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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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2
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Neuhaus JD, Wild R, Eyring J, Irobalieva RN, Kowal J, Lin CW, Locher KP, Aebi M. Functional analysis of Ost3p and Ost6p containing yeast oligosaccharyltransferases. Glycobiology 2021; 31:1604-1615. [PMID: 34974622 DOI: 10.1093/glycob/cwab084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 07/14/2021] [Accepted: 08/05/2021] [Indexed: 11/14/2022] Open
Abstract
The oligosaccharyltransferase (OST) is the central enzyme in the N-glycosylation pathway. It transfers a defined oligosaccharide from a lipid-linker onto the asparagine side chain of proteins. The yeast OST consists of eight subunits and exists in two catalytically distinct isoforms that differ in one subunit, Ost3p or Ost6p. The cryo-electron microscopy structure of the Ost6p containing complex was found to be highly similar to the Ost3p containing OST. OST enzymes with altered Ost3p/Ost6p subunits were generated and functionally analyzed. The three C-terminal transmembrane helices were responsible for the higher turnover-rate of the Ost3p vs. the Ost6p containing enzyme in vitro and the more severe hypoglycosylation in Ost3p lacking strains in vivo. Glycosylation of specific OST target sites required the N-terminal thioredoxin domain of Ost3p or Ost6p. This Ost3p/Ost6p dependence was glycosylation site but not protein specific. We concluded that the Ost3p/Ost6p subunits modulate the catalytic activity of OST and provide additional specificity for OST substrate recognition.
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Affiliation(s)
- Julia D Neuhaus
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Rebekka Wild
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.,Institut de Biologie Structurale, CNRS, CEA, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Rossitza N Irobalieva
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.,Functional Genomic Center Zurich, 8057 Zurich, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
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3
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Eyring J, Lin CW, Ngwa EM, Boilevin J, Pesciullesi G, Locher KP, Darbre T, Reymond JL, Aebi M. Substrate specificities and reaction kinetics of the yeast oligosaccharyltransferase isoforms. J Biol Chem 2021; 296:100809. [PMID: 34023382 PMCID: PMC8191290 DOI: 10.1016/j.jbc.2021.100809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/07/2021] [Accepted: 05/19/2021] [Indexed: 12/02/2022] Open
Abstract
Oligosaccharyltransferase (OST) catalyzes the central step in N-linked protein glycosylation, the transfer of a preassembled oligosaccharide from its lipid carrier onto asparagine residues of secretory proteins. The prototypic hetero-octameric OST complex from the yeast Saccharomyces cerevisiae exists as two isoforms that contain either Ost3p or Ost6p, both noncatalytic subunits. These two OST complexes have different protein substrate specificities in vivo. However, their detailed biochemical mechanisms and the basis for their different specificities are not clear. The two OST complexes were purified from genetically engineered strains expressing only one isoform. The kinetic properties and substrate specificities were characterized using a quantitative in vitro glycosylation assay with short peptides and different synthetic lipid-linked oligosaccharide (LLO) substrates. We found that the peptide sequence close to the glycosylation sequon affected peptide affinity and turnover rate. The length of the lipid moiety affected LLO affinity, while the lipid double-bond stereochemistry had a greater influence on LLO turnover rates. The two OST complexes had similar affinities for both the peptide and LLO substrates but showed significantly different turnover rates. These data provide the basis for a functional analysis of the Ost3p and Ost6p subunits.
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Affiliation(s)
- Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland; Functional Genomics Center Zürich, University of Zürich/ETH Zürich, Zürich, Switzerland
| | - Elsy Mankah Ngwa
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Giorgio Pesciullesi
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.
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4
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Fluck EC, Pumroy RA, Moiseenkova-Bell VY. Production and purification of TRPV2 and TRPV5 for structural and functional studies. Methods Enzymol 2021; 653:49-74. [PMID: 34099181 DOI: 10.1016/bs.mie.2021.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transient receptor potential (TRP) vanilloid 2 (TRPV2) and TRP vanilloid 5 (TRPV5) cation channels play an important role in various physiological and pathophysiological processes. The heterologous expression and purification of these channels is critical for functional and structural characterization of these important proteins. Full-length rat TRPV2 and rabbit TRPV5 can both be expressed in Saccharomyces cerevisiae and affinity purified using the 1D4 epitope and antibody to yield pure, functional channels. Further, these channels can be reconstituted into lipid nanodiscs for a more functionally relevant environment. Presented here are protocols for the expression of full-length rat TRPV2 and rabbit TRPV5 in Saccharomyces cerevisiae, their affinity purification, and their reconstitution into nanodiscs for structural and functional studies.
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Affiliation(s)
- Edwin C Fluck
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, United States; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ruth A Pumroy
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, United States
| | - Vera Y Moiseenkova-Bell
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, United States.
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5
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Mahmoudi Gomari M, Saraygord-Afshari N, Farsimadan M, Rostami N, Aghamiri S, Farajollahi MM. Opportunities and challenges of the tag-assisted protein purification techniques: Applications in the pharmaceutical industry. Biotechnol Adv 2020; 45:107653. [PMID: 33157154 DOI: 10.1016/j.biotechadv.2020.107653] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 10/22/2020] [Accepted: 10/29/2020] [Indexed: 01/16/2023]
Abstract
Tag-assisted protein purification is a method of choice for both academic researches and large-scale industrial demands. Application of the purification tags in the protein production process can help to save time and cost, but the design and application of tagged fusion proteins are challenging. An appropriate tagging strategy must provide sufficient expression yield and high purity for the final protein products while preserving their native structure and function. Thanks to the recent advances in the bioinformatics and emergence of high-throughput techniques (e.g. SEREX), many new tags are introduced to the market. A variety of interfering and non-interfering tags have currently broadened their application scope beyond the traditional use as a simple purification tool. They can take part in many biochemical and analytical features and act as solubility and protein expression enhancers, probe tracker for online visualization, detectors of post-translational modifications, and carrier-driven tags. Given the variability and growing number of the purification tags, here we reviewed the protein- and peptide-structured purification tags used in the affinity, ion-exchange, reverse phase, and immobilized metal ion affinity chromatographies. We highlighted the demand for purification tags in the pharmaceutical industry and discussed the impact of self-cleavable tags, aggregating tags, and nanotechnology on both the column-based and column-free purification techniques.
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Affiliation(s)
- Mohammad Mahmoudi Gomari
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Neda Saraygord-Afshari
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran.
| | - Marziye Farsimadan
- Department of Biology, Faculty of Sciences, University of Guilan, Rasht, Iran
| | - Neda Rostami
- Department of Chemical Engineering, Faculty of Engineering, Arak University, Iran
| | - Shahin Aghamiri
- Student research committee, Department of medical biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad M Farajollahi
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
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6
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Phosphatidylserine flipping by the P4-ATPase ATP8A2 is electrogenic. Proc Natl Acad Sci U S A 2019; 116:16332-16337. [PMID: 31371510 DOI: 10.1073/pnas.1910211116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phospholipid flippases (P4-ATPases) utilize ATP to translocate specific phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of biological membranes, thus generating and maintaining transmembrane lipid asymmetry essential for a variety of cellular processes. P4-ATPases belong to the P-type ATPase protein family, which also encompasses the ion transporting P2-ATPases: Ca2+-ATPase, Na+,K+-ATPase, and H+,K+-ATPase. In comparison with the P2-ATPases, understanding of P4-ATPases is still very limited. The electrogenicity of P4-ATPases has not been explored, and it is not known whether lipid transfer between membrane bilayer leaflets can lead to displacement of charge across the membrane. A related question is whether P4-ATPases countertransport ions or other substrates in the opposite direction, similar to the P2-ATPases. Using an electrophysiological method based on solid supported membranes, we observed the generation of a transient electrical current by the mammalian P4-ATPase ATP8A2 in the presence of ATP and the negatively charged lipid substrate phosphatidylserine, whereas only a diminutive current was generated with the lipid substrate phosphatidylethanolamine, which carries no or little charge under the conditions of the measurement. The current transient seen with phosphatidylserine was abolished by the mutation E198Q, which blocks dephosphorylation. Likewise, mutation I364M, which causes the neurological disorder cerebellar ataxia, mental retardation, and disequilibrium (CAMRQ) syndrome, strongly interfered with the electrogenic lipid translocation. It is concluded that the electrogenicity is associated with a step in the ATPase reaction cycle directly involved in translocation of the lipid. These measurements also showed that no charged substrate is being countertransported, thereby distinguishing the P4-ATPase from P2-ATPases.
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7
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Agosto MA, Anastassov IA, Robichaux MA, Wensel TG. A Large Endoplasmic Reticulum-Resident Pool of TRPM1 in Retinal ON-Bipolar Cells. eNeuro 2018; 5:ENEURO.0143-18.2018. [PMID: 30027108 PMCID: PMC6051591 DOI: 10.1523/eneuro.0143-18.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 12/22/2022] Open
Abstract
The chemical signal of light onset, a decrease in glutamate release from rod and cone photoreceptors, is processed by a postsynaptic G protein signaling cascade in ON-bipolar cells (BPCs). The metabotropic glutamate receptor mGluR6, along with other cascade elements, is localized synaptically at the BPC dendritic tips. The effector ion channel protein transient receptor potential melastatin-1 (TRPM1), in contrast, is located not only at the dendritic tips but also in BPC bodies and axons. Little is known about the intracellular localization of TRPM1, or its trafficking route to the dendritic tip plasma membrane. Recombinant TRPM1 expressed in mammalian cells colocalized with endoplasmic reticulum (ER) markers, with little or none detected at the plasma membrane. In mouse retina, somatic TRPM1 was similarly intracellular, and not at the plasma membrane. Labeling of ER membranes by expression of a fluorescent marker showed that in BPCs the ER extends into axons and dendrites, but not dendritic tips. In cell bodies, TRPM1 colocalized with the ER, and not with the Golgi apparatus. Fluorescence protease protection (FPP) assays with TRPM1-GFP fusions in heterologous cells revealed that the N and C termini are both accessible to the cytoplasm, consistent with the transmembrane domain topology of related TRP channels. These results indicate that the majority of TRPM1 is present in the ER, from which it can potentially be transported to the dendritic tips as needed for ON light responses. The excess of ER-resident TRPM1 relative to the amount needed at the dendritic tips suggests a potential new function for TRPM1 in the ER.
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Affiliation(s)
- Melina A. Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Ivan A. Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Michael A. Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Theodore G. Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
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8
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Gantzel RH, Mogensen LS, Mikkelsen SA, Vilsen B, Molday RS, Vestergaard AL, Andersen JP. Disease mutations reveal residues critical to the interaction of P4-ATPases with lipid substrates. Sci Rep 2017; 7:10418. [PMID: 28874751 PMCID: PMC5585164 DOI: 10.1038/s41598-017-10741-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/14/2017] [Indexed: 02/08/2023] Open
Abstract
Phospholipid flippases (P4-ATPases) translocate specific phospholipids from the exoplasmic to the cytoplasmic leaflet of membranes. While there is good evidence that the overall molecular structure of flippases is similar to that of P-type ATPase ion-pumps, the transport pathway for the “giant” lipid substrate has not been determined. ATP8A2 is a flippase with selectivity toward phosphatidylserine (PS), possessing a net negatively charged head group, whereas ATP8B1 exhibits selectivity toward the electrically neutral phosphatidylcholine (PC). Setting out to elucidate the functional consequences of flippase disease mutations, we have identified residues of ATP8A2 that are critical to the interaction with the lipid substrate during the translocation process. Among the residues pinpointed are I91 and L308, which are positioned near proposed translocation routes through the protein. In addition we pinpoint two juxtaposed oppositely charged residues, E897 and R898, in the exoplasmic loop between transmembrane helices 5 and 6. The glutamate is conserved between PS and PC flippases, whereas the arginine is replaced by a negatively charged aspartate in ATP8B1. Our mutational analysis suggests that the glutamate repels the PS head group, whereas the arginine minimizes this repulsion in ATP8A2, thereby contributing to control the entry of the phospholipid substrate into the translocation pathway.
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Affiliation(s)
- Rasmus H Gantzel
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Louise S Mogensen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Stine A Mikkelsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.,Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Anna L Vestergaard
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark.,Laboratory for Immuno-Endocrinology, Department of Biomedical Sciences, University of Copenhagen, DK-2200, Copenhagen N, Denmark
| | - Jens P Andersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark.
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9
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Hite RK, MacKinnon R. Structural Titration of Slo2.2, a Na +-Dependent K + Channel. Cell 2017; 168:390-399.e11. [PMID: 28111072 DOI: 10.1016/j.cell.2016.12.030] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/12/2016] [Accepted: 12/20/2016] [Indexed: 01/03/2023]
Abstract
The stable structural conformations that occur along the complete reaction coordinate for ion channel opening have never been observed. In this study, we describe the equilibrium ensemble of structures of Slo2.2, a neuronal Na+-activated K+ channel, as a function of the Na+ concentration. We find that Slo2.2 exists in multiple closed conformations whose relative occupancies are independent of Na+ concentration. An open conformation emerges from an ensemble of closed conformations in a highly Na+-dependent manner, without evidence of Na+-dependent intermediates. In other words, channel opening is a highly concerted, switch-like process. The midpoint of the structural titration matches that of the functional titration. A maximum open conformation probability approaching 1.0 and maximum functional open probability approaching 0.7 imply that, within the class of open channels, there is a subclass that is not permeable to ions.
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Affiliation(s)
- Richard K Hite
- Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA
| | - Roderick MacKinnon
- Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA.
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10
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Cryo-EM structure of the open high-conductance Ca 2+-activated K + channel. Nature 2016; 541:46-51. [PMID: 27974795 DOI: 10.1038/nature20608] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 11/03/2016] [Indexed: 12/12/2022]
Abstract
The Ca2+-activated K+ channel, Slo1, has an unusually large conductance and contains a voltage sensor and multiple chemical sensors. Dual activation by membrane voltage and Ca2+ renders Slo1 central to processes that couple electrical signalling to Ca2+-mediated events such as muscle contraction and neuronal excitability. Here we present the cryo-electron microscopy structure of a full-length Slo1 channel from Aplysia californica in the presence of Ca2+ and Mg2+ at a resolution of 3.5 Å. The channel adopts an open conformation. Its voltage-sensor domain adopts a non-domain-swapped attachment to the pore and contacts the cytoplasmic Ca2+-binding domain from a neighbouring subunit. Unique structural features of the Slo1 voltage sensor suggest that it undergoes different conformational changes than other known voltage sensors. The structure reveals the molecular details of three distinct divalent cation-binding sites identified through electrophysiological studies of mutant Slo1 channels.
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11
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Structural basis for gating the high-conductance Ca 2+-activated K + channel. Nature 2016; 541:52-57. [PMID: 27974801 DOI: 10.1038/nature20775] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/09/2016] [Indexed: 12/17/2022]
Abstract
The precise control of an ion channel gate by environmental stimuli is crucial for the fulfilment of its biological role. The gate in Slo1 K+ channels is regulated by two separate stimuli, intracellular Ca2+ concentration and membrane voltage. Slo1 is thus central to understanding the relationship between intracellular Ca2+ and membrane excitability. Here we present the Slo1 structure from Aplysia californica in the absence of Ca2+ and compare it with the Ca2+-bound channel. We show that Ca2+ binding at two unique binding sites per subunit stabilizes an expanded conformation of the Ca2+ sensor gating ring. These conformational changes are propagated from the gating ring to the pore through covalent linkers and through protein interfaces formed between the gating ring and the voltage sensors. The gating ring and the voltage sensors are directly connected through these interfaces, which allow membrane voltage to regulate gating of the pore by influencing the Ca2+ sensors.
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12
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Yadav DK, Yadav N, Yadav S, Haque S, Tuteja N. An insight into fusion technology aiding efficient recombinant protein production for functional proteomics. Arch Biochem Biophys 2016; 612:57-77. [DOI: 10.1016/j.abb.2016.10.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 10/15/2016] [Accepted: 10/18/2016] [Indexed: 11/27/2022]
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13
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Tena-Campos M, Ramon E, Lupala CS, Pérez JJ, Koch KW, Garriga P. Zinc Is Involved in Depression by Modulating G Protein-Coupled Receptor Heterodimerization. Mol Neurobiol 2015; 53:2003-2015. [PMID: 25855059 DOI: 10.1007/s12035-015-9153-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 03/19/2015] [Indexed: 12/01/2022]
Abstract
5-Hydroxytryptamine 1A receptor and galanin receptor 1 belong to the G protein-coupled receptors superfamily, and they have been described to heterodimerize triggering an anomalous physiological state that would underlie depression. Zinc supplementation has been widely reported to improve treatment against major depressive disorder. Our work has focused on the study and characterization of these receptors and its relationships with zinc both under purified conditions and in cell culture. To this aim, we have designed a strategy to purify the receptors in a conformationally active state. We have used receptors tagged with the monoclonal Rho-1D4 antibody and employed ligand-assisted purification in order to successfully purify both receptors in a properly folded and active state. The interaction between both purified receptors has been analyzed by surface plasmon resonance in order to determine the kinetics of dimerization. Zinc effect on heteromer has also been tested using the same methodology but exposing the 5-hydroxytryptamine 1A receptor to zinc before the binding experiment. These results, combined with Förster resonance energy transfer (FRET) measurements, in the absence and presence of zinc, suggest that this ion is capable of disrupting this interaction. Moreover, molecular modeling suggests that there is a coincidence between zinc-binding sites and heterodimerization interfaces for the serotonin receptor. Our results establish a rational explanation for the role of zinc in the molecular processes associated with receptor-receptor interactions and its relationship with depression, in agreement with previously reported evidence for the positive effects of zinc in depression treatment, and the involvement of our target dimer in the same disease.
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Affiliation(s)
- Mercè Tena-Campos
- Departament d'Enginyeria Química, Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222, Terrassa, Catalonia, Spain
| | - Eva Ramon
- Departament d'Enginyeria Química, Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222, Terrassa, Catalonia, Spain
| | - Cecylia S Lupala
- Departament d'Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, ETSEIB, Avda. Diagonal 647, 08028, Barcelona, Catalonia, Spain
| | - Juan J Pérez
- Departament d'Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, ETSEIB, Avda. Diagonal 647, 08028, Barcelona, Catalonia, Spain
| | - Karl-W Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129, Oldenburg, Germany
| | - Pere Garriga
- Departament d'Enginyeria Química, Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222, Terrassa, Catalonia, Spain.
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14
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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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15
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Seiradake E, Zhao Y, Lu W, Aricescu AR, Jones EY. Production of cell surface and secreted glycoproteins in mammalian cells. Methods Mol Biol 2015; 1261:115-27. [PMID: 25502196 DOI: 10.1007/978-1-4939-2230-7_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Mammalian protein expression systems are becoming increasingly popular for the production of eukaryotic secreted and cell surface proteins. Here we describe methods to produce recombinant proteins in adherent or suspension human embryonic kidney cell cultures, using transient transfection or stable cell lines. The protocols are easy to scale up and cost-efficient, making them suitable for protein crystallization projects and other applications that require high protein yields.
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Affiliation(s)
- Elena Seiradake
- The Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford, OX3 7BN, UK
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16
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Blocker KM, Britton ZT, Naranjo AN, McNeely PM, Young CL, Robinson AS. Recombinant G Protein-Coupled Receptor Expression in Saccharomyces cerevisiae for Protein Characterization. Methods Enzymol 2015; 556:165-83. [DOI: 10.1016/bs.mie.2014.12.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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17
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Molday LL, Molday RS. 1D4: a versatile epitope tag for the purification and characterization of expressed membrane and soluble proteins. Methods Mol Biol 2014; 1177:1-15. [PMID: 24943310 DOI: 10.1007/978-1-4939-1034-2_1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Incorporation of short epitope tags into proteins for recognition by commercially available monoclonal or polyclonal antibodies has greatly facilitated the detection, characterization, localization, and purification of heterologously expressed proteins for structure-function studies. A number of tags have been developed, but many epitope-antibody combinations do not work effectively for all immunochemical techniques due to the nature of the tag and the specificity of the antibodies. A highly versatile, multipurpose epitope tag is the 9 amino acid C-terminal 1D4 peptide. This peptide tag together with the Rho1D4 monoclonal antibody can be used to detect proteins in complex mixtures by western blotting and ELISA assays, localize proteins in cells by immunofluorescence and immunoelectron microscopic labeling techniques, identify subunits and interacting proteins by co-immunoprecipitation, and purify functionally active proteins including membrane proteins by immunoaffinity chromatography. In this chapter we describe various immunochemical procedures which can be used for the detection, purification and localization of 1D4-tagged proteins for structure-function studies.
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Affiliation(s)
- Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
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18
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Quazi F, Molday RS. Differential phospholipid substrates and directional transport by ATP-binding cassette proteins ABCA1, ABCA7, and ABCA4 and disease-causing mutants. J Biol Chem 2013; 288:34414-26. [PMID: 24097981 DOI: 10.1074/jbc.m113.508812] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
ABCA1, ABCA7, and ABCA4 are members of the ABCA subfamily of ATP-binding cassette transporters that share extensive sequence and structural similarity. Mutations in ABCA1 cause Tangier disease characterized by defective cholesterol homeostasis and high density lipoprotein (HDL) deficiency. Mutations in ABCA4 are responsible for Stargardt disease, a degenerative disorder associated with severe loss in central vision. Although cell-based studies have implicated ABCA proteins in lipid transport, the substrates and direction of transport have not been firmly established. We have purified and reconstituted ABCA1, ABCA7, and ABCA4 into liposomes for fluorescent-lipid transport studies. ABCA1 actively exported or flipped phosphatidylcholine, phosphatidylserine, and sphingomyelin from the cytoplasmic to the exocytoplasmic leaflet of membranes, whereas ABCA7 preferentially exported phosphatidylserine. In contrast, ABCA4 transported phosphatidylethanolamine in the reverse direction. The same phospholipids stimulated the ATPase activity of these ABCA transporters. The transport and ATPase activities of ABCA1 and ABCA4 were reduced by 25% in the presence of 20% cholesterol. Nine ABCA1 Tangier mutants and the corresponding ABCA4 Stargardt mutants showed significantly reduced phospholipid transport activity and subcellular mislocalization. These studies provide the first direct evidence for ABCA1 and ABCA7 functioning as phospholipid transporters and suggest that this activity is an essential step in the loading of apoA-1 with phospholipids for HDL formation.
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Affiliation(s)
- Faraz Quazi
- From the Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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19
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Bell CH, Healey E, van Erp S, Bishop B, Tang C, Gilbert RJ, Aricescu AR, Pasterkamp RJ, Siebold C. Structure of the repulsive guidance molecule (RGM)-neogenin signaling hub. Science 2013; 341:77-80. [PMID: 23744777 PMCID: PMC4730555 DOI: 10.1126/science.1232322] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Repulsive guidance molecule family members (RGMs) control fundamental and diverse cellular processes, including motility and adhesion, immune cell regulation, and systemic iron metabolism. However, it is not known how RGMs initiate signaling through their common cell-surface receptor, neogenin (NEO1). Here, we present crystal structures of the NEO1 RGM-binding region and its complex with human RGMB (also called dragon). The RGMB structure reveals a previously unknown protein fold and a functionally important autocatalytic cleavage mechanism and provides a framework to explain numerous disease-linked mutations in RGMs. In the complex, two RGMB ectodomains conformationally stabilize the juxtamembrane regions of two NEO1 receptors in a pH-dependent manner. We demonstrate that all RGM-NEO1 complexes share this architecture, which therefore represents the core of multiple signaling pathways.
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Affiliation(s)
- Christian H. Bell
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Eleanor Healey
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Susan van Erp
- Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, CG Utrecht 3584, Netherlands
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Chenxiang Tang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Robert J.C. Gilbert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A. Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - R. Jeroen Pasterkamp
- Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, CG Utrecht 3584, Netherlands
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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20
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Grunbeck A, Huber T, Sakmar TP. Mapping a ligand binding site using genetically encoded photoactivatable crosslinkers. Methods Enzymol 2013; 520:307-22. [PMID: 23332706 DOI: 10.1016/b978-0-12-391861-1.00014-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
G protein-coupled receptor (GPCR) signaling complexes are important for mediating many different biological processes. Uncovering the mechanism for how a ligand triggers a GPCR to elicit a specific response is an active area of research. One step toward understanding this mechanism is through identifying a ligand's binding site on a GPCR. We have optimized a targeted photocrosslinking technology to detect the residues in a receptor that are within a precise distance from a bound ligand in the receptor-ligand complex. Here, we describe the method for introducing photoactivable crosslinkers into a GPCR using the amber stop codon suppression technology. In addition, we review the steps to identify the binding site of a fluorescein-tagged peptide ligand and a tritium-labeled small molecule ligand.
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Affiliation(s)
- Amy Grunbeck
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, USA
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21
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Palczewski K, Orban T. From atomic structures to neuronal functions of g protein-coupled receptors. Annu Rev Neurosci 2013; 36:139-64. [PMID: 23682660 DOI: 10.1146/annurev-neuro-062012-170313] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are essential mediators of signal transduction, neurotransmission, ion channel regulation, and other cellular events. GPCRs are activated by diverse stimuli, including light, enzymatic processing of their N-termini, and binding of proteins, peptides, or small molecules such as neurotransmitters. GPCR dysfunction caused by receptor mutations and environmental challenges contributes to many neurological diseases. Moreover, modern genetic technology has helped identify a rich array of mono- and multigenic defects in humans and animal models that connect such receptor dysfunction with disease affecting neuronal function. The visual system is especially suited to investigate GPCR structure and function because advanced imaging techniques permit structural studies of photoreceptor neurons at both macro and molecular levels that, together with biochemical and physiological assessment in animal models, provide a more complete understanding of GPCR signaling.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA.
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22
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Reboul E, Dyka FM, Quazi F, Molday RS. Cholesterol transport via ABCA1: new insights from solid-phase binding assay. Biochimie 2012. [PMID: 23201557 DOI: 10.1016/j.biochi.2012.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
It is now well established that the ATP-binding cassette transporter A1 (ABCA1) plays a pivotal role in HDL metabolism, reverse cholesterol transport and net efflux of cellular cholesterol and phospholipids. We aimed to resolve some uncertainties related to the putative function of ABCA1 as a mediator of lipid transport by using a methodology developed in the laboratory to isolate a protein and study its interactions with other compounds. ABCA1 was tagged with the 1D4 peptide at the C terminus and expressed in human HEK 293 cells. Preliminary experiments showed that the tag modified neither the protein expression/localization within the cells nor the ability of ABCA1 to promote cholesterol cellular efflux to apolipoprotein A-I. ABCA1-1D4 was then purified and reconstituted in liposomes. ABCA1 displayed an ATPase activity in phospholipid liposomes that was significantly decreased by cholesterol. Finally, interactions with either cholesterol or apolipoprotein A-I were assessed by binding experiments with protein immobilized on an immunoaffinity matrix. Solid-phase binding assays showed no direct binding of cholesterol or apolipoprotein A-I to ABCA1. Overall, our data support the hypothesis that ABCA1 is able to mediate the transport of cholesterol from cells without direct interaction and that apo A-I primarily binds to membrane surface or accessory protein(s).
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Affiliation(s)
- Emmanuelle Reboul
- INRA, UMR1260 Nutrition Obesity and Risk of Thrombosis, F-13385 Marseille, France.
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23
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Su L, Sampaio AV, Jones KB, Pacheco M, Goytain A, Lin S, Poulin N, Yi L, Rossi FM, Kast J, Capecchi MR, Underhill TM, Nielsen TO. Deconstruction of the SS18-SSX fusion oncoprotein complex: insights into disease etiology and therapeutics. Cancer Cell 2012; 21:333-47. [PMID: 22439931 PMCID: PMC3734954 DOI: 10.1016/j.ccr.2012.01.010] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/23/2011] [Accepted: 01/24/2012] [Indexed: 01/27/2023]
Abstract
Synovial sarcoma is a translocation-associated sarcoma where the underlying chromosomal event generates SS18-SSX fusion transcripts. In vitro and in vivo studies have shown that the SS18-SSX fusion oncoprotein is both necessary and sufficient to support tumorigenesis; however, its mechanism of action remains poorly defined. We have purified a core SS18-SSX complex and discovered that SS18-SSX serves as a bridge between activating transcription factor 2 (ATF2) and transducin-like enhancer of split 1 (TLE1), resulting in repression of ATF2 target genes. Disruption of these components by siRNA knockdown or treatment with HDAC inhibitors rescues target gene expression, leading to growth suppression and apoptosis. Together, these studies define a fundamental role for aberrant ATF2 transcriptional dysregulation in the etiology of synovial sarcoma.
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Affiliation(s)
- Le Su
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Arthur V. Sampaio
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Kevin B. Jones
- Department of Orthopaedics and Center for Children’s Cancer Research, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, United States
- Department of Human Genetics and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112, United States
| | - Marina Pacheco
- Department of Pathology and Laboratory Medicine, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Angela Goytain
- Department of Pathology and Laboratory Medicine, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Shujun Lin
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Neal Poulin
- Department of Pathology and Laboratory Medicine, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Lin Yi
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Fabio M. Rossi
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Juergen Kast
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Mario R. Capecchi
- Department of Human Genetics and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112, United States
| | - T. Michael Underhill
- Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Torsten O. Nielsen
- Department of Pathology and Laboratory Medicine, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
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24
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Critical role of a transmembrane lysine in aminophospholipid transport by mammalian photoreceptor P4-ATPase ATP8A2. Proc Natl Acad Sci U S A 2012; 109:1449-54. [PMID: 22307598 DOI: 10.1073/pnas.1108862109] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
ATP8A2 is a P(4)-ATPase ("flippase") located in membranes of retinal photoreceptors, brain cells, and testis, where it mediates transport of aminophospholipids toward the cytoplasmic leaflet. It has long been an enigma whether the mechanism of P(4)-ATPases resembles that of the well-characterized cation-transporting P-type ATPases, and it is unknown whether the flippases interact directly with the lipid and with counterions. Our results demonstrate that ATP8A2 forms a phosphoenzyme intermediate at the conserved aspartate (Asp(416)) in the P-type ATPase signature sequence and exists in E(1)P and E(2)P forms similar to the archetypical P-type ATPases. Using the properties of the phosphoenzyme, the partial reaction steps of the transport cycle were examined, and the roles of conserved residues Asp(196), Glu(198), Lys(873), and Asn(874) in the transport mechanism were elucidated. The former two residues in the A-domain T/D-G-E-S/T motif are involved in catalysis of E(2)P dephosphorylation, the glutamate being essential. Transported aminophospholipids activate the dephosphorylation similar to K(+) activation of dephosphorylation in Na(+),K(+)-ATPase. Lys(873) mutants (particularly K873A and K873E) display a markedly reduced sensitivity to aminophospholipids. Hence, Lys(873), located in transmembrane segment M5 at a "hot spot" for cation binding in Ca(2+)-ATPase and Na(+),K(+)-ATPase, appears to participate directly in aminophospholipid binding or to mediate a crucial interaction within the ATP8A2-CDC50 complex. By contrast, Lys(865) is unimportant for aminophospholipid sensitivity. Binding of Na(+), H(+), K(+), Cl(-), or Ca(2+) to the E(1) form as a counterion is not required for activation of phosphorylation from ATP. Therefore, phospholipids could be the only substrate transported by ATP8A2.
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25
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Young CL, Britton ZT, Robinson AS. Recombinant protein expression and purification: A comprehensive review of affinity tags and microbial applications. Biotechnol J 2012; 7:620-34. [DOI: 10.1002/biot.201100155] [Citation(s) in RCA: 312] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/23/2011] [Accepted: 11/29/2011] [Indexed: 12/27/2022]
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26
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Janz JM, Ren Y, Looby R, Kazmi MA, Sachdev P, Grunbeck A, Haggis L, Chinnapen D, Lin AY, Seibert C, McMurry T, Carlson KE, Muir TW, Hunt S, Sakmar TP. Direct interaction between an allosteric agonist pepducin and the chemokine receptor CXCR4. J Am Chem Soc 2011; 133:15878-81. [PMID: 21905700 DOI: 10.1021/ja206661w] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cell surface heptahelical G protein-coupled receptors (GPCRs) mediate critical cellular signaling pathways and are important pharmaceutical drug targets. (1) In addition to traditional small-molecule approaches, lipopeptide-based GPCR-derived pepducins have emerged as a new class of pharmaceutical agents. (2, 3) To better understand how pepducins interact with targeted receptors, we developed a cell-based photo-cross-linking approach to study the interaction between the pepducin agonist ATI-2341 and its target receptor, chemokine C-X-C-type receptor 4 (CXCR4). A pepducin analogue, ATI-2766, formed a specific UV-light-dependent cross-link to CXCR4 and to mutants with truncations of the N-terminus, the known chemokine docking site. These results demonstrate that CXCR4 is the direct binding target of ATI-2341 and suggest a new mechanism for allosteric modulation of GPCR activity. Adaptation and application of our findings should prove useful in further understanding pepducin modulation of GPCRs as well as enable new experimental approaches to better understand GPCR signal transduction.
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Affiliation(s)
- Jay M Janz
- Anchor Therapeutics, Cambridge, Massachusetts 02142, United States.
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27
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Jensen VL, Bialas NJ, Bishop-Hurley SL, Molday LL, Kida K, Nguyen PAT, Blacque OE, Molday RS, Leroux MR, Riddle DL. Localization of a guanylyl cyclase to chemosensory cilia requires the novel ciliary MYND domain protein DAF-25. PLoS Genet 2010; 6:e1001199. [PMID: 21124868 PMCID: PMC2991253 DOI: 10.1371/journal.pgen.1001199] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 10/07/2010] [Indexed: 11/19/2022] Open
Abstract
In harsh conditions, Caenorhabditis elegans arrests development to enter a non-aging, resistant diapause state called the dauer larva. Olfactory sensation modulates the TGF-β and insulin signaling pathways to control this developmental decision. Four mutant alleles of daf-25 (abnormal DAuer Formation) were isolated from screens for mutants exhibiting constitutive dauer formation and found to be defective in olfaction. The daf-25 dauer phenotype is suppressed by daf-10/IFT122 mutations (which disrupt ciliogenesis), but not by daf-6/PTCHD3 mutations (which prevent environmental exposure of sensory cilia), implying that DAF-25 functions in the cilia themselves. daf-25 encodes the C. elegans ortholog of mammalian Ankmy2, a MYND domain protein of unknown function. Disruption of DAF-25, which localizes to sensory cilia, produces no apparent cilia structure anomalies, as determined by light and electron microscopy. Hinting at its potential function, the dauer phenotype, epistatic order, and expression profile of daf-25 are similar to daf-11, which encodes a cilium-localized guanylyl cyclase. Indeed, we demonstrate that DAF-25 is required for proper DAF-11 ciliary localization. Furthermore, the functional interaction is evolutionarily conserved, as mouse Ankmy2 interacts with guanylyl cyclase GC1 from ciliary photoreceptors. The interaction may be specific because daf-25 mutants have normally-localized OSM-9/TRPV4, TAX-4/CNGA1, CHE-2/IFT80, CHE-11/IFT140, CHE-13/IFT57, BBS-8, OSM-5/IFT88, and XBX-1/D2LIC in the cilia. Intraflagellar transport (IFT) (required to build cilia) is not defective in daf-25 mutants, although the ciliary localization of DAF-25 itself is influenced in che-11 mutants, which are defective in retrograde IFT. In summary, we have discovered a novel ciliary protein that plays an important role in cGMP signaling by localizing a guanylyl cyclase to the sensory organelle.
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Affiliation(s)
- Victor L. Jensen
- Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Nathan J. Bialas
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Sharon L. Bishop-Hurley
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
- CSIRO-Livestock Industries, Queensland Biosciences Precinct, Brisbane, Australia
| | - Laurie L. Molday
- Centre for Macular Research, University of British Columbia, Vancouver, Canada
| | - Katarzyna Kida
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | | | - Oliver E. Blacque
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Robert S. Molday
- Centre for Macular Research, University of British Columbia, Vancouver, Canada
| | - Michel R. Leroux
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Donald L. Riddle
- Medical Genetics, University of British Columbia, Vancouver, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
- * E-mail:
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28
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Bonar P, Casey JR. Purification of functional human Cl(-)/HCO(3)(-) exchanger, AE1, over-expressed in Saccharomyces cerevisiae. Protein Expr Purif 2010; 74:106-15. [PMID: 20609390 DOI: 10.1016/j.pep.2010.06.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 01/29/2023]
Abstract
There is no high-resolution structure for the membrane domain of the human erythrocyte anion exchanger, AE1 (Band 3). In this report, we have developed an expression and purification strategy for AE1 to be used in crystallization trials. Saccharomyces cerevisiae strain BJ5457 was transformed with an expression vector encoding the AE1 membrane domain (AE1MD, amino acids 388-911), fused C-terminally to an epitope tag, corresponding to the nine C-terminal amino acids of rhodopsin. The fusion protein, AE1MD-Rho, was expressed at a concentration of 0.3 mg/l of culture. Confocal immunofluorescence microscopy and sucrose gradient ultracentrifugation revealed that AE1MD-Rho did not process to the plasma membrane of S. cerevisiae, but was retained in an intracellular membrane fraction. Treatment with the endoglycosidase, PNGase F, showed that AE1MD-Rho is not N-glycosylated. AE1MD-Rho solubilized from yeast membranes, with Fos-choline detergent, was purified to 93% homogeneity in a single-step, using a 1D4 antibody affinity resin, in amounts up to 2.5 mg from 18 l of culture. The ability of purified AE1MD-Rho to transport sulfate was examined in reconstituted vesicles. The rate of sulfate efflux mediated by vesicles reconstituted with AE1MD-Rho was indistinguishable from vesicles with purified erythrocyte-source AE1. Using this purification strategy, sufficient amounts of functional, homogeneous AE1MD-Rho can be purified to enable crystallization trials.
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Affiliation(s)
- Pamela Bonar
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada T6G 2H7
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29
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Komolov KE, Aguilà M, Toledo D, Manyosa J, Garriga P, Koch KW. On-chip photoactivation of heterologously expressed rhodopsin allows kinetic analysis of G-protein signaling by surface plasmon resonance spectroscopy. Anal Bioanal Chem 2010; 397:2967-76. [PMID: 20544180 DOI: 10.1007/s00216-010-3876-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/07/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022]
Abstract
Surface plasmon resonance spectroscopy allows the study of protein interaction dynamics in real-time. Application of this technique to G-protein coupled receptors, the largest family of receptors involved in signal transduction, has been complicated by their low level of expression and the critical dependence of their native conformation on the hydrophobic transmembrane lipid environment. Here, we investigate and compare three different strategies to immobilize rhodopsin, a prototypical G-protein coupled receptor on a sensor chip surface using antibodies and a lectin for receptor capturing. By further probing of different experimental conditions (pH, detergent type) we identified the optimal factors to maintain rhodopsin in a functional conformation and extended this approach to recombinant rhodopsin that was heterologously expressed in COS cells. Functional operation of rhodopsin on the sensor chip surface was proven by its activation and subsequent light-stimulated G-protein coupling. The influence of these experimental parameters on the association and dissociation kinetics of G-protein receptor coupling was determined. Thereby, we found that the kinetics of G(t) interaction were not changed by the strategy of immobilization or the type of detergent. Regeneration of opsin directly on a chip allowed recycling of the immobilized native and recombinant receptor. Thus, the approach provides an experimental framework for choosing the most suitable conditions for the solubilization, immobilization, and for functional tests of rhodopsin on a biosensor surface.
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Affiliation(s)
- Konstantin E Komolov
- Biochemistry group, Faculty V, IBU, University of Oldenburg, 26111 Oldenburg, Germany
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30
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Binding of retinoids to ABCA4, the photoreceptor ABC transporter associated with Stargardt macular degeneration. Methods Mol Biol 2010; 652:163-76. [PMID: 20552428 DOI: 10.1007/978-1-60327-325-1_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters, which has been implicated in the clearance of all-trans retinal derivatives from rod and cone photoreceptor cells following photoexcitation as part of the visual cycle. Mutations in ABCA4 are known to cause Stargardt macular degeneration and related disorders, associated with a severe loss in vision. Recently, a solid-phase binding assay has been developed to identify retinoids that likely serve as substrates for this transporter. In this procedure, monoclonal antibodies directed either against an epitope within ABCA4 (Rim 3F4 antibody) or against the 9 amino acid 1D4 epitope tag engineered onto the C-terminus of expressed ABCA4 (Rho 1D4 antibody) are covalently bound to a Sepharose matrix. This immunoaffinity matrix is then used to isolate ABCA4 from photoreceptor outer segments or transfected cells. All-trans retinal is added to immobilized ABCA4 in the presence of a phospholipid mixture containing phosphatidylethanolamine. The bound retinoid is then analyzed directly by spectrophotometry or identified by HPLC and/or mass spectrometry following extraction with organic solvents. Using this procedure, it has been shown that unprotonated N-retinylidene-phosphatidylethanolamine binds with high affinity to ABCA4 and is released by the addition of ATP. These procedures and related radiometric assays using titrated retinal have been used to study the binding of N-retinylidene-PE to wild-type and mutant ABCA4 in the absence and presence of nucleotides for structure-function studies.
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