4251
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Forsberg BO, Aibara S, Kimanius D, Paul B, Lindahl E, Amunts A. Cryo-EM reconstruction of the chlororibosome to 3.2 Å resolution within 24 h. IUCRJ 2017; 4:723-727. [PMID: 29123673 PMCID: PMC5668856 DOI: 10.1107/s205225251701226x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
The introduction of direct detectors and the automation of data collection in cryo-EM have led to a surge in data, creating new opportunities for advancing computational processing. In particular, on-the-fly workflows that connect data collection with three-dimensional reconstruction would be valuable for more efficient use of cryo-EM and its application as a sample-screening tool. Here, accelerated on-the-fly analysis is reported with optimized organization of the data-processing tools, image acquisition and particle alignment that make it possible to reconstruct the three-dimensional density of the 70S chlororibosome to 3.2 Å resolution within 24 h of tissue harvesting. It is also shown that it is possible to achieve even faster processing at comparable quality by imposing some limits to data use, as illustrated by a 3.7 Å resolution map that was obtained in only 80 min on a desktop computer. These on-the-fly methods can be employed as an assessment of data quality from small samples and extended to high-throughput approaches.
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Affiliation(s)
- Björn O. Forsberg
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Shintaro Aibara
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Dari Kimanius
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Bijoya Paul
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Erik Lindahl
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
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4252
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Baldwin PR, Tan YZ, Eng ET, Rice WJ, Noble AJ, Negro CJ, Cianfrocco MA, Potter CS, Carragher B. Big data in cryoEM: automated collection, processing and accessibility of EM data. Curr Opin Microbiol 2017; 43:1-8. [PMID: 29100109 DOI: 10.1016/j.mib.2017.10.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/27/2017] [Accepted: 10/09/2017] [Indexed: 11/24/2022]
Abstract
The scope and complexity of cryogenic electron microscopy (cryoEM) data has greatly increased, and will continue to do so, due to recent and ongoing technical breakthroughs that have led to much improved resolutions for macromolecular structures solved using this method. This big data explosion includes single particle data as well as tomographic tilt series, both generally acquired as direct detector movies of ∼10-100 frames per image or per tilt-series. We provide a brief survey of the developments leading to the current status, and describe existing cryoEM pipelines, with an emphasis on the scope of data acquisition, methods for automation, and use of cloud storage and computing.
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Affiliation(s)
- Philip R Baldwin
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - Yong Zi Tan
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edward T Eng
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - William J Rice
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - Alex J Noble
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - Carl J Negro
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - Michael A Cianfrocco
- Life Sciences Institute and Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Clinton S Potter
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Bridget Carragher
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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4253
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Guo H, Bueler SA, Rubinstein JL. Atomic model for the dimeric F O region of mitochondrial ATP synthase. Science 2017; 358:936-940. [PMID: 29074581 DOI: 10.1126/science.aao4815] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/11/2017] [Indexed: 01/01/2023]
Abstract
Mitochondrial adenosine triphosphate (ATP) synthase produces the majority of ATP in eukaryotic cells, and its dimerization is necessary to create the inner membrane folds, or cristae, characteristic of mitochondria. Proton translocation through the membrane-embedded FO region turns the rotor that drives ATP synthesis in the soluble F1 region. Although crystal structures of the F1 region have illustrated how this rotation leads to ATP synthesis, understanding how proton translocation produces the rotation has been impeded by the lack of an experimental atomic model for the FO region. Using cryo-electron microscopy, we determined the structure of the dimeric FO complex from Saccharomyces cerevisiae at a resolution of 3.6 angstroms. The structure clarifies how the protons travel through the complex, how the complex dimerizes, and how the dimers bend the membrane to produce cristae.
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Affiliation(s)
- Hui Guo
- Hospital for Sick Children Research Institute, Toronto, Ontario M5G 0A4, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Stephanie A Bueler
- Hospital for Sick Children Research Institute, Toronto, Ontario M5G 0A4, Canada
| | - John L Rubinstein
- Hospital for Sick Children Research Institute, Toronto, Ontario M5G 0A4, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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4254
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Achieving better-than-3-Å resolution by single-particle cryo-EM at 200 keV. Nat Methods 2017; 14:1075-1078. [PMID: 28991891 PMCID: PMC5679434 DOI: 10.1038/nmeth.4461] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/29/2017] [Indexed: 12/12/2022]
Abstract
Nearly 98% of single particle cryo-EM structures resolved to better than 4 Å resolution have been determined using 300 keV transmission electron microscopes. We demonstrate that it is possible to obtain reconstructions of macromolecular complexes at a range of sizes to better than 3 Å resolution using a 200 keV transmission electron microscope. These structures are of sufficient quality to unambiguously assign amino acid rotameric conformations and identify ordered water molecules.
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4255
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Ereño-Orbea J, Sicard T, Cui H, Mazhab-Jafari MT, Benlekbir S, Guarné A, Rubinstein JL, Julien JP. Molecular basis of human CD22 function and therapeutic targeting. Nat Commun 2017; 8:764. [PMID: 28970495 PMCID: PMC5624926 DOI: 10.1038/s41467-017-00836-6] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 07/28/2017] [Indexed: 12/13/2022] Open
Abstract
CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As a B-cell-restricted antigen, CD22 is targeted in therapies against dysregulated B cells that cause autoimmune diseases and blood cancers. Here we report the crystal structure of human CD22 at 2.1 Å resolution, which reveals that specificity for α2-6 sialic acid ligands is dictated by a pre-formed β-hairpin as a unique mode of recognition across sialic acid-binding immunoglobulin-type lectins. The CD22 ectodomain adopts an extended conformation that facilitates concomitant CD22 nanocluster formation on B cells and binding to trans ligands to avert autoimmunity in mammals. We structurally delineate the CD22 site targeted by the therapeutic antibody epratuzumab at 3.1 Å resolution and determine a critical role for CD22 N-linked glycosylation in antibody engagement. Our studies provide molecular insights into mechanisms governing B-cell inhibition and valuable clues for the design of immune modulators in B-cell dysfunction.The B-cell-specific co-receptor CD22 is a therapeutic target for depleting dysregulated B cells. Here the authors structurally characterize the ectodomain of CD22 and present its crystal structure with the bound therapeutic antibody epratuzumab, which gives insights into the mechanism of inhibition of B-cell activation.
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Affiliation(s)
- June Ereño-Orbea
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
| | - Taylor Sicard
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Hong Cui
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
| | - Mohammad T Mazhab-Jafari
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
| | - Samir Benlekbir
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
| | - Alba Guarné
- Department of Biochemistry and Biomedical Science, McMaster University, Hamilton, ON, Canada, L8S 4L8
| | - John L Rubinstein
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, M5G 1L7
| | - Jean-Philippe Julien
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada, M5G 0A4.
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8.
- Department of Immunology, University of Toronto, Toronto, ON, Canada, M5S 1A8.
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4256
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Jiang W, Tang L. Atomic cryo-EM structures of viruses. Curr Opin Struct Biol 2017; 46:122-129. [PMID: 28787658 PMCID: PMC5683926 DOI: 10.1016/j.sbi.2017.07.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/12/2017] [Accepted: 07/19/2017] [Indexed: 01/30/2023]
Abstract
During the development of single particle cryo-EM in past five decades, icosahedral viruses have led the resolution progress owing to their large mass and high symmetry. Many technical advances in cryo-EM were first established with viruses. Since reaching ∼4Å resolution in 2008, it has become a relatively routine task to solve the atomic structure of isolated viruses. The future of structural virology will be increasingly focused on remaining challenges including solving structures of jumbo viruses, intermediate functional states during assembly, maturation, and infection, and in situ structures. Recent demonstrations of near-atomic resolution structure with electron tomography and sub-tomogram averaging opens a new direction for high resolution studies of pleomorphic viruses and the pleomorphic states of icosahedral viruses that have defied past efforts using the single particle cryo-EM approach.
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Affiliation(s)
- Wen Jiang
- Department of Biological Sciences, Immunology and Infectious Disease, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907, USA; Department of Chemistry, Immunology and Infectious Disease, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907, USA; Markey Center for Structural Biology, Immunology and Infectious Disease, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907, USA; Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907, USA.
| | - Liang Tang
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA.
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4257
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Asymmetric Cryo-EM Structure of Anthrax Toxin Protective Antigen Pore with Lethal Factor N-Terminal Domain. Toxins (Basel) 2017; 9:toxins9100298. [PMID: 28937604 PMCID: PMC5666345 DOI: 10.3390/toxins9100298] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 11/17/2022] Open
Abstract
The anthrax lethal toxin consists of protective antigen (PA) and lethal factor (LF). Understanding both the PA pore formation and LF translocation through the PA pore is crucial to mitigating and perhaps preventing anthrax disease. To better understand the interactions of the LF-PA engagement complex, the structure of the LFN-bound PA pore solubilized by a lipid nanodisc was examined using cryo-EM. CryoSPARC was used to rapidly sort particle populations of a heterogeneous sample preparation without imposing symmetry, resulting in a refined 17 Å PA pore structure with 3 LFN bound. At pH 7.5, the contributions from the three unstructured LFN lysine-rich tail regions do not occlude the Phe clamp opening. The open Phe clamp suggests that, in this translocation-compromised pH environment, the lysine-rich tails remain flexible and do not interact with the pore lumen region.
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4258
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Greenberg I, Shkolnisky Y. Common lines modeling for reference free Ab-initio reconstruction in cryo-EM. J Struct Biol 2017; 200:106-117. [PMID: 28943480 DOI: 10.1016/j.jsb.2017.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 09/17/2017] [Accepted: 09/20/2017] [Indexed: 10/18/2022]
Abstract
We consider the problem of estimating an unbiased and reference-free ab initio model for non-symmetric molecules from images generated by single-particle cryo-electron microscopy. The proposed algorithm finds the globally optimal assignment of orientations that simultaneously respects all common lines between all images. The contribution of each common line to the estimated orientations is weighted according to a statistical model for common lines' detection errors. The key property of the proposed algorithm is that it finds the global optimum for the orientations given the common lines. In particular, any local optima in the common lines energy landscape do not affect the proposed algorithm. As a result, it is applicable to thousands of images at once, very robust to noise, completely reference free, and not biased towards any initial model. A byproduct of the algorithm is a set of measures that allow to asses the reliability of the obtained ab initio model. We demonstrate the algorithm using class averages from two experimental data sets, resulting in ab initio models with resolutions of 20Å or better, even from class averages consisting of as few as three raw images per class.
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Affiliation(s)
- Ido Greenberg
- Department of Applied Mathematics, School of Mathematical Sciences, Tel-Aviv University, Israel.
| | - Yoel Shkolnisky
- Department of Applied Mathematics, School of Mathematical Sciences, Tel-Aviv University, Israel.
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4259
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Measuring the effects of particle orientation to improve the efficiency of electron cryomicroscopy. Nat Commun 2017; 8:629. [PMID: 28931821 PMCID: PMC5607000 DOI: 10.1038/s41467-017-00782-3] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 07/27/2017] [Indexed: 11/29/2022] Open
Abstract
The orientation distribution of a single-particle electron cryomicroscopy specimen limits the resolution of the reconstructed density map. Here we define a statistical quantity, the efficiency, Eod, which characterises the orientation distribution via its corresponding point spread function. The efficiency measures the ability of the distribution to provide uniform information and resolution in all directions of the reconstruction, independent of other factors. This metric allows rapid and rigorous evaluation of specimen preparation methods, assisting structure determination to high resolution with minimal data. A number of parameters influence the resolution of a cryo-EM structure. Here the authors investigate the effects of specimen orientation in single particle cryo-EM and present open-source software for rapidly assessing orientation distributions to improve data collection.
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4260
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Reboul CF, Eager M, Elmlund D, Elmlund H. Single-particle cryo-EM-Improved ab initio 3D reconstruction with SIMPLE/PRIME. Protein Sci 2017; 27:51-61. [PMID: 28795512 DOI: 10.1002/pro.3266] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/30/2017] [Accepted: 08/02/2017] [Indexed: 12/14/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) and single-particle analysis now enables the determination of high-resolution structures of macromolecular assemblies that have resisted X-ray crystallography and other approaches. We developed the SIMPLE open-source image-processing suite for analysing cryo-EM images of single-particles. A core component of SIMPLE is the probabilistic PRIME algorithm for identifying clusters of images in 2D and determine relative orientations of single-particle projections in 3D. Here, we extend our previous work on PRIME and introduce new stochastic optimization algorithms that improve the robustness of the approach. Our refined method for identification of homogeneous subsets of images in accurate register substantially improves the resolution of the cluster centers and of the ab initio 3D reconstructions derived from them. We now obtain maps with a resolution better than 10 Å by exclusively processing cluster centers. Excellent parallel code performance on over-the-counter laptops and CPU workstations is demonstrated.
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Affiliation(s)
- Cyril F Reboul
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Michael Eager
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Dominika Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Hans Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
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4261
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4262
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Deville C, Carroni M, Franke KB, Topf M, Bukau B, Mogk A, Saibil HR. Structural pathway of regulated substrate transfer and threading through an Hsp100 disaggregase. SCIENCE ADVANCES 2017; 3:e1701726. [PMID: 28798962 PMCID: PMC5544394 DOI: 10.1126/sciadv.1701726] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/05/2017] [Indexed: 05/03/2023]
Abstract
Refolding aggregated proteins is essential in combating cellular proteotoxic stress. Together with Hsp70, Hsp100 chaperones, including Escherichia coli ClpB, form a powerful disaggregation machine that threads aggregated polypeptides through the central pore of tandem adenosine triphosphatase (ATPase) rings. To visualize protein disaggregation, we determined cryo-electron microscopy structures of inactive and substrate-bound ClpB in the presence of adenosine 5'-O-(3-thiotriphosphate), revealing closed AAA+ rings with a pronounced seam. In the substrate-free state, a marked gradient of resolution, likely corresponding to mobility, spans across the AAA+ rings with a dynamic hotspot at the seam. On the seam side, the coiled-coil regulatory domains are locked in a horizontal, inactive orientation. On the opposite side, the regulatory domains are accessible for Hsp70 binding, substrate targeting, and activation. In the presence of the model substrate casein, the polypeptide threads through the entire pore channel and increased nucleotide occupancy correlates with higher ATPase activity. Substrate-induced domain displacements indicate a pathway of regulated substrate transfer from Hsp70 to the ClpB pore, inside which a spiral of loops contacts the substrate. The seam pore loops undergo marked displacements, along with ordering of the regulatory domains. These asymmetric movements suggest a mechanism for ATPase activation and substrate threading during disaggregation.
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Affiliation(s)
- Célia Deville
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Marta Carroni
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Kamila B. Franke
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Maya Topf
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Bernd Bukau
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Helen R. Saibil
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
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4263
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Murata K, Wolf M. Cryo-electron microscopy for structural analysis of dynamic biological macromolecules. Biochim Biophys Acta Gen Subj 2017; 1862:324-334. [PMID: 28756276 DOI: 10.1016/j.bbagen.2017.07.020] [Citation(s) in RCA: 175] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/22/2017] [Accepted: 07/25/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND Since the introduction of what became today's standard for cryo-embedding of biological macromolecules at native conditions more than 30years ago, techniques and equipment have been drastically improved and the structure of biomolecules can now be studied at near atomic resolution by cryo-electron microscopy (cryo-EM) while capturing multiple dynamic states. Here we review the recent progress in cryo-EM for structural studies of dynamic biological macromolecules. SCOPE OF REVIEW We provide an overview of the cryo-EM method and introduce contemporary studies to investigate biomolecular structure and dynamics, including examples from the recent literature. MAJOR CONCLUSIONS Cryo-EM is a powerful tool for the investigation of biological macromolecular structures including analysis of their dynamics by using advanced image-processing algorithms. The method has become even more widely applicable with present-day single particle analysis and electron tomography. GENERAL SIGNIFICANCE The cryo-EM method can be used to determine the three-dimensional structure of biomacromolecules in near native condition at close to atomic resolution, and has the potential to reveal conformations of dynamic molecular complexes. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato.
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Affiliation(s)
- Kazuyoshi Murata
- National Institute for Physiological Sciences, 38 Myodaiji, Okazaki, Aichi 444-8585, Japan.
| | - Matthias Wolf
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology, 7542 Onna, Onna-Son, Kunigami, Okinawa 904-0411, Japan.
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4264
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Wright AV, Liu JJ, Knott GJ, Doxzen KW, Nogales E, Doudna JA. Structures of the CRISPR genome integration complex. Science 2017; 357:1113-1118. [PMID: 28729350 DOI: 10.1126/science.aao0679] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 07/13/2017] [Indexed: 12/21/2022]
Abstract
CRISPR-Cas systems depend on the Cas1-Cas2 integrase to capture and integrate short foreign DNA fragments into the CRISPR locus, enabling adaptation to new viruses. We present crystal structures of Cas1-Cas2 bound to both donor and target DNA in intermediate and product integration complexes, as well as a cryo-electron microscopy structure of the full CRISPR locus integration complex, including the accessory protein IHF (integration host factor). The structures show unexpectedly that indirect sequence recognition dictates integration site selection by favoring deformation of the repeat and the flanking sequences. IHF binding bends the DNA sharply, bringing an upstream recognition motif into contact with Cas1 to increase both the specificity and efficiency of integration. These results explain how the Cas1-Cas2 CRISPR integrase recognizes a sequence-dependent DNA structure to ensure site-selective CRISPR array expansion during the initial step of bacterial adaptive immunity.
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Affiliation(s)
- Addison V Wright
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jun-Jie Liu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Gavin J Knott
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kevin W Doxzen
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. .,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.,Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.,Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA.,Center for RNA Systems Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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4265
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Addressing preferred specimen orientation in single-particle cryo-EM through tilting. Nat Methods 2017; 14:793-796. [PMID: 28671674 DOI: 10.1038/nmeth.4347] [Citation(s) in RCA: 558] [Impact Index Per Article: 79.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/18/2017] [Indexed: 12/18/2022]
Abstract
We present a strategy for tackling preferred specimen orientation in single-particle cryogenic electron microscopy by employing tilts during data collection. We also describe a tool to quantify the resulting directional resolution using 3D Fourier shell correlation volumes. We applied these methods to determine the structures at near-atomic resolution of the influenza hemagglutinin trimer, which adopts a highly preferred specimen orientation, and of ribosomal biogenesis intermediates, which adopt moderately preferred orientations.
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4266
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Clare DK, Siebert CA, Hecksel C, Hagen C, Mordhorst V, Grange M, Ashton AW, Walsh MA, Grünewald K, Saibil HR, Stuart DI, Zhang P. Electron Bio-Imaging Centre (eBIC): the UK national research facility for biological electron microscopy. Acta Crystallogr D Struct Biol 2017; 73:488-495. [PMID: 28580910 PMCID: PMC5458490 DOI: 10.1107/s2059798317007756] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 05/24/2017] [Indexed: 12/13/2022] Open
Abstract
The recent resolution revolution in cryo-EM has led to a massive increase in demand for both time on high-end cryo-electron microscopes and access to cryo-electron microscopy expertise. In anticipation of this demand, eBIC was set up at Diamond Light Source in collaboration with Birkbeck College London and the University of Oxford, and funded by the Wellcome Trust, the UK Medical Research Council (MRC) and the Biotechnology and Biological Sciences Research Council (BBSRC) to provide access to high-end equipment through peer review. eBIC is currently in its start-up phase and began by offering time on a single FEI Titan Krios microscope equipped with the latest generation of direct electron detectors from two manufacturers. Here, the current status and modes of access for potential users of eBIC are outlined. In the first year of operation, 222 d of microscope time were delivered to external research groups, with 95 visits in total, of which 53 were from unique groups. The data collected have generated multiple high- to intermediate-resolution structures (2.8-8 Å), ten of which have been published. A second Krios microscope is now in operation, with two more due to come online in 2017. In the next phase of growth of eBIC, in addition to more microscope time, new data-collection strategies and sample-preparation techniques will be made available to external user groups. Finally, all raw data are archived, and a metadata catalogue and automated pipelines for data analysis are being developed.
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Affiliation(s)
- Daniel K. Clare
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - C. Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Corey Hecksel
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Christoph Hagen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Valerie Mordhorst
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Michael Grange
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Alun W. Ashton
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Martin A. Walsh
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot OX11 0FA, England
| | - Kay Grünewald
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Helen R. Saibil
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Crystallography, Institute for Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, England
| | - David I. Stuart
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Peijun Zhang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
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4267
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Mechanistic Insights Into Catalytic RNA-Protein Complexes Involved in Translation of the Genetic Code. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017. [PMID: 28683922 DOI: 10.1016/bs.apcsb.2017.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The contemporary world is an "RNA-protein world" rather than a "protein world" and tracing its evolutionary origins is of great interest and importance. The different RNAs that function in close collaboration with proteins are involved in several key physiological processes, including catalysis. Ribosome-the complex megadalton cellular machinery that translates genetic information encoded in nucleotide sequence to amino acid sequence-epitomizes such an association between RNA and protein. RNAs that can catalyze biochemical reactions are known as ribozymes. They usually employ general acid-base catalytic mechanism, often involving the 2'-OH of RNA that activates and/or stabilizes a nucleophile during the reaction pathway. The protein component of such RNA-protein complexes (RNPCs) mostly serves as a scaffold which provides an environment conducive for the RNA to function, or as a mediator for other interacting partners. In this review, we describe those RNPCs that are involved at different stages of protein biosynthesis and in which RNA performs the catalytic function; the focus of the account is on highlighting mechanistic aspects of these complexes. We also provide a perspective on such associations in the context of proofreading during translation of the genetic code. The latter aspect is not much appreciated and recent works suggest that this is an avenue worth exploring, since an understanding of the subject can provide useful insights into how RNAs collaborate with proteins to ensure fidelity during these essential cellular processes. It may also aid in comprehending evolutionary aspects of such associations.
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4268
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Ripstein ZA, Huang R, Augustyniak R, Kay LE, Rubinstein JL. Structure of a AAA+ unfoldase in the process of unfolding substrate. eLife 2017; 6. [PMID: 28390173 PMCID: PMC5423775 DOI: 10.7554/elife.25754] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 04/06/2017] [Indexed: 12/19/2022] Open
Abstract
AAA+ unfoldases are thought to unfold substrate through the central pore of their hexameric structures, but how this process occurs is not known. VAT, the Thermoplasma acidophilum homologue of eukaryotic CDC48/p97, works in conjunction with the proteasome to degrade misfolded or damaged proteins. We show that in the presence of ATP, VAT with its regulatory N-terminal domains removed unfolds other VAT complexes as substrate. We captured images of this transient process by electron cryomicroscopy (cryo-EM) to reveal the structure of the substrate-bound intermediate. Substrate binding breaks the six-fold symmetry of the complex, allowing five of the six VAT subunits to constrict into a tight helix that grips an ~80 Å stretch of unfolded protein. The structure suggests a processive hand-over-hand unfolding mechanism, where each VAT subunit releases the substrate in turn before re-engaging further along the target protein, thereby unfolding it.
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Affiliation(s)
- Zev A Ripstein
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Rui Huang
- Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Rafal Augustyniak
- Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Lewis E Kay
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - John L Rubinstein
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada
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4269
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Biyani N, Righetto RD, McLeod R, Caujolle-Bert D, Castano-Diez D, Goldie KN, Stahlberg H. Focus: The interface between data collection and data processing in cryo-EM. J Struct Biol 2017; 198:124-133. [PMID: 28344036 DOI: 10.1016/j.jsb.2017.03.007] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 12/15/2022]
Abstract
We present a new software package called Focus that interfaces cryo-transmission electron microscopy (cryo-EM) data collection with computer image processing. Focus creates a user-friendly environment to import and manage data recorded by direct electron detectors and perform elemental image processing tasks in a high-throughput manner while new data is being acquired at the microscope. It provides the functionality required to remotely monitor the progress of data collection and data processing, which is essential now that automation in cryo-EM allows a steady flow of images of single particles, two-dimensional crystals, or electron tomography data to be recorded in overnight sessions. The rapid detection of any errors that may occur greatly increases the productivity of recording sessions at the electron microscope.
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Affiliation(s)
- Nikhil Biyani
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
| | - Ricardo D Righetto
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
| | - Robert McLeod
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
| | | | | | - Kenneth N Goldie
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland.
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