1
|
Qiang M, Dong X, Zha Z, Zuo XK, Song XL, Zhao L, Yuan C, Huang C, Tao P, Hu Q, Li WG, Hu W, Li J, Nie Y, Buratto D, Zonta F, Ma P, Yu Z, Liu L, Zhang Y, Yang B, Xie J, Xu TL, Qu Z, Yang G, Lerner RA. Selection of an ASIC1a-blocking combinatorial antibody that protects cells from ischemic death. Proc Natl Acad Sci U S A 2018; 115:E7469-E7477. [PMID: 30042215 PMCID: PMC6094137 DOI: 10.1073/pnas.1807233115] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Acid-sensing ion channels (ASICs) have emerged as important, albeit challenging therapeutic targets for pain, stroke, etc. One approach to developing therapeutic agents could involve the generation of functional antibodies against these channels. To select such antibodies, we used channels assembled in nanodiscs, such that the target ASIC1a has a configuration as close as possible to its natural state in the plasma membrane. This methodology allowed selection of functional antibodies that inhibit acid-induced opening of the channel in a dose-dependent way. In addition to regulation of pH, these antibodies block the transport of cations, including calcium, thereby preventing acid-induced cell death in vitro and in vivo. As proof of concept for the use of these antibodies to modulate ion channels in vivo, we showed that they potently protect brain cells from death after an ischemic stroke. Thus, the methodology described here should be general, thereby allowing selection of antibodies to other important ASICs, such as those involved in pain, neurodegeneration, and other conditions.
Collapse
Affiliation(s)
- Min Qiang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Xue Dong
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Zhao Zha
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Xiao-Kun Zuo
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
- Department of Neurosurgery, Affiliated Haikou Hospital, Xiangya Medical College of Central South University, 570100 Haikou, China
| | - Xing-Lei Song
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
| | - Lixia Zhao
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Chao Yuan
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Chen Huang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
| | - Pingdong Tao
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Qin Hu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
| | - Wei-Guang Li
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
| | - Wanhui Hu
- iHuman Institute, ShanghaiTech University, 201210 Shanghai, China
| | - Jie Li
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yan Nie
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Damiano Buratto
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Francesco Zonta
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Peixiang Ma
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Zheng Yu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
- University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Lili Liu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Yi Zhang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Bei Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China
| | - Jia Xie
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037
| | - Tian-Le Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China
| | - Zhihu Qu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China;
| | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China;
| | - Richard A Lerner
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210 Shanghai, China;
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037
| |
Collapse
|
2
|
Lamarche LB, Kumar RP, Trieu MM, Devine EL, Cohen-Abeles LE, Theobald DL, Oprian DD. Purification and Characterization of RhoPDE, a Retinylidene/Phosphodiesterase Fusion Protein and Potential Optogenetic Tool from the Choanoflagellate Salpingoeca rosetta. Biochemistry 2017; 56:5812-5822. [PMID: 28976747 DOI: 10.1021/acs.biochem.7b00519] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
RhoPDE is a type I rhodopsin/phosphodiesterase gene fusion product from the choanoflagellate Salpingoeca rosetta. The gene was discovered around the time that a similar type I rhodopsin/guanylyl cyclase fusion protein, RhoGC, was shown to control phototaxis of an aquatic fungus through a cGMP signaling pathway. RhoPDE has potential as an optogenetic tool catalyzing the hydrolysis of cyclic nucleotides. Here we provide an expression and purification system for RhoPDE, as well as a crystal structure of the C-terminal phosphodiesterase catalytic domain. We show that RhoPDE contains an even number of transmembrane segments, with N- and C-termini both located on the cytoplasmic surface of the cell membrane. The purified protein exhibits an absorption maximum at 490 nm in the dark state, which shifts to 380 nm upon exposure to light. The protein acts as a cGMP-selective phosphodiesterase. However, the activity does not appear to be modulated by light. The protein is also active with cAMP as a substrate, but with a roughly 5-7-fold lower kcat. A truncation consisting solely of the phosphodiesterase domain is also active with a kcat for cGMP roughly 6-9-fold lower than that of the full-length protein. The isolated PDE domain was crystallized, and the X-ray structure showed the protein to be a dimer similar to human PDE9. We anticipate that the purification system introduced here will enable further structural and biochemical experiments to improve our understanding of the function and mechanism of this unique fusion protein.
Collapse
Affiliation(s)
- Lindsey B Lamarche
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Ramasamy P Kumar
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Melissa M Trieu
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Erin L Devine
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Luke E Cohen-Abeles
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Douglas L Theobald
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Daniel D Oprian
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| |
Collapse
|
3
|
Trieu MM, Devine EL, Lamarche LB, Ammerman AE, Greco JA, Birge RR, Theobald DL, Oprian DD. Expression, purification, and spectral tuning of RhoGC, a retinylidene/guanylyl cyclase fusion protein and optogenetics tool from the aquatic fungus Blastocladiella emersonii. J Biol Chem 2017; 292:10379-10389. [PMID: 28473465 DOI: 10.1074/jbc.m117.789636] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/03/2017] [Indexed: 02/03/2023] Open
Abstract
RhoGC is a rhodopsin (Rho)-guanylyl cyclase (GC) gene fusion molecule that is central to zoospore phototaxis in the aquatic fungus Blastocladiella emersonii It has generated considerable excitement because of its demonstrated potential as a tool for optogenetic manipulation of cell-signaling pathways involving cyclic nucleotides. However, a reliable method for expressing and purifying RhoGC is currently lacking. We present here an expression and purification system for isolation of the full-length RhoGC protein expressed in HEK293 cells in detergent solution. The protein exhibits robust light-dependent guanylyl cyclase activity, whereas a truncated form lacking the 17- to 20-kDa N-terminal domain is completely inactive under identical conditions. Moreover, we designed several RhoGC mutants to increase the utility of the protein for optogenetic studies. The first class we generated has altered absorption spectra designed for selective activation by different wavelengths of light. Two mutants were created with blue-shifted (E254D, λmax = 390 nm; D380N, λmax = 506 nm) and one with red-shifted (D380E, λmax = 533 nm) absorption maxima relative to the wild-type protein (λmax = 527 nm). We also engineered a double mutant, E497K/C566D, that changes the enzyme to a specific, light-stimulated adenylyl cyclase that catalyzes the formation of cAMP from ATP. We anticipate that this expression/purification system and these RhoGC mutants will facilitate mechanistic and structural exploration of this important enzyme.
Collapse
Affiliation(s)
- Melissa M Trieu
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| | - Erin L Devine
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| | - Lindsey B Lamarche
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| | - Aaron E Ammerman
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| | - Jordan A Greco
- the Departments of Chemistry and Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269
| | - Robert R Birge
- the Departments of Chemistry and Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269
| | - Douglas L Theobald
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| | - Daniel D Oprian
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454 and
| |
Collapse
|
4
|
Abstract
Conformational equilibria of G-protein-coupled receptors (GPCRs) are intimately involved in intracellular signaling. Here conformational substates of the GPCR rhodopsin are investigated in micelles of dodecyl maltoside (DDM) and in phospholipid nanodiscs by monitoring the spatial positions of transmembrane helices 6 and 7 at the cytoplasmic surface using site-directed spin labeling and double electron-electron resonance spectroscopy. The photoactivated receptor in DDM is dominated by one conformation with weak pH dependence. In nanodiscs, however, an ensemble of pH-dependent conformational substates is observed, even at pH 6.0 where the MIIbH+ form defined by proton uptake and optical spectroscopic methods is reported to be the sole species present in native disk membranes. In nanodiscs, the ensemble of substates in the photoactivated receptor spontaneously decays to that characteristic of the inactive state with a lifetime of ∼16 min at 20 °C. Importantly, transducin binding to the activated receptor selects a subset of the ensemble in which multiple substates are apparently retained. The results indicate that in a native-like lipid environment rhodopsin activation is not analogous to a simple binary switch between two defined conformations, but the activated receptor is in equilibrium between multiple conformers that in principle could recognize different binding partners.
Collapse
|
5
|
Abstract
Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.
Collapse
Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Stephen G Sligar
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| |
Collapse
|
6
|
The power, pitfalls and potential of the nanodisc system for NMR-based studies. Biol Chem 2016; 397:1335-1354. [DOI: 10.1515/hsz-2016-0224] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/19/2016] [Indexed: 12/21/2022]
Abstract
Abstract
The choice of a suitable membrane mimicking environment is of fundamental importance for the characterization of structure and function of membrane proteins. In this respect, usage of the lipid bilayer nanodisc technology provides a unique potential for nuclear magnetic resonance (NMR)-based studies. This review summarizes the recent advances in this field, focusing on (i) the strengths of the system, (ii) the bottlenecks that may be faced, and (iii) promising capabilities that may be explored in future studies.
Collapse
|
7
|
Functional Stability of the Human Kappa Opioid Receptor Reconstituted in Nanodiscs Revealed by a Time-Resolved Scintillation Proximity Assay. PLoS One 2016; 11:e0150658. [PMID: 27035823 PMCID: PMC4817975 DOI: 10.1371/journal.pone.0150658] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 02/16/2016] [Indexed: 11/19/2022] Open
Abstract
Long-term functional stability of isolated membrane proteins is crucial for many in vitro applications used to elucidate molecular mechanisms, and used for drug screening platforms in modern pharmaceutical industry. Compared to soluble proteins, the understanding at the molecular level of membrane proteins remains a challenge. This is partly due to the difficulty to isolate and simultaneously maintain their structural and functional stability, because of their hydrophobic nature. Here we show, how scintillation proximity assay can be used to analyze time-resolved high-affinity ligand binding to membrane proteins solubilized in various environments. The assay was used to establish conditions that preserved the biological function of isolated human kappa opioid receptor. In detergent solution the receptor lost high-affinity ligand binding to a radiolabelled ligand within minutes at room temperature. After reconstitution in Nanodiscs made of phospholipid bilayer the half-life of high-affinity ligand binding to the majority of receptors increased 70-fold compared to detergent solubilized receptors—a level of stability that is appropriate for further downstream applications. Time-resolved scintillation proximity assay has the potential to screen numerous conditions in parallel to obtain high levels of stable and active membrane proteins, which are intrinsically unstable in detergent solution, and with minimum material consumption.
Collapse
|
8
|
Zhang M, Huang R, Ackermann R, Im SC, Waskell L, Schwendeman A, Ramamoorthy A. Reconstitution of the Cytb5-CytP450 Complex in Nanodiscs for Structural Studies using NMR Spectroscopy. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600073] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Meng Zhang
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
| | - Rui Huang
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
| | - Rose Ackermann
- Department of Medicinal Chemistry; The Biointerfaces Institute; University of Michigan; North Campus Research Complex; Ann Arbor MI 48109 USA
| | - Sang-Choul Im
- Department of Anesthesiology; University of Michigan and VA Medical Center; Ann Arbor MI 48105 USA
| | - Lucy Waskell
- Department of Anesthesiology; University of Michigan and VA Medical Center; Ann Arbor MI 48105 USA
| | - Anna Schwendeman
- Department of Medicinal Chemistry; The Biointerfaces Institute; University of Michigan; North Campus Research Complex; Ann Arbor MI 48109 USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
| |
Collapse
|
9
|
Zhang M, Huang R, Ackermann R, Im SC, Waskell L, Schwendeman A, Ramamoorthy A. Reconstitution of the Cytb5-CytP450 Complex in Nanodiscs for Structural Studies using NMR Spectroscopy. Angew Chem Int Ed Engl 2016; 55:4497-9. [PMID: 26924779 DOI: 10.1002/anie.201600073] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 01/22/2016] [Indexed: 11/05/2022]
Abstract
Cytochrome P450s (P450s) are a superfamily of enzymes responsible for the catalysis of a wide range of substrates. Dynamic interactions between full-length membrane-bound P450 and its redox partner cytochrome b5 (cytb5 ) have been found to be important for the enzymatic activity of P450. However, the stability of the circa 70 kDa membrane-bound complex in model membranes renders high-resolution structural NMR studies particularly difficult. To overcome these challenges, reconstitution of the P450-cytb5 complex in peptide-based nanodiscs, containing no detergents, has been demonstrated, which are characterized by size exclusion chromatography and NMR spectroscopy. In addition, NMR experiments are used to identify the binding interface of the P450-cytb5 complex in the nanodisc. This is the first successful demonstration of a protein-protein complex in a nanodisc using NMR structural studies and should be useful to obtain valuable structural information on membrane-bound protein complexes.
Collapse
Affiliation(s)
- Meng Zhang
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA
| | - Rui Huang
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA
| | - Rose Ackermann
- Department of Medicinal Chemistry, The Biointerfaces Institute, University of Michigan, North Campus Research Complex, Ann Arbor, MI, 48109, USA
| | - Sang-Choul Im
- Department of Anesthesiology, University of Michigan and VA Medical Center, Ann Arbor, MI, 48105, USA
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan and VA Medical Center, Ann Arbor, MI, 48105, USA
| | - Anna Schwendeman
- Department of Medicinal Chemistry, The Biointerfaces Institute, University of Michigan, North Campus Research Complex, Ann Arbor, MI, 48109, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA. .,Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA.
| |
Collapse
|
10
|
Raschle T, Lin C, Jungmann R, Shih WM, Wagner G. Controlled Co-reconstitution of Multiple Membrane Proteins in Lipid Bilayer Nanodiscs Using DNA as a Scaffold. ACS Chem Biol 2015; 10:2448-54. [PMID: 26356202 DOI: 10.1021/acschembio.5b00627] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Nanodiscs constitute a tool for the solubilization of membrane proteins in a lipid bilayer, thus offering a near-native membrane environment. Many membrane proteins interact with other membrane proteins; however, the co-reconstitution of multiple membrane proteins in a single nanodisc is a random process that is adversely affected by several factors, including protein aggregation. Here, we present an approach for the controlled co-reconstitution of multiple membrane proteins in a single nanodisc. The temporary attachment of designated oligonucleotides to individual membrane proteins enables the formation of stable, detergent-solubilized membrane protein complexes by base-pairing of complementary oligonucleotide sequences, thus facilitating the insertion of the membrane protein complex into nanodiscs with defined stoichiometry and composition. As a proof of principle, nanodiscs containing a heterodimeric and heterotrimeric membrane protein complex were reconstituted using a fluorescently labeled voltage-gated anion channel (VDAC) as a model system.
Collapse
Affiliation(s)
- Thomas Raschle
- Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Chenxiang Lin
- Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
| | - Ralf Jungmann
- Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
| | - William M. Shih
- Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
| | - Gerhard Wagner
- Department of Biological Chemistry
and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| |
Collapse
|
11
|
Van Eps N, Caro LN, Morizumi T, Ernst OP. Characterizing rhodopsin signaling by EPR spectroscopy: from structure to dynamics. Photochem Photobiol Sci 2015; 14:1586-97. [PMID: 26140679 DOI: 10.1039/c5pp00191a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy, together with spin labeling techniques, has played a major role in the characterization of rhodopsin, the photoreceptor protein and G protein-coupled receptor (GPCR) in rod cells. Two decades ago, these biophysical tools were the first to identify transmembrane helical movements in rhodopsin upon photo-activation, a critical step in the study of GPCR signaling. EPR methods were employed to identify functional loop dynamics within rhodopsin, to measure light-induced millisecond timescale changes in rhodopsin conformation, to characterize the effects of partial agonists on the apoprotein opsin, and to study lipid interactions with rhodopsin. With the emergence of advanced pulsed EPR techniques, the stage was set to determine the amplitude of structural changes in rhodopsin and the dynamics in the rhodopsin signaling complexes. Work in this area has yielded invaluable information about mechanistic properties of GPCRs. Using EPR techniques, receptors are studied in native-like membrane environments and the effects of lipids on conformational equilibria can be explored. This perspective addresses the impact of EPR methods on rhodopsin and GPCR structural biology, highlighting historical discoveries made with spin labeling techniques, and outlining exciting new directions in the field.
Collapse
Affiliation(s)
- Ned Van Eps
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | | | | |
Collapse
|
12
|
Malhotra K, Alder NN. Advances in the use of nanoscale bilayers to study membrane protein structure and function. Biotechnol Genet Eng Rev 2015; 30:79-93. [PMID: 25023464 DOI: 10.1080/02648725.2014.921502] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Within the last decade, nanoscale lipid bilayers have emerged as powerful experimental systems in the analysis of membrane proteins (MPs) for both basic and applied research. These discoidal lipid lamellae are stabilized by annuli of specially engineered amphipathic polypeptides (nanodiscs) or polymers (SMALPs/Lipodisqs®). As biomembrane mimetics, they are well suited for the reconstitution of MPs within a controlled lipid environment. Moreover, because they are water-soluble, they are amenable to solution-based biochemical and biophysical experimentation. Hence, due to their solubility, size, stability, and monodispersity, nanoscale lipid bilayers offer technical advantages over more traditional MP analytic approaches such as detergent solubilization and reconstitution into lipid vesicles. In this article, we review some of the most recent advances in the synthesis of polypeptide- and polymer-bound nanoscale lipid bilayers and their application in the study of MP structure and function.
Collapse
Affiliation(s)
- Ketan Malhotra
- a Department of Molecular and Cell Biology , University of Connecticut , Storrs , CT 06269 , USA
| | | |
Collapse
|
13
|
Maeda S, Sun D, Singhal A, Foggetta M, Schmid G, Standfuss J, Hennig M, Dawson RJP, Veprintsev DB, Schertler GFX. Crystallization scale preparation of a stable GPCR signaling complex between constitutively active rhodopsin and G-protein. PLoS One 2014; 9:e98714. [PMID: 24979345 PMCID: PMC4076187 DOI: 10.1371/journal.pone.0098714] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/07/2014] [Indexed: 11/29/2022] Open
Abstract
The activation of the G-protein transducin (Gt) by rhodopsin (Rho) has been intensively studied for several decades. It is the best understood example of GPCR activation mechanism and serves as a template for other GPCRs. The structure of the Rho/G protein complex, which is transiently formed during the signaling reaction, is of particular interest. It can help understanding the molecular details of how retinal isomerization leads to the G protein activation, as well as shed some light on how GPCR recognizes its cognate G protein. The native Rho/Gt complex isolated from bovine retina suffers from low stability and loss of the retinal ligand. Recently, we reported that constitutively active mutant of rhodopsin E113Q forms a Rho/Gt complex that is stable in detergent solution. Here, we introduce methods for a large scale preparation of the complex formed by the thermo-stabilized and constitutively active rhodopsin mutant N2C/M257Y/D282C(RhoM257Y) and the native Gt purified from bovine retinas. We demonstrate that the light-activated rhodopsin in this complex contains a covalently bound unprotonated retinal and therefore corresponds to the active metarhodopin II state; that the isolated complex is active and dissociates upon addition of GTPγS; and that the stoichiometry corresponds to a 1∶1 molar ratio of rhodopsin to the heterotrimeric G-protein. And finally, we show that the rhodopsin also forms stable complex with Gi. This complex has significantly higher thermostability than RhoM257Y/Gt complex and is resistant to a variety of detergents. Overall, our data suggest that the RhoM257Y/Gi complex is an ideal target for future structural and mechanistic studies of signaling in the visual system.
Collapse
Affiliation(s)
- Shoji Maeda
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Dawei Sun
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Ankita Singhal
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Marcello Foggetta
- pRED Pharma Research and Early Development, Small Molecule Research, Discovery Technologies, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Georg Schmid
- pRED Pharma Research and Early Development, Small Molecule Research, Discovery Technologies, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Joerg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Michael Hennig
- pRED Pharma Research and Early Development, Small Molecule Research, Discovery Technologies, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Roger J. P. Dawson
- pRED Pharma Research and Early Development, Small Molecule Research, Discovery Technologies, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Dmitry B. Veprintsev
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
- * E-mail: (DBV); (GFXS)
| | - Gebhard F. X. Schertler
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland and Department of Biology, ETH Zurich, Zurich, Switzerland
- * E-mail: (DBV); (GFXS)
| |
Collapse
|