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Chmelova K, Gao T, Polak M, Schenkmayerova A, Croll TI, Shaikh TR, Skarupova J, Chaloupkova R, Diederichs K, Read RJ, Damborsky J, Novacek J, Marek M. Multimeric structure of a subfamily III haloalkane dehalogenase-like enzyme solved by combination of cryo-EM and x-ray crystallography. Protein Sci 2023; 32:e4751. [PMID: 37574754 PMCID: PMC10503415 DOI: 10.1002/pro.4751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/25/2023] [Accepted: 08/08/2023] [Indexed: 08/15/2023]
Abstract
Haloalkane dehalogenase (HLD) enzymes employ an SN 2 nucleophilic substitution mechanism to erase halogen substituents in diverse organohalogen compounds. Subfamily I and II HLDs are well-characterized enzymes, but the mode and purpose of multimerization of subfamily III HLDs are unknown. Here we probe the structural organization of DhmeA, a subfamily III HLD-like enzyme from the archaeon Haloferax mediterranei, by combining cryo-electron microscopy (cryo-EM) and x-ray crystallography. We show that full-length wild-type DhmeA forms diverse quaternary structures, ranging from small oligomers to large supramolecular ring-like assemblies of various sizes and symmetries. We optimized sample preparation steps, enabling three-dimensional reconstructions of an oligomeric species by single-particle cryo-EM. Moreover, we engineered a crystallizable mutant (DhmeAΔGG ) that provided diffraction-quality crystals. The 3.3 Å crystal structure reveals that DhmeAΔGG forms a ring-like 20-mer structure with outer and inner diameter of ~200 and ~80 Å, respectively. An enzyme homodimer represents a basic repeating building unit of the crystallographic ring. Three assembly interfaces (dimerization, tetramerization, and multimerization) were identified to form the supramolecular ring that displays a negatively charged exterior, while its interior part harboring catalytic sites is positively charged. Localization and exposure of catalytic machineries suggest a possible processing of large negatively charged macromolecular substrates.
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Affiliation(s)
- Klaudia Chmelova
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
| | - Tadeja Gao
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
| | - Martin Polak
- Central European Institute of TechnologyMasaryk UniversityBrnoCzech Republic
| | - Andrea Schenkmayerova
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
| | - Tristan I. Croll
- Department of Hematology, Cambridge Institute for Medical ResearchUniversity of CambridgeCambridgeUK
| | - Tanvir R. Shaikh
- Central European Institute of TechnologyMasaryk UniversityBrnoCzech Republic
- Institute of NeuropathologyUniversity Medical Center GöttingenGöttingenGermany
| | - Jana Skarupova
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
| | - Radka Chaloupkova
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
| | - Kay Diederichs
- Department of BiologyUniversity of KonstanzKonstanzGermany
| | - Randy J. Read
- Department of Hematology, Cambridge Institute for Medical ResearchUniversity of CambridgeCambridgeUK
| | - Jiri Damborsky
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
| | - Jiri Novacek
- Central European Institute of TechnologyMasaryk UniversityBrnoCzech Republic
| | - Martin Marek
- Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of ScienceMasaryk UniversityBrnoCzech Republic
- International Clinical Research CenterSt. Anne's University Hospital BrnoBrnoCzech Republic
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2
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Hunkler S, Diederichs K, Kukharenko O, Peter C. Fast conformational clustering of extensive molecular dynamics simulation data. J Chem Phys 2023; 158:144109. [PMID: 37061476 DOI: 10.1063/5.0142797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
We present an unsupervised data processing workflow that is specifically designed to obtain a fast conformational clustering of long molecular dynamics simulation trajectories. In this approach, we combine two dimensionality reduction algorithms (cc_analysis and encodermap) with a density-based spatial clustering algorithm (hierarchical density-based spatial clustering of applications with noise). The proposed scheme benefits from the strengths of the three algorithms while avoiding most of the drawbacks of the individual methods. Here, the cc_analysis algorithm is applied for the first time to molecular simulation data. The encodermap algorithm complements cc_analysis by providing an efficient way to process and assign large amounts of data to clusters. The main goal of the procedure is to maximize the number of assigned frames of a given trajectory while keeping a clear conformational identity of the clusters that are found. In practice, we achieve this by using an iterative clustering approach and a tunable root-mean-square-deviation-based criterion in the final cluster assignment. This allows us to find clusters of different densities and different degrees of structural identity. With the help of four protein systems, we illustrate the capability and performance of this clustering workflow: wild-type and thermostable mutant of the Trp-cage protein (TC5b and TC10b), NTL9, and Protein B. Each of these test systems poses their individual challenges to the scheme, which, in total, give a nice overview of the advantages and potential difficulties that can arise when using the proposed method.
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Affiliation(s)
- Simon Hunkler
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | - Kay Diederichs
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | | | - Christine Peter
- Department of Chemistry, University of Konstanz, Konstanz, Germany
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3
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Martynowycz MW, Shiriaeva A, Clabbers MTB, Nicolas WJ, Weaver SJ, Hattne J, Gonen T. A robust approach for MicroED sample preparation of lipidic cubic phase embedded membrane protein crystals. Nat Commun 2023; 14:1086. [PMID: 36841804 PMCID: PMC9968316 DOI: 10.1038/s41467-023-36733-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/15/2023] [Indexed: 02/26/2023] Open
Abstract
Crystallizing G protein-coupled receptors (GPCRs) in lipidic cubic phase (LCP) often yields crystals suited for the cryogenic electron microscopy (cryoEM) method microcrystal electron diffraction (MicroED). However, sample preparation is challenging. Embedded crystals cannot be targeted topologically. Here, we use an integrated fluorescence light microscope (iFLM) inside of a focused ion beam and scanning electron microscope (FIB-SEM) to identify fluorescently labeled GPCR crystals. Crystals are targeted using the iFLM and LCP is milled using a plasma focused ion beam (pFIB). The optimal ion source for preparing biological lamellae is identified using standard crystals of proteinase K. Lamellae prepared using either argon or xenon produced the highest quality data and structures. MicroED data are collected from the milled lamellae and the structures are determined. This study outlines a robust approach to identify and mill membrane protein crystals for MicroED and demonstrates plasma ion-beam milling is a powerful tool for preparing biological lamellae.
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Affiliation(s)
- Michael W Martynowycz
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Anna Shiriaeva
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Max T B Clabbers
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - William J Nicolas
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Sara J Weaver
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Johan Hattne
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA. .,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA. .,Department of Physiology, University of California, Los Angeles, CA, 90095, USA.
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4
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Latonduine-1-Amino-Hydantoin Hybrid, Triazole-Fused Latonduine Schiff Bases and Their Metal Complexes: Synthesis, X-ray and Electron Diffraction, Molecular Docking Studies and Antiproliferative Activity. INORGANICS 2023. [DOI: 10.3390/inorganics11010030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A series of latonduine derivatives, namely 11-nitro-indolo[2,3-d]benzazepine-7-(1-amino-hydantoin) (B), triazole-fused indolo[2,3-d]benzazepine-based Schiff bases HL1 and HL2 and metal complexes [M(p-cymene)(HL1)Cl]Cl, where M = Ru (1), Os (2), and [Cu(HL2)Cl2] (3) were synthesized and characterized by spectroscopic techniques (UV–vis, 1H, 13C, 15N–1H HSQC NMR) and ESI mass spectrometry. The molecular structures of B and HL1 were confirmed by single-crystal X-ray diffraction, while that of 3 by electron diffraction of nanometer size crystalline sample. Molecular docking calculations of species B in the binding pocket of PIM-1 enzyme revealed that the 1-amino-hydantoin moiety is not involved in any hydrogen-bonding interactions, even though a good accommodation of the host molecule in the ATP binding pocket of the enzyme was found. The antiproliferative activity of organic compounds B, HL1 and HL2, as well as complexes 1–3 was investigated in lung adenocarcinoma A549, colon adenocarcinoma LS-174 and triple-negative breast adenocarcinoma MDA-MB-231 cells and normal human lung fibroblast cells MRC-5 by MTT assays; then, the results are discussed.
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5
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Schneps CM, Ganguly A, Crane BR. Room-temperature serial synchrotron crystallography of Drosophila cryptochrome. Acta Crystallogr D Struct Biol 2022; 78:975-985. [PMID: 35916222 PMCID: PMC9344480 DOI: 10.1107/s2059798322007008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/08/2022] [Indexed: 11/10/2022] Open
Abstract
Fixed-target serial crystallography allows the high-throughput collection of diffraction data from small crystals at room temperature. This methodology is particularly useful for difficult samples that have sensitivity to radiation damage or intolerance to cryoprotection measures; fixed-target methods also have the added benefit of low sample consumption. Here, this method is applied to the structure determination of the circadian photoreceptor cryptochrome (CRY), previous structures of which have been determined at cryogenic temperature. In determining the structure, several data-filtering strategies were tested for combining observations from the hundreds of crystals that contributed to the final data set. Removing data sets based on the average correlation coefficient among equivalent reflection intensities between a given data set and all others was most effective at improving the data quality and maintaining overall completeness. CRYs are light sensors that undergo conformational photoactivation. Comparisons between the cryogenic and room-temperature CRY structures reveal regions of enhanced mobility at room temperature in loops that have functional importance within the CRY family of proteins. The B factors of the room-temperature structure correlate well with those predicted from molecular-dynamics simulations.
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6
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Foos N, Rizk M, Nanao MH. Single-support serial isomorphous replacement phasing. Acta Crystallogr D Struct Biol 2022; 78:716-724. [PMID: 35647919 PMCID: PMC9159287 DOI: 10.1107/s2059798322003977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 04/11/2022] [Indexed: 11/11/2022] Open
Abstract
A simple method for serial single isomorphous replacement, which exploits natural differences in heavy-atom occupancy, is presented. The use of single isomorphous replacement (SIR) has become less widespread due to difficulties in sample preparation and the identification of isomorphous native and derivative data sets. Non-isomorphism becomes even more problematic in serial experiments, because it adds natural inter-crystal non-isomorphism to heavy-atom-soaking-induced non-isomorphism. Here, a method that can successfully address these issues (and indeed can benefit from differences in heavy-atom occupancy) and additionally significantly simplifies the SIR experiment is presented. A single heavy-atom soak into a microcrystalline slurry is performed, followed by automated serial data collection of partial data sets. This produces a set of data collections with a gradient of heavy-atom occupancies, which are reflected in differential merging statistics. These differences can be exploited by an optimized genetic algorithm to segregate the pool of data sets into ‘native’ and ‘derivative’ groups, which can then be used to successfully determine phases experimentally by SIR.
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Healey RD, Basu S, Humm AS, Leyrat C, Cong X, Golebiowski J, Dupeux F, Pica A, Granier S, Márquez JA. An automated platform for structural analysis of membrane proteins through serial crystallography. CELL REPORTS METHODS 2021; 1:None. [PMID: 34723237 PMCID: PMC8545655 DOI: 10.1016/j.crmeth.2021.100102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/07/2021] [Accepted: 09/22/2021] [Indexed: 11/01/2022]
Abstract
Membrane proteins are central to many pathophysiological processes, yet remain very difficult to analyze structurally. Moreover, high-throughput structure-based drug discovery has not yet been exploited for membrane proteins because of lack of automation. Here, we present a facile and versatile platform for in meso membrane protein crystallization, enabling rapid atomic structure determination at both cryogenic and room temperatures. We apply this approach to human integral membrane proteins, which allowed us to identify different conformational states of intramembrane enzyme-product complexes and analyze by molecular dynamics simulations the structural dynamics of the ADIPOR2 integral membrane protein. Finally, we demonstrate an automated pipeline combining high-throughput microcrystal soaking, automated laser-based harvesting, and serial crystallography, enabling screening of small-molecule libraries with membrane protein crystals grown in meso. This approach brings needed automation to this important class of drug targets and enables high-throughput structure-based ligand discovery with membrane proteins.
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Affiliation(s)
- Robert D. Healey
- IGF, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Shibom Basu
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Anne-Sophie Humm
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Cedric Leyrat
- IGF, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Xiaojing Cong
- IGF, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Jérôme Golebiowski
- Institute of Chemistry of Nice UMR7272, Université Côte d’Azur, CNRS, 28 Avenue Valrose, 06108 Nice, France
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Technology, 711-873 Daegu, South Korea
| | - Florine Dupeux
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France
- Institut de Biologie Structurale, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Andrea Pica
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France
- ALPX S.A.S. 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Sébastien Granier
- IGF, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - José Antonio Márquez
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France
- ALPX S.A.S. 71 Avenue des Martyrs, 38000 Grenoble, France
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8
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Baba S, Matsuura H, Kawamura T, Sakai N, Nakamura Y, Kawano Y, Mizuno N, Kumasaka T, Yamamoto M, Hirata K. Guidelines for de novo phasing using multiple small-wedge data collection. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:1284-1295. [PMID: 34475278 PMCID: PMC8415328 DOI: 10.1107/s1600577521008067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 08/05/2021] [Indexed: 05/30/2023]
Abstract
Intense micro-focus X-ray beamlines available at synchrotron facilities have achieved high-quality data collection even from the microcrystals of membrane proteins. The automatic data collection system developed at SPring-8, named ZOO, has contributed to many structure determinations of membrane proteins using small-wedge synchrotron crystallography (SWSX) datasets. The `small-wedge' (5-20°) datasets are collected from multiple crystals and then merged to obtain the final structure factors. To our knowledge, no systematic investigation on the dose dependence of data accuracy has so far been reported for SWSX, which is between `serial crystallography' and `rotation crystallography'. Thus, herein, we investigated the optimal dose conditions for experimental phasing with SWSX. Phase determination using anomalous scattering signals was found to be more difficult at higher doses. Furthermore, merging more homogeneous datasets grouped by hierarchical clustering with controlled doses mildly reduced the negative factors in data collection, such as `lack of signal' and `radiation damage'. In turn, as more datasets were merged, more probable phases could be obtained across a wider range of doses. Therefore, our findings show that it is essential to choose a lower dose than 10 MGy for de novo structure determination by SWSX. In particular, data collection using a dose of 5 MGy proved to be optimal in balancing the amount of signal available while reducing the amount of damage as much as possible.
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Affiliation(s)
- Seiki Baba
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Hiroaki Matsuura
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-Cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Takashi Kawamura
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Naoki Sakai
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-Cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Yuki Nakamura
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Yoshiaki Kawano
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-Cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Nobuhiro Mizuno
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Takashi Kumasaka
- Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Masaki Yamamoto
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-Cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kunio Hirata
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-Cho, Sayo-gun, Hyogo 679-5148, Japan
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9
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Agonists and allosteric modulators promote signaling from different metabotropic glutamate receptor 5 conformations. Cell Rep 2021; 36:109648. [PMID: 34469715 PMCID: PMC8424648 DOI: 10.1016/j.celrep.2021.109648] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/08/2021] [Accepted: 08/11/2021] [Indexed: 11/20/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are dimeric G-protein-coupled receptors activated by the main excitatory neurotransmitter, L-glutamate. mGluR activation by agonists binding in the venus flytrap domain is regulated by positive (PAM) or negative (NAM) allosteric modulators binding to the 7-transmembrane domain (7TM). We report the cryo-electron microscopy structures of fully inactive and intermediate-active conformations of mGlu5 receptor bound to an antagonist and a NAM or an agonist and a PAM, respectively, as well as the crystal structure of the 7TM bound to a photoswitchable NAM. The agonist induces a large movement between the subunits, bringing the 7TMs together and stabilizing a 7TM conformation structurally similar to the inactive state. Using functional approaches, we demonstrate that the PAM stabilizes a 7TM active conformation independent of the conformational changes induced by agonists, representing an alternative mode of mGlu activation. These findings provide a structural basis for different mGluR activation modes. Cryo-EM analysis of thermostabilized mGlu5 receptor bound to inhibitors or activators X-ray structure of trans-Alloswitch-1 bound to thermostable mGlu5 7TMs Photopharmacology provides insight into allosteric regulation of mGlu5 7TMs Multiple conformations of mGlu5 receptor activate G protein
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10
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Guimarães BG, Golinelli-Pimpaneau B. De novo crystal structure determination of double stranded RNA binding domain using only the sulfur anomalous diffraction in SAD phasing. Curr Res Struct Biol 2021; 3:112-120. [PMID: 34235491 PMCID: PMC8244422 DOI: 10.1016/j.crstbi.2021.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 10/25/2022] Open
Abstract
Single-wavelength anomalous dispersion (SAD)-phasing using sulfur as the unique anomalous scatterer is a powerful method to solve the phase problem in protein crystallography. However, it is not yet widely used by non-expert crystallographers. We report here the structure determination of the double stranded RNA binding domain of human dihydrouridine synthase using the sulfur-SAD method and highly redundant data collected at 1.8 Å ("off-edge"), at which the estimated overall anomalous signal was 1.08%. High multiplicity data were collected on a single crystal rotated along the ϕ or ω axis at different κ angles, with the primary beam intensity being attenuated from 50% to 95%, compared to data collection at 0.98 Å, to reduce radiation damage. SHELXD succeeded to locate 14 out 15 sulfur sites only using the data sets recorded with highest beam attenuation, which provided phases sufficient for structure solving. In an attempt to stimulate the use of sulfur-SAD phasing by a broader community of crystallographers, we describe our experimental strategy together with a compilation of previous successful cases, suggesting that sulfur-SAD phasing should be attempted for determining the de novo structure of any protein with average sulfur content diffracting better than 3 Å resolution.
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Affiliation(s)
| | - Béatrice Golinelli-Pimpaneau
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
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11
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Li H, Huang CY, Govorunova EG, Sineshchekov OA, Yi A, Rothschild KJ, Wang M, Zheng L, Spudich JL. The crystal structure of bromide-bound GtACR1 reveals a pre-activated state in the transmembrane anion tunnel. eLife 2021; 10:65903. [PMID: 33998458 PMCID: PMC8172240 DOI: 10.7554/elife.65903] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 05/16/2021] [Indexed: 12/16/2022] Open
Abstract
The crystal structure of the light-gated anion channel GtACR1 reported in our previous Research Article (Li et al., 2019) revealed a continuous tunnel traversing the protein from extracellular to intracellular pores. We proposed the tunnel as the conductance channel closed by three constrictions: C1 in the extracellular half, mid-membrane C2 containing the photoactive site, and C3 on the cytoplasmic side. Reported here, the crystal structure of bromide-bound GtACR1 reveals structural changes that relax the C1 and C3 constrictions, including a novel salt-bridge switch mechanism involving C1 and the photoactive site. These findings indicate that substrate binding induces a transition from an inactivated state to a pre-activated state in the dark that facilitates channel opening by reducing free energy in the tunnel constrictions. The results provide direct evidence that the tunnel is the closed form of the channel of GtACR1 and shed light on the light-gated channel activation mechanism.
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Affiliation(s)
- Hai Li
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center - McGovern Medical School, Houston, United States
| | - Chia-Ying Huang
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Elena G Govorunova
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center - McGovern Medical School, Houston, United States
| | - Oleg A Sineshchekov
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center - McGovern Medical School, Houston, United States
| | - Adrian Yi
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, United States
| | - Kenneth J Rothschild
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, United States
| | - Meitian Wang
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Lei Zheng
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center - McGovern Medical School, Houston, United States
| | - John L Spudich
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center - McGovern Medical School, Houston, United States
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