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Structural insights into the regulation of human serine palmitoyltransferase complexes. Nat Struct Mol Biol 2021; 28:240-248. [PMID: 33558761 PMCID: PMC9812531 DOI: 10.1038/s41594-020-00551-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/16/2020] [Indexed: 01/31/2023]
Abstract
Sphingolipids are essential lipids in eukaryotic membranes. In humans, the first and rate-limiting step of sphingolipid synthesis is catalyzed by the serine palmitoyltransferase holocomplex, which consists of catalytic components (SPTLC1 and SPTLC2) and regulatory components (ssSPTa and ORMDL3). However, the assembly, substrate processing and regulation of the complex are unclear. Here, we present 8 cryo-electron microscopy structures of the human serine palmitoyltransferase holocomplex in various functional states at resolutions of 2.6-3.4 Å. The structures reveal not only how catalytic components recognize the substrate, but also how regulatory components modulate the substrate-binding tunnel to control enzyme activity: ssSPTa engages SPTLC2 and shapes the tunnel to determine substrate specificity. ORMDL3 blocks the tunnel and competes with substrate binding through its amino terminus. These findings provide mechanistic insights into sphingolipid biogenesis governed by the serine palmitoyltransferase complex.
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102
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Gilbert RJC. Electron microscopy as a critical tool in the determination of pore forming mechanisms in proteins. Methods Enzymol 2021; 649:71-102. [PMID: 33712203 DOI: 10.1016/bs.mie.2021.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electron microscopy has consistently played an important role in the description of pore-forming protein systems. The discovery of pore-forming proteins has depended on visualization of the structural pores formed by their oligomeric protein complexes, and as electron microscopy has advanced technologically so has the degree of insight it has been able to give. This review considers a large number of published studies of pore-forming complexes in prepore and pore states determined using single-particle cryo-electron microscopy. Sample isolation and preparation, imaging and image analysis, structure determination and optimization of results are all discussed alongside challenges which pore-forming proteins particularly present. The review also considers the use made of cryo-electron tomography to study pores within their membrane environment and which will prove an increasingly important approach for the future.
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Affiliation(s)
- Robert J C Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
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103
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Beckers M, Mann D, Sachse C. Structural interpretation of cryo-EM image reconstructions. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 160:26-36. [PMID: 32735944 DOI: 10.1016/j.pbiomolbio.2020.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/03/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
The productivity of single-particle cryo-EM as a structure determination method has rapidly increased as many novel biological structures are being elucidated. The ultimate result of the cryo-EM experiment is an atomic model that should faithfully represent the computed image reconstruction. Although the principal approach of atomic model building and refinement from maps resembles that of the X-ray crystallographic methods, there are important differences due to the unique properties resulting from the 3D image reconstructions. In this review, we discuss the practiced work-flow from the cryo-EM image reconstruction to the atomic model. We give an overview of (i) resolution determination methods in cryo-EM including local and directional resolution variation, (ii) cryo-EM map contrast optimization including complementary map types that can help in identifying ambiguous density features, (iii) atomic model building and (iv) refinement in various resolution regimes including (v) their validation and (vi) discuss differences between X-ray and cryo-EM maps. Based on the methods originally developed for X-ray crystallography, the path from 3D image reconstruction to atomic coordinates has become an integral and important part of the cryo-EM structure determination work-flow that routinely delivers atomic models.
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Affiliation(s)
- Maximilian Beckers
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117, Heidelberg, Germany; Candidate for Joint PhD Degree from EMBL and Heidelberg University, Faculty of Biosciences, Germany; Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Daniel Mann
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Carsten Sachse
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany; Chemistry Department, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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104
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Balestrini A, Joseph V, Dourado M, Reese RM, Shields SD, Rougé L, Bravo DD, Chernov-Rogan T, Austin CD, Chen H, Wang L, Villemure E, Shore DGM, Verma VA, Hu B, Chen Y, Leong L, Bjornson C, Hötzel K, Gogineni A, Lee WP, Suto E, Wu X, Liu J, Zhang J, Gandham V, Wang J, Payandeh J, Ciferri C, Estevez A, Arthur CP, Kortmann J, Wong RL, Heredia JE, Doerr J, Jung M, Vander Heiden JA, Roose-Girma M, Tam L, Barck KH, Carano RAD, Ding HT, Brillantes B, Tam C, Yang X, Gao SS, Ly JQ, Liu L, Chen L, Liederer BM, Lin JH, Magnuson S, Chen J, Hackos DH, Elstrott J, Rohou A, Safina BS, Volgraf M, Bauer RN, Riol-Blanco L. A TRPA1 inhibitor suppresses neurogenic inflammation and airway contraction for asthma treatment. J Exp Med 2021; 218:211821. [PMID: 33620419 PMCID: PMC7918756 DOI: 10.1084/jem.20201637] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/19/2020] [Accepted: 12/23/2020] [Indexed: 12/31/2022] Open
Abstract
Despite the development of effective therapies, a substantial proportion of asthmatics continue to have uncontrolled symptoms, airflow limitation, and exacerbations. Transient receptor potential cation channel member A1 (TRPA1) agonists are elevated in human asthmatic airways, and in rodents, TRPA1 is involved in the induction of airway inflammation and hyperreactivity. Here, the discovery and early clinical development of GDC-0334, a highly potent, selective, and orally bioavailable TRPA1 antagonist, is described. GDC-0334 inhibited TRPA1 function on airway smooth muscle and sensory neurons, decreasing edema, dermal blood flow (DBF), cough, and allergic airway inflammation in several preclinical species. In a healthy volunteer Phase 1 study, treatment with GDC-0334 reduced TRPA1 agonist-induced DBF, pain, and itch, demonstrating GDC-0334 target engagement in humans. These data provide therapeutic rationale for evaluating TRPA1 inhibition as a clinical therapy for asthma.
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Affiliation(s)
- Alessia Balestrini
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Victory Joseph
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Michelle Dourado
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Rebecca M Reese
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Shannon D Shields
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Lionel Rougé
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Daniel D Bravo
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Tania Chernov-Rogan
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Cary D Austin
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Huifen Chen
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Lan Wang
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Elisia Villemure
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Daniel G M Shore
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Vishal A Verma
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Baihua Hu
- Pharmaron-Beijing Co. Ltd., BDA, Beijing, People's Republic of China
| | - Yong Chen
- Pharmaron-Beijing Co. Ltd., BDA, Beijing, People's Republic of China
| | - Laurie Leong
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Chris Bjornson
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Kathy Hötzel
- Department of Pathology, Genentech, Inc., South San Francisco, CA
| | - Alvin Gogineni
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Wyne P Lee
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Eric Suto
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Xiumin Wu
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - John Liu
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Juan Zhang
- Department of Translational Immunology, Genentech, Inc., South San Francisco, CA
| | - Vineela Gandham
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Jianyong Wang
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Claudio Ciferri
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Alberto Estevez
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | | | - Jens Kortmann
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Ryan L Wong
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Jose E Heredia
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
| | - Jonas Doerr
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Min Jung
- Department of OMNI Bioinformatics, Genentech, Inc., South San Francisco, CA
| | | | - Merone Roose-Girma
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Lucinda Tam
- Department of Molecular Biology, Genentech, Inc., South San Francisco, CA
| | - Kai H Barck
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Richard A D Carano
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Han Ting Ding
- Department of Clinical Pharmacology, Genentech, Inc., South San Francisco, CA
| | - Bobby Brillantes
- Department of Biomolecular Resources, Genentech, Inc., South San Francisco, CA
| | - Christine Tam
- Department of Biomolecular Resources, Genentech, Inc., South San Francisco, CA
| | - Xiaoying Yang
- Department of Product Development Biometric Biostatistics, Genentech, Inc., South San Francisco, CA
| | - Simon S Gao
- Department of Clinical Imaging, Genentech, Inc., South San Francisco, CA
| | - Justin Q Ly
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Liling Liu
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Liuxi Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Bianca M Liederer
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA
| | - Joseph H Lin
- Department of Early Clinical Development, Genentech, Inc., South San Francisco, CA
| | - Steven Magnuson
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Jun Chen
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA
| | - David H Hackos
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA
| | - Justin Elstrott
- Department of Biomedical Imaging, Genentech, Inc., South San Francisco, CA
| | - Alexis Rohou
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA
| | - Brian S Safina
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Matthew Volgraf
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA
| | - Rebecca N Bauer
- Department of OMNI-Biomarker Development, Genentech, Inc., South San Francisco, CA
| | - Lorena Riol-Blanco
- Department of Immunology Discovery, Genentech, Inc., South San Francisco, CA
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105
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Kschonsak M, Rougé L, Arthur CP, Hoangdung H, Patel N, Kim I, Johnson MC, Kraft E, Rohou AL, Gill A, Martinez-Martin N, Payandeh J, Ciferri C. Structures of HCMV Trimer reveal the basis for receptor recognition and cell entry. Cell 2021; 184:1232-1244.e16. [PMID: 33626330 DOI: 10.1016/j.cell.2021.01.036] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/10/2021] [Accepted: 01/21/2021] [Indexed: 01/19/2023]
Abstract
Human cytomegalovirus (HCMV) infects the majority of the human population and represents the leading viral cause of congenital birth defects. HCMV utilizes the glycoproteins gHgLgO (Trimer) to bind to platelet-derived growth factor receptor alpha (PDGFRα) and transforming growth factor beta receptor 3 (TGFβR3) to gain entry into multiple cell types. This complex is targeted by potent neutralizing antibodies and represents an important candidate for therapeutics against HCMV. Here, we determine three cryogenic electron microscopy (cryo-EM) structures of the trimer and the details of its interactions with four binding partners: the receptor proteins PDGFRα and TGFβR3 as well as two broadly neutralizing antibodies. Trimer binding to PDGFRα and TGFβR3 is mutually exclusive, suggesting that they function as independent entry receptors. In addition, Trimer-PDGFRα interaction has an inhibitory effect on PDGFRα signaling. Our results provide a framework for understanding HCMV receptor engagement, neutralization, and the development of anti-viral strategies against HCMV.
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Affiliation(s)
- Marc Kschonsak
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA.
| | - Lionel Rougé
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA
| | | | - Ho Hoangdung
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA
| | - Nidhi Patel
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA
| | - Ingrid Kim
- Department of Antibody Engineering, Genentech, South San Francisco, CA 94080, USA
| | - Matthew C Johnson
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA
| | - Edward Kraft
- Department of BioMolecular Resources, Genentech, South San Francisco, CA 94080, USA
| | - Alexis L Rohou
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA
| | - Avinash Gill
- Department of Antibody Engineering, Genentech, South San Francisco, CA 94080, USA
| | - Nadia Martinez-Martin
- Department of Microchemistry, Proteomics and Lipidomics Department, Genentech, South San Francisco, CA 94080, USA.
| | - Jian Payandeh
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA; Department of Antibody Engineering, Genentech, South San Francisco, CA 94080, USA.
| | - Claudio Ciferri
- Department of Structural Biology, Genentech, South San Francisco, CA 94080, USA.
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106
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Wrobel AG, Benton DJ, Xu P, Calder LJ, Borg A, Roustan C, Martin SR, Rosenthal PB, Skehel JJ, Gamblin SJ. Structure and binding properties of Pangolin-CoV spike glycoprotein inform the evolution of SARS-CoV-2. Nat Commun 2021; 12:837. [PMID: 33547281 PMCID: PMC7864994 DOI: 10.1038/s41467-021-21006-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 01/04/2021] [Indexed: 01/07/2023] Open
Abstract
Coronaviruses of bats and pangolins have been implicated in the origin and evolution of the pandemic SARS-CoV-2. We show that spikes from Guangdong Pangolin-CoVs, closely related to SARS-CoV-2, bind strongly to human and pangolin ACE2 receptors. We also report the cryo-EM structure of a Pangolin-CoV spike protein and show it adopts a fully-closed conformation and that, aside from the Receptor-Binding Domain, it resembles the spike of a bat coronavirus RaTG13 more than that of SARS-CoV-2.
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Affiliation(s)
- Antoni G Wrobel
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK.
| | - Donald J Benton
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK.
| | - Pengqi Xu
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK
- Precision Medicine Center, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Lesley J Calder
- Structural Biology of Cells and Viruses Laboratory, Francis Crick Institute, NW1 1AT, London, UK
| | - Annabel Borg
- Structural Biology Science Technology Platform, Francis Crick Institute, NW1 1AT, London, UK
| | - Chloë Roustan
- Structural Biology Science Technology Platform, Francis Crick Institute, NW1 1AT, London, UK
| | - Stephen R Martin
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, Francis Crick Institute, NW1 1AT, London, UK
| | - John J Skehel
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK
| | - Steven J Gamblin
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, NW1 1AT, London, UK.
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107
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Multi-particle cryo-EM refinement with M visualizes ribosome-antibiotic complex at 3.5 Å in cells. Nat Methods 2021; 18:186-193. [PMID: 33542511 PMCID: PMC7611018 DOI: 10.1038/s41592-020-01054-7] [Citation(s) in RCA: 237] [Impact Index Per Article: 79.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 12/22/2020] [Indexed: 01/30/2023]
Abstract
Cryo-electron microscopy (cryo-EM) enables macromolecular structure determination in vitro and inside cells. In addition to aligning individual particles, accurate registration of sample motion and three-dimensional deformation during exposures are crucial for achieving high-resolution reconstructions. Here we describe M, a software tool that establishes a reference-based, multi-particle refinement framework for cryo-EM data and couples a comprehensive spatial deformation model to in silico correction of electron-optical aberrations. M provides a unified optimization framework for both frame-series and tomographic tilt-series data. We show that tilt-series data can provide the same resolution as frame-series data on a purified protein specimen, indicating that the alignment step no longer limits the resolution obtainable from tomographic data. In combination with Warp and RELION, M resolves to residue level a 70S ribosome bound to an antibiotic inside intact bacterial cells. Our work provides a computational tool that facilitates structural biology in cells.
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108
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Kang JY, Llewellyn E, Chen J, Olinares PDB, Brewer J, Chait BT, Campbell EA, Darst SA. Structural basis for transcription complex disruption by the Mfd translocase. eLife 2021; 10:62117. [PMID: 33480355 PMCID: PMC7864632 DOI: 10.7554/elife.62117] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 01/21/2021] [Indexed: 12/30/2022] Open
Abstract
Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) that preferentially removes lesions from the template-strand (t-strand) that stall RNA polymerase (RNAP) elongation complexes (ECs). Mfd mediates TCR in bacteria by removing the stalled RNAP concealing the lesion and recruiting Uvr(A)BC. We used cryo-electron microscopy to visualize Mfd engaging with a stalled EC and attempting to dislodge the RNAP. We visualized seven distinct Mfd-EC complexes in both ATP and ADP-bound states. The structures explain how Mfd is remodeled from its repressed conformation, how the UvrA-interacting surface of Mfd is hidden during most of the remodeling process to prevent premature engagement with the NER pathway, how Mfd alters the RNAP conformation to facilitate disassembly, and how Mfd forms a processive translocation complex after dislodging the RNAP. Our results reveal an elaborate mechanism for how Mfd kinetically discriminates paused from stalled ECs and disassembles stalled ECs to initiate TCR.
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Affiliation(s)
- Jin Young Kang
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
| | - Eliza Llewellyn
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
| | - James Chen
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
| | - Paul Dominic B Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States
| | - Joshua Brewer
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
| | - Seth A Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, United States
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109
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Rangarajan ES, Izard T. The Cryogenic Electron Microscopy Structure of the Cell Adhesion Regulator Metavinculin Reveals an Isoform-Specific Kinked Helix in Its Cytoskeleton Binding Domain. Int J Mol Sci 2021; 22:E645. [PMID: 33440717 PMCID: PMC7827843 DOI: 10.3390/ijms22020645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 11/16/2022] Open
Abstract
Vinculin and its heart-specific splice variant metavinculin are key regulators of cell adhesion processes. These membrane-bound cytoskeletal proteins regulate the cell shape by binding to several other proteins at cell-cell and cell-matrix junctions. Vinculin and metavinculin link integrin adhesion molecules to the filamentous actin network. Loss of both proteins prevents cell adhesion and cell spreading and reduces the formation of stress fibers, focal adhesions, or lamellipodia extensions. The binding of talin at cell-matrix junctions or of α-catenin at cell-cell junctions activates vinculin and metavinculin by releasing their autoinhibitory head-tail interaction. Once activated, vinculin and metavinculin bind F-actin via their five-helix bundle tail domains. Unlike vinculin, metavinculin has a 68-amino-acid insertion before the second α-helix of this five-helix F-actin-binding domain. Here, we present the full-length cryogenic electron microscopy structure of metavinculin that captures the dynamics of its individual domains and unveiled a hallmark structural feature, namely a kinked isoform-specific α-helix in its F-actin-binding domain. Our identified conformational landscape of metavinculin suggests a structural priming mechanism that is consistent with the cell adhesion functions of metavinculin in response to mechanical and cellular cues. Our findings expand our understanding of metavinculin function in the heart with implications for the etiologies of cardiomyopathies.
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Affiliation(s)
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL 33458, USA;
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110
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Ramírez-Aportela E, Maluenda D, Fonseca YC, Conesa P, Marabini R, Heymann JB, Carazo JM, Sorzano COS. FSC-Q: a CryoEM map-to-atomic model quality validation based on the local Fourier shell correlation. Nat Commun 2021; 12:42. [PMID: 33397925 PMCID: PMC7782520 DOI: 10.1038/s41467-020-20295-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 11/23/2020] [Indexed: 12/17/2022] Open
Abstract
In recent years, advances in cryoEM have dramatically increased the resolution of reconstructions and, with it, the number of solved atomic models. It is widely accepted that the quality of cryoEM maps varies locally; therefore, the evaluation of the maps-derived structural models must be done locally as well. In this article, a method for the local analysis of the map-to-model fit is presented. The algorithm uses a comparison of two local resolution maps. The first is the local FSC (Fourier shell correlation) between the full map and the model, while the second is calculated between the half maps normally used in typical single particle analysis workflows. We call the quality measure "FSC-Q", and it is a quantitative estimation of how much of the model is supported by the signal content of the map. Furthermore, we show that FSC-Q may be helpful to detect overfitting. It can be used to complement other methods, such as the Q-score method that estimates the resolvability of atoms.
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Affiliation(s)
- Erney Ramírez-Aportela
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
| | - David Maluenda
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Yunior C Fonseca
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Pablo Conesa
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Roberto Marabini
- Univ. Autónoma de Madrid, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - J Bernard Heymann
- Laboratory of Structural Biology Research, NIAMS, NIH, Bethesda, MD, USA
| | - Jose Maria Carazo
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
| | - Carlos Oscar S Sorzano
- Biocomputing Unit, National Center for Biotechnology (CSIC), Darwin 3, Campus Univ. Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain. .,Univ. CEU San Pablo, Campus Urb. Montepríncipe, Boadilla del Monte, 28668, Madrid, Spain.
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111
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Aiyer S, Zhang C, Baldwin PR, Lyumkis D. Evaluating Local and Directional Resolution of Cryo-EM Density Maps. Methods Mol Biol 2021; 2215:161-187. [PMID: 33368004 PMCID: PMC8294179 DOI: 10.1007/978-1-0716-0966-8_8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A systematic and quantitative evaluation of cryo-EM maps is necessary to judge their quality and to capture all possible sources of error. A single value for global resolution is insufficient to accurately describe the quality of a reconstructed density. We describe the estimation and evaluation of two additional resolution measures, local and directional resolution, using methods based on the Fourier shell correlation (FSC). We apply the protocol to samples that encompass different types of pathologies a user is expected to encounter and provide analyses on how to interpret the output files and resulting maps. Implementation of these tools will facilitate density interpretation and can guide the user in adapting their experiments to improve the quality of cryo-EM maps, and by extension atomic models.
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Affiliation(s)
- Sriram Aiyer
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Cheng Zhang
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Philp R Baldwin
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, La Jolla, CA, USA.
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112
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Cragnolini T, Sahota H, Joseph AP, Sweeney A, Malhotra S, Vasishtan D, Topf M. TEMPy2: a Python library with improved 3D electron microscopy density-fitting and validation workflows. Acta Crystallogr D Struct Biol 2021; 77:41-47. [PMID: 33404524 PMCID: PMC7787107 DOI: 10.1107/s2059798320014928] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/10/2020] [Indexed: 11/10/2022] Open
Abstract
Structural determination of molecular complexes by cryo-EM requires large, often complex processing of the image data that are initially obtained. Here, TEMPy2, an update of the TEMPy package to process, optimize and assess cryo-EM maps and the structures fitted to them, is described. New optimization routines, comprehensive automated checks and workflows to perform these tasks are described.
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Affiliation(s)
- Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Harpal Sahota
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Aaron Sweeney
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Sony Malhotra
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Daven Vasishtan
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
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113
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Said N, Hilal T, Sunday ND, Khatri A, Bürger J, Mielke T, Belogurov GA, Loll B, Sen R, Artsimovitch I, Wahl MC. Steps toward translocation-independent RNA polymerase inactivation by terminator ATPase ρ. Science 2021; 371:eabd1673. [PMID: 33243850 PMCID: PMC7864586 DOI: 10.1126/science.abd1673] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/26/2020] [Indexed: 12/31/2022]
Abstract
Factor-dependent transcription termination mechanisms are poorly understood. We determined a series of cryo-electron microscopy structures portraying the hexameric adenosine triphosphatase (ATPase) ρ on a pathway to terminating NusA/NusG-modified elongation complexes. An open ρ ring contacts NusA, NusG, and multiple regions of RNA polymerase, trapping and locally unwinding proximal upstream DNA. NusA wedges into the ρ ring, initially sequestering RNA. Upon deflection of distal upstream DNA over the RNA polymerase zinc-binding domain, NusA rotates underneath one capping ρ subunit, which subsequently captures RNA. After detachment of NusG and clamp opening, RNA polymerase loses its grip on the RNA:DNA hybrid and is inactivated. Our structural and functional analyses suggest that ρ, and other termination factors across life, may use analogous strategies to allosterically trap transcription complexes in a moribund state.
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Affiliation(s)
- Nelly Said
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Tarek Hilal
- Research Center of Electron Microscopy and Core Facility BioSupraMol, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Nicholas D Sunday
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Ajay Khatri
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
- Graduate Studies, Regional Centre for Biotechnology, Faridabad, Haryana, India
| | - Jörg Bürger
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
- Institute of Medical Physics und Biophysics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Thorsten Mielke
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
| | | | - Bernhard Loll
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Ranjan Sen
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Irina Artsimovitch
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
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114
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Benton DJ, Wrobel AG, Xu P, Roustan C, Martin SR, Rosenthal PB, Skehel JJ, Gamblin SJ. Receptor binding and priming of the spike protein of SARS-CoV-2 for membrane fusion. Nature 2020; 588:327-330. [PMID: 32942285 PMCID: PMC7116727 DOI: 10.1038/s41586-020-2772-0] [Citation(s) in RCA: 551] [Impact Index Per Article: 137.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/11/2020] [Indexed: 11/09/2022]
Abstract
Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is initiated by virus binding to the ACE2 cell-surface receptors1-4, followed by fusion of the virus and cell membranes to release the virus genome into the cell. Both receptor binding and membrane fusion activities are mediated by the virus spike glycoprotein5-7. As with other class-I membrane-fusion proteins, the spike protein is post-translationally cleaved, in this case by furin, into the S1 and S2 components that remain associated after cleavage8-10. Fusion activation after receptor binding is proposed to involve the exposure of a second proteolytic site (S2'), cleavage of which is required for the release of the fusion peptide11,12. Here we analyse the binding of ACE2 to the furin-cleaved form of the SARS-CoV-2 spike protein using cryo-electron microscopy. We classify ten different molecular species, including the unbound, closed spike trimer, the fully open ACE2-bound trimer and dissociated monomeric S1 bound to ACE2. The ten structures describe ACE2-binding events that destabilize the spike trimer, progressively opening up, and out, the individual S1 components. The opening process reduces S1 contacts and unshields the trimeric S2 core, priming the protein for fusion activation and dissociation of ACE2-bound S1 monomers. The structures also reveal refolding of an S1 subdomain after ACE2 binding that disrupts interactions with S2, which involves Asp61413-15 and leads to the destabilization of the structure of S2 proximal to the secondary (S2') cleavage site.
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Affiliation(s)
- Donald J Benton
- Strutural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
| | - Antoni G Wrobel
- Strutural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
| | - Pengqi Xu
- Precision Medicine Center, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
- Francis Crick Institute, London, UK
| | - Chloë Roustan
- Structural Biology Science Technology Platform, Francis Crick Institute, London, UK
| | - Stephen R Martin
- Strutural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, Francis Crick Institute, London, UK
| | - John J Skehel
- Strutural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
| | - Steven J Gamblin
- Strutural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
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115
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Punjani A, Zhang H, Fleet DJ. Non-uniform refinement: adaptive regularization improves single-particle cryo-EM reconstruction. Nat Methods 2020; 17:1214-1221. [PMID: 33257830 DOI: 10.1038/s41592-020-00990-8] [Citation(s) in RCA: 704] [Impact Index Per Article: 176.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 10/06/2020] [Indexed: 11/09/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) is widely used to study biological macromolecules that comprise regions with disorder, flexibility or partial occupancy. For example, membrane proteins are often kept in solution with detergent micelles and lipid nanodiscs that are locally disordered. Such spatial variability negatively impacts computational three-dimensional (3D) reconstruction with existing iterative refinement algorithms that assume rigidity. We introduce non-uniform refinement, an algorithm based on cross-validation optimization, which automatically regularizes 3D density maps during refinement to account for spatial variability. Unlike common shift-invariant regularizers, non-uniform refinement systematically removes noise from disordered regions, while retaining signal useful for aligning particle images, yielding dramatically improved resolution and 3D map quality in many cases. We obtain high-resolution reconstructions for multiple membrane proteins as small as 100 kDa, demonstrating increased effectiveness of cryo-EM for this class of targets critical in structural biology and drug discovery. Non-uniform refinement is implemented in the cryoSPARC software package.
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Affiliation(s)
- Ali Punjani
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada. .,Structura Biotechnology Inc., Toronto, Ontario, Canada.
| | - Haowei Zhang
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada
| | - David J Fleet
- Department of Computer Sciences, University of Toronto, Toronto, Ontario, Canada. .,Vector Institute, Toronto, Ontario, Canada.
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116
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Piccoli L, Park YJ, Tortorici MA, Czudnochowski N, Walls AC, Beltramello M, Silacci-Fregni C, Pinto D, Rosen LE, Bowen JE, Acton OJ, Jaconi S, Guarino B, Minola A, Zatta F, Sprugasci N, Bassi J, Peter A, De Marco A, Nix JC, Mele F, Jovic S, Rodriguez BF, Gupta SV, Jin F, Piumatti G, Lo Presti G, Pellanda AF, Biggiogero M, Tarkowski M, Pizzuto MS, Cameroni E, Havenar-Daughton C, Smithey M, Hong D, Lepori V, Albanese E, Ceschi A, Bernasconi E, Elzi L, Ferrari P, Garzoni C, Riva A, Snell G, Sallusto F, Fink K, Virgin HW, Lanzavecchia A, Corti D, Veesler D. Mapping Neutralizing and Immunodominant Sites on the SARS-CoV-2 Spike Receptor-Binding Domain by Structure-Guided High-Resolution Serology. Cell 2020; 183:1024-1042.e21. [PMID: 32991844 PMCID: PMC7494283 DOI: 10.1016/j.cell.2020.09.037] [Citation(s) in RCA: 998] [Impact Index Per Article: 249.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/28/2020] [Accepted: 09/11/2020] [Indexed: 12/28/2022]
Abstract
Analysis of the specificity and kinetics of neutralizing antibodies (nAbs) elicited by SARS-CoV-2 infection is crucial for understanding immune protection and identifying targets for vaccine design. In a cohort of 647 SARS-CoV-2-infected subjects, we found that both the magnitude of Ab responses to SARS-CoV-2 spike (S) and nucleoprotein and nAb titers correlate with clinical scores. The receptor-binding domain (RBD) is immunodominant and the target of 90% of the neutralizing activity present in SARS-CoV-2 immune sera. Whereas overall RBD-specific serum IgG titers waned with a half-life of 49 days, nAb titers and avidity increased over time for some individuals, consistent with affinity maturation. We structurally defined an RBD antigenic map and serologically quantified serum Abs specific for distinct RBD epitopes leading to the identification of two major receptor-binding motif antigenic sites. Our results explain the immunodominance of the receptor-binding motif and will guide the design of COVID-19 vaccines and therapeutics.
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MESH Headings
- Angiotensin-Converting Enzyme 2
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/immunology
- Antibodies, Neutralizing/blood
- Antibodies, Neutralizing/chemistry
- Antibodies, Neutralizing/immunology
- Antibodies, Viral/blood
- Antibodies, Viral/chemistry
- Antibodies, Viral/immunology
- Antigen-Antibody Reactions
- Betacoronavirus/immunology
- Betacoronavirus/isolation & purification
- Betacoronavirus/metabolism
- Binding Sites
- COVID-19
- Coronavirus Infections/pathology
- Coronavirus Infections/virology
- Epitope Mapping/methods
- Epitopes/chemistry
- Epitopes/immunology
- Humans
- Immunoglobulin A/blood
- Immunoglobulin A/immunology
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Immunoglobulin M/blood
- Immunoglobulin M/immunology
- Kinetics
- Molecular Dynamics Simulation
- Pandemics
- Peptidyl-Dipeptidase A/chemistry
- Peptidyl-Dipeptidase A/metabolism
- Pneumonia, Viral/pathology
- Pneumonia, Viral/virology
- Protein Binding
- Protein Domains/immunology
- Protein Structure, Quaternary
- SARS-CoV-2
- Spike Glycoprotein, Coronavirus/chemistry
- Spike Glycoprotein, Coronavirus/genetics
- Spike Glycoprotein, Coronavirus/immunology
- Spike Glycoprotein, Coronavirus/metabolism
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Affiliation(s)
- Luca Piccoli
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Young-Jun Park
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - M Alejandra Tortorici
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA; Institut Pasteur and CNRS UMR 3569, Unité de Virologie Structurale, 75015 Paris, France
| | | | - Alexandra C Walls
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | | | | | - Dora Pinto
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | | | - John E Bowen
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Oliver J Acton
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Stefano Jaconi
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Barbara Guarino
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Andrea Minola
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Fabrizia Zatta
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Nicole Sprugasci
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Jessica Bassi
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Alessia Peter
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Anna De Marco
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - Jay C Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Federico Mele
- Institute for Research in Biomedicine, Università della Svizzera italiana, 6500 Bellinzona, Switzerland
| | - Sandra Jovic
- Institute for Research in Biomedicine, Università della Svizzera italiana, 6500 Bellinzona, Switzerland
| | | | | | - Feng Jin
- Vir Biotechnology, San Francisco, CA 94158, USA
| | - Giovanni Piumatti
- Division of Primary Care, Geneva University Hospitals, 1205 Geneva, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera italiana, 6900 Lugano, Switzerland
| | - Giorgia Lo Presti
- Clinic of Internal Medicine and Infectious Diseases, Clinica Luganese Moncucco, 6900 Lugano, Switzerland
| | | | - Maira Biggiogero
- Clinic of Internal Medicine and Infectious Diseases, Clinica Luganese Moncucco, 6900 Lugano, Switzerland
| | - Maciej Tarkowski
- III Division of Infectious Diseases, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital, 20157 Milan, Italy
| | - Matteo S Pizzuto
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | | | | | | | - David Hong
- Vir Biotechnology, San Francisco, CA 94158, USA
| | | | - Emiliano Albanese
- Institute of Public Health, Università della Svizzera italiana, 6900 Lugano, Switzerland
| | - Alessandro Ceschi
- Faculty of Biomedical Sciences, Università della Svizzera italiana, 6900 Lugano, Switzerland; Division of Clinical Pharmacology and Toxicology, Institute of Pharmacological Sciences of Southern Switzerland, Ente Ospedaliero Cantonale, 6900 Lugano, Switzerland; Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, 8091 Zurich, Switzerland
| | - Enos Bernasconi
- Division of Infectious Diseases, Ente Ospedaliero Cantonale, Ospedale Civico and Ospedale Italiano, 6900 Lugano, Switzerland
| | - Luigia Elzi
- Division of Infectious Diseases, Ente Ospedaliero Cantonale, Ospedale Regionale Bellinzona e Valli and Ospedale Regionale, 6600 Locarno, Switzerland
| | - Paolo Ferrari
- Department of Nephrology, Ospedale Civico Lugano, Ente Ospedaliero Cantonale, 6900 Lugano, Switzerland; Prince of Wales Hospital Clinical School, University of New South Wales, Sydney, NSW 2052, Australia
| | - Christian Garzoni
- Clinic of Internal Medicine and Infectious Diseases, Clinica Luganese Moncucco, 6900 Lugano, Switzerland
| | - Agostino Riva
- III Division of Infectious Diseases, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital, 20157 Milan, Italy
| | | | - Federica Sallusto
- Institute for Research in Biomedicine, Università della Svizzera italiana, 6500 Bellinzona, Switzerland
| | - Katja Fink
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | | | | | - Davide Corti
- Humabs BioMed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland.
| | - David Veesler
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
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117
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A Non-covalent Ligand Reveals Biased Agonism of the TRPA1 Ion Channel. Neuron 2020; 109:273-284.e4. [PMID: 33152265 DOI: 10.1016/j.neuron.2020.10.014] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/31/2020] [Accepted: 10/09/2020] [Indexed: 12/19/2022]
Abstract
The TRPA1 ion channel is activated by electrophilic compounds through the covalent modification of intracellular cysteine residues. How non-covalent agonists activate the channel and whether covalent and non-covalent agonists elicit the same physiological responses are not understood. Here, we report the discovery of a non-covalent agonist, GNE551, and determine a cryo-EM structure of the TRPA1-GNE551 complex, revealing a distinct binding pocket and ligand-interaction mechanism. Unlike the covalent agonist allyl isothiocyanate, which elicits channel desensitization, tachyphylaxis, and transient pain, GNE551 activates TRPA1 into a distinct conducting state without desensitization and induces persistent pain. Furthermore, GNE551-evoked pain is relatively insensitive to antagonist treatment. Thus, we demonstrate the biased agonism of TRPA1, a finding that has important implications for the discovery of effective drugs tailored to different disease etiologies.
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118
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Penczek PA. Reliable cryo-EM resolution estimation with modified Fourier shell correlation. IUCRJ 2020; 7:995-1008. [PMID: 33209314 PMCID: PMC7642792 DOI: 10.1107/s2052252520011574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
A modified Fourier shell correlation (mFSC) methodology is introduced that is aimed at addressing two fundamental problems that mar the use of the FSC: the strong influence of mask-induced artifacts on resolution estimation and the lack of assessment of FSC uncertainties stemming from the inability to determine the associated number of degrees of freedom. It is shown that by simply changing the order of the steps in which the FSC is computed, the correlations induced by masking of the input data can be eliminated. In addition, to further reduce artifacts, a smooth Gaussian window function is used to outline the regions of reciprocal space within which the mFSC is computed. Next, it is shown that the number of degrees of freedom (ndf) of the system is approximated well by combining the ndf associated with the Gaussian window in reciprocal space with further reduction of the ndf owing to the use of the mask in real space. It is demonstrated through the application of the mFSC to both single-particle and helical structures that the mFSC yields reliable, mask-induced artifact-free results as a result of the introduced modifications. Since the adverse effect of the mask is eliminated, it also becomes possible to compute robust local resolutions both per voxel of a 3D map as well as, in a newly developed approach, per functional subunit, segment or even larger secondary element of the studied complex.
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Affiliation(s)
- Pawel A. Penczek
- Department of Biochemistry and Molecular Biology, The University of Texas – Houston Medical Center, 6431 Fannin Street, Houston, TX 77030, USA
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119
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Antibody-mediated disruption of the SARS-CoV-2 spike glycoprotein. Nat Commun 2020; 11:5337. [PMID: 33087721 PMCID: PMC7577971 DOI: 10.1038/s41467-020-19146-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/22/2020] [Indexed: 01/17/2023] Open
Abstract
The CR3022 antibody, selected from a group of SARS-CoV monoclonal antibodies for its ability to cross-react with SARS-CoV-2, has been examined for its ability to bind to the ectodomain of the SARS-CoV-2 spike glycoprotein. Using cryo-electron microscopy we show that antibody binding requires rearrangements in the S1 domain that result in dissociation of the spike. Here, the authors characterise the binding and neutralisation properties of CR3022, a neutralising Ab isolated from a convalescent SARS patient, against SARS-CoV-2 spike trimers and show using Cryo-EM the disruption of SARS-CoV-2 spike by CR3022 Fab.
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120
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Tan YZ, Rubinstein JL. Through-grid wicking enables high-speed cryoEM specimen preparation. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2020; 76:1092-1103. [PMID: 33135680 DOI: 10.1107/s2059798320012474] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 09/10/2020] [Indexed: 01/23/2023]
Abstract
Blotting times for conventional cryoEM specimen preparation complicate time-resolved studies and lead to some specimens adopting preferred orientations or denaturing at the air-water interface. Here, it is shown that solution sprayed onto one side of a holey cryoEM grid can be wicked through the grid by a glass-fiber filter held against the opposite side, often called the `back', of the grid, producing a film suitable for vitrification. This process can be completed in tens of milliseconds. Ultrasonic specimen application and through-grid wicking were combined in a high-speed specimen-preparation device that was named `Back-it-up' or BIU. The high liquid-absorption capacity of the glass fiber compared with self-wicking grids makes the method relatively insensitive to the amount of sample applied. Consequently, through-grid wicking produces large areas of ice that are suitable for cryoEM for both soluble and detergent-solubilized protein complexes. The speed of the device increases the number of views for a specimen that suffers from preferred orientations.
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Affiliation(s)
- Yong Zi Tan
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
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121
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Righetto RD, Anton L, Adaixo R, Jakob RP, Zivanov J, Mahi MA, Ringler P, Schwede T, Maier T, Stahlberg H. High-resolution cryo-EM structure of urease from the pathogen Yersinia enterocolitica. Nat Commun 2020; 11:5101. [PMID: 33037208 PMCID: PMC7547064 DOI: 10.1038/s41467-020-18870-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 09/15/2020] [Indexed: 01/09/2023] Open
Abstract
Urease converts urea into ammonia and carbon dioxide and makes urea available as a nitrogen source for all forms of life except animals. In human bacterial pathogens, ureases also aid in the invasion of acidic environments such as the stomach by raising the surrounding pH. Here, we report the structure of urease from the pathogen Yersinia enterocolitica at 2 Å resolution from cryo-electron microscopy. Y. enterocolitica urease is a dodecameric assembly of a trimer of three protein chains, ureA, ureB and ureC. The high data quality enables detailed visualization of the urease bimetal active site and of the impact of radiation damage. The obtained structure is of sufficient quality to support drug development efforts. Urease is a nickel enzyme responsible for catalyzing the conversion of urea into ammonia and carbon dioxide. Here the authors report a high resolution cryo-EM structure of urease from the bacterial pathogen Yersinia enterocolitica, providing a detailed visualization of the urease bimetal active site and a basis for drug development.
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Affiliation(s)
- Ricardo D Righetto
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Leonie Anton
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland
| | - Ricardo Adaixo
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Roman P Jakob
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland
| | - Jasenko Zivanov
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Mohamed-Ali Mahi
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland.,SIB Swiss Institute of Bioinformatics, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland
| | - Philippe Ringler
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Torsten Schwede
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland.,SIB Swiss Institute of Bioinformatics, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland
| | - Timm Maier
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056, Basel, Switzerland.
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland.
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122
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Wu M, Lander GC. Present and Emerging Methodologies in Cryo-EM Single-Particle Analysis. Biophys J 2020; 119:1281-1289. [PMID: 32919493 PMCID: PMC7567993 DOI: 10.1016/j.bpj.2020.08.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/22/2020] [Accepted: 08/26/2020] [Indexed: 11/25/2022] Open
Abstract
Over the past decade, technical and methodological improvements in cryogenic electron microscopy (cryo-EM) single-particle analysis have enabled routine high-resolution structural analyses of biological macromolecules, resulting in a flood of new molecular insights into protracted biological questions. However, despite the tremendous progress and success of the field in recent years, opportunities for improvement remain in various aspects of the cryo-EM single-particle analysis workflow (e.g., sample preparation, image acquisition and processing, and structure validation). Here, we review recent advances that have contributed to the principal methods in cryo-EM and identify persisting challenges and bottlenecks that will require further methodological and hardware development.
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Affiliation(s)
- Mengyu Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California.
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123
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Beckers M, Sachse C. Permutation testing of Fourier shell correlation for resolution estimation of cryo-EM maps. J Struct Biol 2020; 212:107579. [DOI: 10.1016/j.jsb.2020.107579] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 07/01/2020] [Accepted: 07/15/2020] [Indexed: 11/16/2022]
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124
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Acebrón I, Righetto RD, Schoenherr C, de Buhr S, Redondo P, Culley J, Rodríguez CF, Daday C, Biyani N, Llorca O, Byron A, Chami M, Gräter F, Boskovic J, Frame MC, Stahlberg H, Lietha D. Structural basis of Focal Adhesion Kinase activation on lipid membranes. EMBO J 2020; 39:e104743. [PMID: 32779739 PMCID: PMC7527928 DOI: 10.15252/embj.2020104743] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/01/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
Focal adhesion kinase (FAK) is a key component of the membrane proximal signaling layer in focal adhesion complexes, regulating important cellular processes, including cell migration, proliferation, and survival. In the cytosol, FAK adopts an autoinhibited state but is activated upon recruitment into focal adhesions, yet how this occurs or what induces structural changes is unknown. Here, we employ cryo-electron microscopy to reveal how FAK associates with lipid membranes and how membrane interactions unlock FAK autoinhibition to promote activation. Intriguingly, initial binding of FAK to the membrane causes steric clashes that release the kinase domain from autoinhibition, allowing it to undergo a large conformational change and interact itself with the membrane in an orientation that places the active site toward the membrane. In this conformation, the autophosphorylation site is exposed and multiple interfaces align to promote FAK oligomerization on the membrane. We show that interfaces responsible for initial dimerization and membrane attachment are essential for FAK autophosphorylation and resulting cellular activity including cancer cell invasion, while stable FAK oligomerization appears to be needed for optimal cancer cell proliferation in an anchorage-independent manner. Together, our data provide structural details of a key membrane bound state of FAK that is primed for efficient autophosphorylation and activation, hence revealing the critical event in integrin mediated FAK activation and signaling at focal adhesions.
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Affiliation(s)
- Iván Acebrón
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
| | - Ricardo D Righetto
- Center for Cellular Imaging and NanoAnalyticsBiozentrumUniversity of BaselBaselSwitzerland
| | - Christina Schoenherr
- Cancer Research UK Edinburgh CentreInstitute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Svenja de Buhr
- Heidelberg Institute for Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Pilar Redondo
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
| | - Jayne Culley
- Cancer Research UK Edinburgh CentreInstitute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Carlos F Rodríguez
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
| | - Csaba Daday
- Heidelberg Institute for Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Nikhil Biyani
- Center for Cellular Imaging and NanoAnalyticsBiozentrumUniversity of BaselBaselSwitzerland
| | - Oscar Llorca
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
| | - Adam Byron
- Cancer Research UK Edinburgh CentreInstitute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Mohamed Chami
- Center for Cellular Imaging and NanoAnalyticsBiozentrumUniversity of BaselBaselSwitzerland
| | - Frauke Gräter
- Heidelberg Institute for Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Jasminka Boskovic
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
| | - Margaret C Frame
- Cancer Research UK Edinburgh CentreInstitute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUK
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalyticsBiozentrumUniversity of BaselBaselSwitzerland
| | - Daniel Lietha
- Structural Biology ProgrammeSpanish National Cancer Research CentreMadridSpain
- Centro de Investigaciones Biológicas Margarita SalasSpanish National Research Council (CSIC)MadridSpain
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125
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Chen J, Malone B, Llewellyn E, Grasso M, Shelton PM, Olinares PDB, Maruthi K, Eng ET, Vatandaslar H, Chait BT, Kapoor TM, Darst SA, Campbell EA. Structural Basis for Helicase-Polymerase Coupling in the SARS-CoV-2 Replication-Transcription Complex. Cell 2020; 182:1560-1573.e13. [PMID: 32783916 PMCID: PMC7386476 DOI: 10.1016/j.cell.2020.07.033] [Citation(s) in RCA: 309] [Impact Index Per Article: 77.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/10/2020] [Accepted: 07/22/2020] [Indexed: 01/21/2023]
Abstract
SARS-CoV-2 is the causative agent of the 2019-2020 pandemic. The SARS-CoV-2 genome is replicated and transcribed by the RNA-dependent RNA polymerase holoenzyme (subunits nsp7/nsp82/nsp12) along with a cast of accessory factors. One of these factors is the nsp13 helicase. Both the holo-RdRp and nsp13 are essential for viral replication and are targets for treating the disease COVID-19. Here we present cryoelectron microscopic structures of the SARS-CoV-2 holo-RdRp with an RNA template product in complex with two molecules of the nsp13 helicase. The Nidovirales order-specific N-terminal domains of each nsp13 interact with the N-terminal extension of each copy of nsp8. One nsp13 also contacts the nsp12 thumb. The structure places the nucleic acid-binding ATPase domains of the helicase directly in front of the replicating-transcribing holo-RdRp, constraining models for nsp13 function. We also observe ADP-Mg2+ bound in the nsp12 N-terminal nidovirus RdRp-associated nucleotidyltransferase domain, detailing a new pocket for anti-viral therapy development.
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Affiliation(s)
- James Chen
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Brandon Malone
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Eliza Llewellyn
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Michael Grasso
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Patrick M.M. Shelton
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Paul Dominic B. Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Kashyap Maruthi
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA
| | - Edward T. Eng
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA
| | - Hasan Vatandaslar
- Institute of Molecular Health Sciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Brian T. Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Tarun M. Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Seth A. Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA,Corresponding author
| | - Elizabeth A. Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA,Corresponding author
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126
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Lü Y, Zeng X, Tian X, Shi X, Wang H, Zheng X, Liu X, Zhao X, Gao X, Xu M. Spark-based parallel calculation of 3D fourier shell correlation for macromolecule structure local resolution estimation. BMC Bioinformatics 2020; 21:391. [PMID: 32938398 PMCID: PMC7495889 DOI: 10.1186/s12859-020-03680-6] [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] [Indexed: 12/05/2022] Open
Abstract
Background Resolution estimation is the main evaluation criteria for the reconstruction of macromolecular 3D structure in the field of cryoelectron microscopy (cryo-EM). At present, there are many methods to evaluate the 3D resolution for reconstructed macromolecular structures from Single Particle Analysis (SPA) in cryo-EM and subtomogram averaging (SA) in electron cryotomography (cryo-ET). As global methods, they measure the resolution of the structure as a whole, but they are inaccurate in detecting subtle local changes of reconstruction. In order to detect the subtle changes of reconstruction of SPA and SA, a few local resolution methods are proposed. The mainstream local resolution evaluation methods are based on local Fourier shell correlation (FSC), which is computationally intensive. However, the existing resolution evaluation methods are based on multi-threading implementation on a single computer with very poor scalability. Results This paper proposes a new fine-grained 3D array partition method by key-value format in Spark. Our method first converts 3D images to key-value data (K-V). Then the K-V data is used for 3D array partitioning and data exchange in parallel. So Spark-based distributed parallel computing framework can solve the above scalability problem. In this distributed computing framework, all 3D local FSC tasks are simultaneously calculated across multiple nodes in a computer cluster. Through the calculation of experimental data, 3D local resolution evaluation algorithm based on Spark fine-grained 3D array partition has a magnitude change in computing speed compared with the mainstream FSC algorithm under the condition that the accuracy remains unchanged, and has better fault tolerance and scalability. Conclusions In this paper, we proposed a K-V format based fine-grained 3D array partition method in Spark to parallel calculating 3D FSC for getting a 3D local resolution density map. 3D local resolution density map evaluates the three-dimensional density maps reconstructed from single particle analysis and subtomogram averaging. Our proposed method can significantly increase the speed of the 3D local resolution evaluation, which is important for the efficient detection of subtle variations among reconstructed macromolecular structures.
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Affiliation(s)
- Yongchun Lü
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China. .,University of Chinese Academy of Sciences, Beijing, China.
| | - Xiangrui Zeng
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, USA
| | - Xinhui Tian
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China
| | - Xiao Shi
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China
| | - Hui Wang
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China
| | - Xiaohui Zheng
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaodong Liu
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China
| | - Xiaofang Zhao
- Institute of Computing Technology of the Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xin Gao
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, Thuwal, Saudi Arabia
| | - Min Xu
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, USA.
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127
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Chung SC, Lin HH, Niu PY, Huang SH, Tu IP, Chang WH. Pre-pro is a fast pre-processor for single-particle cryo-EM by enhancing 2D classification. Commun Biol 2020; 3:508. [PMID: 32917929 PMCID: PMC7486923 DOI: 10.1038/s42003-020-01229-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 07/13/2020] [Indexed: 01/04/2023] Open
Abstract
2D classification plays a pivotal role in analyzing single particle cryo-electron microscopy images. Here, we introduce a simple and loss-less pre-processor that incorporates a fast dimension-reduction (2SDR) de-noiser to enhance 2D classification. By implementing this 2SDR pre-processor prior to a representative classification algorithm like RELION and ISAC, we compare the performances with and without the pre-processor. Tests on multiple cryo-EM experimental datasets show the pre-processor can make classification faster, improve yield of good particles and increase the number of class-average images to generate better initial models. Testing on the nanodisc-embedded TRPV1 dataset with high heterogeneity using a 3D reconstruction workflow with an initial model from class-average images highlights the pre-processor improves the final resolution to 2.82 Å, close to 0.9 Nyquist. Those findings and analyses suggest the 2SDR pre-processor, of minimal cost, is widely applicable for boosting 2D classification, while its generalization to accommodate neural network de-noisers is envisioned.
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Affiliation(s)
- Szu-Chi Chung
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Hsin-Hung Lin
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Po-Yao Niu
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Shih-Hsin Huang
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - I-Ping Tu
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan.
| | - Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan.
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128
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Abstract
A density-modification procedure for improving maps from single-particle electron cryogenic microscopy (cryo-EM) is presented. The theoretical basis of the method is identical to that of maximum-likelihood density modification, previously used to improve maps from macromolecular X-ray crystallography. Key differences from applications in crystallography are that the errors in Fourier coefficients are largely in the phases in crystallography but in both phases and amplitudes in cryo-EM, and that half-maps with independent errors are available in cryo-EM. These differences lead to a distinct approach for combination of information from starting maps with information obtained in the density-modification process. The density-modification procedure was applied to a set of 104 datasets and improved map-model correlation and increased the visibility of details in many of the maps. The procedure requires two unmasked half-maps and a sequence file or other source of information on the volume of the macromolecule that has been imaged.
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129
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Billesbølle CB, Azumaya CM, Kretsch RC, Powers AS, Gonen S, Schneider S, Arvedson T, Dror RO, Cheng Y, Manglik A. Structure of hepcidin-bound ferroportin reveals iron homeostatic mechanisms. Nature 2020; 586:807-811. [PMID: 32814342 PMCID: PMC7906036 DOI: 10.1038/s41586-020-2668-z] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/15/2020] [Indexed: 01/01/2023]
Abstract
The serum iron level in humans is tightly controlled by the action of the hormone hepcidin on the iron efflux transporter ferroportin. Hepcidin regulates iron absorption and recycling by inducing ferroportin internalization and degradation1. Aberrant ferroportin activity can lead to diseases of iron overload, like hemochromatosis, or iron limitation anemias2. Here, we determined cryogenic electron microscopy (cryo-EM) structures of ferroportin in lipid nanodiscs, both in the apo state and in complex with cobalt, an iron mimetic, and hepcidin. These structures and accompanying molecular dynamics simulations identify two metal binding sites within the N- and C-domains of ferroportin. Hepcidin binds ferroportin in an outward-open conformation and completely occludes the iron efflux pathway to inhibit transport. The carboxy-terminus of hepcidin directly contacts the divalent metal in the ferroportin C-domain. We further show that hepcidin binding to ferroportin is coupled to iron binding, with an 80-fold increase in hepcidin affinity in the presence of iron. These results suggest a model for hepcidin regulation of ferroportin, where only iron loaded ferroportin molecules are targeted for degradation. More broadly, our structural and functional insights are likely to enable more targeted manipulation of the hepcidin-ferroportin axis in disorders of iron homeostasis.
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Affiliation(s)
- Christian B Billesbølle
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Caleigh M Azumaya
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Rachael C Kretsch
- Department of Computer Science, Stanford University, Stanford, CA, USA.,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.,Biophysics Program, Stanford University, Stanford, CA, USA
| | - Alexander S Powers
- Department of Computer Science, Stanford University, Stanford, CA, USA.,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.,Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Shane Gonen
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.,Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA, USA.,Department of Molecular Biology and Biochemistry, University of California, Irvine, Biological Sciences III, Irvine, CA, USA
| | - Simon Schneider
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Straße 9, Frankfurt am Main, Germany
| | - Tara Arvedson
- Department of Oncology Research, Amgen Inc., South San Francisco, CA, USA
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA.,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.,Biophysics Program, Stanford University, Stanford, CA, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA. .,Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA, USA.
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA. .,Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, USA.
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130
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Ramlaul K, Palmer CM, Nakane T, Aylett CHS. Mitigating local over-fitting during single particle reconstruction with SIDESPLITTER. J Struct Biol 2020; 211:107545. [PMID: 32534144 PMCID: PMC7369633 DOI: 10.1016/j.jsb.2020.107545] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/28/2020] [Accepted: 06/02/2020] [Indexed: 01/31/2023]
Abstract
Single particle analysis has become a key structural biology technique. Experimental images are extremely noisy, and during iterative refinement it is possible to stably incorporate noise into the reconstruction. Such "over-fitting" can lead to misinterpretation of the structure and flawed biological results. Several strategies are routinely used to prevent over-fitting, the most common being independent refinement of two sides of a split dataset. In this study, we show that over-fitting remains an issue within regions of low local signal-to-noise, despite independent refinement of half datasets. We propose a modification of the refinement process through the application of a local signal-to-noise filter: SIDESPLITTER. We show that our approach can reduce over-fitting for both idealised and experimental data while maintaining independence between the two sides of a split refinement. SIDESPLITTER refinement leads to improved density, and can also lead to improvement of the final resolution in extreme cases where datasets are prone to severe over-fitting, such as small membrane proteins.
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Affiliation(s)
- Kailash Ramlaul
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College Road, South Kensington, London SW7 2BB, United Kingdom
| | - Colin M Palmer
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Takanori Nakane
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Christopher H S Aylett
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College Road, South Kensington, London SW7 2BB, United Kingdom.
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131
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Wrobel AG, Benton DJ, Xu P, Roustan C, Martin SR, Rosenthal PB, Skehel JJ, Gamblin SJ. SARS-CoV-2 and bat RaTG13 spike glycoprotein structures inform on virus evolution and furin-cleavage effects. Nat Struct Mol Biol 2020; 27:763-767. [PMID: 32647346 PMCID: PMC7610980 DOI: 10.1038/s41594-020-0468-7] [Citation(s) in RCA: 381] [Impact Index Per Article: 95.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 06/24/2020] [Indexed: 01/06/2023]
Abstract
SARS-CoV-2 is thought to have emerged from bats, possibly via a secondary host. Here, we investigate the relationship of spike (S) glycoprotein from SARS-CoV-2 with the S protein of a closely related bat virus, RaTG13. We determined cryo-EM structures for RaTG13 S and for both furin-cleaved and uncleaved SARS-CoV-2 S; we compared these with recently reported structures for uncleaved SARS-CoV-2 S. We also biochemically characterized their relative stabilities and affinities for the SARS-CoV-2 receptor ACE2. Although the overall structures of human and bat virus S proteins are similar, there are key differences in their properties, including a more stable precleavage form of human S and about 1,000-fold tighter binding of SARS-CoV-2 to human receptor. These observations suggest that cleavage at the furin-cleavage site decreases the overall stability of SARS-CoV-2 S and facilitates the adoption of the open conformation that is required for S to bind to the ACE2 receptor.
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MESH Headings
- Angiotensin-Converting Enzyme 2
- Animals
- Betacoronavirus/genetics
- Betacoronavirus/metabolism
- Betacoronavirus/ultrastructure
- Binding Sites
- COVID-19
- Chiroptera/virology
- Coronavirus Infections/virology
- Cryoelectron Microscopy
- Evolution, Molecular
- Furin/chemistry
- Gene Expression
- HEK293 Cells
- Host-Pathogen Interactions/genetics
- Humans
- Models, Molecular
- Pandemics
- Peptidyl-Dipeptidase A/chemistry
- Peptidyl-Dipeptidase A/genetics
- Peptidyl-Dipeptidase A/metabolism
- Pneumonia, Viral/virology
- Protein Binding
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- Protein Interaction Domains and Motifs
- Protein Isoforms/chemistry
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Stability
- Proteolysis
- Receptors, Virus/chemistry
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- SARS-CoV-2
- Spike Glycoprotein, Coronavirus/chemistry
- Spike Glycoprotein, Coronavirus/genetics
- Spike Glycoprotein, Coronavirus/metabolism
- Structural Homology, Protein
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Affiliation(s)
- Antoni G Wrobel
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
| | - Donald J Benton
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
| | - Pengqi Xu
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
- Precision Medicine Center, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Chloë Roustan
- Structural Biology Science Technology Platform, Francis Crick Institute, London, UK
| | - Stephen R Martin
- Structural Biology Science Technology Platform, Francis Crick Institute, London, UK
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, Francis Crick Institute, London, UK
| | - John J Skehel
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
| | - Steven J Gamblin
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
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132
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Structure of the human sodium leak channel NALCN. Nature 2020; 587:313-318. [DOI: 10.1038/s41586-020-2570-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/02/2020] [Indexed: 01/17/2023]
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133
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Ortiz S, Stanisic L, Rodriguez BA, Rampp M, Hummer G, Cossio P. Validation tests for cryo-EM maps using an independent particle set. J Struct Biol X 2020; 4:100032. [PMID: 32743544 PMCID: PMC7385033 DOI: 10.1016/j.yjsbx.2020.100032] [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] [Indexed: 12/27/2022] Open
Abstract
Cryo-electron microscopy (cryo-EM) has revolutionized structural biology by providing 3D density maps of biomolecules at near-atomic resolution. However, map validation is still an open issue. Despite several efforts from the community, it is possible to overfit 3D maps to noisy data. Here, we develop a novel methodology that uses a small independent particle set (not used during the 3D refinement) to validate the maps. The main idea is to monitor how the map probability evolves over the control set during the 3D refinement. The method is complementary to the gold-standard procedure, which generates two reconstructions at each iteration. We low-pass filter the two reconstructions for different frequency cutoffs, and we calculate the probability of each filtered map given the control set. For high-quality maps, the probability should increase as a function of the frequency cutoff and the refinement iteration. We also compute the similarity between the densities of probability distributions of the two reconstructions. As higher frequencies are included, the distributions become more dissimilar. We optimized the BioEM package to perform these calculations, and tested it over systems ranging from quality data to pure noise. Our results show that with our methodology, it possible to discriminate datasets that are constructed from noise particles. We conclude that validation against a control particle set provides a powerful tool to assess the quality of cryo-EM maps.
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Affiliation(s)
- Sebastian Ortiz
- Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia
| | - Luka Stanisic
- Max Planck Computing and Data Facility, 85748 Garching, Germany
| | - Boris A Rodriguez
- Grupo de Fósica Atómica y Molecular, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia
| | - Markus Rampp
- Max Planck Computing and Data Facility, 85748 Garching, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
- Institute of Biophysics, Goethe University, 60438 Frankfurt am Main, Germany
| | - Pilar Cossio
- Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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Chen J, Malone B, Llewellyn E, Grasso M, Shelton PMM, Olinares PDB, Maruthi K, Eng E, Vatandaslar H, Chait BT, Kapoor T, Darst SA, Campbell EA. Structural basis for helicase-polymerase coupling in the SARS-CoV-2 replication-transcription complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32676607 PMCID: PMC7359531 DOI: 10.1101/2020.07.08.194084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
SARS-CoV-2 is the causative agent of the 2019-2020 pandemic. The SARS-CoV-2 genome is replicated-transcribed by the RNA-dependent RNA polymerase holoenzyme (subunits nsp7/nsp82/nsp12) along with a cast of accessory factors. One of these factors is the nsp13 helicase. Both the holo-RdRp and nsp13 are essential for viral replication and are targets for treating the disease COVID-19. Here we present cryo-electron microscopic structures of the SARS-CoV-2 holo-RdRp with an RNA template-product in complex with two molecules of the nsp13 helicase. The Nidovirus-order-specific N-terminal domains of each nsp13 interact with the N-terminal extension of each copy of nsp8. One nsp13 also contacts the nsp12-thumb. The structure places the nucleic acid-binding ATPase domains of the helicase directly in front of the replicating-transcribing holo-RdRp, constraining models for nsp13 function. We also observe ADP-Mg2+ bound in the nsp12 N-terminal nidovirus RdRp-associated nucleotidyltransferase domain, detailing a new pocket for anti-viral therapeutic development.
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Affiliation(s)
- James Chen
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, 10065 USA
| | - Brandon Malone
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, 10065 USA
| | - Eliza Llewellyn
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, 10065 USA
| | - Michael Grasso
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, 10065 USA
| | - Patrick M M Shelton
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, 10065 USA
| | - Paul Dominic B Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, 10065 USA
| | - Kashyap Maruthi
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027 USA
| | - Ed Eng
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027 USA
| | - Hasan Vatandaslar
- Institute of Molecular Health Sciences, ETH Zurich, 8093 Zürich, Switzerland
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, 10065 USA
| | - Tarun Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, 10065 USA
| | - Seth A Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, 10065 USA
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, 10065 USA
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135
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Vilas JL, Heymann JB, Tagare HD, Ramirez-Aportela E, Carazo JM, Sorzano C. Local resolution estimates of cryoEM reconstructions. Curr Opin Struct Biol 2020; 64:74-78. [PMID: 32645578 DOI: 10.1016/j.sbi.2020.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/28/2020] [Accepted: 06/04/2020] [Indexed: 11/16/2022]
Abstract
The field of cryoEM has quickly advanced in last years with the new biochemical, technological, methodological and computational developments. It has allowed significant progresses in Structural Biology, typically reaching quasi-atomic resolutions in the reconstructed maps. However, this rapid advance has also generated new questions relevant to resolution estimates. The global resolution metrics and their criteria have been deeply discussed in the last decade, but despite that, it remains as an important issue in the field. Recently, the introduction of local resolution measurements has changed how cryoEM reconstructions are interpreted, providing information about the existence of heterogeneity, flexibility, and angular assignment errors, and using it as a tool to aid in modeling. In this review we revisit the concept of local resolution and the different algorithms in the current state of the art. However, the concept of local resolution is not uniquely defined, and each implementation measures different features. This may lead to inappropriate interpretation of local resolution maps. Hence, a set of good practices is provided in this review to avoid misleading and over-interpretation of the reconstructions.
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Affiliation(s)
- J L Vilas
- Department of Biomedical Engineering, Yale University, New Haven, United States
| | - J B Heymann
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - H D Tagare
- Department of Biomedical Engineering, Yale University, New Haven, United States
| | - E Ramirez-Aportela
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - J M Carazo
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - Cos Sorzano
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain; Univ. San Pablo-CEU, Campus Urb. Monteprincipe, 28668 Boadilla del Monte, Madrid, Spain.
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136
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Tan YZ, Rodrigues J, Keener JE, Zheng RB, Brunton R, Kloss B, Giacometti SI, Rosário AL, Zhang L, Niederweis M, Clarke OB, Lowary TL, Marty MT, Archer M, Potter CS, Carragher B, Mancia F. Cryo-EM structure of arabinosyltransferase EmbB from Mycobacterium smegmatis. Nat Commun 2020; 11:3396. [PMID: 32636380 PMCID: PMC7341804 DOI: 10.1038/s41467-020-17202-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/18/2020] [Indexed: 01/21/2023] Open
Abstract
Arabinosyltransferase B (EmbB) belongs to a family of membrane-bound glycosyltransferases that build the lipidated polysaccharides of the mycobacterial cell envelope, and are targets of anti-tuberculosis drug ethambutol. We present the 3.3 Å resolution single-particle cryo-electron microscopy structure of Mycobacterium smegmatis EmbB, providing insights on substrate binding and reaction mechanism. Mutations that confer ethambutol resistance map mostly around the putative active site, suggesting this to be the location of drug binding.
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Affiliation(s)
- Yong Zi Tan
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA
- National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027, USA
| | - José Rodrigues
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), 2780-157, Oeiras, Portugal
| | - James E Keener
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Ruixiang Blake Zheng
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Richard Brunton
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Brian Kloss
- Center on Membrane Protein Production and Analysis, New York Structural Biology Center, New York, NY, 10027, USA
| | - Sabrina I Giacometti
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Ana L Rosário
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), 2780-157, Oeiras, Portugal
| | - Lei Zhang
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA
- Department of Anesthesiology, Columbia University, New York, NY, 10032, USA
| | - Todd L Lowary
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
- Institute of Biological Chemistry, Academia Sinica, Academia Road, Section 2, #128, Nangang, Taipei, 11529, Taiwan
| | - Michael T Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
- Bio5 Institute, University of Arizona, Tucson, AZ, 85721, USA
| | - Margarida Archer
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), 2780-157, Oeiras, Portugal
| | - Clinton S Potter
- National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027, USA
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Bridget Carragher
- National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027, USA.
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, 10027, USA.
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, 10032, USA.
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA.
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137
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Loveland AB, Demo G, Korostelev AA. Cryo-EM of elongating ribosome with EF-Tu•GTP elucidates tRNA proofreading. Nature 2020; 584:640-645. [PMID: 32612237 PMCID: PMC7483604 DOI: 10.1038/s41586-020-2447-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 04/10/2020] [Indexed: 11/13/2022]
Abstract
Ribosomes accurately decode mRNA by proofreading each aminoacyl-tRNA delivered by elongation factor EF-Tu1. Understanding the molecular mechanism of proofreading requires visualizing GTP-catalyzed elongation, which has remained a challenge2–4. Here, time-resolved cryo-EM revealed 33 states following aminoacyl-tRNA delivery by EF-Tu•GTP. Instead of locking cognate tRNA upon initial recognition, the ribosomal decoding center (DC) dynamically monitors codon-anticodon interactions before and after GTP hydrolysis. GTP hydrolysis allows EF-Tu’s GTPase domain to extend away, releasing EF-Tu from tRNA. Then, the 30S subunit locks cognate tRNA in the DC, and rotates, enabling the tRNA to bypass 50S protrusions during accommodation into the peptidyl transferase center. By contrast, the DC fails to lock near-cognate tRNA, allowing dissociation of near-cognate tRNA during both initial selection (before GTP hydrolysis) and proofreading (after GTP hydrolysis). These findings reveal structural similarity between initial selection5,6 and the previously unseen proofreading, which together govern efficient rejection of incorrect tRNA.
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Affiliation(s)
- Anna B Loveland
- RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Gabriel Demo
- RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Andrei A Korostelev
- RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.
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138
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Zimmet A, Van Eeuwen T, Boczkowska M, Rebowski G, Murakami K, Dominguez R. Cryo-EM structure of NPF-bound human Arp2/3 complex and activation mechanism. SCIENCE ADVANCES 2020; 6:6/23/eaaz7651. [PMID: 32917641 PMCID: PMC7274804 DOI: 10.1126/sciadv.aaz7651] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 04/16/2020] [Indexed: 05/12/2023]
Abstract
Actin-related protein (Arp) 2/3 complex nucleates branched actin networks that drive cell motility. It consists of seven proteins, including two actin-related subunits (Arp2 and Arp3). Two nucleation-promoting factors (NPFs) bind Arp2/3 complex during activation, but the order, specific interactions, and contribution of each NPF to activation are unresolved. Here, we report the cryo-electron microscopy structure of recombinantly expressed human Arp2/3 complex with two WASP family NPFs bound and address the mechanism of activation. A cross-linking assay that captures the transition of the Arps into the activated filament-like conformation shows that actin binding to NPFs favors this transition. Actin-NPF binding to Arp2 precedes binding to Arp3 and is sufficient to promote the filament-like conformation but not activation. Structure-guided mutagenesis of the NPF-binding sites reveals their distinct roles in activation and shows that, contrary to budding yeast Arp2/3 complex, NPF-mediated delivery of actin at the barbed end of both Arps is required for activation of human Arp2/3 complex.
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Affiliation(s)
- Austin Zimmet
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Trevor Van Eeuwen
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malgorzata Boczkowska
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Grzegorz Rebowski
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kenji Murakami
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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139
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Benton DJ, Gamblin SJ, Rosenthal PB, Skehel JJ. Structural transitions in influenza haemagglutinin at membrane fusion pH. Nature 2020; 583:150-153. [PMID: 32461688 PMCID: PMC7116728 DOI: 10.1038/s41586-020-2333-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/16/2020] [Indexed: 12/22/2022]
Abstract
Infection by enveloped viruses involves fusion of their lipid envelopes with cellular membranes to release the viral genome into cells. For HIV, Ebola, influenza and numerous other viruses, envelope glycoproteins bind the infecting virion to cell-surface receptors and mediate membrane fusion. In the case of influenza, the receptor-binding glycoprotein is the haemagglutinin (HA), and following receptor-mediated uptake of the bound virus by endocytosis1, it is the HA that mediates fusion of the virus envelope with the membrane of the endosome2. Each subunit of the trimeric HA consists of two disulfide-linked polypeptides, HA1 and HA2. The larger, virus-membrane-distal, HA1 mediates receptor binding; the smaller, membrane-proximal, HA2 anchors HA in the envelope and contains the fusion peptide, a region that is directly involved in membrane interaction3. The low pH of endosomes activates fusion by facilitating irreversible conformational changes in the glycoprotein. The structures of the initial HA at neutral pH and the final HA at fusion pH have been investigated by electron microscopy4,5 and X-ray crystallography6–8. Here, to further study the process of fusion, we incubate HA for different times at pH 5.0 and directly image structural changes using single-particle cryo-electron microscopy. We describe three distinct, previously undescribed forms of HA, most notably a 150 Å-long triple-helical coil of HA2, which may bridge between the viral and endosomal membranes. Comparison of these structures reveals concerted conformational rearrangements through which the HA mediates membrane fusion.
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Affiliation(s)
- Donald J Benton
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK.
| | - Steven J Gamblin
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, Francis Crick Institute, London, UK.
| | - John J Skehel
- Structural Biology of Disease Processes Laboratory, Francis Crick Institute, London, UK
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140
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Shin M, Puchades C, Asmita A, Puri N, Adjei E, Wiseman RL, Karzai AW, Lander GC. Structural basis for distinct operational modes and protease activation in AAA+ protease Lon. SCIENCE ADVANCES 2020; 6:eaba8404. [PMID: 32490208 PMCID: PMC7239648 DOI: 10.1126/sciadv.aba8404] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/09/2020] [Indexed: 05/21/2023]
Abstract
Substrate-bound structures of AAA+ protein translocases reveal a conserved asymmetric spiral staircase architecture wherein a sequential ATP hydrolysis cycle drives hand-over-hand substrate translocation. However, this configuration is unlikely to represent the full conformational landscape of these enzymes, as biochemical studies suggest distinct conformational states depending on the presence or absence of substrate. Here, we used cryo-electron microscopy to determine structures of the Yersinia pestis Lon AAA+ protease in the absence and presence of substrate, uncovering the mechanistic basis for two distinct operational modes. In the absence of substrate, Lon adopts a left-handed, "open" spiral organization with autoinhibited proteolytic active sites. Upon the addition of substrate, Lon undergoes a reorganization to assemble an enzymatically active, right-handed "closed" conformer with active protease sites. These findings define the mechanistic principles underlying the operational plasticity required for processing diverse protein substrates.
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Affiliation(s)
- Mia Shin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Cristina Puchades
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ananya Asmita
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Neha Puri
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Eric Adjei
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - R. Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - A. Wali Karzai
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Gabriel C. Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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141
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Expression of quasi-equivalence and capsid dimorphism in the Hepadnaviridae. PLoS Comput Biol 2020; 16:e1007782. [PMID: 32310951 PMCID: PMC7192502 DOI: 10.1371/journal.pcbi.1007782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 04/30/2020] [Accepted: 03/10/2020] [Indexed: 12/13/2022] Open
Abstract
Hepatitis B virus (HBV) is a leading cause of liver disease. The capsid is an essential component of the virion and it is therefore of interest how it assembles and disassembles. The capsid protein is unusual both for its rare fold and that it polymerizes according to two different icosahedral symmetries, causing the polypeptide chain to exist in seven quasi-equivalent environments: A, B, and C in AB and CC dimers in T = 3 capsids, and A, B, C, and D in AB and CD dimers in T = 4 capsids. We have compared the two capsids by cryo-EM at 3.5 Å resolution. To ensure a valid comparison, the two capsids were prepared and imaged under identical conditions. We find that the chains have different conformations and potential energies, with the T = 3 C chain having the lowest. Three of the four quasi-equivalent dimers are asymmetric with respect to conformation and potential energy; however, the T = 3 CC dimer is symmetrical and has the lowest potential energy although its intra-dimer interface has the least free energy of formation. Of all the inter-dimer interfaces, the CB interface has the least area and free energy, in both capsids. From the calculated energies of higher-order groupings of dimers discernible in the lattices we predict early assembly intermediates, and indeed we observe such structures by negative stain EM of in vitro assembly reactions. By sequence analysis and computational alanine scanning we identify key residues and motifs involved in capsid assembly. Our results explain several previously reported observations on capsid assembly, disassembly, and dimorphism. Hepatitis B virus has infected approximately one third of the human population and causes almost 1 million deaths from liver disease annually. The capsid is a defining feature of a virus, distinct from host components, and therefore a target for intervention. Unusually for a virus, Hepatitis B assembles two capsids, with different geometries, from the same dimeric protein. Geometric principles dictate that the subunits in this system occupy seven different environments. From comparing the two capsids by cryo-electron microscopy at high resolution under the exact same conditions we find that the polypeptide chains adopt seven different conformations. We use these structures to calculate potential energies (analogous to elastic deformation or strain) for the individual chains, dimers, and several higher-order groupings discernible in the two lattices. We also calculate the binding energies between chains. We find that some groupings have substantially lower energy and are therefore potentially more stable, allowing us to predict likely intermediates on the two assembly pathways. We also observe such intermediates by electron microscopy of in vitro capsid assembly reactions. This is the first structural characterization of the early assembly intermediates of this important human pathogen.
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142
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Beckers M, Palmer CM, Sachse C. Confidence maps: statistical inference of cryo-EM maps. Acta Crystallogr D Struct Biol 2020; 76:332-339. [PMID: 32254057 PMCID: PMC7137106 DOI: 10.1107/s2059798320002995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/03/2020] [Indexed: 11/11/2022] Open
Abstract
Confidence maps provide complementary information for interpreting cryo-EM densities as they indicate statistical significance with respect to background noise. They can be thresholded by specifying the expected false-discovery rate (FDR), and the displayed volume shows the parts of the map that have the corresponding level of significance. Here, the basic statistical concepts of confidence maps are reviewed and practical guidance is provided for their interpretation and usage inside the CCP-EM suite. Limitations of the approach are discussed and extensions towards other error criteria such as the family-wise error rate are presented. The observed map features can be rendered at a common isosurface threshold, which is particularly beneficial for the interpretation of weak and noisy densities. In the current article, a practical guide is provided to the recommended usage of confidence maps.
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Affiliation(s)
- Maximilian Beckers
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Colin M. Palmer
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Carsten Sachse
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons 3/Structural Biology, Forschungszentrum Jülich, 52425 Jülich, Germany
- JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425 Jülich, Germany
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143
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Koukos P, Bonvin A. Integrative Modelling of Biomolecular Complexes. J Mol Biol 2020; 432:2861-2881. [DOI: 10.1016/j.jmb.2019.11.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022]
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144
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Dodd T, Yan C, Ivanov I. Simulation-Based Methods for Model Building and Refinement in Cryoelectron Microscopy. J Chem Inf Model 2020; 60:2470-2483. [PMID: 32202798 DOI: 10.1021/acs.jcim.0c00087] [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] [Indexed: 11/29/2022]
Abstract
Advances in cryoelectron microscopy (cryo-EM) have revolutionized the structural investigation of large macromolecular assemblies. In this review, we first provide a broad overview of modeling methods used for flexible fitting of molecular models into cryo-EM density maps. We give special attention to approaches rooted in molecular simulations-atomistic molecular dynamics and Monte Carlo. Concise descriptions of the methods are given along with discussion of their advantages, limitations, and most popular alternatives. We also describe recent extensions of the widely used molecular dynamics flexible fitting (MDFF) method and discuss how different model-building techniques could be incorporated into new hybrid modeling schemes and simulation workflows. Finally, we provide two illustrative examples of model-building and refinement strategies employing MDFF, cascade MDFF, and RosettaCM. These examples come from recent cryo-EM studies that elucidated transcription preinitiation complexes and shed light on the functional roles of these assemblies in gene expression and gene regulation.
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Affiliation(s)
- Thomas Dodd
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
| | - Chunli Yan
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
| | - Ivaylo Ivanov
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
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145
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Arnold FM, Weber MS, Gonda I, Gallenito MJ, Adenau S, Egloff P, Zimmermann I, Hutter CAJ, Hürlimann LM, Peters EE, Piel J, Meloni G, Medalia O, Seeger MA. The ABC exporter IrtAB imports and reduces mycobacterial siderophores. Nature 2020; 580:413-417. [PMID: 32296173 PMCID: PMC7170716 DOI: 10.1038/s41586-020-2136-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/24/2020] [Indexed: 12/17/2022]
Abstract
Intracellular replication of the deadly pathogen Mycobacterium tuberculosis relies on the production of small organic molecules called siderophores to scavenge iron from host proteins1. M. tuberculosis produces two classes of siderophores, lipid-bound mycobactin and soluble carboxymycobactin2, 3. Functional studies revealed that iron-loaded carboxymycobactin is imported into the cytoplasm by the ABC transporter IrtAB4, which features an additional cytoplasmic siderophore interaction domain (SID)5. However, IrtAB’s predicted ABC exporter fold seemingly contradicts its import function. Here, we show that membrane-reconstituted IrtAB is sufficient to import mycobactins, which are then reduced by the SID to facilitate iron release. Structure determination by X-ray crystallography and cryo-EM confirms IrtAB’s ABC exporter fold, but also reveals structural peculiarities at the transmembrane region of IrtAB resulting in a partially collapsed inward-facing substrate binding cavity. The SID is positioned in close proximity to the inner membrane leaflet, which allows the reduction of membrane-inserted mycobactin. Enzymatic ATPase activity and in vivo growth assays show that IrtAB prefers mycobactin over carboxymycobactin as its substrate. Our study provides insights into an unusual ABC exporter that evolved as highly specialized siderophore import machinery in mycobacteria.
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Affiliation(s)
- Fabian M Arnold
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Miriam S Weber
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Imre Gonda
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Marc J Gallenito
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, TX, USA
| | - Sophia Adenau
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Pascal Egloff
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.,Linkster Therapeutics, Zurich, Switzerland
| | - Iwan Zimmermann
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.,Linkster Therapeutics, Zurich, Switzerland
| | - Cedric A J Hutter
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Lea M Hürlimann
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Eike E Peters
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Jörn Piel
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, TX, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
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146
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Stepwise Promoter Melting by Bacterial RNA Polymerase. Mol Cell 2020; 78:275-288.e6. [PMID: 32160514 DOI: 10.1016/j.molcel.2020.02.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/21/2020] [Accepted: 02/19/2020] [Indexed: 01/22/2023]
Abstract
Transcription initiation requires formation of the open promoter complex (RPo). To generate RPo, RNA polymerase (RNAP) unwinds the DNA duplex to form the transcription bubble and loads the DNA into the RNAP active site. RPo formation is a multi-step process with transient intermediates of unknown structure. We use single-particle cryoelectron microscopy to visualize seven intermediates containing Escherichia coli RNAP with the transcription factor TraR en route to forming RPo. The structures span the RPo formation pathway from initial recognition of the duplex promoter in a closed complex to the final RPo. The structures and supporting biochemical data define RNAP and promoter DNA conformational changes that delineate steps on the pathway, including previously undetected transient promoter-RNAP interactions that contribute to populating the intermediates but do not occur in RPo. Our work provides a structural basis for understanding RPo formation and its regulation, a major checkpoint in gene expression throughout evolution.
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147
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Wu M, Lander GC, Herzik MA. Sub-2 Angstrom resolution structure determination using single-particle cryo-EM at 200 keV. J Struct Biol X 2020; 4:100020. [PMID: 32647824 PMCID: PMC7337053 DOI: 10.1016/j.yjsbx.2020.100020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 11/30/2022] Open
Abstract
Although the advent of direct electron detectors (DEDs) and software developments have enabled the routine use of single-particle cryogenic electron microscopy (cryo-EM) for structure determination of well-behaved specimens to high-resolution, there nonetheless remains a discrepancy between the resolutions attained for biological specimens and the information limits of modern transmission electron microscopes (TEMs). Instruments operating at 300 kV equipped with DEDs are the current paradigm for high-resolution single-particle cryo-EM, while 200 kV TEMs remain comparatively underutilized for purposes beyond sample screening. Here, we expand upon our prior work and demonstrate that one such 200 kV microscope, the Talos Arctica, equipped with a K2 DED is capable of determining structures of macromolecules to as high as ∼1.7 Å resolution. At this resolution, ordered water molecules are readily assigned and holes in aromatic residues can be clearly distinguished in the reconstructions. This work emphasizes the utility of 200 kV electrons for high-resolution single-particle cryo-EM and applications such as structure-based drug design.
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Affiliation(s)
- Mengyu Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Gabriel C. Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Mark A. Herzik
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, United States
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148
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Abstract
Cross-validation is used to determine the validity of a model on unseen data by assessing if the model is overfitted to noise. It is widely used in many fields, from artificial intelligence to structural biology in X-ray crystallography and nuclear magnetic resonance. Although there are concerns of map overfitting in cryo-electron microscopy (cryo-EM), cross-validation is rarely used. The problem is that establishing a performance metric of the maps over unseen data (given by 2D-projection images) is difficult due to the low signal-to-noise ratios in the individual particles. Here, I present recent advances for cryo-EM map reconstruction. I highlight that the gold-standard procedure can fail to detect map overfitting in certain cases, showing the necessity of assessing the map quality on unbiased data. Finally, I describe the challenges and advantages of developing a robust cross-validation methodology for cryo-EM.
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Affiliation(s)
- Pilar Cossio
- Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia UdeA, Calle 70 No. 52-21, Medellin, Colombia.,Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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149
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Rougé L, Chiang N, Steffek M, Kugel C, Croll TI, Tam C, Estevez A, Arthur CP, Koth CM, Ciferri C, Kraft E, Payandeh J, Nakamura G, Koerber JT, Rohou A. Structure of CD20 in complex with the therapeutic monoclonal antibody rituximab. Science 2020; 367:1224-1230. [PMID: 32079680 DOI: 10.1126/science.aaz9356] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 02/06/2020] [Indexed: 12/13/2022]
Abstract
Cluster of differentiation 20 (CD20) is a B cell membrane protein that is targeted by monoclonal antibodies for the treatment of malignancies and autoimmune disorders but whose structure and function are unknown. Rituximab (RTX) has been in clinical use for two decades, but how it activates complement to kill B cells remains poorly understood. We obtained a structure of CD20 in complex with RTX, revealing CD20 as a compact double-barrel dimer bound by two RTX antigen-binding fragments (Fabs), each of which engages a composite epitope and an extensive homotypic Fab:Fab interface. Our data suggest that RTX cross-links CD20 into circular assemblies and lead to a structural model for complement recruitment. Our results further highlight the potential relevance of homotypic Fab:Fab interactions in targeting oligomeric cell-surface markers.
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Affiliation(s)
- Lionel Rougé
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Nancy Chiang
- Department of Antibody Engineering, Genentech Inc., South San Francisco, CA 94080, USA
| | - Micah Steffek
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Christine Kugel
- Department of Biomolecular Resources, Genentech Inc., South San Francisco, CA 94080, USA
| | - Tristan I Croll
- Cambridge Institute for Medical Research, University of Cambridge, Keith Peters Building, Cambridge CB2 0XY, UK
| | - Christine Tam
- Department of Biomolecular Resources, Genentech Inc., South San Francisco, CA 94080, USA
| | - Alberto Estevez
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Christopher P Arthur
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Christopher M Koth
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Claudio Ciferri
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | - Edward Kraft
- Department of Biomolecular Resources, Genentech Inc., South San Francisco, CA 94080, USA
| | - Jian Payandeh
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA. .,Department of Antibody Engineering, Genentech Inc., South San Francisco, CA 94080, USA
| | - Gerald Nakamura
- Department of Antibody Engineering, Genentech Inc., South San Francisco, CA 94080, USA.
| | - James T Koerber
- Department of Antibody Engineering, Genentech Inc., South San Francisco, CA 94080, USA.
| | - Alexis Rohou
- Department of Structural Biology, Genentech Inc., South San Francisco, CA 94080, USA.
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150
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Structural basis of ligand recognition and self-activation of orphan GPR52. Nature 2020; 579:152-157. [PMID: 32076264 DOI: 10.1038/s41586-020-2019-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/23/2020] [Indexed: 11/08/2022]
Abstract
GPR52 is a class-A orphan G-protein-coupled receptor that is highly expressed in the brain and represents a promising therapeutic target for the treatment of Huntington's disease and several psychiatric disorders1,2. Pathological malfunction of GPR52 signalling occurs primarily through the heterotrimeric Gs protein2, but it is unclear how GPR52 and Gs couple for signal transduction and whether a native ligand or other activating input is required. Here we present the high-resolution structures of human GPR52 in three states: a ligand-free state, a Gs-coupled self-activation state and a potential allosteric ligand-bound state. Together, our structures reveal that extracellular loop 2 occupies the orthosteric binding pocket and operates as a built-in agonist, conferring an intrinsically high level of basal activity to GPR523. A fully active state is achieved when Gs is coupled to GPR52 in the absence of an external agonist. The receptor also features a side pocket for ligand binding. These insights into the structure and function of GPR52 could improve our understanding of other self-activated GPCRs, enable the identification of endogenous and tool ligands, and guide drug discovery efforts that target GPR52.
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