents results in improved, charge-reduced native mass spectra and reduced dissociation of subunits. Polyamine detergents open new opportunities to investigate membrane proteins in different detergent environments that have thwarted previous native MS studies.
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Affiliation(s)
- Yun Zhu
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Bo-Ji Peng
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Smriti Kumar
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Lauren Stover
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Jing-Yuan Chang
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Jixing Lyu
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Tianqi Zhang
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Samantha Schrecke
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Djavdat Azizov
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Lei Fang
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA.
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA.
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2
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Cho S, Park TH. Advances in the Production of Olfactory Receptors for Industrial Use. Adv Biol (Weinh) 2023; 7:e2200251. [PMID: 36593488 DOI: 10.1002/adbi.202200251] [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: 09/14/2022] [Revised: 12/11/2022] [Indexed: 01/04/2023]
Abstract
In biological olfactory systems, olfactory receptors (ORs) can recognize and discriminate between thousands of volatile organic compounds with very high sensitivity and specificity. The superior properties of ORs have led to the development of OR-based biosensors that have shown promising potential in many applications over the past two decades. In particular, newly designed technologies in gene synthesis, protein expression, solubilization, purification, and membrane mimetics for membrane proteins have greatly opened up the previously inaccessible industrial potential of ORs. In this review, gene design, expression and solubilization strategies, and purification and reconstitution methods available for modern industrial applications are examined, with a focus on ORs. The limitations of current OR production technology are also estimated, and future directions for further progress are suggested.
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Affiliation(s)
- Seongyeon Cho
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Tai Hyun Park
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
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3
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Dmitrieva DA, Kotova TV, Safronova NA, Sadova AA, Dashevskii DE, Mishin AV. Protein Design Strategies for the Structural–Functional Studies of G Protein-Coupled Receptors. BIOCHEMISTRY (MOSCOW) 2023; 88:S192-S226. [PMID: 37069121 DOI: 10.1134/s0006297923140110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
G protein-coupled receptors (GPCRs) are an important family of membrane proteins responsible for many physiological functions in human body. High resolution GPCR structures are required to understand their molecular mechanisms and perform rational drug design, as GPCRs play a crucial role in a variety of diseases. That is difficult to obtain for the wild-type proteins because of their low stability. In this review, we discuss how this problem can be solved by using protein design strategies developed to obtain homogeneous stabilized GPCR samples for crystallization and cryoelectron microscopy.
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Affiliation(s)
- Daria A Dmitrieva
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Tatiana V Kotova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Nadezda A Safronova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Alexandra A Sadova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Dmitrii E Dashevskii
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Alexey V Mishin
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.
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4
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Yeliseev A, van den Berg A, Zoubak L, Hines K, Stepnowski S, Williston K, Yan W, Gawrisch K, Zmuda J. Thermostability of a recombinant G protein-coupled receptor expressed at high level in mammalian cell culture. Sci Rep 2020; 10:16805. [PMID: 33033368 PMCID: PMC7546613 DOI: 10.1038/s41598-020-73813-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/15/2020] [Indexed: 12/13/2022] Open
Abstract
Rational design of pharmaceutical drugs targeting integral membrane G protein-coupled receptors (GPCR) requires thorough understanding of ligand binding and mechanism of activation through high resolution structural studies of purified proteins. Due to inherent conformational flexibility of GPCR, stabilization of these proteins solubilized from cell membranes into detergents is a challenging task. Here, we take advantage of naturally occurring post-translational modifications for stabilization of purified GPCR in detergent micelles. The recombinant cannabinoid CB2 receptor was expressed at high yield in Expi293F mammalian cell cultures, solubilized and purified in Façade detergent. We report superior stability of the mammalian cell-expressed receptor compared to its E.coli-expressed counterpart, due to contributions from glycosylation of the N terminus and palmitoylation of the C terminus of CB2. Finally, we demonstrate that the mammalian Expi293F amino acid labelling kit is suitable for preparation of multi-milligram quantities of high quality, selectively stable isotope-labeled GPCR for studies by nuclear magnetic resonance.
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Affiliation(s)
- Alexei Yeliseev
- National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, 20892, USA.
| | | | - Lioudmila Zoubak
- National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, 20892, USA
| | - Kirk Hines
- National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, 20892, USA
| | - Sam Stepnowski
- ThermoFisher Scientific, 7335 Executive Way, Frederick, MD, 21704, USA
| | - Kyle Williston
- ThermoFisher Scientific, 7335 Executive Way, Frederick, MD, 21704, USA
| | - Wanhua Yan
- ThermoFisher Scientific, 7335 Executive Way, Frederick, MD, 21704, USA
| | - Klaus Gawrisch
- National Institute on Alcoholism and Alcohol Abuse, NIH, Bethesda, MD, 20892, USA
| | - Jonathan Zmuda
- ThermoFisher Scientific, 7335 Executive Way, Frederick, MD, 21704, USA
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5
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Lee Y, Warne T, Nehmé R, Pandey S, Dwivedi-Agnihotri H, Chaturvedi M, Edwards PC, García-Nafría J, Leslie AGW, Shukla AK, Tate CG. Molecular basis of β-arrestin coupling to formoterol-bound β 1-adrenoceptor. Nature 2020; 583:862-866. [PMID: 32555462 DOI: 10.1038/s41586-020-2419-1] [Citation(s) in RCA: 144] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/07/2020] [Indexed: 12/15/2022]
Abstract
The β1-adrenoceptor (β1AR) is a G-protein-coupled receptor (GPCR) that couples1 to the heterotrimeric G protein Gs. G-protein-mediated signalling is terminated by phosphorylation of the C terminus of the receptor by GPCR kinases (GRKs) and by coupling of β-arrestin 1 (βarr1, also known as arrestin 2), which displaces Gs and induces signalling through the MAP kinase pathway2. The ability of synthetic agonists to induce signalling preferentially through either G proteins or arrestins-known as biased agonism3-is important in drug development, because the therapeutic effect may arise from only one signalling cascade, whereas the other pathway may mediate undesirable side effects4. To understand the molecular basis for arrestin coupling, here we determined the cryo-electron microscopy structure of the β1AR-βarr1 complex in lipid nanodiscs bound to the biased agonist formoterol5, and the crystal structure of formoterol-bound β1AR coupled to the G-protein-mimetic nanobody6 Nb80. βarr1 couples to β1AR in a manner distinct to that7 of Gs coupling to β2AR-the finger loop of βarr1 occupies a narrower cleft on the intracellular surface, and is closer to transmembrane helix H7 of the receptor when compared with the C-terminal α5 helix of Gs. The conformation of the finger loop in βarr1 is different from that adopted by the finger loop of visual arrestin when it couples to rhodopsin8. β1AR coupled to βarr1 shows considerable differences in structure compared with β1AR coupled to Nb80, including an inward movement of extracellular loop 3 and the cytoplasmic ends of H5 and H6. We observe weakened interactions between formoterol and two serine residues in H5 at the orthosteric binding site of β1AR, and find that formoterol has a lower affinity for the β1AR-βarr1 complex than for the β1AR-Gs complex. The structural differences between these complexes of β1AR provide a foundation for the design of small molecules that could bias signalling in the β-adrenoceptors.
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Affiliation(s)
- Yang Lee
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Tony Warne
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Rony Nehmé
- MRC Laboratory of Molecular Biology, Cambridge, UK.,Creoptix AG, Wädenswil, Switzerland
| | - Shubhi Pandey
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
| | | | - Madhu Chaturvedi
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
| | | | - Javier García-Nafría
- Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC), Zaragoza, Spain.,Laboratorio de Microscopías Avanzadas, University of Zaragoza, Zaragoza, Spain
| | | | - Arun K Shukla
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
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6
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Delgado L, Franke B, Frigård T, Isogai S. Automated multistep column chromatography on ÄKTA pure system using in-line sample dilution. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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7
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Errey JC, Fiez-Vandal C. Production of membrane proteins in industry: The example of GPCRs. Protein Expr Purif 2020; 169:105569. [DOI: 10.1016/j.pep.2020.105569] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/07/2020] [Accepted: 01/12/2020] [Indexed: 01/08/2023]
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8
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Warne T, Edwards PC, Doré AS, Leslie AGW, Tate CG. Molecular basis for high-affinity agonist binding in GPCRs. Science 2019; 364:775-778. [PMID: 31072904 PMCID: PMC6586556 DOI: 10.1126/science.aau5595] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 04/29/2019] [Indexed: 12/22/2022]
Abstract
G protein-coupled receptors (GPCRs) in the G protein-coupled active state have higher affinity for agonists as compared with when they are in the inactive state, but the molecular basis for this is unclear. We have determined four active-state structures of the β1-adrenoceptor (β1AR) bound to conformation-specific nanobodies in the presence of agonists of varying efficacy. Comparison with inactive-state structures of β1AR bound to the identical ligands showed a 24 to 42% reduction in the volume of the orthosteric binding site. Potential hydrogen bonds were also shorter, and there was up to a 30% increase in the number of atomic contacts between the receptor and ligand. This explains the increase in agonist affinity of GPCRs in the active state for a wide range of structurally distinct agonists.
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Affiliation(s)
- Tony Warne
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Patricia C Edwards
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Andrew S Doré
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abington, Cambridge CB21 6GT, UK
| | - Andrew G W Leslie
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Christopher G Tate
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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9
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Yen HY, Hoi KK, Liko I, Hedger G, Horrell MR, Song W, Wu D, Heine P, Warne T, Lee Y, Carpenter B, Plückthun A, Tate CG, Sansom MSP, Robinson CV. PtdIns(4,5)P 2 stabilizes active states of GPCRs and enhances selectivity of G-protein coupling. Nature 2018; 559:423-427. [PMID: 29995853 PMCID: PMC6059376 DOI: 10.1038/s41586-018-0325-6] [Citation(s) in RCA: 190] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 05/14/2018] [Indexed: 11/21/2022]
Abstract
G-protein-coupled receptors (GPCRs) are involved in many physiological processes and are therefore key drug targets1. Although detailed structural information is available for GPCRs, the effects of lipids on the receptors, and on downstream coupling of GPCRs to G proteins are largely unknown. Here we use native mass spectrometry to identify endogenous lipids bound to three class A GPCRs. We observed preferential binding of phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) over related lipids and confirm that the intracellular surface of the receptors contain hotspots for PtdIns(4,5)P2 binding. Endogenous lipids were also observed bound directly to the trimeric Gαsβγ protein complex of the adenosine A2A receptor (A2AR) in the gas phase. Using engineered Gα subunits (mini-Gαs, mini-Gαi and mini-Gα12)2, we demonstrate that the complex of mini-Gαs with the β1 adrenergic receptor (β1AR) is stabilized by the binding of two PtdIns(4,5)P2 molecules. By contrast, PtdIns(4,5)P2 does not stabilize coupling between β1AR and other Gα subunits (mini-Gαi or mini-Gα12) or a high-affinity nanobody. Other endogenous lipids that bind to these receptors have no effect on coupling, highlighting the specificity of PtdIns(4,5)P2. Calculations of potential of mean force and increased GTP turnover by the activated neurotensin receptor when coupled to trimeric Gαiβγ complex in the presence of PtdIns(4,5)P2 provide further evidence for a specific effect of PtdIns(4,5)P2 on coupling. We identify key residues on cognate Gα subunits through which PtdIns(4,5)P2 forms bridging interactions with basic residues on class A GPCRs. These modulating effects of lipids on receptors suggest consequences for understanding function, G-protein selectivity and drug targeting of class A GPCRs.
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MESH Headings
- Animals
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Heterotrimeric GTP-Binding Proteins/metabolism
- Humans
- Molecular Dynamics Simulation
- Phosphatidylinositol 4,5-Diphosphate/metabolism
- Protein Stability
- Rats
- Receptors, Adrenergic, alpha-2/chemistry
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Neurotensin/chemistry
- Receptors, Neurotensin/genetics
- Receptors, Neurotensin/metabolism
- Single-Chain Antibodies/chemistry
- Single-Chain Antibodies/metabolism
- Substrate Specificity
- Turkeys
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Affiliation(s)
- Hsin-Yung Yen
- Chemical Research Laboratory, University of Oxford, Oxford, UK
- OMass Technologies, Kidlington, UK
| | - Kin Kuan Hoi
- Chemical Research Laboratory, University of Oxford, Oxford, UK
| | - Idlir Liko
- Chemical Research Laboratory, University of Oxford, Oxford, UK
- OMass Technologies, Kidlington, UK
| | - George Hedger
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Wanling Song
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Di Wu
- Chemical Research Laboratory, University of Oxford, Oxford, UK
| | - Philipp Heine
- Biochemisches Institut, Universität Zürich, Zurich, Switzerland
| | - Tony Warne
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Yang Lee
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Byron Carpenter
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, The University of Warwick, Coventry, UK
| | | | | | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, UK.
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10
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Wang J, Liu Y, Zhang J, Han Z, Wang W, Liu Y, Wei D, Huang W. Cell-free expression, purification, and characterization of the functional β2-adrenergic receptor for multianalyte detection of β-agonists. BIOCHEMISTRY (MOSCOW) 2017; 82:1346-1353. [DOI: 10.1134/s0006297917110128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Nehmé R, Carpenter B, Singhal A, Strege A, Edwards PC, White CF, Du H, Grisshammer R, Tate CG. Mini-G proteins: Novel tools for studying GPCRs in their active conformation. PLoS One 2017; 12:e0175642. [PMID: 28426733 PMCID: PMC5398546 DOI: 10.1371/journal.pone.0175642] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/29/2017] [Indexed: 01/08/2023] Open
Abstract
Mini-G proteins are the engineered GTPase domains of Gα subunits. They couple to GPCRs and recapitulate the increase in agonist affinity observed upon coupling of a native heterotrimeric G protein. Given the small size and stability of mini-G proteins, and their ease of expression and purification, they are ideal for biophysical studies of GPCRs in their fully active state. The first mini-G protein developed was mini-Gs. Here we extend the family of mini-G proteins to include mini-Golf, mini-Gi1, mini-Go1 and the chimeras mini-Gs/q and mini-Gs/i. The mini-G proteins were shown to couple to relevant GPCRs and to form stable complexes with purified receptors that could be purified by size exclusion chromatography. Agonist-bound GPCRs coupled to a mini-G protein showed higher thermal stability compared to the agonist-bound receptor alone. Fusion of GFP at the N-terminus of mini-G proteins allowed receptor coupling to be monitored by fluorescence-detection size exclusion chromatography (FSEC) and, in a separate assay, the affinity of mini-G protein binding to detergent-solubilised receptors was determined. This work provides the foundation for the development of any mini-G protein and, ultimately, for the structure determination of GPCRs in a fully active state.
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Affiliation(s)
- Rony Nehmé
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Byron Carpenter
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ankita Singhal
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Annette Strege
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Courtney F. White
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
| | - Haijuan Du
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
| | - Reinhard Grisshammer
- Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, United States of America
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12
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Carpenter B, Tate CG. Engineering a minimal G protein to facilitate crystallisation of G protein-coupled receptors in their active conformation. Protein Eng Des Sel 2016; 29:583-594. [PMID: 27672048 PMCID: PMC5181381 DOI: 10.1093/protein/gzw049] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 08/01/2016] [Accepted: 08/23/2016] [Indexed: 11/13/2022] Open
Abstract
G protein-coupled receptors (GPCRs) modulate cytoplasmic signalling in response to extracellular stimuli, and are important therapeutic targets in a wide range of diseases. Structure determination of GPCRs in all activation states is important to elucidate the precise mechanism of signal transduction and to facilitate optimal drug design. However, due to their inherent instability, crystallisation of GPCRs in complex with cytoplasmic signalling proteins, such as heterotrimeric G proteins and β-arrestins, has proved challenging. Here, we describe the design of a minimal G protein, mini-Gs, which is composed solely of the GTPase domain from the adenylate cyclase stimulating G protein Gs. Mini-Gs is a small, soluble protein, which efficiently couples GPCRs in the absence of Gβγ subunits. We engineered mini-Gs, using rational design mutagenesis, to form a stable complex with detergent-solubilised β1-adrenergic receptor (β1AR). Mini G proteins induce similar pharmacological and structural changes in GPCRs as heterotrimeric G proteins, but eliminate many of the problems associated with crystallisation of these complexes, specifically their large size, conformational dynamics and instability in detergent. They are therefore novel tools, which will facilitate the biochemical and structural characterisation of GPCRs in their active conformation.
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Affiliation(s)
- Byron Carpenter
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus , Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Christopher G Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus , Francis Crick Avenue, Cambridge CB2 0QH, UK
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13
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Magnani F, Serrano-Vega MJ, Shibata Y, Abdul-Hussein S, Lebon G, Miller-Gallacher J, Singhal A, Strege A, Thomas JA, Tate CG. A mutagenesis and screening strategy to generate optimally thermostabilized membrane proteins for structural studies. Nat Protoc 2016; 11:1554-71. [PMID: 27466713 PMCID: PMC5268090 DOI: 10.1038/nprot.2016.088] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The thermostability of an integral membrane protein (MP) in detergent solution is a key parameter that dictates the likelihood of obtaining well-diffracting crystals that are suitable for structure determination. However, many mammalian MPs are too unstable for crystallization. We developed a thermostabilization strategy based on systematic mutagenesis coupled to a radioligand-binding thermostability assay that can be applied to receptors, ion channels and transporters. It takes ∼6-12 months to thermostabilize a G-protein-coupled receptor (GPCR) containing 300 amino acid (aa) residues. The resulting thermostabilized MPs are more easily crystallized and result in high-quality structures. This methodology has facilitated structure-based drug design applied to GPCRs because it is possible to determine multiple structures of the thermostabilized receptors bound to low-affinity ligands. Protocols and advice are given on how to develop thermostability assays for MPs and how to combine mutations to make an optimally stable mutant suitable for structural studies. The steps in the procedure include the generation of ∼300 site-directed mutants by Ala/Leu scanning mutagenesis, the expression of each mutant in mammalian cells by transient transfection and the identification of thermostable mutants using a thermostability assay that is based on binding of an (125)I-labeled radioligand to the unpurified, detergent-solubilized MP. Individual thermostabilizing point mutations are then combined to make an optimally stable MP that is suitable for structural biology and other biophysical studies.
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Affiliation(s)
| | | | | | | | | | | | - Ankita Singhal
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Annette Strege
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Jennifer A. Thomas
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Christopher G. Tate
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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14
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Di Bartolo N, Compton ELR, Warne T, Edwards PC, Tate CG, Schertler GFX, Booth PJ. Complete Reversible Refolding of a G-Protein Coupled Receptor on a Solid Support. PLoS One 2016; 11:e0151582. [PMID: 26982879 PMCID: PMC4794186 DOI: 10.1371/journal.pone.0151582] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 03/01/2016] [Indexed: 12/22/2022] Open
Abstract
The factors defining the correct folding and stability of integral membrane proteins are poorly understood. Folding of only a few select membrane proteins has been scrutinised, leaving considerable deficiencies in knowledge for large protein families, such as G protein coupled receptors (GPCRs). Complete reversible folding, which is problematic for any membrane protein, has eluded this dominant receptor family. Moreover, attempts to recover receptors from denatured states are inefficient, yielding at best 40–70% functional protein. We present a method for the reversible unfolding of an archetypal family member, the β1-adrenergic receptor, and attain 100% recovery of the folded, functional state, in terms of ligand binding, compared to receptor which has not been subject to any unfolding and retains its original, folded structure. We exploit refolding on a solid support, which could avoid unwanted interactions and aggregation that occur in bulk solution. We determine the changes in structure and function upon unfolding and refolding. Additionally, we employ a method that is relatively new to membrane protein folding; pulse proteolysis. Complete refolding of β1-adrenergic receptor occurs in n-decyl-β-D-maltoside (DM) micelles from a urea-denatured state, as shown by regain of its original helical structure, ligand binding and protein fluorescence. The successful refolding strategy on a solid support offers a defined method for the controlled refolding and recovery of functional GPCRs and other membrane proteins that suffer from instability and irreversible denaturation once isolated from their native membranes.
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Affiliation(s)
- Natalie Di Bartolo
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
- * E-mail:
| | - Emma L. R. Compton
- Organisational and Staff Development Unit, University of Strathclyde, Glasgow, United Kingdom
| | - Tony Warne
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Patricia C. Edwards
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Christopher G. Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | | | - Paula J. Booth
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
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15
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Wang J, She Y, Wang M, Jin M, Li Y, Wang J, Liu Y. Multiresidue Method for Analysis of β Agonists in Swine Urine by Enzyme Linked Receptor Assay Based on β2 Adrenergic Receptor Expressed in HEK293 Cells. PLoS One 2015; 10:e0139176. [PMID: 26422475 PMCID: PMC4589316 DOI: 10.1371/journal.pone.0139176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 09/08/2015] [Indexed: 11/23/2022] Open
Abstract
A novel enzyme-linked receptor assay (ELRA) based on β2-adrenergic receptor (β2-AR) has been developed for rapid and high-throughput detection of β-adrenergic agonists (β-agonists) in urine. Human embryonic kidney cells (HEK293) were introduced as the expression system to enhance the functionality of the recombinant β2-AR, and the attempt to detect β-agonists in swine urine using such approaches was accomplished unprecedentedly. In this article, a recombinant porcine β2-AR was produced in the inner membrane of HEK293 cells and purified from crude membrane protein by nickel-nitrilotriacetic acid affinity chromatography. After activity identification, the recombinant receptor was used in the development of direct competitive ELRA. Several parameters such as blocking buffer and blocking process were optimized and the performance of the system was determined. The IC50 concentrations of clenbuterol, salbutamol, and ractopamine were 34, 53 and 63 μg/L, and the average recovery rates were 68.2%, 60.3% and 65.5%, respectively. ELRA based on β2-AR shows a series of advantages such as safety, easy operation, and high efficiency, making it promising for the rapid screening of β-agonists in animal urine.
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Affiliation(s)
- Jian Wang
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
- Department of Food Science, Hebei North University, Zhangjiakou, 075000, P. R. China
| | - Yongxin She
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
| | - Miao Wang
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
| | - Maojun Jin
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
| | - Yongfei Li
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
| | - Jing Wang
- Institute of Quality Standards and Testing Technology for Agro-products of CAAS, Key Laboratory of Agro-Product Quality and Safety, Ministry of Agriculture, Beijing, 100081, P. R. China
- * E-mail:
| | - Yuan Liu
- Department of Food Science, Hebei North University, Zhangjiakou, 075000, P. R. China
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16
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Sato T, Baker J, Warne T, Brown GA, Leslie AGW, Congreve M, Tate CG. Pharmacological Analysis and Structure Determination of 7-Methylcyanopindolol-Bound β1-Adrenergic Receptor. Mol Pharmacol 2015; 88:1024-34. [PMID: 26385885 DOI: 10.1124/mol.115.101030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/17/2015] [Indexed: 11/22/2022] Open
Abstract
Comparisons between structures of the β1-adrenergic receptor (AR) bound to either agonists, partial agonists, or weak partial agonists led to the proposal that rotamer changes of Ser(5.46), coupled to a contraction of the binding pocket, are sufficient to increase the probability of receptor activation. (RS)-4-[3-(tert-butylamino)-2-hydroxypropoxy]-1H-indole-2-carbonitrile (cyanopindolol) is a weak partial agonist of β1AR and, based on the hypothesis above, we predicted that the addition of a methyl group to form 4-[(2S)-3-(tert-butylamino)-2-hydroxypropoxy]-7-methyl-1H-indole-2-carbonitrile (7-methylcyanopindolol) would dramatically reduce its efficacy. An eight-step synthesis of 7-methylcyanopindolol was developed and its pharmacology was analyzed. 7-Methylcyanopindolol bound with similar affinity to cyanopindolol to both β1AR and β2AR. As predicted, the efficacy of 7-methylcyanopindolol was reduced significantly compared with cyanopindolol, acting as a very weak partial agonist of turkey β1AR and an inverse agonist of human β2AR. The structure of 7-methylcyanopindolol-bound β1AR was determined to 2.4-Å resolution and found to be virtually identical to the structure of cyanopindolol-bound β1AR. The major differences in the orthosteric binding pocket are that it has expanded by 0.3 Å in 7-methylcyanopindolol-bound β1AR and the hydroxyl group of Ser(5.46) is positioned 0.8 Å further from the ligand, with respect to the position of the Ser(5.46) side chain in cyanopindolol-bound β1AR. Thus, the molecular basis for the reduction in efficacy of 7-methylcyanopindolol compared with cyanopindolol may be regarded as the opposite of the mechanism proposed for the increase in efficacy of agonists compared with antagonists.
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Affiliation(s)
- Tomomi Sato
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Jillian Baker
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Tony Warne
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Giles A Brown
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Andrew G W Leslie
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Miles Congreve
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
| | - Christopher G Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (T.S., T.W., A.G.W.L., C.G.T.); Heptares Therapeutics Ltd, Welwyn Garden City, United Kingdom (G.A.B., M.C.); School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (J.B.); KEK High Energy Accelerator Research Organization, Institute of Materials Structure Science, Structural Biology Research Center, Tsukuba, Japan (T.S.)
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Heydenreich FM, Vuckovic Z, Matkovic M, Veprintsev DB. Stabilization of G protein-coupled receptors by point mutations. Front Pharmacol 2015; 6:82. [PMID: 25941489 PMCID: PMC4403299 DOI: 10.3389/fphar.2015.00082] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/31/2015] [Indexed: 11/13/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are flexible integral membrane proteins involved in transmembrane signaling. Their involvement in many physiological processes makes them interesting targets for drug development. Determination of the structure of these receptors will help to design more specific drugs, however, their structural characterization has so far been hampered by the low expression and their inherent instability in detergents which made protein engineering indispensable for structural and biophysical characterization. Several approaches to stabilize the receptors in a particular conformation have led to breakthroughs in GPCR structure determination. These include truncations of the flexible regions, stabilization by antibodies and nanobodies, fusion partners, high affinity and covalently bound ligands as well as conformational stabilization by mutagenesis. In this review we focus on stabilization of GPCRs by insertion of point mutations, which lead to increased conformational and thermal stability as well as improved expression levels. We summarize existing mutagenesis strategies with different coverage of GPCR sequence space and depth of information, design and transferability of mutations and the molecular basis for stabilization. We also discuss whether mutations alter the structure and pharmacological properties of GPCRs.
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Affiliation(s)
- Franziska M Heydenreich
- Laboratory of Biomolecular Research, Paul Scherrer Institut Villigen, Switzerland ; Department of Biology, ETH Zürich Zürich, Switzerland
| | - Ziva Vuckovic
- Laboratory of Biomolecular Research, Paul Scherrer Institut Villigen, Switzerland ; Department of Biology, ETH Zürich Zürich, Switzerland
| | - Milos Matkovic
- Laboratory of Biomolecular Research, Paul Scherrer Institut Villigen, Switzerland ; Department of Biology, ETH Zürich Zürich, Switzerland
| | - Dmitry B Veprintsev
- Laboratory of Biomolecular Research, Paul Scherrer Institut Villigen, Switzerland ; Department of Biology, ETH Zürich Zürich, Switzerland
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18
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Thomas JA, Tate CG. Quality control in eukaryotic membrane protein overproduction. J Mol Biol 2015; 426:4139-4154. [PMID: 25454020 PMCID: PMC4271737 DOI: 10.1016/j.jmb.2014.10.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/12/2014] [Accepted: 10/13/2014] [Indexed: 10/25/2022]
Abstract
The overexpression of authentically folded eukaryotic membrane proteins in milligramme quantities is a fundamental prerequisite for structural studies. One of the most commonly used expression systems for the production of mammalian membrane proteins is the baculovirus expression system in insect cells. However, a detailed analysis by radioligand binding and comparative Western blotting of G protein-coupled receptors and a transporter produced in insect cells showed that a considerable proportion of the expressed protein was misfolded and incapable of ligand binding. In contrast, production of the same membrane proteins in stable inducible mammalian cell lines suggested that the majority was folded correctly. It was noted that detergent solubilisation of the misfolded membrane proteins using either digitonin or dodecylmaltoside was considerablyless efficient than using sodium dodecyl sulfate or foscholine-12, whilst these detergents were equally efficient at solubilising correctly folded membrane proteins. This provides a simple and rapid test to suggest whether heterologously expressed mammalian membrane proteins are indeed correctly folded, without requiring radioligand binding assays. This will greatly facilitate the high-throughput production of fully functional membrane proteins for structural studies.
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Affiliation(s)
- Jennifer A Thomas
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Christopher G Tate
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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19
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Egloff P, Deluigi M, Heine P, Balada S, Plückthun A. A cleavable ligand column for the rapid isolation of large quantities of homogeneous and functional neurotensin receptor 1 variants from E. coli. Protein Expr Purif 2015; 108:106-114. [DOI: 10.1016/j.pep.2014.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/03/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022]
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20
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Milić D, Veprintsev DB. Large-scale production and protein engineering of G protein-coupled receptors for structural studies. Front Pharmacol 2015; 6:66. [PMID: 25873898 PMCID: PMC4379943 DOI: 10.3389/fphar.2015.00066] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 03/13/2015] [Indexed: 01/26/2023] Open
Abstract
Structural studies of G protein-coupled receptors (GPCRs) gave insights into molecular mechanisms of their action and contributed significantly to molecular pharmacology. This is primarily due to technical advances in protein engineering, production and crystallization of these important receptor targets. On the other hand, NMR spectroscopy of GPCRs, which can provide information about their dynamics, still remains challenging due to difficulties in preparation of isotopically labeled receptors and their low long-term stabilities. In this review, we discuss methods used for expression and purification of GPCRs for crystallographic and NMR studies. We also summarize protein engineering methods that played a crucial role in obtaining GPCR crystal structures.
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Affiliation(s)
- Dalibor Milić
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen Switzerland
| | - Dmitry B Veprintsev
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen Switzerland ; Department of Biology, Eidgenössische Technische Hochschule Zürich, Zürich Switzerland
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21
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Kouvatsos N, Niarchos A, Zisimopoulou P, Eliopoulos E, Poulas K, Tzartos S. Purification and functional characterization of a truncated human α4β2 nicotinic acetylcholine receptor. Int J Biol Macromol 2014; 70:320-6. [PMID: 25014634 DOI: 10.1016/j.ijbiomac.2014.06.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Revised: 06/18/2014] [Accepted: 06/19/2014] [Indexed: 10/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChR) are abundant in the brain and are essential in cognitive function, learning and memory. Previous efforts on α4β2 nAChR had been focused on functional and pharmacological characterization, where high expression yield is not essential. For structural studies though, large amounts of pure protein is important but heterologous overexpression of membrane proteins can be a burdensome task, especially if high amounts are required. In the current study, a truncated mutant of the human α4β2 nAChR was designed in order to improve expression and solubility and to obtain material suitable for high resolution structural studies. We showed that the wild type α4β2 nAChR presented low expression and solubilization yield both of which were improved with the truncated construct. The truncated nAChR showed similar binding profile to the wild type, was purified by a two-step chromatography and isolated in high purity and adequate quantity.
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Affiliation(s)
- Nikolaos Kouvatsos
- Department of Neurobiology, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR11521 Athens, Greece
| | | | - Paraskevi Zisimopoulou
- Department of Neurobiology, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR11521 Athens, Greece
| | - Elias Eliopoulos
- Department of Agricultural Biotechnology, Agricultural University of Athens, Holy Street 75, GR11855 Athens, Greece
| | | | - Socrates Tzartos
- Department of Neurobiology, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR11521 Athens, Greece; Department of Pharmacy, University of Patras, GR26500 Patras, Greece.
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22
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Miller-Gallacher JL, Nehmé R, Warne T, Edwards PC, Schertler GFX, Leslie AGW, Tate CG. The 2.1 Å resolution structure of cyanopindolol-bound β1-adrenoceptor identifies an intramembrane Na+ ion that stabilises the ligand-free receptor. PLoS One 2014; 9:e92727. [PMID: 24663151 PMCID: PMC3963952 DOI: 10.1371/journal.pone.0092727] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/25/2014] [Indexed: 12/30/2022] Open
Abstract
The β1-adrenoceptor (β1AR) is a G protein-coupled receptor (GPCR) that is activated by the endogenous agonists adrenaline and noradrenaline. We have determined the structure of an ultra-thermostable β1AR mutant bound to the weak partial agonist cyanopindolol to 2.1 Å resolution. High-quality crystals (100 μm plates) were grown in lipidic cubic phase without the assistance of a T4 lysozyme or BRIL fusion in cytoplasmic loop 3, which is commonly employed for GPCR crystallisation. An intramembrane Na+ ion was identified co-ordinated to Asp872.50, Ser1283.39 and 3 water molecules, which is part of a more extensive network of water molecules in a cavity formed between transmembrane helices 1, 2, 3, 6 and 7. Remarkably, this water network and Na+ ion is highly conserved between β1AR and the adenosine A2A receptor (rmsd of 0.3 Å), despite an overall rmsd of 2.4 Å for all Cα atoms and only 23% amino acid identity in the transmembrane regions. The affinity of agonist binding and nanobody Nb80 binding to β1AR is unaffected by Na+ ions, but the stability of the receptor is decreased by 7.5°C in the absence of Na+. Mutation of amino acid side chains that are involved in the co-ordination of either Na+ or water molecules in the network decreases the stability of β1AR by 5–10°C. The data suggest that the intramembrane Na+ and associated water network stabilise the ligand-free state of β1AR, but still permits the receptor to form the activated state which involves the collapse of the Na+ binding pocket on agonist binding.
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Affiliation(s)
| | - Rony Nehmé
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
| | - Tony Warne
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
| | - Patricia C. Edwards
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
| | - Gebhard F. X. Schertler
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
| | - Andrew G. W. Leslie
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
| | - Christopher G. Tate
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire, United Kingdom
- * E-mail:
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Bertheleme N, Chae PS, Singh S, Mossakowska D, Hann MM, Smith KJ, Hubbard JA, Dowell SJ, Byrne B. Unlocking the secrets of the gatekeeper: Methods for stabilizing and crystallizing GPCRs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2583-91. [DOI: 10.1016/j.bbamem.2013.07.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/01/2013] [Accepted: 07/08/2013] [Indexed: 02/07/2023]
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Abstract
Since the publication of the first X-ray structure of a GPCR (G-protein couple receptor) in 2000, the rate at which subsequent ones have appeared has steadily increased. This has required the development of new methodology to overcome the challenges presented by instability of isolated GPCRs, combined with a systematic optimization of existing approaches for protein expression, purification and crystallization. In addition, quality control measures that are predictive of successful outcomes have been identified. Repeated attempts at solving the structures of GPCRs have highlighted experimental approaches that are most likely to lead to success, and have allowed definition of a first-pass protocol for new receptors.
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25
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Christopher JA, Brown J, Doré AS, Errey JC, Koglin M, Marshall FH, Myszka DG, Rich RL, Tate CG, Tehan B, Warne T, Congreve M. Biophysical fragment screening of the β1-adrenergic receptor: identification of high affinity arylpiperazine leads using structure-based drug design. J Med Chem 2013; 56:3446-55. [PMID: 23517028 PMCID: PMC3654563 DOI: 10.1021/jm400140q] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Biophysical fragment screening of a thermostabilized β1-adrenergic receptor (β1AR) using surface plasmon resonance (SPR) enabled the identification of moderate affinity, high ligand efficiency (LE) arylpiperazine hits 7 and 8. Subsequent hit to lead follow-up confirmed the activity of the chemotype, and a structure-based design approach using protein-ligand crystal structures of the β1AR resulted in the identification of several fragments that bound with higher affinity, including indole 19 and quinoline 20. In the first example of GPCR crystallography with ligands derived from fragment screening, structures of the stabilized β1AR complexed with 19 and 20 were determined at resolutions of 2.8 and 2.7 Å, respectively.
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Affiliation(s)
- John A Christopher
- Heptares Therapeutics Ltd. , BioPark, Welwyn Garden City, Hertfordshire, AL7 3AX, U.K.
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Crystal structure of oligomeric β1-adrenergic G protein-coupled receptors in ligand-free basal state. Nat Struct Mol Biol 2013; 20:419-25. [PMID: 23435379 PMCID: PMC3618578 DOI: 10.1038/nsmb.2504] [Citation(s) in RCA: 215] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 01/03/2013] [Indexed: 01/23/2023]
Abstract
G protein-coupled receptors (GPCRs) mediate transmembrane signaling. Before ligand binding, GPCRs exist in a basal state. Crystal structures of several GPCRs bound with antagonists or agonists have been solved. However, the crystal structure of the ligand-free basal state of a GPCR, the starting point of GPCR activation and function, has not been determined. Here we report the X-ray crystal structure of the first ligand-free basal state of a GPCR in a lipid membrane-like environment. Oligomeric turkey β1-adrenergic receptors display two alternating dimer interfaces. One interface involves the transmembrane domain (TM) 1, TM2, the C-terminal H8, and the extracellular loop 1. The other interface engages residues from TM4, TM5, the intracellular loop 2 and the extracellular loop 2. Structural comparisons show that this ligand-free state is in an inactive conformation. This provides the structural information regarding GPCR dimerization and oligomerization.
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27
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Brueckner F, Piscitelli CL, Tsai CJ, Standfuss J, Deupi X, Schertler GFX. Structure of β-adrenergic receptors. Methods Enzymol 2013; 520:117-51. [PMID: 23332698 DOI: 10.1016/b978-0-12-391861-1.00006-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
β-Adrenergic receptors (βARs) control key physiological functions by transducing signals encoded in catecholamine hormones and neurotransmitters to activate intracellular signaling pathways. As members of the large family of G protein-coupled receptors (GPCRs), βARs have a seven-transmembrane helix topology and signal via G protein- and arrestin-dependent pathways. Until 2007, three-dimensional structural information of GPCRs activated by diffusible ligands, including βARs, was limited to homology models that used the related photoreceptor rhodopsin as a template. Over many years, several labs have developed strategies that have finally allowed the structures of the turkey β(1)AR and the human β(2)AR to be determined experimentally. The challenges to overcome included heterologous receptor overexpression, design of stabilized and crystallizable modified receptor constructs, ligand-affinity purification of active receptor and the development of novel techniques in crystallization and microcrystallography. The structures of βARs in complex with inverse agonists, antagonists, and agonists have revealed the binding mode of ligands with different efficacies, have allowed to obtain insights into ligand selectivity, and have provided better templates for drug design. Also, the structures of β(2)AR in complex with a G protein and a G protein-mimicking nanobody have provided important insights into the mechanism of receptor activation and G protein coupling. This chapter summarizes the strategies and methods that have been successfully applied to the structural studies of βARs. These are exemplified with detailed protocols toward the structure determination of stabilized turkey β(1)AR-ligand complexes. We also discuss the spectacular insights into adrenergic receptor function that were obtained from the structures.
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Affiliation(s)
- Florian Brueckner
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen PSI, Switzerland
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28
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Crystal structures of a stabilized β1-adrenoceptor bound to the biased agonists bucindolol and carvedilol. Structure 2012; 20:841-9. [PMID: 22579251 PMCID: PMC3384003 DOI: 10.1016/j.str.2012.03.014] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 02/06/2012] [Accepted: 03/03/2012] [Indexed: 01/02/2023]
Abstract
The β1-adrenoceptor (β1AR) is the site of action of beta blockers used in the treatment of cardiac-related illnesses. Two beta blockers, carvedilol and bucindolol, show distinctive activities compared to other beta blockers and have been proposed as treatments tailored to the Arg/Gly3898.56 polymorphism of the human β1AR. Both carvedilol and bucindolol are classified as biased agonists, because they stimulate G protein-independent signaling, while acting as either inverse or partial agonists of the G protein pathway. We have determined the crystal structures of a thermostabilized avian β1AR mutant bound to bucindolol and to carvedilol at 3.2 and 2.3 Å resolution, respectively. In comparison to other beta blockers, bucindolol and carvedilol interact with additional residues, in extracellular loop 2 and transmembrane helix 7, which may promote G protein-independent signaling. The structures also suggest that there may be a structural explanation for the pharmacological differences arising from the Arg/Gly3898.56 polymorphism.
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Shiroishi M, Tsujimoto H, Makyio H, Asada H, Yurugi-Kobayashi T, Shimamura T, Murata T, Nomura N, Haga T, Iwata S, Kobayashi T. Platform for the rapid construction and evaluation of GPCRs for crystallography in Saccharomyces cerevisiae. Microb Cell Fact 2012; 11:78. [PMID: 22694812 PMCID: PMC3495400 DOI: 10.1186/1475-2859-11-78] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 06/13/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recent successes in the determination of G-protein coupled receptor (GPCR) structures have relied on the ability of receptor variants to overcome difficulties in expression and purification. Therefore, the quick screening of functionally expressed stable receptor variants is vital. RESULTS We developed a platform using Saccharomyces cerevisiae for the rapid construction and evaluation of functional GPCR variants for structural studies. This platform enables us to perform a screening cycle from construction to evaluation of variants within 6-7 days. We firstly confirmed the functional expression of 25 full-length class A GPCRs in this platform. Then, in order to improve the expression level and stability, we generated and evaluated the variants of the four GPCRs (hADRB2, hCHRM2, hHRH1 and hNTSR1). These stabilized receptor variants improved both functional activity and monodispersity. Finally, the expression level of the stabilized hHRH1 in Pichia pastoris was improved up to 65 pmol/mg from negligible expression of the functional full-length receptor in S. cerevisiae at first screening. The stabilized hHRH1 was able to be purified for use in crystallization trials. CONCLUSIONS We demonstrated that the S. cerevisiae system should serve as an easy-to-handle and rapid platform for the construction and evaluation of GPCR variants. This platform can be a powerful prescreening method to identify a suitable GPCR variant for crystallography.
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Affiliation(s)
- Mitsunori Shiroishi
- Iwata Human Receptor Crystallography project, ERATO, JST, Kyoto 606-8501, Japan.
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Singh S, Zhang M, Bertheleme N, Strange PG, Byrne B. Purification of the human G protein-coupled receptor adenosine A(2a)R in a stable and functional form expressed in Pichia pastoris. ACTA ACUST UNITED AC 2012; Chapter 29:29.4.1-29.4.17. [PMID: 22294329 DOI: 10.1002/0471140864.ps2904s67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The isolation of membrane proteins with the aim of producing highly pure, homogeneous, stable, and functional material remains challenging, and it is often necessary to develop protein-specific purification protocols by trial and error. One key tool that is required in the development of a suitable protocol is a functional assay. This unit describes a range of different protocols for isolation of the human adenosine A2a receptor (A(2a)R). These protocols show the importance of developing a robust method for comparing the quality of protein obtained by a combination of biophysical analyses including SDS-PAGE, analytical size-exclusion chromatography, and functional analysis. One of the keys to isolating and maintaining a functional receptor, found not only in the optimal protocol described here but in other published examples, is that there should be no more than two chromatographic steps.
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Affiliation(s)
- Shweta Singh
- Membrane Protein Crystallography Group, Division of Molecular Biosciences, Imperial College London, UK
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31
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Singh S, Zhang M, Bertheleme N, Kara E, Strange PG, Byrne B. Radioligand binding analysis as a tool for quality control of GPCR production for structural characterization: adenosine A(2a)R as a template for study. CURRENT PROTOCOLS IN PROTEIN SCIENCE 2012; Chapter 29:29.3.1-29.3.22. [PMID: 22294328 DOI: 10.1002/0471140864.ps2903s67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Functional characterization of G protein-coupled receptors is essential to ascertain the suitability of a protein target for downstream studies and to help develop optimal expression and isolation procedures. Radioligand binding analysis is a well-established technique, which allows direct measurement of the amount of functional receptor in a sample. It can be readily applied to both membrane-bound and soluble receptor samples and is an ideal method for monitoring the amount of functional protein at each stage in the expression and isolation process. This unit presents protocols for the radioligand binding analysis of the human adenosine A(2a) receptor and provides examples of how these assays can be used at several stages to help optimize expression, solubilization, and isolation procedures.
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Affiliation(s)
- Shweta Singh
- Membrane Protein Crystallography Group, Division of Molecular Biosciences, Imperial College London, London, UK
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32
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G-protein-coupled receptor inactivation by an allosteric inverse-agonist antibody. Nature 2012; 482:237-40. [PMID: 22286059 PMCID: PMC3303121 DOI: 10.1038/nature10750] [Citation(s) in RCA: 240] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 12/02/2011] [Indexed: 12/18/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest class of cell-surface receptors, and these membrane proteins exist in equilibrium between inactive and active states.1-13 Conformational changes induced by extracellular ligands binding to GPCRs result in a cellular response through the activation of G-proteins. The A2A adenosine receptor (A2AAR) is responsible for regulating blood flow to the cardiac muscle and is important in the regulation of glutamate and dopamine release in the brain.14 In this study, we have successfully raised a mouse monoclonal antibody against human A2AAR that prevents agonist but not antagonist binding to the extracellular ligand-binding pocket. The structure of the A2AAR-antibody Fab fragment (Fab2838) complex reveals that the fragment, unexpectedly, recognises the intracellular surface of A2AAR and that its complementarity determining region, CDR-H3, penetrates into the receptor. CDR-H3 is located in a similar position to the G-protein C-terminal fragment in the active opsin structure1 and to the CDR-3 of the nanobody in the active β2 adrenergic receptor structure2 but locks the A2AAR in an inactive conformation. These results shed light on a novel strategy to modulate GPCR activity.
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Miller JL, Tate CG. Engineering an ultra-thermostable β(1)-adrenoceptor. J Mol Biol 2011; 413:628-38. [PMID: 21907721 DOI: 10.1016/j.jmb.2011.08.057] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/26/2011] [Accepted: 08/29/2011] [Indexed: 02/04/2023]
Abstract
Conformational thermostabilisation of G-protein-coupled receptors is a successful strategy for their structure determination. The thermostable mutants tolerate short-chain detergents, such as octylglucoside and nonylglucoside, which are ideal for crystallography, and in addition, the receptors are preferentially in a single conformational state. The first thermostabilised receptor to have its structure determined was the β(1)-adrenoceptor mutant β(1)AR-m23 bound to the antagonist cyanopindolol, and recently, additional structures have been determined with agonist bound. Here, we describe further stabilisation of β(1)AR-m23 by the addition of three thermostabilising mutations (I129V, D322K, and Y343L) to make a mutant receptor that is 31 °C more thermostable than the wild-type receptor in dodecylmaltoside and is 13 °C more thermostable than β(1)AR-m23 in nonylglucoside. Although a number of thermostabilisation methods were tried, including rational design of disulfide bonds and engineered zinc bridges, the two most successful strategies to improve the thermostability of β(1)AR-m23 were an engineered salt bridge and leucine scanning mutagenesis. The three additional thermostabilising mutations did not significantly affect the pharmacological properties of β(1)AR-m23, but the new mutant receptor was significantly more stable in short-chain detergents such as heptylthioglucoside and denaturing detergents such as SDS.
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Shiroishi M, Kobayashi T, Ogasawara S, Tsujimoto H, Ikeda-Suno C, Iwata S, Shimamura T. Production of the stable human histamine H₁ receptor in Pichia pastoris for structural determination. Methods 2011; 55:281-6. [PMID: 21903167 DOI: 10.1016/j.ymeth.2011.08.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Revised: 08/21/2011] [Accepted: 08/22/2011] [Indexed: 12/15/2022] Open
Abstract
G-protein coupled receptors (GPCRs) play essential roles in regulation of many physiological processes and are one of the major targets of pharmaceutical drugs. The 3D structure can provide important information for the understanding of GPCR function and the design of new drugs. However, the success of structure determination relies largely on the production of recombinant GPCRs, because the expression levels of GPCRs are very low in native tissues except rhodopsin. All non-rhodopsin GPCRs whose structures were determined so far were expressed in insect cells and the availability of other hosts was unknown. Recently, we succeeded to determine the structure of human histamine H(1) receptor (H(1)R) expressed in Pichia pastoris. Here, we report the expression and purification procedures of recombinant H(1)R used in the structural determination. The receptor was designed to possess a N-terminal 19-residue deletion and a replacement of the third cytoplasmic loop with T4-lysozyme. The receptor was verified to show similar binding activities with the receptor expressed in other hosts. The receptor was purified by the immobilized metal ion affinity chromatography and used for the crystallographic study that resulted in the successful structure determination.
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Affiliation(s)
- Mitsunori Shiroishi
- Human Receptor Crystallography Project, ERATO, Japan Science and Technology Agency, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Baker JG, Proudman RGW, Tate CG. The pharmacological effects of the thermostabilising (m23) mutations and intra and extracellular (β36) deletions essential for crystallisation of the turkey β-adrenoceptor. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2011; 384:71-91. [PMID: 21547538 PMCID: PMC3116118 DOI: 10.1007/s00210-011-0648-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 04/18/2011] [Indexed: 11/30/2022]
Abstract
The X-ray crystal structure of the turkey β-adrenoceptor has recently been determined. However, mutations were introduced into the native receptor that was essential for structure determination. These may cause alterations to the receptor pharmacology. It is therefore essential to understand the effects of these mutations on the pharmacological characteristics of the receptor. This study examined the pharmacological effects of both the m23 mutations and the β36 deletions, both alone and then in combination in the β36-m23 mutant used in the crystallisation and structure determination of the turkey β-adrenoceptor. Stable CHO-K1 cell lines were made of each of the receptor mutants and the affinity and efficacy of ligands assessed by (3)H-CGP 12177 whole cell ligand binding, (3)H-cAMP accumulation, and CRE-SPAP gene transcription assays. The m23 mutations reduced affinity for agonists, partial agonists and neutral antagonists by about tenfold whilst the β36 deletions alone had no effect on ligand affinity. Both sets of changes appeared to reduce the agonist activation of the receptor. Both the m23 and the β36 receptors retained two active agonist-induced receptor conformations similar to that of the original tβtrunc receptor. The combined β36-m23 receptor bound ligands with similar affinity to the m23 receptor; however, agonist activation was only observed with a few agonists including the catecholamines. Although the combination of mutations severely reduced the activation ability, the final crystallised receptor (β36-m23) was still a fully functional receptor capable of binding agonist and antagonist ligands and activating intracellular agonist responses.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, C Floor Medical School, University of Nottingham, Queen's Medical Centre, UK.
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Lebon G, Warne T, Edwards PC, Bennett K, Langmead CJ, Leslie AGW, Tate CG. Agonist-bound adenosine A2A receptor structures reveal common features of GPCR activation. Nature 2011; 474:521-5. [PMID: 21593763 PMCID: PMC3146096 DOI: 10.1038/nature10136] [Citation(s) in RCA: 671] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/21/2011] [Indexed: 12/18/2022]
Abstract
Adenosine receptors and β-adrenoceptors are G-protein-coupled receptors (GPCRs) that activate intracellular G proteins on binding the agonists adenosine or noradrenaline, respectively. GPCRs have similar structures consisting of seven transmembrane helices that contain well-conserved sequence motifs, indicating that they are probably activated by a common mechanism. Recent structures of β-adrenoceptors highlight residues in transmembrane region 5 that initially bind specifically to agonists rather than to antagonists, indicating that these residues have an important role in agonist-induced activation of receptors. Here we present two crystal structures of the thermostabilized human adenosine A(2A) receptor (A(2A)R-GL31) bound to its endogenous agonist adenosine and the synthetic agonist NECA. The structures represent an intermediate conformation between the inactive and active states, because they share all the features of GPCRs that are thought to be in a fully activated state, except that the cytoplasmic end of transmembrane helix 6 partially occludes the G-protein-binding site. The adenine substituent of the agonists binds in a similar fashion to the chemically related region of the inverse agonist ZM241385 (ref. 8). Both agonists contain a ribose group, not found in ZM241385, which extends deep into the ligand-binding pocket where it makes polar interactions with conserved residues in H7 (Ser 277(7.42) and His 278(7.43); superscripts refer to Ballesteros-Weinstein numbering) and non-polar interactions with residues in H3. In contrast, the inverse agonist ZM241385 does not interact with any of these residues and comparison with the agonist-bound structures indicates that ZM241385 sterically prevents the conformational change in H5 and therefore it acts as an inverse agonist. Comparison of the agonist-bound structures of A(2A)R with the agonist-bound structures of β-adrenoceptors indicates that the contraction of the ligand-binding pocket caused by the inward motion of helices 3, 5 and 7 may be a common feature in the activation of all GPCRs.
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Affiliation(s)
- Guillaume Lebon
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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37
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Two distinct conformations of helix 6 observed in antagonist-bound structures of a beta1-adrenergic receptor. Proc Natl Acad Sci U S A 2011; 108:8228-32. [PMID: 21540331 DOI: 10.1073/pnas.1100185108] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The β(1)-adrenergic receptor (β(1)AR) is a G-protein-coupled receptor whose inactive state structure was determined using a thermostabilized mutant (β(1)AR-M23). However, it was not thought to be in a fully inactivated state because there was no salt bridge between Arg139 and Glu285 linking the cytoplasmic ends of transmembrane helices 3 and 6 (the R(3.50) - D/E(6.30) "ionic lock"). Here we compare eight new structures of β(1)AR-M23, determined from crystallographically independent molecules in four different crystals with three different antagonists bound. These structures are all in the inactive R state and show clear electron density for cytoplasmic loop 3 linking transmembrane helices 5 and 6 that had not been seen previously. Despite significantly different crystal packing interactions, there are only two distinct conformations of the cytoplasmic end of helix 6, bent and straight. In the bent conformation, the Arg139-Glu285 salt bridge is present, as in the crystal structure of dark-state rhodopsin. The straight conformation, observed in previously solved structures of β-receptors, results in the ends of helices 3 and 6 being too far apart for the ionic lock to form. In the bent conformation, the R(3.50)-E(6.30) distance is significantly longer than in rhodopsin, suggesting that the interaction is also weaker, which could explain the high basal activity in β(1)AR compared to rhodopsin. Many mutations that increase the constitutive activity of G-protein-coupled receptors are found in the bent region at the cytoplasmic end of helix 6, supporting the idea that this region plays an important role in receptor activation.
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38
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Asada H, Uemura T, Yurugi-Kobayashi T, Shiroishi M, Shimamura T, Tsujimoto H, Ito K, Sugawara T, Nakane T, Nomura N, Murata T, Haga T, Iwata S, Kobayashi T. Evaluation of the Pichia pastoris expression system for the production of GPCRs for structural analysis. Microb Cell Fact 2011; 10:24. [PMID: 21513509 PMCID: PMC3094209 DOI: 10.1186/1475-2859-10-24] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 04/22/2011] [Indexed: 11/18/2022] Open
Abstract
Background Various protein expression systems, such as Escherichia coli (E. coli), Saccharomyces cerevisiae (S. cerevisiae), Pichia pastoris (P. pastoris), insect cells and mammalian cell lines, have been developed for the synthesis of G protein-coupled receptors (GPCRs) for structural studies. Recently, the crystal structures of four recombinant human GPCRs, namely β2 adrenergic receptor, adenosine A2a receptor, CXCR4 and dopamine D3 receptor, were successfully determined using an insect cell expression system. GPCRs expressed in insect cells are believed to undergo mammalian-like posttranscriptional modifications and have similar functional properties than in mammals. Crystal structures of GPCRs have not yet been solved using yeast expression systems. In the present study, P. pastoris and insect cell expression systems for the human muscarinic acetylcholine receptor M2 subtype (CHRM2) were developed and the quantity and quality of CHRM2 synthesized by both expression systems were compared for the application in structural studies. Results The ideal conditions for the expression of CHRM2 in P. pastoris were 60 hr at 20°C in a buffer of pH 7.0. The specific activity of the expressed CHRM2 was 28.9 pmol/mg of membrane protein as determined by binding assays using [3H]-quinuclidinyl benzilate (QNB). Although the specific activity of the protein produced by P. pastoris was lower than that of Sf9 insect cells, CHRM2 yield in P. pastoris was 2-fold higher than in Sf9 insect cells because P. pastoris was cultured at high cell density. The dissociation constant (Kd) for QNB in P. pastoris was 101.14 ± 15.07 pM, which was similar to that in Sf9 insect cells (86.23 ± 8.57 pM). There were no differences in the binding affinity of CHRM2 for QNB between P. pastoris and Sf9 insect cells. Conclusion Compared to insect cells, P. pastoris is easier to handle, can be grown at lower cost, and can be expressed quicker at a large scale. Yeast, P. pastoris, and insect cells are all effective expression systems for GPCRs. The results of the present study strongly suggested that protein expression in P. pastoris can be applied to the structural and biochemical studies of GPCRs.
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Affiliation(s)
- Hidetsugu Asada
- Iwata Human Receptor Crystallography project, ERATO, JST, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
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Lebon G, Bennett K, Jazayeri A, Tate CG. Thermostabilisation of an agonist-bound conformation of the human adenosine A(2A) receptor. J Mol Biol 2011; 409:298-310. [PMID: 21501622 PMCID: PMC3145977 DOI: 10.1016/j.jmb.2011.03.075] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/31/2011] [Accepted: 03/31/2011] [Indexed: 11/02/2022]
Abstract
The adenosine A(2A) receptor (A(2A)R) is a G-protein-coupled receptor that plays a key role in transmembrane signalling mediated by the agonist adenosine. The structure of A(2A)R was determined recently in an antagonist-bound conformation, which was facilitated by the T4 lysozyme fusion in cytoplasmic loop 3 and the considerable stabilisation conferred on the receptor by the bound inverse agonist ZM241385. Unfortunately, the natural agonist adenosine does not sufficiently stabilise the receptor for the formation of diffraction-quality crystals. As a first step towards determining the structure of A(2A)R bound to an agonist, the receptor was thermostabilised by systematic mutagenesis in the presence of the bound agonist [(3)H]5'-N-ethylcarboxamidoadenosine (NECA). Four thermostabilising mutations were identified that when combined to give mutant A(2A)R-GL26, conferred a greater than 200-fold decrease in its rate of unfolding compared to the wild-type receptor. Pharmacological analysis suggested that A(2A)R-GL26 is stabilised in an agonist-bound conformation because antagonists bind with up to 320-fold decreased affinity. None of the thermostabilising mutations are in the ZM241385 binding pocket, suggesting that the mutations affect ligand binding by altering the conformation of the receptor rather than through direct interactions with ligands. A(2A)R-GL26 shows considerable stability in short-chain detergents, which has allowed its purification and crystallisation.
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Hovers J, Potschies M, Polidori A, Pucci B, Raynal S, Bonneté F, Serrano-Vega MJ, Tate CG, Picot D, Pierre Y, Popot JL, Nehmé R, Bidet M, Mus-Veteau I, Busskamp H, Jung KH, Marx A, Timmins PA, Welte W. A class of mild surfactants that keep integral membrane proteins water-soluble for functional studies and crystallization. Mol Membr Biol 2011; 28:171-81. [PMID: 21314479 DOI: 10.3109/09687688.2011.552440] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mixed protein-surfactant micelles are used for in vitro studies and 3D crystallization when solutions of pure, monodisperse integral membrane proteins are required. However, many membrane proteins undergo inactivation when transferred from the biomembrane into micelles of conventional surfactants with alkyl chains as hydrophobic moieties. Here we describe the development of surfactants with rigid, saturated or aromatic hydrocarbon groups as hydrophobic parts. Their stabilizing properties are demonstrated with three different integral membrane proteins. The temperature at which 50% of the binding sites for specific ligands are lost is used as a measure of stability and dodecyl-β-D-maltoside ('C12-b-M') as a reference for conventional surfactants. One surfactant increased the stability of two different G protein-coupled receptors and the human Patched protein receptor by approximately 10°C compared to C12-b-M. Another surfactant yielded the highest stabilization of the human Patched protein receptor compared to C12-b-M (13°C) but was inferior for the G protein-coupled receptors. In addition, one of the surfactants was successfully used to stabilize and crystallize the cytochrome b(6 )f complex from Chlamydomonas reinhardtii. The structure was solved to the same resolution as previously reported in C12-b-M.
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Affiliation(s)
- Jens Hovers
- Fachbereich Biologie, Universität Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany
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Warne T, Moukhametzianov R, Baker JG, Nehmé R, Edwards PC, Leslie AG, Schertler GF, Tate CG. The structural basis for agonist and partial agonist action on a β(1)-adrenergic receptor. Nature 2011; 469:241-4. [PMID: 21228877 PMCID: PMC3023143 DOI: 10.1038/nature09746] [Citation(s) in RCA: 488] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 12/09/2010] [Indexed: 12/02/2022]
Abstract
β-adrenergic receptors (βARs) are G-protein-coupled receptors (GPCRs) that activate intracellular G proteins upon binding catecholamine agonist ligands such as adrenaline and noradrenaline. Synthetic ligands have been developed that either activate or inhibit βARs for the treatment of asthma, hypertension or cardiac dysfunction. These ligands are classified as either full agonists, partial agonists or antagonists, depending on whether the cellular response is similar to that of the native ligand, reduced or inhibited, respectively. However, the structural basis for these different ligand efficacies is unknown. Here we present four crystal structures of the thermostabilized turkey (Meleagris gallopavo) β(1)-adrenergic receptor (β(1)AR-m23) bound to the full agonists carmoterol and isoprenaline and the partial agonists salbutamol and dobutamine. In each case, agonist binding induces a 1 Å contraction of the catecholamine-binding pocket relative to the antagonist bound receptor. Full agonists can form hydrogen bonds with two conserved serine residues in transmembrane helix 5 (Ser(5.42) and Ser(5.46)), but partial agonists only interact with Ser(5.42) (superscripts refer to Ballesteros-Weinstein numbering). The structures provide an understanding of the pharmacological differences between different ligand classes, illuminating how GPCRs function and providing a solid foundation for the structure-based design of novel ligands with predictable efficacies.
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Affiliation(s)
- Tony Warne
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | | | | | - Rony Nehmé
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | | | | | - Gebhard F.X. Schertler
- Joint corresponding authors: MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK, , , Telephone +44-(0)1223-402266, Fax +44-(0)1223-213556
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Fragment Screening of Stabilized G-Protein-Coupled Receptors Using Biophysical Methods. Methods Enzymol 2011; 493:115-36. [DOI: 10.1016/b978-0-12-381274-2.00005-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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White JF, Grisshammer R. Stability of the neurotensin receptor NTS1 free in detergent solution and immobilized to affinity resin. PLoS One 2010; 5:e12579. [PMID: 20830205 PMCID: PMC2935352 DOI: 10.1371/journal.pone.0012579] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2010] [Accepted: 08/08/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Purification of recombinant membrane receptors is commonly achieved by use of an affinity tag followed by an additional chromatography step if required. This second step may exploit specific receptor properties such as ligand binding. However, the effects of multiple purification steps on protein yield and integrity are often poorly documented. We have previously reported a robust two-step purification procedure for the recombinant rat neurotensin receptor NTS1 to give milligram quantities of functional receptor protein. First, histidine-tagged receptors are enriched by immobilized metal affinity chromatography using Ni-NTA resin. Second, remaining contaminants in the Ni-NTA column eluate are removed by use of a subsequent neurotensin column yielding pure NTS1. Whilst the neurotensin column eluate contained functional receptor protein, we observed in the neurotensin column flow-through misfolded NTS1. METHODS AND FINDINGS To investigate the origin of the misfolded receptors, we estimated the amount of functional and misfolded NTS1 at each purification step by radio-ligand binding, densitometry of Coomassie stained SDS-gels, and protein content determination. First, we observed that correctly folded NTS1 suffers damage by exposure to detergent and various buffer compositions as seen by the loss of [(3)H]neurotensin binding over time. Second, exposure to the neurotensin affinity resin generated additional misfolded receptor protein. CONCLUSION Our data point towards two ways by which misfolded NTS1 may be generated: Damage by exposure to buffer components and by close contact of the receptor to the neurotensin affinity resin. Because NTS1 in detergent solution is stabilized by neurotensin, we speculate that the occurrence of aggregated receptor after contact with the neurotensin resin is the consequence of perturbations in the detergent belt surrounding the NTS1 transmembrane core. Both effects reduce the yield of functional receptor protein.
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Affiliation(s)
- Jim F. White
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland, United States of America
| | - Reinhard Grisshammer
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland, United States of America
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Sf9 cells: a versatile model system to investigate the pharmacological properties of G protein-coupled receptors. Pharmacol Ther 2010; 128:387-418. [PMID: 20705094 DOI: 10.1016/j.pharmthera.2010.07.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 11/23/2022]
Abstract
The Sf9 cell/baculovirus expression system is widely used for high-level protein expression, often with the purpose of purification. However, proteins may also be functionally expressed in the defined Sf9 cell environment. According to the literature, the pharmacology of G-protein-coupled receptors (GPCRs) functionally reconstituted in Sf9 cells is similar to the receptor properties in mammalian cells. Sf9 cells express both recombinant GPCRs and G-proteins at much higher levels than mammalian cells. Sf9 cells can be grown in suspension culture, providing an inexpensive way of obtaining large protein amounts. Co-infection with various baculoviruses allows free combination of GPCRs with different G-proteins. The absence of constitutively active receptors in Sf9 cells provides an excellent signal-to background ratio in functional assays, allowing the detection of agonist-independent receptor activity and of small ligand-induced signals including partial agonistic and inverse agonistic effects. Insect cell Gα(i)-like proteins mostly do not couple productively to mammalian GPCRs. Thus, unlike in mammalian cells, Sf9 cells do not require pertussis toxin treatment to obtain a Gα(i)-free environment. Co-expression of GPCRs with Gα(i1), Gα(i2), Gα(i3) or Gα(o) in Sf9 cells allows the generation of a selectivity profile for these Gα(i/o)-isoforms. Additionally, GPCR-G-protein combinations can be compared with defined 1:1 stoichiometry by expressing GPCR-Gα fusion proteins. Sf9 cells can also be employed for ligand screening in medicinal chemistry programs, using radioligand binding assays or functional assays, like the steady-state GTPase- or [(35)S]GTPγS binding assay. This review shows that Sf9 cells are a versatile model system to investigate the pharmacological properties of GPCRs.
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The crystallographic structure of the human adenosine A2A receptor in a high-affinity antagonist-bound state: implications for GPCR drug screening and design. Curr Opin Struct Biol 2010; 20:401-14. [DOI: 10.1016/j.sbi.2010.05.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 05/09/2010] [Indexed: 01/28/2023]
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Kim C, Vink M, Hu M, Love J, Stokes DL, Ubarretxena-Belandia I. An automated pipeline to screen membrane protein 2D crystallization. ACTA ACUST UNITED AC 2010; 11:155-66. [PMID: 20349145 DOI: 10.1007/s10969-010-9088-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 03/11/2010] [Indexed: 12/21/2022]
Abstract
Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified membrane proteins, the detergent in a protein-lipid-detergent ternary mixture must be removed, generally by dialysis, under conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices. To identify these conditions a wide range of parameters such as pH, lipid composition, lipid-to-protein ratio, ionic strength and ligands must be screened in a procedure involving four steps: crystallization, specimen preparation for electron microscopy, image acquisition, and evaluation. Traditionally, these steps have been carried out manually and, as a result, the scope of 2D crystallization trials has been limited. We have therefore developed an automated pipeline to screen the formation of 2D crystals. We employed a 96-well dialysis block for reconstitution of the target protein over a wide range of conditions designed to promote crystallization. A 96-position magnetic platform and a liquid handling robot were used to prepare negatively stained specimens in parallel. Robotic grid insertion into the electron microscope and computerized image acquisition ensures rapid evaluation of the crystallization screen. To date, 38 2D crystallization screens have been conducted for 15 different membrane proteins, totaling over 3000 individual crystallization experiments. Three of these proteins have yielded diffracting 2D crystals. Our automated pipeline outperforms traditional 2D crystallization methods in terms of throughput and reproducibility.
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Affiliation(s)
- Changki Kim
- The New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
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Serrano-Vega MJ, Tate CG. Transferability of thermostabilizing mutations between beta-adrenergic receptors. Mol Membr Biol 2010; 26:385-96. [PMID: 19883298 DOI: 10.3109/09687680903208239] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In previous work we described six point mutations that thermostabilised the turkey beta(1)-adrenergic receptor (tbeta(1)AR). The thermostable mutant, tbeta(1)AR-m23, had an apparent T(m) 21 degrees C higher than the native protein when solubilized in dodecylmaltoside (DDM) and, in addition, was significantly more stable in short chain detergents, which allowed its crystallization and structure determination. Identification of thermostabilizing mutations in tbeta(1)AR was performed by systematic mutagenesis followed by expressing and assaying each of the 318 mutants for their thermostability. This is time-consuming, so to facilitate studies on related receptors, we have studied the transferability of these mutations to the human adrenergic receptors, hbeta(1)AR and hbeta(2)AR, which have, respectively, 76% and 59% sequence identity to tbeta(2)AR, excluding the N- and C-termini. Thermostability assays revealed that hbeta(1)AR was much more unstable than tbeta(2)AR, whereas hbeta(2)AR was more stable than tbeta(1)AR. Addition of the 6 thermostabilizing mutations in tbeta(2)AR-m23 into both hbeta(2)AR and hbeta(2)AR increased their apparent T(m)s by 17 degrees C and 11 degrees C, respectively. In addition, the mutations affected the global conformation of the human receptors so that they were predominantly in the antagonist bound form, as was originally observed for tbeta(2)AR-m23. Thus, once thermostabilizing mutations have been identified in one G protein-coupled receptor, stabilization of close members within the subfamily is rapidly obtainable.
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Warne T, Serrano-Vega MJ, Tate CG, Schertler GFX. Development and crystallization of a minimal thermostabilised G protein-coupled receptor. Protein Expr Purif 2009; 65:204-13. [PMID: 19297694 DOI: 10.1016/j.pep.2009.01.014] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Structure determination of G protein-coupled receptors is still in its infancy and many factors affect whether crystals are obtained and whether the diffraction is of sufficient quality for structure determination. We recently solved the structure of a thermostabilised turkey beta 1-adrenergic receptor by crystallization in the presence of the detergent octylthioglucoside. Three factors were essential for this success. Firstly, truncations were required at the N-terminus to give optimal expression. Secondly, 6 thermostabilising point mutations were incorporated to make the receptor sufficiently stable in short-chain detergents to allow crystallization. Thirdly, truncations at the C-terminus and within cytoplasmic loop 3, in combination with the removal of the palmitoylation site, were required to obtain well-diffracting crystals in octylthioglucoside. Here, we describe the strategy employed and the utility of thermostability assays in assessing how point mutations, truncations, detergents and ligands combine to develop a construct that forms diffraction-grade crystals.
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Affiliation(s)
- Tony Warne
- MRC Laboratory of Molecular Biology, Structural Studies, Hills Road, Cambridge CB2 0QH, UK
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Yurugi-Kobayashi T, Asada H, Shiroishi M, Shimamura T, Funamoto S, Katsuta N, Ito K, Sugawara T, Tokuda N, Tsujimoto H, Murata T, Nomura N, Haga K, Haga T, Iwata S, Kobayashi T. Comparison of functional non-glycosylated GPCRs expression in Pichia pastoris. Biochem Biophys Res Commun 2009; 380:271-6. [PMID: 19167344 DOI: 10.1016/j.bbrc.2009.01.053] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Accepted: 01/13/2009] [Indexed: 11/27/2022]
Abstract
N-linked glycosylation is the most common post-translational modification of G-protein-coupled receptors (GPCRs) and is correlated to the localization and function of the receptors depending on each receptor. However, heterogeneity of glycosylation can interfere with protein crystallization. The removal of N-linked glycosylation from membrane proteins improves the ability to crystallize these proteins. We screened 25 non-glycosylated GPCRs for functional receptor production in the methylotrophic yeast Pichia pastoris using specific ligand-receptor binding assays. We found that five clones were expressed at greater than 10 pmol/mg, 9 clones at 1-10 pmol/mg and 11 clones at less than 1 pmol/mg of membrane protein. Further optimization of culture parameters including culture scale, induction time, pH and temperature enabled us to achieve expression of a functional human muscarinic acetylcholine receptor subtype 2 (CHRM2) with a B(max) value of 51.2 pmol/mg of membrane protein. Approximately 1.9 mg of the human CHRM2 was produced from a 1-L culture.
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Affiliation(s)
- Takami Yurugi-Kobayashi
- Iwata Human Receptor Crystallography Project, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Konoe-cho, Yoshida, Sakyo-Ku, Kyoto 606-8501, Japan
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Abstract
Structural and functional analysis of most G-protein-coupled receptors (GPCRs) requires their expression and purification in functional form. The produced amount of recombinant membrane-inserted receptors depends on the optimal combination of a particular GPCR and production host; optimization of expression is still a matter of trial-and-error. Prior to purification, receptors must be extracted from the membranes by use of detergent(s). The choice of an appropriate detergent for solubilization and purification is crucial to maintain receptors in their functional state. The initial enrichment can be carried out by affinity chromatography using a general affinity tag (e.g., poly-histidine tag). If the first purification step does not yield pure receptor protein, purification to homogeneity can often be achieved by use of a subsequent receptor-specific ligand column. If suitable immobilized ligands are not available, size exclusion chromatography or other techniques need to be applied. Many GPCRs become unstable upon detergent extraction from lipid membranes, and measures for stabilization are discussed. As an example, the purification of a functional neurotensin receptor to homogeneity in milligram quantities is given below.
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Affiliation(s)
- Reinhard Grisshammer
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, MD 20852, USA, telephone +1 301-594-9223, fax +1 301-480-3934,
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