1
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Chan LM, Courteau BJ, Maker A, Wu M, Basanta B, Mehmood H, Bulkley D, Joyce D, Lee BC, Mick S, Czarnik C, Gulati S, Lander GC, Verba KA. High-resolution single-particle imaging at 100-200 keV with the Gatan Alpine direct electron detector. J Struct Biol 2024; 216:108108. [PMID: 38944401 DOI: 10.1016/j.jsb.2024.108108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/03/2024] [Accepted: 06/26/2024] [Indexed: 07/01/2024]
Abstract
Developments in direct electron detector technology have played a pivotal role in enabling high-resolution structural studies by cryo-EM at 200 and 300 keV. Yet, theory and recent experiments indicate advantages to imaging at 100 keV, energies for which the current detectors have not been optimized. In this study, we evaluated the Gatan Alpine detector, designed for operation at 100 and 200 keV. Compared to the Gatan K3, Alpine demonstrated a significant DQE improvement at these energies, specifically a ∼ 4-fold improvement at Nyquist at 100 keV. In single-particle cryo-EM experiments, Alpine datasets yielded better than 2 Å resolution reconstructions of apoferritin at 120 and 200 keV on a ThermoFisher Scientific (TFS) Glacios microscope fitted with a non-standard SP-Twin lens. We also achieved a ∼ 3.2 Å resolution reconstruction of a 115 kDa asymmetric protein complex, proving Alpine's effectiveness with complex biological samples. In-depth analysis revealed that Alpine reconstructions are comparable to K3 reconstructions at 200 keV, and remarkably, reconstruction from Alpine at 120 keV on a TFS Glacios surpassed all but the 300 keV data from a TFS Titan Krios with GIF/K3. Additionally, we show Alpine's capability for high-resolution data acquisition and screening on lower-end systems by obtaining ∼ 3 Å resolution reconstructions of apoferritin and aldolase at 100 keV and detailed 2D averages of a 55 kDa sample using a side-entry cryo holder. Overall, we show that Gatan Alpine performs well with the standard 200 keV imaging systems and may potentially capture the benefits of lower accelerating voltages, bringing smaller sized particles within the scope of cryo-EM.
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Affiliation(s)
- Lieza M Chan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Brandon J Courteau
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Allison Maker
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Mengyu Wu
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States
| | - Benjamin Basanta
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States
| | - Hev Mehmood
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - David Bulkley
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | | | | | | | | | | | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States.
| | - Kliment A Verba
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States.
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2
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Dickerson JL, McCubbin PTN, Brooks‐Bartlett JC, Garman EF. Doses for X-ray and electron diffraction: New features in RADDOSE-3D including intensity decay models. Protein Sci 2024; 33:e5005. [PMID: 38923423 PMCID: PMC11196903 DOI: 10.1002/pro.5005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/17/2024] [Accepted: 04/15/2024] [Indexed: 06/28/2024]
Abstract
New features in the dose estimation program RADDOSE-3D are summarised. They include the facility to enter a diffraction intensity decay model which modifies the "Diffraction Weighted Dose" output from a "Fluence Weighted Dose" to a "Diffraction-Decay Weighted Dose", a description of RADDOSE-ED for use in electron diffraction experiments, where dose is historically quoted in electrons/Å2 rather than in gray (Gy), and finally the development of a RADDOSE-3D GUI, enabling easy access to all the options available in the program.
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Affiliation(s)
- Joshua L. Dickerson
- Department of Biochemistry, Dorothy Crowfoot Hodgkin BuildingUniversity of OxfordOxfordUK
- MRC Laboratory of Molecular BiologyCambridge Biomedical CampusCambridgeUK
| | - Patrick T. N. McCubbin
- Department of Biochemistry, Dorothy Crowfoot Hodgkin BuildingUniversity of OxfordOxfordUK
- Division of Structural Biology, Nuffield Department of MedicineUniversity of OxfordOxfordUK
| | | | - Elspeth F. Garman
- Department of Biochemistry, Dorothy Crowfoot Hodgkin BuildingUniversity of OxfordOxfordUK
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3
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McGuire KL, Cook BD, Narehood SM, Herzik MA. Tuning ice thickness using the chameleon for high-quality cryoEM data collection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.01.592094. [PMID: 38746094 PMCID: PMC11092644 DOI: 10.1101/2024.05.01.592094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Advances in single-particle cryogenic electron microscopy (cryoEM) now allow for routine structure determination of well-behaved biological specimens to high-resolution. Despite advances in the electron microscope, direct electron detectors, and data processing software, the preparation of high-quality grids with thin layers of vitreous ice containing the specimen of interest in random orientations remains a critical bottleneck for many projects. Although numerous efforts have been dedicated to overcoming hurdles frequently encountered during specimen vitrification using traditional blot-and-plunge specimen preparation techniques, the development of blot-free grid preparation devices provide a unique opportunity to carefully tune ice thickness, particle density, and specimen behavior during the vitrification process for improvements in image quality. Here, we describe critical steps of high-quality grid preparation using a SPT Labtech chameleon, evaluation of grid quality/ice thickness using the chameleon software, high-throughput imaging in the electron microscope, and recommend steps for troubleshooting grid preparation when standard parameters fail to yield suitable specimen.
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Affiliation(s)
- Kelly L. McGuire
- Department of Chemistry and Biochemistry, University of California, San Diego, California, US
| | - Brian D. Cook
- Department of Chemistry and Biochemistry, University of California, San Diego, California, US
| | - Sarah M. Narehood
- Department of Chemistry and Biochemistry, University of California, San Diego, California, US
| | - Mark A. Herzik
- Department of Chemistry and Biochemistry, University of California, San Diego, California, US
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4
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Harano K, Nakamuro T, Nakamura E. Cinematographic study of stochastic chemical events at atomic resolution. Microscopy (Oxf) 2024; 73:101-116. [PMID: 37864546 DOI: 10.1093/jmicro/dfad052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 09/07/2023] [Accepted: 10/20/2023] [Indexed: 10/23/2023] Open
Abstract
The advent of single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM) has created a new field of 'cinematic chemistry,' allowing for the cinematographic recording of dynamic behaviors of organic and inorganic molecules and their assembly. However, the limited electron dose per frame of video images presents a major challenge in SMART-EM. Recent advances in direct electron counting cameras and techniques to enhance image quality through the implementation of a denoising algorithm have enabled the tracking of stochastic molecular motions and chemical reactions with sub-millisecond temporal resolution and sub-angstrom localization precision. This review showcases the development of dynamic molecular imaging using the SMART-EM technique, highlighting insights into nanomechanical behavior during molecular shuttle motion, pathways of multistep chemical reactions, and elucidation of crystallization processes at the atomic level.
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Affiliation(s)
- Koji Harano
- Center for Basic Research on Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Takayuki Nakamuro
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Eiichi Nakamura
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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5
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Zhang T, Britton TB. Multi-exposure diffraction pattern fusion applied to enable wider-angle transmission Kikuchi diffraction with direct electron detectors. Ultramicroscopy 2024; 257:113902. [PMID: 38086289 DOI: 10.1016/j.ultramic.2023.113902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 10/27/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024]
Abstract
Diffraction pattern analysis can be used to reveal the crystalline structure of materials, and this information is used to nano- and micro-structure of advanced engineering materials that enable modern life. For nano-structured materials typically diffraction pattern analysis is performed in the transmission electron microscope (TEM) and TEM diffraction patterns typically have a limited angular range (less than a few degrees) due to the long camera length, and this requires analysis of multiple patterns to probe a unit cell. As a different approach, wide angle Kikuchi patterns can be captured using an on-axis detector in the scanning electron microscope (SEM) with a shorter camera length. These 'transmission Kikuchi diffraction' (TKD) patterns present a direct projection of the unit cell and can be routinely analysed using EBSD-based methods and dynamical diffraction theory. In the present work, we enhance this analysis significantly and present a multi-exposure diffraction pattern fusion method that increases the dynamic range of the detected patterns captured with a Timepix3-based direct electron detector (DED). This method uses an easy-to-apply exposure fusion routine to collect data and extend the dynamic range, as well as normalise the intensity distribution within these very wide (>95°) angle patterns. The potential of this method is demonstrated with full diffraction sphere reprojection and highlight potential of the approach to rapidly probe the structure of nano-structured materials in the scanning electron microscope.
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Affiliation(s)
- Tianbi Zhang
- Department of Materials Engineering, The University of British Columbia, 309-6350 Stores Road, Vancouver, BC V6T 1Z4 Canada
| | - T Ben Britton
- Department of Materials Engineering, The University of British Columbia, 309-6350 Stores Road, Vancouver, BC V6T 1Z4 Canada.
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6
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DeRonja J, Nowell M, Wright S, Kacher J. Generational assessment of EBSD detectors for cross-correlation-based analysis: From scintillators to direct detection. Ultramicroscopy 2024; 257:113913. [PMID: 38141535 DOI: 10.1016/j.ultramic.2023.113913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 11/17/2023] [Accepted: 12/19/2023] [Indexed: 12/25/2023]
Abstract
Introduced over ten years ago, cross-correlation-based electron backscatter diffraction has enabled high precision measurements of crystallographic rotations and elastic strain gradients at high spatial resolution. Since that time, there have been remarkable improvements in electron detector technology, including the advent of ultra-high speed detectors and the commercialization of direct detectors. In this study, we assess the efficacy of multiple generations of electron detectors for cross-correlation-based analysis using a single crystal Si sample as a reference. We show that, while improvements in precision are modest, there have been significant gains in the rate at which high-quality diffraction patterns can be collected. This has important implications in the size of datasets that can be collected and reduces the impact of drift and sample contamination.
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Affiliation(s)
| | | | | | - Josh Kacher
- Georgia Institute of Technology, Atlanta, GA 30332, United States.
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7
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Chan LM, Courteau BJ, Maker A, Wu M, Basanta B, Mehmood H, Bulkley D, Joyce D, Lee BC, Mick S, Gulati S, Lander GC, Verba KA. High-resolution single-particle imaging at 100-200 keV with the Gatan Alpine direct electron detector. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580363. [PMID: 38405886 PMCID: PMC10888765 DOI: 10.1101/2024.02.14.580363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Developments in direct electron detector technology have played a pivotal role in enabling high-resolution structural studies by cryo-EM at 200 and 300 keV. Yet, theory and recent experiments indicate advantages to imaging at 100 keV, energies for which the current detectors have not been optimized. In this study, we evaluated the Gatan Alpine detector, designed for operation at 100 and 200 keV. Compared to the Gatan K3, Alpine demonstrated a significant DQE improvement at these voltages, specifically a ~4-fold improvement at Nyquist at 100 keV. In single-particle cryo-EM experiments, Alpine datasets yielded better than 2 Å resolution reconstructions of apoferritin at 120 and 200 keV on a ThermoFisher Scientific (TFS) Glacios microscope. We also achieved a ~3.2 Å resolution reconstruction for a 115 kDa asymmetric protein complex, proving its effectiveness with complex biological samples. In-depth analysis revealed that Alpine reconstructions are comparable to K3 reconstructions at 200 keV, and remarkably, reconstruction from Alpine at 120 keV on a TFS Glacios surpassed all but the 300 keV data from a TFS Titan Krios with GIF/K3. Additionally, we show Alpine's capability for high-resolution data acquisition and screening on lower-end systems by obtaining ~3 Å resolution reconstructions of apoferritin and aldolase at 100 keV and detailed 2D averages of a 55 kDa sample using a side-entry cryo holder. Overall, we show that Gatan Alpine performs well with the standard 200 keV imaging systems and may potentially capture the benefits of lower accelerating voltages, possibly bringing smaller sized particles within the scope of cryo-EM.
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Affiliation(s)
- Lieza M Chan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Brandon J Courteau
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Allison Maker
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - Mengyu Wu
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States
| | - Benjamin Basanta
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States
| | - Hevatib Mehmood
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
| | - David Bulkley
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | | | | | | | | | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92024, United States
| | - Kliment A Verba
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States
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8
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Wei J, Moore K, Bammes B, Levin BDA, Hagopian N, Jacobs R, Morgan D, Voyles PM. Deep Learning Approach for High-accuracy Electron Counting of Monolithic Active Pixel Sensor-type Direct Electron Detectors at Increased Electron Dose. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:2026-2036. [PMID: 38066670 DOI: 10.1093/micmic/ozad132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/25/2023] [Accepted: 11/05/2023] [Indexed: 12/23/2023]
Abstract
Electron counting can be performed algorithmically for monolithic active pixel sensor direct electron detectors to eliminate readout noise and Landau noise arising from the variability in the amount of deposited energy for each electron. Errors in existing counting algorithms include mistakenly counting a multielectron strike as a single electron event, and inaccurately locating the incident position of the electron due to lateral spread of deposited energy and dark noise. Here, we report a supervised deep learning (DL) approach based on Faster region-based convolutional neural network (R-CNN) to recognize single electron events at varying electron doses and voltages. The DL approach shows high accuracy according to the near-ideal modulation transfer function (MTF) and detector quantum efficiency for sparse images. It predicts, on average, 0.47 pixel deviation from the incident positions for 200 kV electrons versus 0.59 pixel using the conventional counting method. The DL approach also shows better robustness against coincidence loss as the electron dose increases, maintaining the MTF at half Nyquist frequency above 0.83 as the electron density increases to 0.06 e-/pixel. Thus, the DL model extends the advantages of counting analysis to higher dose rates than conventional methods.
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Affiliation(s)
- Jingrui Wei
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI 53706, USA
| | - Kalani Moore
- Direct Electron L.P., 13240 Evening Crk S Dr Ste. 311, San Diego, CA 92128, USA
| | - Benjamin Bammes
- Direct Electron L.P., 13240 Evening Crk S Dr Ste. 311, San Diego, CA 92128, USA
| | - Barnaby D A Levin
- Direct Electron L.P., 13240 Evening Crk S Dr Ste. 311, San Diego, CA 92128, USA
| | - Nicholas Hagopian
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI 53706, USA
| | - Ryan Jacobs
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI 53706, USA
| | - Dane Morgan
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI 53706, USA
| | - Paul M Voyles
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI 53706, USA
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9
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Ochner H, Bharat TAM. Charting the molecular landscape of the cell. Structure 2023; 31:1297-1305. [PMID: 37699393 PMCID: PMC7615466 DOI: 10.1016/j.str.2023.08.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 09/14/2023]
Abstract
Biological function of macromolecules is closely tied to their cellular location, as well as to interactions with other molecules within the native environment of the cell. Therefore, to obtain detailed mechanistic insights into macromolecular functionality, one of the outstanding targets for structural biology is to produce an atomic-level understanding of the cell. One structural biology technique that has already been used to directly derive atomic models of macromolecules from cells, without any additional external information, is electron cryotomography (cryoET). In this perspective article, we discuss possible routes to chart the molecular landscape of the cell by advancing cryoET imaging as well as by embedding cryoET into correlative imaging workflows.
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Affiliation(s)
- Hannah Ochner
- Structural Studies Division, MRC Laboratory of Molecular Biology, CB2 0QH Cambridge, UK
| | - Tanmay A M Bharat
- Structural Studies Division, MRC Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.
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10
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Yang Q, Wu C, Zhu D, Li J, Cheng J, Zhang X. The reduction of FIB damage on cryo-lamella by lowering energy of ion beam revealed by a quantitative analysis. Structure 2023; 31:1275-1281.e4. [PMID: 37527655 DOI: 10.1016/j.str.2023.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/08/2023] [Accepted: 07/05/2023] [Indexed: 08/03/2023]
Abstract
Focused ion beam (FIB) is widely used for thinning frozen cells to produce lamellae for cryo-electron microscopy imaging and for protein structures study in vivo. However, FIB damages the lamellae and a quantitative experimental analysis of the damage is lacking. We used a 30-keV gallium FIB to prepare lamellae of a highly concentrated icosahedral virus sample. The viruses were grouped according to their distance from the surface of lamellae and reconstructed. Damage to the approximately 20-nm-thick outermost lamella surface was similar to that from exposure to 16 e-/Å2 in a 300-kV cryo-electron microscope at high-resolution range. The damage was negligible at a depth beyond 50 nm, which was reduced to 30 nm if 8-keV Ga+ was used during polishing. We designed extra steps in the reconstruction refinement to maximize undamaged signals and increase the resolution. The results demonstrated that low-energy beam polishing was essential for high-quality thinner lamellae.
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Affiliation(s)
- Qi Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China; University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Chunling Wu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China
| | - Dongjie Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China
| | - Junxi Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China; University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Jing Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China.
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11
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Basanta B, Chen W, Pride DE, Lander GC. Fabrication of Monolayer Graphene-Coated Grids for Cryoelectron Microscopy. J Vis Exp 2023:10.3791/65702. [PMID: 37747197 PMCID: PMC11141527 DOI: 10.3791/65702] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023] Open
Abstract
Cryogenic electron microscopy (cryoEM) has emerged as a powerful technique for probing the atomic structure of macromolecular complexes. Sample preparation for cryoEM requires preserving specimens in a thin layer of vitreous ice, typically suspended within the holes of a fenestrated support film. However, all commonly used sample preparation approaches for cryoEM studies expose the specimen to the air-water interface, introducing a strong hydrophobic effect on the specimen that often results in denaturation, aggregation, and complex dissociation. Further, preferred hydrophobic interactions between regions of the specimen and the air-water interface impact the orientations adopted by the macromolecules, resulting in 3D reconstructions with anisotropic directional resolution. Adsorption of cryoEM specimens to a monolayer of graphene has been shown to help mitigate interactions with the air-water interface while minimizing the introduction of background noise. Graphene supports also offer the benefit of substantially lowering the required concentration of proteins required for cryoEM imaging. Despite the advantages of these supports, graphene-coated grids are not widely used by the cryoEM community due to the prohibitive expense of commercial options and the challenges associated with large-scale in-house production. This paper describes an efficient method for preparing batches of cryoEM grids that have nearly full coverage of monolayer graphene.
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Affiliation(s)
- Benjamin Basanta
- Department of Structural and Computational Biology, Scripps Research
| | - Wenqian Chen
- Department of Structural and Computational Biology, Scripps Research
| | - Daniel E Pride
- Department of Structural and Computational Biology, Scripps Research
| | - Gabriel C Lander
- Department of Structural and Computational Biology, Scripps Research;
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12
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Cheng J, Liu T, You X, Zhang F, Sui SF, Wan X, Zhang X. Determining protein structures in cellular lamella at pseudo-atomic resolution by GisSPA. Nat Commun 2023; 14:1282. [PMID: 36922493 PMCID: PMC10017804 DOI: 10.1038/s41467-023-36175-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 01/18/2023] [Indexed: 03/17/2023] Open
Abstract
Cryo-electron tomography is a major tool used to study the structure of protein complexes in situ. However, the throughput of tilt-series image data collection is still quite low. Here, we show that GisSPA, a GPU accelerated program, can translationally and rotationally localize the target protein complex in cellular lamellae, as prepared with a focused ion beam, using single cryo-electron microscopy images without tilt-series, and reconstruct the protein complex at near-atomic resolution. GisSPA allows high-throughput data collection without the acquisition of tilt-series images and reconstruction of the tomogram, which is essential for high-resolution reconstruction of asymmetric or low-symmetry protein complexes. We demonstrate the power of GisSPA with 3.4-Å and 3.9-Å resolutions of resolving phycobilisome and tetrameric photosystem II complex structures in cellular lamellae, respectively. In this work, we present GisSPA as a practical tool that facilitates high-resolution in situ protein structure determination.
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Affiliation(s)
- Jing Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Tong Liu
- High Performance Computer Research Center, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xin You
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Fa Zhang
- Beijing Institute of Technology, Beijing, 100081, China
| | - Sen-Fang Sui
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xiaohua Wan
- Beijing Institute of Technology, Beijing, 100081, China.
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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13
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Harrison PJ, Vecerkova T, Clare DK, Quigley A. A review of the approaches used to solve sub-100 kDa membrane proteins by cryo-electron microscopy. J Struct Biol 2023; 215:107959. [PMID: 37004781 DOI: 10.1016/j.jsb.2023.107959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 03/07/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
Membrane proteins (MPs) are essential components of all biological membranes, contributing to key cellular functions that include signalling, molecular transport and energy metabolism. Consequently, MPs are important biomedical targets for therapeutics discovery. Despite hardware and software developments in cryo-electron microscopy, as well as MP sample preparation, MPs smaller than 100 kDa remain difficult to study structurally. Significant investment is required to overcome low levels of naturally abundant protein, MP hydrophobicity as well as conformational and compositional instability. Here we have reviewed the sample preparation approaches that have been taken to successfully express, purify and prepare small MPs for analysis by cryo-EM (those with a total solved molecular weight of under 100 kDa), as well as examining the differing approaches towards data processing and ultimately obtaining a structural solution. We highlight common challenges at each stage in the process as well as strategies that have been developed to overcome these issues. Finally, we discuss future directions and opportunities for the study of sub-100 kDa membrane proteins by cryo-EM.
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14
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Peng R, Fu X, Mendez JH, Randolph PS, Bammes BE, Stagg SM. Characterizing the resolution and throughput of the Apollo direct electron detector. J Struct Biol X 2022; 7:100080. [PMID: 36578473 PMCID: PMC9791170 DOI: 10.1016/j.yjsbx.2022.100080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
Advances in electron detection have been essential to the success of high-resolution cryo-EM structure determination. A new generation of direct electron detector called the Apollo, has been developed by Direct Electron. The Apollo uses a novel event-based MAPS detector custom designed for ultra-fast electron counting. We have evaluated this new camera, finding that it delivers high detective quantum efficiency (DQE) and low coincidence loss, enabling high-quality electron counting data acquisition at up to nearly 80 input electrons per pixel per second. We further characterized the performance of Apollo for single particle cryo-EM on real biological samples. Using mouse apoferritin, Apollo yielded better than 1.9 Å resolution reconstructions at all three tested dose rates from a half-day data collection session each. With longer collection time and improved specimen preparation, mouse apoferritin was reconstructed to 1.66 Å resolution. Applied to a more challenging small protein aldolase, we obtained a 2.24 Å resolution reconstruction. The high quality of the map indicates that the Apollo has sufficiently high DQE to reconstruct smaller proteins and complexes with high-fidelity. Our results demonstrate that the Apollo camera performs well across a broad range of dose rates and is capable of capturing high quality data that produce high-resolution reconstructions for large and small single particle samples.
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Affiliation(s)
- Ruizhi Peng
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
| | - Xiaofeng Fu
- Department of Biological Sciences, 319 Stadium Drive, Tallahassee, FL 32306, United States
| | - Joshua H. Mendez
- Simons Electron Microscopy Center, 89 Convent Avenue, New York, NY 10027, United States
| | - Peter S. Randolph
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
| | - Benjamin E. Bammes
- Direct Electron LP, 13240 Evening Creek Drive South, Suite 311, San Diego, CA 92128, United States
| | - Scott M. Stagg
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States,Department of Biological Sciences, 319 Stadium Drive, Tallahassee, FL 32306, United States,Corresponding author at: Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
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15
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Clabbers MTB, Martynowycz MW, Hattne J, Nannenga BL, Gonen T. Electron-counting MicroED data with the K2 and K3 direct electron detectors. J Struct Biol 2022; 214:107886. [PMID: 36044956 PMCID: PMC9999727 DOI: 10.1016/j.jsb.2022.107886] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 08/19/2022] [Accepted: 08/24/2022] [Indexed: 12/30/2022]
Abstract
Microcrystal electron diffraction (MicroED) uses electron cryo-microscopy (cryo-EM) to collect diffraction data from small crystals during continuous rotation of the sample. As a result of advances in hardware as well as methods development, the data quality has continuously improved over the past decade, to the point where even macromolecular structures can be determined ab initio. Detectors suitable for electron diffraction should ideally have fast readout to record data in movie mode, and high sensitivity at low exposure rates to accurately report the intensities. Direct electron detectors are commonly used in cryo-EM imaging for their sensitivity and speed, but despite their availability are generally not used in diffraction. Primary concerns with diffraction experiments are the dynamic range and coincidence loss, which will corrupt the measurement if the flux exceeds the count rate of the detector. Here, we describe instrument setup and low-exposure MicroED data collection in electron-counting mode using K2 and K3 direct electron detectors and show that the integrated intensities can be effectively used to solve structures of two macromolecules between 1.2 Å and 2.8 Å resolution. Even though a beam stop was not used with the K3 studies we did not observe damage to the camera. As these cameras are already available in many cryo-EM facilities, this provides opportunities for users who do not have access to dedicated facilities for MicroED.
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Affiliation(s)
- Max T B Clabbers
- Department of Biological Chemistry, University of California, Los Angeles CA 90095, United States; Howard Hughes Medical Institute, University of California, Los Angeles CA 90095, United States
| | - Michael W Martynowycz
- Department of Biological Chemistry, University of California, Los Angeles CA 90095, United States; Howard Hughes Medical Institute, University of California, Los Angeles CA 90095, United States
| | - Johan Hattne
- Department of Biological Chemistry, University of California, Los Angeles CA 90095, United States; Howard Hughes Medical Institute, University of California, Los Angeles CA 90095, United States
| | - Brent L Nannenga
- Chemical Engineering, School for Engineering of Matter, Arizona State University, Tempe, AZ, United States; Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, United States
| | - Tamir Gonen
- Department of Biological Chemistry, University of California, Los Angeles CA 90095, United States; Howard Hughes Medical Institute, University of California, Los Angeles CA 90095, United States; Department of Physiology, University of California, Los Angeles CA 90095, United States.
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16
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Sheng Y, Harrison PJ, Vogirala V, Yang Z, Strain-Damerell C, Frosio T, Himes BA, Siebert CA, Zhang P, Clare DK. Application of super-resolution and correlative double sampling in cryo-electron microscopy. Faraday Discuss 2022; 240:261-276. [PMID: 35938521 PMCID: PMC9642007 DOI: 10.1039/d2fd00049k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/24/2022] [Indexed: 01/09/2023]
Abstract
Developments in cryo-EM have allowed atomic or near-atomic resolution structure determination to become routine in single particle analysis (SPA). However, near-atomic resolution structures determined using cryo-electron tomography and sub-tomogram averaging (cryo-ET STA) are much less routine. In this paper, we show that collecting cryo-ET STA data using the same conditions as SPA, with both correlated double sampling (CDS) and the super-resolution mode, allowed apoferritin to be reconstructed out to the physical Nyquist frequency of the images. Even with just two tilt series, STA yields an apoferritin map at 2.9 Å resolution. These results highlight the exciting potential of cryo-ET STA in the future of protein structure determination. While processing SPA data recorded in super-resolution mode may yield structures surpassing the physical Nyquist limit, processing cryo-ET STA data in the super-resolution mode gave no additional resolution benefit. We further show that collecting SPA data in the super-resolution mode, with CDS activated, reduces the estimated B-factor, leading to a reduction in the number of particles required to reach a target resolution without compromising the data size on disk and the area imaged in SerialEM. However, collecting SPA data in CDS does reduce throughput, given that a similar resolution structure, with a slightly larger B-factor, is achievable with optimised parameters for speed in EPU (without CDS).
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Affiliation(s)
- Yuewen Sheng
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Peter J Harrison
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Vinod Vogirala
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Zhengyi Yang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Claire Strain-Damerell
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
- RCaH, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Thomas Frosio
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Benjamin A Himes
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - C Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
| | - Peijun Zhang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
- RCaH, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Daniel K Clare
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
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17
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Xue H, Zhang M, Liu J, Wang J, Ren G. Cryo-electron tomography related radiation-damage parameters for individual-molecule 3D structure determination. Front Chem 2022; 10:889203. [PMID: 36110139 PMCID: PMC9468540 DOI: 10.3389/fchem.2022.889203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/13/2022] [Indexed: 11/28/2022] Open
Abstract
To understand the dynamic structure-function relationship of soft- and biomolecules, the determination of the three-dimensional (3D) structure of each individual molecule (nonaveraged structure) in its native state is sought-after. Cryo-electron tomography (cryo-ET) is a unique tool for imaging an individual object from a series of tilted views. However, due to radiation damage from the incident electron beam, the tolerable electron dose limits image contrast and the signal-to-noise ratio (SNR) of the data, preventing the 3D structure determination of individual molecules, especially at high-resolution. Although recently developed technologies and techniques, such as the direct electron detector, phase plate, and computational algorithms, can partially improve image contrast/SNR at the same electron dose, the high-resolution structure, such as tertiary structure of individual molecules, has not yet been resolved. Here, we review the cryo-electron microscopy (cryo-EM) and cryo-ET experimental parameters to discuss how these parameters affect the extent of radiation damage. This discussion can guide us in optimizing the experimental strategy to increase the imaging dose or improve image SNR without increasing the radiation damage. With a higher dose, a higher image contrast/SNR can be achieved, which is crucial for individual-molecule 3D structure. With 3D structures determined from an ensemble of individual molecules in different conformations, the molecular mechanism through their biochemical reactions, such as self-folding or synthesis, can be elucidated in a straightforward manner.
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Affiliation(s)
- Han Xue
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Meng Zhang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Jianjun Wang
- Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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18
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Heymann JB. The progressive spectral signal-to-noise ratio of cryo-electron micrograph movies as a tool to assess quality and radiation damage. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 220:106799. [PMID: 35405434 PMCID: PMC9149132 DOI: 10.1016/j.cmpb.2022.106799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/15/2022] [Accepted: 03/31/2022] [Indexed: 06/03/2023]
Abstract
BACKGROUND AND OBJECTIVE The quality of a cryoEM reconstruction is fundamentally a function of the signal-to-noise ratio (SNR) of the original micrographs. The SNR embodies multiple aspects of image formation, including microscope details and alignment, specimen composition and thickness, how it is recorded, and how the specimen degrades during imaging. With the advent of direct electron detectors and the recording of a series of images for each micrograph (a movie), we have an opportunity to count every electron and derive fully quantitative results. After alignment of the movie frames of a micrograph, we can calculate the SNR, or its spatial frequency equivalent, the spectral SNR (SSNR). This SSNR reflects residual movement between frames and the progressive effect of radiation damage. The goal is to develop a quantitative analysis of the SSNR and radiation damage to assess and improve the quality of micrographs. METHODS Several test cases were selected from the EMPIAR database and ten micrograph movies downloaded for each case. The movie frames were aligned as rigid bodies to compensate for stage and support movement. The SSNR for subsets of frames was then calculated to assess the effect of residual movement. The progressive SSNR (PSSNR) was subsequently calculated to determine the decrease in signal accumulation as a result of radiation damage. RESULTS In all cases the alignment of the movie frames compensated for global movement to the extent that the effect on the SSNR is negligible. The subset SSNR can be used as a tool to further confirm the extent of residual movement. The progressive SSNR indicates an increase in value up to an asymptote, consistent with the theory for radiation damage. Fitting these curves gives the inherent SNR before exposure, and the critical dose, which decreases with spatial frequency with an exponential parameter roughly between one and two. CONCLUSIONS The implementation of the PSSNR for movie frames provides a tool for assessing micrograph quality and progression of radiation damage. The estimation of the critical dose further quantifies radiation damage and may shed some light on the mechanisms of damage. These are likely both a function of the specimen composition and the imaging parameters used.
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Affiliation(s)
- J Bernard Heymann
- Laboratory for Structural Biology Research, NIAMS, NIH, Bethesda, MD 20892, USA; National Cryo-EM Program, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA.
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19
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Philipp HT, Tate MW, Shanks KS, Mele L, Peemen M, Dona P, Hartong R, van Veen G, Shao YT, Chen Z, Thom-Levy J, Muller DA, Gruner SM. Very-High Dynamic Range, 10,000 Frames/Second Pixel Array Detector for Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-16. [PMID: 35249574 DOI: 10.1017/s1431927622000174] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Precision and accuracy of quantitative scanning transmission electron microscopy (STEM) methods such as ptychography, and the mapping of electric, magnetic, and strain fields depend on the dose. Reasonable acquisition time requires high beam current and the ability to quantitatively detect both large and minute changes in signal. A new hybrid pixel array detector (PAD), the second-generation Electron Microscope Pixel Array Detector (EMPAD-G2), addresses this challenge by advancing the technology of a previous generation PAD, the EMPAD. The EMPAD-G2 images continuously at a frame-rates up to 10 kHz with a dynamic range that spans from low-noise detection of single electrons to electron beam currents exceeding 180 pA per pixel, even at electron energies of 300 keV. The EMPAD-G2 enables rapid collection of high-quality STEM data that simultaneously contain full diffraction information from unsaturated bright-field disks to usable Kikuchi bands and higher-order Laue zones. Test results from 80 to 300 keV are presented, as are first experimental results demonstrating ptychographic reconstructions, strain and polarization maps. We introduce a new information metric, the maximum usable imaging speed (MUIS), to identify when a detector becomes electron-starved, saturated or its pixel count is mismatched with the beam current.
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Affiliation(s)
- Hugh T Philipp
- Laboratory of Atomic and Solid-State Physics (LASSP), Cornell University, Ithaca, NY, USA
| | - Mark W Tate
- Laboratory of Atomic and Solid-State Physics (LASSP), Cornell University, Ithaca, NY, USA
| | - Katherine S Shanks
- Laboratory of Atomic and Solid-State Physics (LASSP), Cornell University, Ithaca, NY, USA
- Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY, USA
| | - Luigi Mele
- R&D Laboratory, Thermo-Fisher Scientific, Achtseweg Noord 5, 5651GGEindhoven, The Netherlands
| | - Maurice Peemen
- R&D Laboratory, Thermo-Fisher Scientific, Achtseweg Noord 5, 5651GGEindhoven, The Netherlands
| | - Pleun Dona
- R&D Laboratory, Thermo-Fisher Scientific, Achtseweg Noord 5, 5651GGEindhoven, The Netherlands
| | - Reinout Hartong
- R&D Laboratory, Thermo-Fisher Scientific, Achtseweg Noord 5, 5651GGEindhoven, The Netherlands
| | - Gerard van Veen
- R&D Laboratory, Thermo-Fisher Scientific, Achtseweg Noord 5, 5651GGEindhoven, The Netherlands
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Zhen Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Julia Thom-Levy
- Laboratory for Elementary-Particle Physics (LEPP), Cornell University, Ithaca, NY, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
| | - Sol M Gruner
- Laboratory of Atomic and Solid-State Physics (LASSP), Cornell University, Ithaca, NY, USA
- Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
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20
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Peck JV, Fay JF, Strauss JD. High-speed high-resolution data collection on a 200 keV cryo-TEM. IUCRJ 2022; 9:243-252. [PMID: 35371504 PMCID: PMC8895008 DOI: 10.1107/s2052252522000069] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/03/2022] [Indexed: 05/12/2023]
Abstract
Limitations to successful single-particle cryo-electron microscopy (cryo-EM) projects include stable sample generation, production of quality cryo-EM grids with randomly oriented particles embedded in thin vitreous ice and access to microscope time. To address the limitation of microscope time, methodologies to more efficiently collect data on a 200 keV Talos Arctica cryo-transmission electron microscope at speeds as fast as 720 movies per hour (∼17 000 per day) were tested. In this study, key parameters were explored to increase data collection speed including: (1) using the beam-image shift method to acquire multiple images per stage position, (2) employing UltrAufoil TEM grids with R0.6/1 hole spacing, (3) collecting hardware-binned data and (4) adjusting the image shift delay factor in SerialEM. Here, eight EM maps of mouse apoferritin at 1.8-1.9 Å resolution were obtained in the analysis with data collection times for each dataset ranging from 56 min to 2 h. An EM map of mouse apoferritin at 1.78 Å was obtained from an overnight data collection at a speed of 500 movies per hour and subgroup analysis performed, with no significant variation observed in data quality by image shift distance and image shift delay. The findings and operating procedures detailed herein allow for rapid turnover of single-particle cryo-EM structure determination.
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Affiliation(s)
- Jared V. Peck
- Biochemistry and Biophysics, University of North Carolina at Chapel Hill, 101 Mason Farm, Chapel Hill, NC 27599, USA
| | - Jonathan F. Fay
- Biochemistry and Biophysics, 6107 Thurston Bowles Building, Chapel Hill, NC 27599, USA
| | - Joshua D. Strauss
- Biochemistry and Biophysics, University of North Carolina at Chapel Hill, 101 Mason Farm, Chapel Hill, NC 27599, USA
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21
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Sun M, Azumaya CM, Tse E, Bulkley DP, Harrington MB, Gilbert G, Frost A, Southworth D, Verba KA, Cheng Y, Agard DA. Practical considerations for using K3 cameras in CDS mode for high-resolution and high-throughput single particle cryo-EM. J Struct Biol 2021; 213:107745. [PMID: 33984504 DOI: 10.1016/j.jsb.2021.107745] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 04/16/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Detector technology plays a pivotal role in high-resolution and high-throughput cryo-EM structure determination. Compared with the first-generation, single-electron counting direct detection camera (Gatan K2), the latest K3 camera is faster, larger, and now offers a correlated-double sampling mode (CDS). Importantly this results in a higher DQE and improved throughput compared to its predecessor. In this study, we focused on optimizing camera data collection parameters for daily use within a cryo-EM facility and explored the balance between throughput and resolution. In total, eight data sets of murine heavy-chain apoferritin were collected at different dose rates and magnifications, using 9-hole image shift data collection strategies. The performance of the camera was characterized by the quality of the resultant 3D reconstructions. Our results demonstrated that the Gatan K3 operating in CDS mode outperformed standard (nonCDS) mode in terms of reconstruction resolution in all tested conditions with 8 electrons per pixel per second being the optimal dose rate. At low magnification (64kx) we were able to achieve reconstruction resolutions of 149% of the physical Nyquist limit (1.8 Å with a 1.346 Å physical pixel size). Low magnification allows more particles to be collected per image, aiding analysis of heterogeneous samples requiring large data sets. At moderate magnification (105kx, 0.834 Å physical pixel size) we achieved a resolution of 1.65 Å within 8-h of data collection, a condition optimal for achieving high-resolution on well behaved samples. Our results also show that for an optimal sample like apoferritin, one can achieve better than 2.5 Å resolution with 5 min of data collection. Together, our studies validate the most efficient ways of imaging protein complexes using the K3 direct detector and will greatly benefit the cryo-EM community.
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Affiliation(s)
- Ming Sun
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | - Caleigh M Azumaya
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | - Eric Tse
- Institute for Neurodegenerative Diseases, University of California, San Francisco, CA 94158, United States
| | - David P Bulkley
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | - Matthew B Harrington
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | - Glenn Gilbert
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States
| | - Adam Frost
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, United States
| | - Daniel Southworth
- Institute for Neurodegenerative Diseases, University of California, San Francisco, CA 94158, United States
| | - Kliment A Verba
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, United States; Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, United States
| | - Yifan Cheng
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States; Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, United States
| | - David A Agard
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States.
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22
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Savitzky BH, Zeltmann SE, Hughes LA, Brown HG, Zhao S, Pelz PM, Pekin TC, Barnard ES, Donohue J, Rangel DaCosta L, Kennedy E, Xie Y, Janish MT, Schneider MM, Herring P, Gopal C, Anapolsky A, Dhall R, Bustillo KC, Ercius P, Scott MC, Ciston J, Minor AM, Ophus C. py4DSTEM: A Software Package for Four-Dimensional Scanning Transmission Electron Microscopy Data Analysis. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:712-743. [PMID: 34018475 DOI: 10.1017/s1431927621000477] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Scanning transmission electron microscopy (STEM) allows for imaging, diffraction, and spectroscopy of materials on length scales ranging from microns to atoms. By using a high-speed, direct electron detector, it is now possible to record a full two-dimensional (2D) image of the diffracted electron beam at each probe position, typically a 2D grid of probe positions. These 4D-STEM datasets are rich in information, including signatures of the local structure, orientation, deformation, electromagnetic fields, and other sample-dependent properties. However, extracting this information requires complex analysis pipelines that include data wrangling, calibration, analysis, and visualization, all while maintaining robustness against imaging distortions and artifacts. In this paper, we present py4DSTEM, an analysis toolkit for measuring material properties from 4D-STEM datasets, written in the Python language and released with an open-source license. We describe the algorithmic steps for dataset calibration and various 4D-STEM property measurements in detail and present results from several experimental datasets. We also implement a simple and universal file format appropriate for electron microscopy data in py4DSTEM, which uses the open-source HDF5 standard. We hope this tool will benefit the research community and help improve the standards for data and computational methods in electron microscopy, and we invite the community to contribute to this ongoing project.
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Affiliation(s)
- Benjamin H Savitzky
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Steven E Zeltmann
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Lauren A Hughes
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Hamish G Brown
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Shiteng Zhao
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Philipp M Pelz
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Thomas C Pekin
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489Berlin, Germany
| | - Edward S Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Jennifer Donohue
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Luis Rangel DaCosta
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI48109, USA
| | - Ellis Kennedy
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Yujun Xie
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | | | | | | | | | | | - Rohan Dhall
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Karen C Bustillo
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Peter Ercius
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Mary C Scott
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Jim Ciston
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Andrew M Minor
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
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23
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Feathers JR, Spoth KA, Fromme JC. Experimental evaluation of super-resolution imaging and magnification choice in single-particle cryo-EM. J Struct Biol X 2021; 5:100047. [PMID: 33817625 PMCID: PMC8008246 DOI: 10.1016/j.yjsbx.2021.100047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/19/2021] [Accepted: 03/09/2021] [Indexed: 11/16/2022] Open
Abstract
The resolution of cryo-EM reconstructions is fundamentally limited by the Nyquist frequency, which is half the sampling frequency of the detector and depends upon the magnification used. In principle, super-resolution imaging should enable reconstructions to surpass the physical Nyquist limit by increasing sampling frequency, yet there are few reports of reconstructions that do so. Here we directly examine the contribution of super-resolution information, obtained with the K3 direct electron detector using a 2-condenser microscope, to single-particle cryo-EM reconstructions surpassing the physical Nyquist limit. We also present a comparative analysis of a sample imaged at four different magnifications. This analysis demonstrates that lower magnifications can be beneficial, despite the loss of higher resolution signal, due to the increased number of particle images obtained. To highlight the potential utility of lower magnification data collection, we produced a 3.5 Å reconstruction of jack bean urease with particles from a single micrograph.
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Affiliation(s)
- J. Ryan Feathers
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853 USA
| | - Katherine A. Spoth
- Cornell Center for Materials Research, Cornell University, Ithaca, NY 14853 USA
| | - J. Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853 USA
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24
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A data reduction and compression description for high throughput time-resolved electron microscopy. Nat Commun 2021; 12:664. [PMID: 33510168 PMCID: PMC7844242 DOI: 10.1038/s41467-020-20694-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 12/09/2020] [Indexed: 12/05/2022] Open
Abstract
Fast, direct electron detectors have significantly improved the spatio-temporal resolution of electron microscopy movies. Preserving both spatial and temporal resolution in extended observations, however, requires storing prohibitively large amounts of data. Here, we describe an efficient and flexible data reduction and compression scheme (ReCoDe) that retains both spatial and temporal resolution by preserving individual electron events. Running ReCoDe on a workstation we demonstrate on-the-fly reduction and compression of raw data streaming off a detector at 3 GB/s, for hours of uninterrupted data collection. The output was 100-fold smaller than the raw data and saved directly onto network-attached storage drives over a 10 GbE connection. We discuss calibration techniques that support electron detection and counting (e.g., estimate electron backscattering rates, false positive rates, and data compressibility), and novel data analysis methods enabled by ReCoDe (e.g., recalibration of data post acquisition, and accurate estimation of coincidence loss). The use of electron detectors with high spatio-temporal resolution is limited by the large amounts of data generated. Here, the authors describe ReCoDe, a data reduction and compression scheme, that preserves individual electron events, and enable on-the-fly reduction and compression of raw data.
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25
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Parent LR, Gnanasekaran K, Korpanty J, Gianneschi NC. 100th Anniversary of Macromolecular Science Viewpoint: Polymeric Materials by In Situ Liquid-Phase Transmission Electron Microscopy. ACS Macro Lett 2021; 10:14-38. [PMID: 35548998 DOI: 10.1021/acsmacrolett.0c00595] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A century ago, Hermann Staudinger proposed the macromolecular theory of polymers, and now, as we enter the second century of polymer science, we face a different set of opportunities and challenges for the development of functional soft matter. Indeed, many fundamental questions remain open, relating to physical structures and mechanisms of phase transformations at the molecular and nanoscale. In this Viewpoint, we describe efforts to develop a dynamic, in situ microscopy tool suited to the study of polymeric materials at the nanoscale that allows for direct observation of discrete structures and processes in solution, as a complement to light, neutron, and X-ray scattering methods. Liquid-phase transmission electron microscopy (LPTEM) is a nascent in situ imaging technique for characterizing and examining solvated nanomaterials in real time. Though still under development, LPTEM has been shown to be capable of several modes of imaging: (1) imaging static solvated materials analogous to cryo-TEM, (2) videography of nanomaterials in motion, (3) observing solutions or nanomaterials undergoing physical and chemical transformations, including synthesis, assembly, and phase transitions, and (4) observing electron beam-induced chemical-materials processes. Herein, we describe opportunities and limitations of LPTEM for polymer science. We review the basic experimental platform of LPTEM and describe the origin of electron beam effects that go hand in hand with the imaging process. These electron beam effects cause perturbation and damage to the sample and solvent that can manifest as artefacts in images and videos. We describe sample-specific experimental guidelines and outline approaches to mitigate, characterize, and quantify beam damaging effects. Altogether, we seek to provide an overview of this nascent field in the context of its potential to contribute to the advancement of polymer science.
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Affiliation(s)
- Lucas R. Parent
- Innovation Partnership Building, The University of Connecticut, Storrs, Connecticut 06269, United States
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26
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Gray DA, White JBR, Oluwole AO, Rath P, Glenwright AJ, Mazur A, Zahn M, Baslé A, Morland C, Evans SL, Cartmell A, Robinson CV, Hiller S, Ranson NA, Bolam DN, van den Berg B. Insights into SusCD-mediated glycan import by a prominent gut symbiont. Nat Commun 2021; 12:44. [PMID: 33398001 PMCID: PMC7782687 DOI: 10.1038/s41467-020-20285-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/19/2020] [Indexed: 01/29/2023] Open
Abstract
In Bacteroidetes, one of the dominant phyla of the mammalian gut, active uptake of large nutrients across the outer membrane is mediated by SusCD protein complexes via a "pedal bin" transport mechanism. However, many features of SusCD function in glycan uptake remain unclear, including ligand binding, the role of the SusD lid and the size limit for substrate transport. Here we characterise the β2,6 fructo-oligosaccharide (FOS) importing SusCD from Bacteroides thetaiotaomicron (Bt1762-Bt1763) to shed light on SusCD function. Co-crystal structures reveal residues involved in glycan recognition and suggest that the large binding cavity can accommodate several substrate molecules, each up to ~2.5 kDa in size, a finding supported by native mass spectrometry and isothermal titration calorimetry. Mutational studies in vivo provide functional insights into the key structural features of the SusCD apparatus and cryo-EM of the intact dimeric SusCD complex reveals several distinct states of the transporter, directly visualising the dynamics of the pedal bin transport mechanism.
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Affiliation(s)
- Declan A Gray
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Joshua B R White
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Abraham O Oluwole
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | | | - Amy J Glenwright
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Adam Mazur
- Biozentrum, University of Basel, Basel, Switzerland
| | - Michael Zahn
- Biozentrum, University of Basel, Basel, Switzerland
| | - Arnaud Baslé
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Carl Morland
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Sasha L Evans
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Alan Cartmell
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | | | - Neil A Ranson
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - David N Bolam
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Bert van den Berg
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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27
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Herzik MA. Setting Up Parallel Illumination on the Talos Arctica for High-Resolution Data Collection. Methods Mol Biol 2021; 2215:125-144. [PMID: 33368002 DOI: 10.1007/978-1-0716-0966-8_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Illuminating a specimen with a parallel electron beam is critical for many experiments in transmission electron microscopy as deviations from this condition cause considerable deterioration of image quality. Carefully establishing parallel illumination is particularly important on two-condenser lens transmission electron microscopes (TEMs) as the parallel illumination condition is limited to a single beam intensity value on these instruments. It was recently shown that a Thermo Fisher Scientific Talos Arctica, a two-condenser lens TEM operating at 200 kV, equipped with a Gatan K2 Summit direct electron detector is capable of resolving frozen-hydrated macromolecules of various sizes and internal symmetries to better than 3 Å resolution using single particle methodologies. A critical aspect of the success of these findings was the careful alignment of the electron microscope to ensure the specimen was illuminated with a parallel electron beam. Here, this chapter describes how to establish parallel illumination conditions in a Talos Arctica TEM for high-resolution cryogenic data collection for structure determination.
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Affiliation(s)
- Mark A Herzik
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA.
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28
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Haberfehlner G, Hoefler SF, Rath T, Trimmel G, Kothleitner G, Hofer F. Benefits of direct electron detection and PCA for EELS investigation of organic photovoltaics materials. Micron 2020; 140:102981. [PMID: 33202362 DOI: 10.1016/j.micron.2020.102981] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
Electron energy-loss spectroscopy (EELS) is a powerful tool for imaging chemical variations at the nanoscale. Here, we investigate a polymer/organic small molecule-blend used as absorber layer in an organic solar cell and employ EELS for distinguishing polymer donor and small molecule acceptor domains in the nanostructured blend based on elemental maps of light elements, such as nitrogen, sulfur or fluorine. Especially for beam sensitive samples, the electron dose needs to be limited, therefore optimized acquisition and data processing strategies are required. We compare data acquired on a post-column energy filter with a direct electron detection camera to data from a conventional CCD camera on the same filter and we investigate the impact of statistical data processing methods (principal components analysis, PCA) on acquired spectra and elemental maps extracted from spectrum images. Our work shows, that the quality of spectra on a direct electron detection camera is far superior to conventional CCD imaging, and thereby allows clear identification of ionization edges and the fine structure of these edges. For the quality of the elemental maps, the application of PCA is essential to allow a clear separation between the donor and acceptor phase in the bulk heterojunction absorber layer of a non-fullerene organic solar cell.
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Affiliation(s)
- Georg Haberfehlner
- Institute of Electron Microscopy and Nanoanalysis, NAWI Graz, Graz University of Technology, Steyrergasse 17, 8010, Graz, Austria.
| | - Sebastian F Hoefler
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria
| | - Thomas Rath
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria
| | - Gregor Trimmel
- Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria
| | - Gerald Kothleitner
- Institute of Electron Microscopy and Nanoanalysis, NAWI Graz, Graz University of Technology, Steyrergasse 17, 8010, Graz, Austria; Graz Centre for Electron Microscopy, Steyrergasse 17, Graz, 8010, Austria
| | - Ferdinand Hofer
- Institute of Electron Microscopy and Nanoanalysis, NAWI Graz, Graz University of Technology, Steyrergasse 17, 8010, Graz, Austria; Graz Centre for Electron Microscopy, Steyrergasse 17, Graz, 8010, Austria
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29
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Madej M, White JBR, Nowakowska Z, Rawson S, Scavenius C, Enghild JJ, Bereta GP, Pothula K, Kleinekathoefer U, Baslé A, Ranson NA, Potempa J, van den Berg B. Structural and functional insights into oligopeptide acquisition by the RagAB transporter from Porphyromonas gingivalis. Nat Microbiol 2020; 5:1016-1025. [PMID: 32393857 PMCID: PMC7610489 DOI: 10.1038/s41564-020-0716-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 03/31/2020] [Indexed: 12/30/2022]
Abstract
Porphyromonas gingivalis, an asaccharolytic member of the Bacteroidetes, is a keystone pathogen in human periodontitis that may also contribute to the development of other chronic inflammatory diseases. P. gingivalis utilizes protease-generated peptides derived from extracellular proteins for growth, but how these peptides enter the cell is not clear. Here, we identify RagAB as the outer-membrane importer for these peptides. X-ray crystal structures show that the transporter forms a dimeric RagA2B2 complex, with the RagB substrate-binding surface-anchored lipoprotein forming a closed lid on the RagA TonB-dependent transporter. Cryo-electron microscopy structures reveal the opening of the RagB lid and thus provide direct evidence for a 'pedal bin' mechanism of nutrient uptake. Together with mutagenesis, peptide-binding studies and RagAB peptidomics, our work identifies RagAB as a dynamic, selective outer-membrane oligopeptide-acquisition machine that is essential for the efficient utilization of proteinaceous nutrients by P. gingivalis.
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Affiliation(s)
- Mariusz Madej
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Joshua B R White
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- The Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
| | - Zuzanna Nowakowska
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Shaun Rawson
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- The Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
| | - Carsten Scavenius
- Interdisciplinary Nanoscience Center (iNANO) and the Department of Molecular Biology, Aarhus University, Aarhus, Denmark
| | - Jan J Enghild
- Interdisciplinary Nanoscience Center (iNANO) and the Department of Molecular Biology, Aarhus University, Aarhus, Denmark
| | - Grzegorz P Bereta
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Karunakar Pothula
- Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen, Germany
| | | | - Arnaud Baslé
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Neil A Ranson
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
| | - Bert van den Berg
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
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30
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The performance evaluation of direct detection electron energy-loss spectroscopy at 200 kV and 80 kV accelerating voltages. Ultramicroscopy 2020; 212:112942. [DOI: 10.1016/j.ultramic.2020.112942] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/10/2020] [Accepted: 01/19/2020] [Indexed: 11/20/2022]
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31
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Heimowitz A, Andén J, Singer A. Reducing bias and variance for CTF estimation in single particle cryo-EM. Ultramicroscopy 2020; 212:112950. [PMID: 32151795 PMCID: PMC9930185 DOI: 10.1016/j.ultramic.2020.112950] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/17/2020] [Accepted: 01/26/2020] [Indexed: 10/25/2022]
Abstract
When using an electron microscope for imaging of particles embedded in vitreous ice, the recorded image, or micrograph, is a significantly degraded version of the tomographic projection of the sample. Apart from noise, the image is affected by the optical configuration of the microscope. This transformation is typically modeled as a convolution with a point spread function. The Fourier transform of this function, known as the contrast transfer function (CTF), is oscillatory, attenuating and amplifying different frequency bands, and sometimes flipping their signs. High-resolution reconstruction requires this CTF to be accounted for, but as its form depends on experimental parameters, it must first be estimated from the micrograph. We present a new method for CTF estimation based on multitaper techniques that reduce bias and variance in the estimate. We also use known properties of the CTF and the background power spectrum to further reduce the variance through background subtraction and steerable basis projection. We show that the resulting power spectrum estimates better capture the zero-crossings of the CTF and yield accurate CTF estimates on several experimental micrographs.
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Affiliation(s)
- Ayelet Heimowitz
- The Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ, United States.
| | - Joakim Andén
- Center for Computational Mathematics, Flatiron Institute, New York, NY, United States.
| | - Amit Singer
- The Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ, United States; Department of Mathematics, Princeton University, Princeton, NJ, United States.
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32
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Schenk AD, Cavadini S, Thomä NH, Genoud C. Live Analysis and Reconstruction of Single-Particle Cryo-Electron Microscopy Data with CryoFLARE. J Chem Inf Model 2020; 60:2561-2569. [PMID: 32233514 DOI: 10.1021/acs.jcim.9b01102] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Efficient, reproducible and accountable single-particle cryo-electron microscopy structure determination is tedious and often impeded by the lack of a standardized procedure for data analysis and processing. To address this issue, we have developed the FMI Live Analysis and Reconstruction Engine (CryoFLARE). CryoFLARE is a modular open-source platform offering easy integration of new processing algorithms developed by the cryo-EM community. It provides a user-friendly interface that allows fast setup of standardized workflows, serving the need of pharmaceutical industry and academia alike who need to optimize throughput of their microscope. To consistently document how data is processed, CryoFLARE contains an integrated reporting facility to create reports. Live analysis and processing parallel to data acquisition are used to monitor and optimize data quality. Problems at the level of the sample preparation (heterogeneity, ice thickness, sparse particles, areas selected for acquisition, etc.) or misalignments of the microscope optics can quickly be detected and rectified before data collection is continued. Interfacing with automated data collection software for retrieval of acquisition metadata reduces user input needed for analysis, and with it minimizes potential sources of errors and workflow inconsistencies. Local and remote export support in Relion-compatible job and data format allows seamless integration into the refinement process. The support for nonlinear workflows and fine-grained scheduling for mixed workflows with separate CPU and GPU based calculation steps ensures optimal use of processing hardware. CryoFLARE's flexibility allows it to be used for all types of image acquisitions, ranging from sample screening to high-resolution data collection, and it offers a new alternative for setting up image processing workflows. It can be used without modifications of the hardware/software delivered by the microscope supplier. As it runs on a server in parallel to the hardware used for acquisition, it can easily be set up for remote display connections and fast control of the acquisition status.
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Affiliation(s)
- Andreas D Schenk
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Simone Cavadini
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Nicolas H Thomä
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Christel Genoud
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
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33
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Li Y, Zhou W, Li Y, Huang W, Zhang Z, Chen G, Wang H, Wu GH, Rolston N, Vila R, Chiu W, Cui Y. Unravelling Atomic Structure and Degradation Mechanisms of Organic-Inorganic Halide Perovskites by Cryo-EM. JOULE 2019; 3:2854-2866. [PMID: 34109301 PMCID: PMC8186345 DOI: 10.1016/j.joule.2019.08.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Despite rapid progress of hybrid organic-inorganic halide perovskite solar cells, using transmission electron microscopy to study their atomic structures has not been possible because of their extreme sensitivity to electron beam irradiation and environmental exposure. Here, we develop cryogenic-electron microscopy (cryo-EM) protocols to preserve an extremely sensitive perovskite, methylammonium lead iodide (MAPbI3) under various operating conditions for atomic-resolution imaging. We discover the precipitation of lead iodide nanoparticles on MAPbI3 nanowire's surface after short UV illumination and surface roughening after only 10 s exposure to air, while these effects remain undetected in conventional x-ray diffraction. We establish a definition for critical electron dose, and find this value for MAPbI3 at cryogenic condition to be 12 e-/Å2 at 1.49 Å spatial resolution. Our results highlight the importance of cryo-EM since traditional techniques cannot capture important nanoscale changes in morphology and structure that have important implications for perovskite solar cell stability and performance.
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Affiliation(s)
- Yanbin Li
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Weijiang Zhou
- Biophysics Program, School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Yuzhang Li
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Wenxiao Huang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Zewen Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Guangxu Chen
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Hansen Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Gong-Her Wu
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
| | - Nicholas Rolston
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Rafael Vila
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Wah Chiu
- Biophysics Program, School of Medicine, Stanford University, Stanford, California 94305, USA
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Lead Contact
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34
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Mendez JH, Mehrani A, Randolph P, Stagg S. Throughput and resolution with a next-generation direct electron detector. IUCRJ 2019; 6:1007-1013. [PMID: 31709056 PMCID: PMC6830211 DOI: 10.1107/s2052252519012661] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 09/11/2019] [Indexed: 05/26/2023]
Abstract
Direct electron detectors (DEDs) have revolutionized cryo-electron microscopy (cryo-EM) by facilitating the correction of beam-induced motion and radiation damage, and also by providing high-resolution image capture. A new-generation DED, the DE64, has been developed by Direct Electron that has good performance in both integrating and counting modes. The camera has been characterized in both modes in terms of image quality, throughput and resolution of cryo-EM reconstructions. The modulation transfer function, noise power spectrum and detective quantum efficiency (DQE) were determined for both modes, as well as the number of images per unit time. Although the DQE for counting mode was superior to that for integrating mode, the data-collection throughput for this mode was more than ten times slower. Since throughput and resolution are related in single-particle cryo-EM, data for apoferritin were collected and reconstructed using integrating mode, integrating mode in conjunction with a Volta phase plate (VPP) and counting mode. Only the counting-mode data resulted in a better than 3 Å resolution reconstruction with similar numbers of particles, and this increased performance could not be compensated for by the increased throughput of integrating mode or by the increased low-frequency contrast of integrating mode with the VPP. These data show that the superior image quality provided by counting mode is more important for high-resolution cryo-EM reconstructions than the superior throughput of integrating mode.
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Affiliation(s)
- Joshua H. Mendez
- Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA
| | - Atousa Mehrani
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, USA
| | - Peter Randolph
- Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA
| | - Scott Stagg
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, USA
- Institute of Molecular Biophysics, Florida State University, 91 Chieftain Way, Tallahassee, FL 32306, USA
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35
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Wilkinson ME, Kumar A, Casañal A. Methods for merging data sets in electron cryo-microscopy. Acta Crystallogr D Struct Biol 2019; 75:782-791. [PMID: 31478901 PMCID: PMC6719665 DOI: 10.1107/s2059798319010519] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 07/23/2019] [Indexed: 11/26/2022] Open
Abstract
Recent developments have resulted in electron cryo-microscopy (cryo-EM) becoming a useful tool for the structure determination of biological macromolecules. For samples containing inherent flexibility, heterogeneity or preferred orientation, the collection of extensive cryo-EM data using several conditions and microscopes is often required. In such a scenario, merging cryo-EM data sets is advantageous because it allows improved three-dimensional reconstructions to be obtained. Since data sets are not always collected with the same pixel size, merging data can be challenging. Here, two methods to combine cryo-EM data are described. Both involve the calculation of a rescaling factor from independent data sets. The effects of errors in the scaling factor on the results of data merging are also estimated. The methods described here provide a guideline for cryo-EM users who wish to combine data sets from the same type of microscope and detector.
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Affiliation(s)
- Max E. Wilkinson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
| | - Ananthanarayanan Kumar
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
| | - Ana Casañal
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England
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36
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Advances in image processing for single-particle analysis by electron cryomicroscopy and challenges ahead. Curr Opin Struct Biol 2018; 52:127-145. [PMID: 30509756 DOI: 10.1016/j.sbi.2018.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/26/2018] [Accepted: 11/17/2018] [Indexed: 12/20/2022]
Abstract
Electron cryomicroscopy (cryoEM) is essential for the study and functional understanding of non-crystalline macromolecules such as proteins. These molecules cannot be imaged using X-ray crystallography or other popular methods. CryoEM has been successfully used to visualize macromolecular complexes such as ribosomes, viruses, and ion channels. Determination of structural models of these at various conformational states leads to insight on how these molecules function. Recent advances in imaging technology have given cryoEM a scientific rebirth. As a result of these technological advances image processing and analysis have yielded molecular structures at atomic resolution. Nevertheless there continue to be challenges in image processing, and in this article we will touch on the most essential in order to derive an accurate three-dimensional model from noisy projection images. Traditional approaches, such as k-means clustering for class averaging, will be provided as background. We will then highlight new approaches for each image processing subproblem, including a 3D reconstruction method for asymmetric molecules using just two projection images and deep learning algorithms for automated particle picking.
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Abstract
Cryo-electron microscopy, or simply cryo-EM, refers mainly to three very different yet closely related techniques: electron crystallography, single-particle cryo-EM, and electron cryotomography. In the past few years, single-particle cryo-EM in particular has triggered a revolution in structural biology and has become a newly dominant discipline. This Review examines the fascinating story of its start and evolution over the past 40-plus years, delves into how and why the recent technological advances have been so groundbreaking, and briefly considers where the technique may be headed in the future.
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Affiliation(s)
- Yifan Cheng
- Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
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38
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Dillard RS, Hampton CM, Strauss JD, Ke Z, Altomara D, Guerrero-Ferreira RC, Kiss G, Wright ER. Biological Applications at the Cutting Edge of Cryo-Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:406-419. [PMID: 30175702 PMCID: PMC6265046 DOI: 10.1017/s1431927618012382] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cryo-electron microscopy (cryo-EM) is a powerful tool for macromolecular to near-atomic resolution structure determination in the biological sciences. The specimen is maintained in a near-native environment within a thin film of vitreous ice and imaged in a transmission electron microscope. The images can then be processed by a number of computational methods to produce three-dimensional information. Recent advances in sample preparation, imaging, and data processing have led to tremendous growth in the field of cryo-EM by providing higher resolution structures and the ability to investigate macromolecules within the context of the cell. Here, we review developments in sample preparation methods and substrates, detectors, phase plates, and cryo-correlative light and electron microscopy that have contributed to this expansion. We also have included specific biological applications.
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Affiliation(s)
- Rebecca S Dillard
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Cheri M Hampton
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Joshua D Strauss
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Zunlong Ke
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Deanna Altomara
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Ricardo C Guerrero-Ferreira
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Gabriella Kiss
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Elizabeth R Wright
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
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39
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Biyani N, Scherer S, Righetto RD, Kowal J, Chami M, Stahlberg H. Image processing techniques for high-resolution structure determination from badly ordered 2D crystals. J Struct Biol 2018; 203:120-134. [PMID: 29689299 DOI: 10.1016/j.jsb.2018.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 11/19/2022]
Abstract
2D electron crystallography can be used to study small membrane proteins in their native environment. Obtaining highly ordered 2D crystals is difficult and time-consuming. However, 2D crystals diffracting to only 10-12 Å can be prepared relatively conveniently in most cases. We have developed image-processing algorithms allowing to generate a high resolution 3D structure from cryo-electron crystallography images of badly ordered crystals. These include movie-mode unbending, refinement over sub-tiles of the images in order to locally refine the sample tilt geometry, implementation of different CTF correction schemes, and an iterative method to apply known constraints in the real and reciprocal space to approximate amplitudes and phases in the so-called missing cone regions. These algorithms applied to a dataset of the potassium channel MloK1 show significant resolution improvements to better than 5 Å.
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Affiliation(s)
- Nikhil Biyani
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Sebastian Scherer
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Ricardo D Righetto
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Julia Kowal
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Mohamed Chami
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland; BioEM Lab, C-CINA, Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland.
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40
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Hentschel J, Burnside C, Mignot I, Leibundgut M, Boehringer D, Ban N. The Complete Structure of the Mycobacterium smegmatis 70S Ribosome. Cell Rep 2018; 20:149-160. [PMID: 28683309 DOI: 10.1016/j.celrep.2017.06.029] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/03/2017] [Accepted: 06/10/2017] [Indexed: 11/24/2022] Open
Abstract
The ribosome carries out the synthesis of proteins in every living cell. It consequently represents a frontline target in anti-microbial therapy. Tuberculosis ranks among the leading causes of death worldwide, due in large part to the combination of difficult-to-treat latency and antibiotic resistance. Here, we present the 3.3-Å cryo-EM structure of the 70S ribosome of Mycobacterium smegmatis, a close relative to the human pathogen Mycobacterium tuberculosis. The structure reveals two additional ribosomal proteins and localizes them to the vicinity of drug-target sites in both the catalytic center and the decoding site of the ribosome. Furthermore, we visualized actinobacterium-specific rRNA and protein expansions that extensively remodel the ribosomal surface with implications for polysome organization. Our results provide a foundation for understanding the idiosyncrasies of mycobacterial translation and reveal atomic details of the structure that will facilitate the design of anti-tubercular therapeutics.
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Affiliation(s)
- Jendrik Hentschel
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Chloe Burnside
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Ingrid Mignot
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Marc Leibundgut
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Daniel Boehringer
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland
| | - Nenad Ban
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, Otto-Stern-Weg 5, Zürich 8093, Switzerland.
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41
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McLeod RA, Diogo Righetto R, Stewart A, Stahlberg H. MRCZ - A file format for cryo-TEM data with fast compression. J Struct Biol 2017; 201:252-257. [PMID: 29175288 DOI: 10.1016/j.jsb.2017.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 11/20/2017] [Accepted: 11/22/2017] [Indexed: 11/17/2022]
Abstract
The introduction of fast CMOS detectors is moving the field of transmission electron microscopy into the computer science field of big data. Automated data pipelines control the instrument and initial processing steps which imposes more onerous data transfer and archiving requirements. Here we conduct a technical demonstration whereby storage and read/write times are improved 10× at a dose rate of 1 e-/pix/frame for data from a Gatan K2 direct-detection device by combination of integer decimation and lossless compression. The example project is hosted at github.com/em-MRCZ and released under the BSD license.
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Affiliation(s)
- Robert A McLeod
- Center for Cellular Imaging and NanoAnalytics (C-CINA), University of Basel, Basel, Switzerland.
| | - Ricardo Diogo Righetto
- Center for Cellular Imaging and NanoAnalytics (C-CINA), University of Basel, Basel, Switzerland
| | - Andy Stewart
- Department of Physics, University of Limerick, Limerick, Ireland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics (C-CINA), University of Basel, Basel, Switzerland
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42
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Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity. Sci Rep 2017; 7:8243. [PMID: 28811485 PMCID: PMC5557959 DOI: 10.1038/s41598-017-07709-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/03/2017] [Indexed: 12/17/2022] Open
Abstract
In many cases, electron counting with direct detection sensors offers improved resolution, lower noise, and higher pixel density compared to conventional, indirect detection sensors for electron microscopy applications. Direct detection technology has previously been utilized, with great success, for imaging and diffraction, but potential advantages for spectroscopy remain unexplored. Here we compare the performance of a direct detection sensor operated in counting mode and an indirect detection sensor (scintillator/fiber-optic/CCD) for electron energy-loss spectroscopy. Clear improvements in measured detective quantum efficiency and combined energy resolution/energy field-of-view are offered by counting mode direct detection, showing promise for efficient spectrum imaging, low-dose mapping of beam-sensitive specimens, trace element analysis, and time-resolved spectroscopy. Despite the limited counting rate imposed by the readout electronics, we show that both core-loss and low-loss spectral acquisition are practical. These developments will benefit biologists, chemists, physicists, and materials scientists alike.
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43
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Xu Y, Bernecky C, Lee CT, Maier KC, Schwalb B, Tegunov D, Plitzko JM, Urlaub H, Cramer P. Architecture of the RNA polymerase II-Paf1C-TFIIS transcription elongation complex. Nat Commun 2017; 8:15741. [PMID: 28585565 PMCID: PMC5467213 DOI: 10.1038/ncomms15741] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 04/25/2017] [Indexed: 02/01/2023] Open
Abstract
The conserved polymerase-associated factor 1 complex (Paf1C) plays multiple roles in chromatin transcription and genomic regulation. Paf1C comprises the five subunits Paf1, Leo1, Ctr9, Cdc73 and Rtf1, and binds to the RNA polymerase II (Pol II) transcription elongation complex (EC). Here we report the reconstitution of Paf1C from Saccharomyces cerevisiae, and a structural analysis of Paf1C bound to a Pol II EC containing the elongation factor TFIIS. Cryo-electron microscopy and crosslinking data reveal that Paf1C is highly mobile and extends over the outer Pol II surface from the Rpb2 to the Rpb3 subunit. The Paf1-Leo1 heterodimer and Cdc73 form opposite ends of Paf1C, whereas Ctr9 bridges between them. Consistent with the structural observations, the initiation factor TFIIF impairs Paf1C binding to Pol II, whereas the elongation factor TFIIS enhances it. We further show that Paf1C is globally required for normal mRNA transcription in yeast. These results provide a three-dimensional framework for further analysis of Paf1C function in transcription through chromatin.
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Affiliation(s)
- Youwei Xu
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
| | - Carrie Bernecky
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
| | - Chung-Tien Lee
- Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.,Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center, Göttingen, Robert-Koch-Strasse 40, Göttingen 37075, Germany
| | - Kerstin C Maier
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
| | - Björn Schwalb
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
| | - Dimitry Tegunov
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.,Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center, Göttingen, Robert-Koch-Strasse 40, Göttingen 37075, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Max Planck Society, Am Fassberg 11, Göttingen 37077, Germany
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44
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Jomaa A, Fu YHH, Boehringer D, Leibundgut M, Shan SO, Ban N. Structure of the quaternary complex between SRP, SR, and translocon bound to the translating ribosome. Nat Commun 2017; 8:15470. [PMID: 28524878 PMCID: PMC5454536 DOI: 10.1038/ncomms15470] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/29/2017] [Indexed: 01/05/2023] Open
Abstract
During co-translational protein targeting, the signal recognition particle (SRP) binds to the translating ribosome displaying the signal sequence to deliver it to the SRP receptor (SR) on the membrane, where the signal peptide is transferred to the translocon. Using electron cryo-microscopy, we have determined the structure of a quaternary complex of the translating Escherichia coli ribosome, the SRP–SR in the ‘activated' state and the translocon. Our structure, supported by biochemical experiments, reveals that the SRP RNA adopts a kinked and untwisted conformation to allow repositioning of the ‘activated' SRP–SR complex on the ribosome. In addition, we observe the translocon positioned through interactions with the SR in the vicinity of the ribosome exit tunnel where the signal sequence is extending beyond its hydrophobic binding groove of the SRP M domain towards the translocon. Our study provides new insights into the mechanism of signal sequence transfer from the SRP to the translocon. Membrane proteins are inserted co-transnationally through the association between ribosome, the signal recognition particle and its receptor, and the membrane-bound translocon. Here the authors present a cryo-EM reconstruction of this quaternary complex in the activated state and propose a model for signal sequence transfer to the translocon.
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Affiliation(s)
- Ahmad Jomaa
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH, Zurich CH-8093, Switzerland
| | - Yu-Hsien Hwang Fu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Daniel Boehringer
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH, Zurich CH-8093, Switzerland
| | - Marc Leibundgut
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH, Zurich CH-8093, Switzerland
| | - Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH, Zurich CH-8093, Switzerland
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45
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Rickgauer JP, Grigorieff N, Denk W. Single-protein detection in crowded molecular environments in cryo-EM images. eLife 2017; 6. [PMID: 28467302 PMCID: PMC5453696 DOI: 10.7554/elife.25648] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/02/2017] [Indexed: 12/22/2022] Open
Abstract
We present an approach to study macromolecular assemblies by detecting component proteins' characteristic high-resolution projection patterns, calculated from their known 3D structures, in single electron cryo-micrographs. Our method detects single apoferritin molecules in vitreous ice with high specificity and determines their orientation and location precisely. Simulations show that high spatial-frequency information and-in the presence of protein background-a whitening filter are essential for optimal detection, in particular for images taken far from focus. Experimentally, we could detect small viral RNA polymerase molecules, distributed randomly among binding locations, inside rotavirus particles. Based on the currently attainable image quality, we estimate a threshold for detection that is 150 kDa in ice and 300 kDa in 100 nm thick samples of dense biological material.
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Affiliation(s)
| | | | - Winfried Denk
- Howard Hughes Medical Institute, Ashburn, United States.,Department of Electrons - Photons - Neurons, Max Planck Institute of Neurobiology, Martinsried, Germany
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46
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The sleeping beauty kissed awake: new methods in electron microscopy to study cellular membranes. Biochem J 2017; 474:1041-1053. [DOI: 10.1042/bcj20160990] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/03/2017] [Accepted: 01/23/2017] [Indexed: 01/12/2023]
Abstract
Electron microscopy (EM) for biological samples, developed in the 1940–1950s, changed our conception about the architecture of eukaryotic cells. It was followed by a period where EM applied to cell biology had seemingly fallen asleep, even though new methods with important implications for modern EM were developed. Among these was the discovery that samples can be preserved by chemical fixation and most importantly by rapid freezing without the formation of crystalline ice, giving birth to the world of cryo-EM. The past 15–20 years are hallmarked by a tremendous interest in EM, driven by important technological advances. Cryo-EM, in particular, is now capable of revealing structures of proteins at a near-atomic resolution owing to improved sample preparation methods, microscopes and cameras. In this review, we focus on the challenges associated with the imaging of membranes by EM and give examples from the field of host–pathogen interactions, in particular of virus-infected cells. Despite the advantages of imaging membranes under native conditions in cryo-EM, conventional EM will remain an important complementary method, in particular if large volumes need to be imaged.
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47
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Robust image alignment for cryogenic transmission electron microscopy. J Struct Biol 2016; 197:279-293. [PMID: 28038834 DOI: 10.1016/j.jsb.2016.12.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 12/13/2016] [Accepted: 12/16/2016] [Indexed: 11/23/2022]
Abstract
Cryo-electron microscopy recently experienced great improvements in structure resolution due to direct electron detectors with improved contrast and fast read-out leading to single electron counting. High frames rates enabled dose fractionation, where a long exposure is broken into a movie, permitting specimen drift to be registered and corrected. The typical approach for image registration, with high shot noise and low contrast, is multi-reference (MR) cross-correlation. Here we present the software package Zorro, which provides robust drift correction for dose fractionation by use of an intensity-normalized cross-correlation and logistic noise model to weight each cross-correlation in the MR model and filter each cross-correlation optimally. Frames are reliably registered by Zorro with low dose and defocus. Methods to evaluate performance are presented, by use of independently-evaluated even- and odd-frame stacks by trajectory comparison and Fourier ring correlation. Alignment of tiled sub-frames is also introduced, and demonstrated on an example dataset. Zorro source code is available at github.com/CINA/zorro.
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48
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Practical aspects of diffractive imaging using an atomic-scale coherent electron probe. Ultramicroscopy 2016; 169:107-121. [DOI: 10.1016/j.ultramic.2016.06.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/16/2016] [Accepted: 06/23/2016] [Indexed: 02/08/2023]
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49
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Wang HW, Lei J, Shi Y. Biological cryo-electron microscopy in China. Protein Sci 2016; 26:16-31. [PMID: 27534377 PMCID: PMC5192968 DOI: 10.1002/pro.3018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 08/11/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022]
Abstract
Cryo‐electron microscopy (cryo‐EM) plays an increasingly more important role in structural biology. With the construction of an arm of the Chinese National Protein Science Facility at Tsinghua University, biological cryo‐EM has entered a phase of rapid development in China. This article briefly reviews the history of biological cryo‐EM in China, describes its current status, comments on its impact on the various biological research fields, and presents future outlook.
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Affiliation(s)
- Hong-Wei Wang
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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50
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Abstract
AbstractThere has been enormous progress during the last few years in the determination of three-dimensional biological structures by single particle electron cryomicroscopy (cryoEM), allowing maps to be obtained with higher resolution and from fewer images than required previously. This is due principally to the introduction of a new type of direct electron detector that has 2- to 3-fold higher detective quantum efficiency than available previously, and to the improvement of the computational algorithms for image processing. In spite of the great strides that have been made, quantitative analysis shows that there are still significant gains to be made provided that the problems associated with image degradation can be solved, possibly by minimising beam-induced specimen movement and charge build up during imaging. If this can be achieved, it should be possible to obtain near atomic resolution structures of smaller single particles, using fewer images and resolving more conformational states than at present, thus realising the full potential of the method. The recent popularity of cryoEM for molecular structure determination also highlights the need for lower cost microscopes, so we encourage development of an inexpensive, 100 keV electron cryomicroscope with a high-brightness field emission gun to make the method accessible to individual groups or institutions that cannot afford the investment and running costs of a state-of-the-art 300 keV installation. A key requisite for successful high-resolution structure determination by cryoEM includes interpretation of images and optimising the biochemistry and grid preparation to obtain nicely distributed macromolecules of interest. We thus include in this review a gallery of cryoEM micrographs that shows illustrative examples of single particle images of large and small macromolecular complexes.
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