1
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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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2
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Acehan D, Spoth KA, Budziszewski GR, Snell ME, Campomizzi CS, Lynch ML, Bowman SE. Reaching the potential of electron diffraction. CELL REPORTS. PHYSICAL SCIENCE 2024; 5:102007. [PMID: 39055735 PMCID: PMC11271257 DOI: 10.1016/j.xcrp.2024.102007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Microcrystal electron diffraction (MicroED) is an emerging structural technique in which submicron crystals are used to generate diffraction data for structural studies. Structures allow for the study of molecular-level architecture and drive hypotheses about modes of action, mechanisms, dynamics, and interactions with other molecules. Combining cryoelectron microscopy (cryo-EM) instrumentation with crystallographic techniques, MicroED has led to three-dimensional structural models of small molecules, peptides, and proteins and has generated tremendous interest due to its ability to use vanishingly small crystals. In this perspective, we describe the current state of the field for MicroED methodologies, including making and detecting crystals of the appropriate size for the technique, as well as ways to best handle and characterize these crystals. Our perspective provides insight into ways to unlock the full range of potential for MicroED to access previously intractable samples and describes areas of future development.
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Affiliation(s)
- Devrim Acehan
- Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA
- University at Buffalo, Jacobs School of Medicine and Biomedical Science, Department of Structural Biology, Buffalo, NY 14203, USA
- University of Rochester, School of Medicine and Dentistry, Department of Biochemistry and Biophysics, Rochester, NY 14642, USA
| | | | | | | | | | - Miranda L. Lynch
- Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA
- University at Buffalo, Jacobs School of Medicine and Biomedical Science, Department of Structural Biology, Buffalo, NY 14203, USA
| | - Sarah E.J. Bowman
- Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA
- University at Buffalo, Jacobs School of Medicine and Biomedical Science, Department of Structural Biology, Buffalo, NY 14203, USA
- University at Buffalo, Jacobs School of Medicine and Biomedical Science, Department of Biochemistry, Buffalo, NY 14203, USA
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3
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Gillman C, Bu G, Danelius E, Hattne J, Nannenga BL, Gonen T. Eliminating the missing cone challenge through innovative approaches. J Struct Biol X 2024; 9:100102. [PMID: 38962493 PMCID: PMC11220036 DOI: 10.1016/j.yjsbx.2024.100102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 07/05/2024] Open
Abstract
Microcrystal electron diffraction (MicroED) has emerged as a powerful technique for unraveling molecular structures from microcrystals too small for X-ray diffraction. However, a significant hurdle arises with plate-like crystals that consistently orient themselves flat on the electron microscopy grid. If the normal of the plate correlates with the axes of the crystal lattice, the crystal orientations accessible for measurement are restricted because the crystal cannot be arbitrarily rotated. This limits the information that can be acquired, resulting in a missing cone of information. We recently introduced a novel crystallization strategy called suspended drop crystallization and proposed that crystals in a suspended drop could effectively address the challenge of preferred crystal orientation. Here we demonstrate the success of the suspended drop approach in eliminating the missing cone in two samples that crystallize as thin plates: bovine liver catalase and the SARS‑CoV‑2 main protease (Mpro). This innovative solution proves indispensable for crystals exhibiting systematic preferred orientations, unlocking new possibilities for structure determination by MicroED.
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Affiliation(s)
- Cody Gillman
- Department of Biological Chemistry, University of California, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Guanhong Bu
- Department of Biological Chemistry, University of California, Los Angeles, CA, USA
| | - Emma Danelius
- Department of Biological Chemistry, University of California, Los Angeles, CA, USA
- Howard Hughes Medical Institute, University of California, Los Angeles CA, USA
| | - Johan Hattne
- Department of Biological Chemistry, University of California, Los Angeles, CA, USA
- Howard Hughes Medical Institute, University of California, Los Angeles CA, USA
| | - Brent L. Nannenga
- Chemical Engineering, School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Tamir Gonen
- Department of Biological Chemistry, University of California, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Howard Hughes Medical Institute, University of California, Los Angeles CA, USA
- Department of Physiology, University of California, Los Angeles, CA, USA
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4
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Gillman C, Bu G, Danelius E, Hattne J, Nannenga B, Gonen T. Eliminating the Missing Cone Challenge through Innovative Approaches. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.11.575283. [PMID: 38293160 PMCID: PMC10827066 DOI: 10.1101/2024.01.11.575283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Microcrystal electron diffraction (MicroED) has emerged as a powerful technique for unraveling molecular structures from microcrystals too small for X-ray diffraction. However, a significant hurdle arises with plate-like crystals that consistently orient themselves flat on the electron microscopy grid. If, as is typically the case, the normal of the plate correlates with the axes of the crystal lattice, the crystal orientations accessible for measurement are restricted because the grid cannot be arbitrarily rotated. This limits the information that can be acquired, resulting in a missing cone of information. We recently introduced a novel crystallization strategy called suspended drop crystallization and proposed that this method could effectively address the challenge of preferred crystal orientation. Here we demonstrate the success of the suspended drop crystallization approach in eliminating the missing cone in two samples that crystallize as thin plates: bovine liver catalase and the COVID-19 main protease (Mpro). This innovative solution proves indispensable for crystals exhibiting preferred orientations, unlocking new possibilities for structure determination by MicroED.
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5
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Skoupý R, Boltje DB, Slouf M, Mrázová K, Láznička T, Taisne CM, Krzyžánek V, Hoogenboom JP, Jakobi AJ. Robust Local Thickness Estimation of Sub-Micrometer Specimen by 4D-STEM. SMALL METHODS 2023; 7:e2300258. [PMID: 37248805 DOI: 10.1002/smtd.202300258] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/21/2023] [Indexed: 05/31/2023]
Abstract
A quantitative four-dimensional scanning transmission electron microscopy (4D-STEM) imaging technique (q4STEM) for local thickness estimation across amorphous specimen such as obtained by focused ion beam (FIB)-milling of lamellae for (cryo-)TEM analysis is presented. This study is based on measuring spatially resolved diffraction patterns to obtain the angular distribution of electron scattering, or the ratio of integrated virtual dark and bright field STEM signals, and their quantitative evaluation using Monte Carlo simulations. The method is independent of signal intensity calibrations and only requires knowledge of the detector geometry, which is invariant for a given instrument. This study demonstrates that the method yields robust thickness estimates for sub-micrometer amorphous specimen using both direct detection and light conversion 2D-STEM detectors in a coincident FIB-SEM and a conventional SEM. Due to its facile implementation and minimal dose reauirements, it is anticipated that this method will find applications for in situ thickness monitoring during lamella fabrication of beam-sensitive materials.
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Affiliation(s)
- Radim Skoupý
- Institute of Scientific Instruments, Czech Academy of Sciences, Brno, 61264, CZ
- Department of Bionanoscience, Delft University of Technology, Delft, 2628 CD, NL
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2628 CJ, NL
- Department of Imaging Physics, Delft University of Technology, Delft, 2628 CJ, NL
| | - Daan B Boltje
- Department of Imaging Physics, Delft University of Technology, Delft, 2628 CJ, NL
| | - Miroslav Slouf
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Prague, 162 00, CZ
| | - Kateřina Mrázová
- Institute of Scientific Instruments, Czech Academy of Sciences, Brno, 61264, CZ
| | - Tomáš Láznička
- Institute of Scientific Instruments, Czech Academy of Sciences, Brno, 61264, CZ
| | - Clémence M Taisne
- Department of Bionanoscience, Delft University of Technology, Delft, 2628 CD, NL
| | - Vladislav Krzyžánek
- Institute of Scientific Instruments, Czech Academy of Sciences, Brno, 61264, CZ
| | - Jacob P Hoogenboom
- Department of Imaging Physics, Delft University of Technology, Delft, 2628 CJ, NL
| | - Arjen J Jakobi
- Department of Bionanoscience, Delft University of Technology, Delft, 2628 CD, NL
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6
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Drevon TR, Waterman DG, Krissinel E. Dynamical diffraction of high-energy electrons by light-atom structures: a multiple forward scattering interpretation. Acta Crystallogr A Found Adv 2023; 79:180-191. [PMID: 36862043 PMCID: PMC9979941 DOI: 10.1107/s2053273322011779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 12/08/2022] [Indexed: 02/11/2023] Open
Abstract
Because of the strong electron-atom interaction, the kinematic theory of diffraction cannot be used to describe the scattering of electrons by an assembly of atoms due to the strong dynamical diffraction that needs to be taken into account. In this paper, the scattering of high-energy electrons by a regular array of light atoms is solved exactly by applying the T-matrix formalism to the corresponding Schrödinger's equation in spherical coordinates. The independent atom model is used, where each atom is represented by a sphere with an effective constant potential. The validity of the forward scattering approximation and the phase grating approximation, assumed by the popular multislice method, is discussed, and an alternative interpretation of multiple scattering is proposed and compared with existing interpretations.
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Affiliation(s)
- Tarik R. Drevon
- STFC, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
- CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
| | - David G. Waterman
- STFC, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
- CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
| | - Eugene Krissinel
- STFC, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
- CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0FA, United Kingdom
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7
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Abstract
Electron crystallography has a storied history which rivals that of its more established X-ray-enabled counterpart. Recent advances in data collection and analysis have sparked a renaissance in the field, opening a new chapter for this venerable technique. Burgeoning interest in electron crystallography has spawned innovative methods described by various interchangeable labels (3D ED, MicroED, cRED, etc.). This Review covers concepts and findings relevant to the practicing crystallographer, with an emphasis on experiments aimed at using electron diffraction to elucidate the atomic structure of three-dimensional molecular crystals.
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Affiliation(s)
- Ambarneil Saha
- UCLA−DOE
Institute for Genomics and Proteomics, University
of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los
Angeles, California 90095, United States
| | - Shervin S. Nia
- UCLA−DOE
Institute for Genomics and Proteomics, University
of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los
Angeles, California 90095, United States
| | - José A. Rodríguez
- UCLA−DOE
Institute for Genomics and Proteomics, University
of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los
Angeles, California 90095, United States
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8
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Clabbers MTB, Shiriaeva A, Gonen T. MicroED: conception, practice and future opportunities. IUCRJ 2022; 9:169-179. [PMID: 35371502 PMCID: PMC8895021 DOI: 10.1107/s2052252521013063] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
This article documents a keynote seminar presented at the IUCr Congress in Prague, 2021. The cryo-EM method microcrystal electron diffraction is described and put in the context of macromolecular electron crystallography from its origins in 2D crystals of membrane proteins to today's application to 3D crystals a millionth the size of that needed for X-ray crystallography. Milestones in method development and applications are described with an outlook to the future.
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Affiliation(s)
- Max T. B. Clabbers
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
| | - Anna Shiriaeva
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095, USA
- Department of Physiology, University of California, Los Angeles, CA 90095, USA
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9
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Microcrystal electron diffraction in macromolecular and pharmaceutical structure determination. DRUG DISCOVERY TODAY. TECHNOLOGIES 2021; 37:93-105. [PMID: 34895659 DOI: 10.1016/j.ddtec.2020.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/05/2023]
Abstract
Microcrystal electron diffraction (MicroED) has recently shown to be a promising technique for structure determination in structural biology and pharmaceutical chemistry. Here, we discuss the unique properties of electrons and motivate its use for diffraction experiments. We review the latest developments in MicroED, and illustrate its applications in macromolecular crystallography, fragment screening and structure guided drug discovery. We discuss the perspectives of MicroED in synthetic chemistry and pharmaceutical development. We anticipate that the rapid advances MicroED showcased here will promote further development of electron crystallography and open up new opportunities for drug discovery.
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10
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Martynowycz MW, Clabbers MTB, Unge J, Hattne J, Gonen T. Benchmarking the ideal sample thickness in cryo-EM. Proc Natl Acad Sci U S A 2021; 118:e2108884118. [PMID: 34873060 PMCID: PMC8670461 DOI: 10.1073/pnas.2108884118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2021] [Indexed: 12/14/2022] Open
Abstract
The relationship between sample thickness and quality of data obtained is investigated by microcrystal electron diffraction (MicroED). Several electron microscopy (EM) grids containing proteinase K microcrystals of similar sizes from the same crystallization batch were prepared. Each grid was transferred into a focused ion beam and a scanning electron microscope in which the crystals were then systematically thinned into lamellae between 95- and 1,650-nm thick. MicroED data were collected at either 120-, 200-, or 300-kV accelerating voltages. Lamellae thicknesses were expressed in multiples of the corresponding inelastic mean free path to allow the results from different acceleration voltages to be compared. The quality of the data and subsequently determined structures were assessed using standard crystallographic measures. Structures were reliably determined with similar quality from crystalline lamellae up to twice the inelastic mean free path. Lower resolution diffraction was observed at three times the mean free path for all three accelerating voltages, but the data quality was insufficient to yield structures. Finally, no coherent diffraction was observed from lamellae thicker than four times the calculated inelastic mean free path. This study benchmarks the ideal specimen thickness with implications for all cryo-EM methods.
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Affiliation(s)
- Michael W Martynowycz
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Max T B Clabbers
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Johan Unge
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Johan Hattne
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Tamir Gonen
- HHMI, University of California, Los Angeles, CA 90095;
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
- Department of Physiology, University of California, Los Angeles, CA 90095
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11
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Zhou W, Bammes B, Mitchell PG, Betz K, Chiu W. Electron crystallography of chiral and non-chiral small molecules. Ultramicroscopy 2021; 232:113417. [PMID: 34695647 DOI: 10.1016/j.ultramic.2021.113417] [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: 07/13/2021] [Revised: 10/05/2021] [Accepted: 10/16/2021] [Indexed: 11/18/2022]
Abstract
Electron crystallography has recently gained attentions in multiple fields of research, as it has been demonstrated to determine atomic structures for inorganic, organic, and macromolecular materials from nano-sized crystals that were not amenable to conventional X-ray crystallography. Here, we demonstrate continuous-rotation microcrystal electron diffraction (microED) in a 200 kV transmission electron microscope using a DE-64 camera-a low-noise direct electron detector that can accommodate a linear response up to ∼1200 electrons per pixel per second at 20 fps with 2x-hardware-binning, making it ideal for acquisition of high-quality diffraction patterns. We have used this method and camera to determine a 0.75 Å structure of an organic molecule, biotin, with an exceptional goodness-of-fit, as well as a 0.88 Å structure of a chiral molecule, L-serine.
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Affiliation(s)
- Weijiang Zhou
- Biophysics Program, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | | | - Patrick G Mitchell
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Kerry Betz
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Wah Chiu
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA; Department of Bioengineering and Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA.
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12
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Clabbers MTB, Xu H. Macromolecular crystallography using microcrystal electron diffraction. Acta Crystallogr D Struct Biol 2021; 77:313-324. [PMID: 33645535 PMCID: PMC7919406 DOI: 10.1107/s2059798320016368] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 12/16/2020] [Indexed: 11/10/2022] Open
Abstract
Microcrystal electron diffraction (MicroED) has recently emerged as a promising method for macromolecular structure determination in structural biology. Since the first protein structure was determined in 2013, the method has been evolving rapidly. Several protein structures have been determined and various studies indicate that MicroED is capable of (i) revealing atomic structures with charges, (ii) solving new protein structures by molecular replacement, (iii) visualizing ligand-binding interactions and (iv) determining membrane-protein structures from microcrystals embedded in lipidic mesophases. However, further development and optimization is required to make MicroED experiments more accurate and more accessible to the structural biology community. Here, we provide an overview of the current status of the field, and highlight the ongoing development, to provide an indication of where the field may be going in the coming years. We anticipate that MicroED will become a robust method for macromolecular structure determination, complementing existing methods in structural biology.
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Affiliation(s)
- Max T. B. Clabbers
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden
| | - Hongyi Xu
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden
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13
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Richards LS, Millán C, Miao J, Martynowycz MW, Sawaya MR, Gonen T, Borges RJ, Usón I, Rodriguez JA. Fragment-based determination of a proteinase K structure from MicroED data using ARCIMBOLDO_SHREDDER. Acta Crystallogr D Struct Biol 2020; 76:703-712. [PMID: 32744252 PMCID: PMC7397493 DOI: 10.1107/s2059798320008049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 06/16/2020] [Indexed: 12/15/2022] Open
Abstract
Structure determination of novel biological macromolecules by X-ray crystallography can be facilitated by the use of small structural fragments, some of only a few residues in length, as effective search models for molecular replacement to overcome the phase problem. Independence from the need for a complete pre-existing model with sequence similarity to the crystallized molecule is the primary appeal of ARCIMBOLDO, a suite of programs which employs this ab initio algorithm for phase determination. Here, the use of ARCIMBOLDO is investigated to overcome the phase problem with the electron cryomicroscopy (cryoEM) method known as microcrystal electron diffraction (MicroED). The results support the use of the ARCIMBOLDO_SHREDDER pipeline to provide phasing solutions for a structure of proteinase K from 1.6 Å resolution data using model fragments derived from the structures of proteins sharing a sequence identity of as low as 20%. ARCIMBOLDO_SHREDDER identified the most accurate polyalanine fragments from a set of distantly related sequence homologues. Alternatively, such templates were extracted in spherical volumes and given internal degrees of freedom to refine towards the target structure. Both modes relied on the rotation function in Phaser to identify or refine fragment models and its translation function to place them. Model completion from the placed fragments proceeded through phase combination of partial solutions and/or density modification and main-chain autotracing using SHELXE. The combined set of fragments was sufficient to arrive at a solution that resembled that determined by conventional molecular replacement using the known target structure as a search model. This approach obviates the need for a single, complete and highly accurate search model when phasing MicroED data, and permits the evaluation of large fragment libraries for this purpose.
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Affiliation(s)
- Logan S. Richards
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Claudia Millán
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Jennifer Miao
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Michael W. Martynowycz
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Michael R. Sawaya
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Department of Physiology, University of California Los Angeles (UCLA), Los Angeles, California, USA
| | - Rafael J. Borges
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Isabel Usón
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
- ICREA, Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08003 Barcelona, Spain
| | - Jose A. Rodriguez
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
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14
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Nannenga BL. MicroED methodology and development. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:014304. [PMID: 32071929 PMCID: PMC7018523 DOI: 10.1063/1.5128226] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 01/24/2020] [Indexed: 06/10/2023]
Abstract
Microcrystal electron diffraction, or MicroED, is a method that is capable of determining structure from very small and thin 3D crystals using a transmission electron microscope. MicroED has been successfully used on microcrystalline samples, including proteins, peptides, and small organic molecules, in many cases to very high resolutions. In this work, the MicroED workflow will be briefly described and areas of future method development will be highlighted. These areas include improvements in sample preparation, data collection, and structure determination.
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Affiliation(s)
- Brent L Nannenga
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287, USA and Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85281, USA
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15
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Gemmi M, Mugnaioli E, Gorelik TE, Kolb U, Palatinus L, Boullay P, Hovmöller S, Abrahams JP. 3D Electron Diffraction: The Nanocrystallography Revolution. ACS CENTRAL SCIENCE 2019; 5:1315-1329. [PMID: 31482114 PMCID: PMC6716134 DOI: 10.1021/acscentsci.9b00394] [Citation(s) in RCA: 203] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Indexed: 05/20/2023]
Abstract
Crystallography of nanocrystalline materials has witnessed a true revolution in the past 10 years, thanks to the introduction of protocols for 3D acquisition and analysis of electron diffraction data. This method provides single-crystal data of structure solution and refinement quality, allowing the atomic structure determination of those materials that remained hitherto unknown because of their limited crystallinity. Several experimental protocols exist, which share the common idea of sampling a sequence of diffraction patterns while the crystal is tilted around a noncrystallographic axis, namely, the goniometer axis of the transmission electron microscope sample stage. This Outlook reviews most important 3D electron diffraction applications for different kinds of samples and problematics, related with both materials and life sciences. Structure refinement including dynamical scattering is also briefly discussed.
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Affiliation(s)
- Mauro Gemmi
- Center
for Nanotechnology Innovation@NEST, Istituto
Italiano di Tecnologia, Piazza S. Silvestro 12, 56127 Pisa, Italy
| | - Enrico Mugnaioli
- Center
for Nanotechnology Innovation@NEST, Istituto
Italiano di Tecnologia, Piazza S. Silvestro 12, 56127 Pisa, Italy
| | - Tatiana E. Gorelik
- University
of Ulm, Central Facility for Electron Microscopy, Electron Microscopy
Group of Materials Science (EMMS), Albert Einstein Allee 11, 89081 Ulm, Germany
| | - Ute Kolb
- Institut
für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Duesbergweg 10-14, 55128 Mainz, Germany
- Institut
für Angewandte Geowissenschaften, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt, Germany
| | - Lukas Palatinus
- Department
of Structure Analysis, Institute of Physics
of the CAS, Na Slovance 2, 182 21 Prague 8, Czechia
| | - Philippe Boullay
- CRISMAT,
Normandie Université, ENSICAEN, UNICAEN, CNRS UMR 6508, 6 Bd Maréchal Juin, F-14050 Cedex Caen, France
| | - Sven Hovmöller
- Inorganic
and Structural Chemistry, Department of Materials and Environmental
Chemistry, Stockholm University, 106 91 Stockholm, Sweden
| | - Jan Pieter Abrahams
- Center
for Cellular Imaging and NanoAnalytics (C−CINA), Biozentrum, Basel University, Mattenstrasse 26, CH-4058 Basel, Switzerland
- Department
of Biology and Chemistry, Paul Scherrer
Institut (PSI), CH-5232 Villigen PSI, Switzerland
- Leiden
Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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16
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Xu H, Lebrette H, Clabbers MTB, Zhao J, Griese JJ, Zou X, Högbom M. Solving a new R2lox protein structure by microcrystal electron diffraction. SCIENCE ADVANCES 2019; 5:eaax4621. [PMID: 31457106 PMCID: PMC6685719 DOI: 10.1126/sciadv.aax4621] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/27/2019] [Indexed: 05/06/2023]
Abstract
Microcrystal electron diffraction (MicroED) has recently shown potential for structural biology. It enables the study of biomolecules from micrometer-sized 3D crystals that are too small to be studied by conventional x-ray crystallography. However, to date, MicroED has only been applied to redetermine protein structures that had already been solved previously by x-ray diffraction. Here, we present the first new protein structure-an R2lox enzyme-solved using MicroED. The structure was phased by molecular replacement using a search model of 35% sequence identity. The resulting electrostatic scattering potential map at 3.0-Å resolution was of sufficient quality to allow accurate model building and refinement. The dinuclear metal cofactor could be located in the map and was modeled as a heterodinuclear Mn/Fe center based on previous studies. Our results demonstrate that MicroED has the potential to become a widely applicable tool for revealing novel insights into protein structure and function.
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Affiliation(s)
- Hongyi Xu
- Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden
- Corresponding author. (H.X.); (M.H.); (X.Z.)
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - Max T. B. Clabbers
- Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden
| | - Jingjing Zhao
- Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden
| | - Julia J. Griese
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
- Department of Cell and Molecular Biology, Uppsala University, 75124 Uppsala, Sweden
| | - Xiaodong Zou
- Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden
- Corresponding author. (H.X.); (M.H.); (X.Z.)
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
- Corresponding author. (H.X.); (M.H.); (X.Z.)
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17
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Latychevskaia T, Abrahams JP. Inelastic scattering and solvent scattering reduce dynamical diffraction in biological crystals. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2019; 75:523-531. [PMID: 32830710 PMCID: PMC6690131 DOI: 10.1107/s2052520619009661] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/07/2019] [Indexed: 05/05/2023]
Abstract
Multi-slice simulations of electron diffraction by three-dimensional protein crystals have indicated that structure solution would be severely impeded by dynamical diffraction, especially when crystals are more than a few unit cells thick. In practice, however, dynamical diffraction turned out to be less of a problem than anticipated on the basis of these simulations. Here it is shown that two scattering phenomena, which are usually omitted from multi-slice simulations, reduce the dynamical effect: solvent scattering reduces the phase differences within the exit beam and inelastic scattering followed by elastic scattering results in diffusion of dynamical scattering out of Bragg peaks. Thus, these independent phenomena provide potential reasons for the apparent discrepancy between theory and practice in protein electron crystallography.
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Affiliation(s)
- Tatiana Latychevskaia
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, Forschungsstrasse 111, Villigen, 5232, Switzerland
| | - Jan Pieter Abrahams
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, Forschungsstrasse 111, Villigen, 5232, Switzerland
- Biozentrum, Basel University, C-CINA, Mattenstrasse 26, Basel, 4058, Switzerland
- IBL, Leiden University, Sylviusweg 72, Leiden, 2333 BE, The Netherlands
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18
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Clabbers MTB, Gruene T, van Genderen E, Abrahams JP. Reducing dynamical electron scattering reveals hydrogen atoms. Acta Crystallogr A Found Adv 2019; 75:82-93. [PMID: 30575586 PMCID: PMC6302931 DOI: 10.1107/s2053273318013918] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/02/2018] [Indexed: 11/26/2022] Open
Abstract
Compared with X-rays, electron diffraction faces a crucial challenge: dynamical electron scattering compromises structure solution and its effects can only be modelled in specific cases. Dynamical scattering can be reduced experimentally by decreasing crystal size but not without a penalty, as it also reduces the overall diffracted intensity. In this article it is shown that nanometre-sized crystals from organic pharmaceuticals allow positional refinement of the hydrogen atoms, even whilst ignoring the effects of dynamical scattering during refinement. To boost the very weak diffraction data, a highly sensitive hybrid pixel detector was employed. A general likelihood-based computational approach was also introduced for further reducing the adverse effects of dynamic scattering, which significantly improved model accuracy, even for protein crystal data at substantially lower resolution.
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Affiliation(s)
- Max T. B. Clabbers
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Tim Gruene
- Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland
| | | | - Jan Pieter Abrahams
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
- Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland
- Leiden Institute of Biology, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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19
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Dunstone MA, de Marco A. Cryo-electron tomography: an ideal method to study membrane-associated proteins. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630150 DOI: 10.1098/rstb.2016.0210] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cryo-electron tomography (cryo-ET) is a three-dimensional imaging technique that makes it possible to analyse the structure of complex and dynamic biological assemblies in their native conditions. The latest technological and image processing developments demonstrate that it is possible to obtain structural information at nanometre resolution. The sample preparation required for the cryo-ET technique does not require the isolation of a protein and other macromolecular complexes from its native environment. Therefore, cryo-ET is emerging as an important tool to study the structure of membrane-associated proteins including pores.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
| | - Alex de Marco
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia .,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
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20
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Sub-ångström cryo-EM structure of a prion protofibril reveals a polar clasp. Nat Struct Mol Biol 2018; 25:131-134. [PMID: 29335561 PMCID: PMC6170007 DOI: 10.1038/s41594-017-0018-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/07/2017] [Indexed: 11/18/2022]
Abstract
The atomic structure of the infectious, protease-resistant, β-sheet-rich and fibrillar mammalian prion remains unknown. Through the cryo-EM method, MicroED, we reveal the sub-1Å resolution structure of a protofibril formed by a wild-type segment from the β2-α2 loop of the bank vole prion protein. The structure of this protofibril reveals a stabilizing network of hydrogen bonds that link polar zippers within a sheet, producing motifs we name ‘polar clasps’. Ultrahigh-resolution cryo-EM structure reveals a prion protofibril stabilized by a dense three-dimensional network of hydrogen bonds.
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21
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Clabbers MTB, van Genderen E, Wan W, Wiegers EL, Gruene T, Abrahams JP. Protein structure determination by electron diffraction using a single three-dimensional nanocrystal. Acta Crystallogr D Struct Biol 2017; 73:738-748. [PMID: 28876237 PMCID: PMC5586247 DOI: 10.1107/s2059798317010348] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 07/12/2017] [Indexed: 11/11/2022] Open
Abstract
Three-dimensional nanometre-sized crystals of macromolecules currently resist structure elucidation by single-crystal X-ray crystallography. Here, a single nanocrystal with a diffracting volume of only 0.14 µm3, i.e. no more than 6 × 105 unit cells, provided sufficient information to determine the structure of a rare dimeric polymorph of hen egg-white lysozyme by electron crystallography. This is at least an order of magnitude smaller than was previously possible. The molecular-replacement solution, based on a monomeric polyalanine model, provided sufficient phasing power to show side-chain density, and automated model building was used to reconstruct the side chains. Diffraction data were acquired using the rotation method with parallel beam diffraction on a Titan Krios transmission electron microscope equipped with a novel in-house-designed 1024 × 1024 pixel Timepix hybrid pixel detector for low-dose diffraction data collection. Favourable detector characteristics include the ability to accurately discriminate single high-energy electrons from X-rays and count them, fast readout to finely sample reciprocal space and a high dynamic range. This work, together with other recent milestones, suggests that electron crystallography can provide an attractive alternative in determining biological structures.
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Affiliation(s)
- M. T. B. Clabbers
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, Basel University, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - E. van Genderen
- Department of Biology and Chemistry, Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland
| | - W. Wan
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - E. L. Wiegers
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - T. Gruene
- Department of Biology and Chemistry, Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland
| | - J. P. Abrahams
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, Basel University, Mattenstrasse 26, CH-4058 Basel, Switzerland
- Department of Biology and Chemistry, Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland
- Leiden Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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22
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Ab initio structure determination from prion nanocrystals at atomic resolution by MicroED. Proc Natl Acad Sci U S A 2016; 113:11232-11236. [PMID: 27647903 DOI: 10.1073/pnas.1606287113] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electrons, because of their strong interaction with matter, produce high-resolution diffraction patterns from tiny 3D crystals only a few hundred nanometers thick in a frozen-hydrated state. This discovery offers the prospect of facile structure determination of complex biological macromolecules, which cannot be coaxed to form crystals large enough for conventional crystallography or cannot easily be produced in sufficient quantities. Two potential obstacles stand in the way. The first is a phenomenon known as dynamical scattering, in which multiple scattering events scramble the recorded electron diffraction intensities so that they are no longer informative of the crystallized molecule. The second obstacle is the lack of a proven means of de novo phase determination, as is required if the molecule crystallized is insufficiently similar to one that has been previously determined. We show with four structures of the amyloid core of the Sup35 prion protein that, if the diffraction resolution is high enough, sufficiently accurate phases can be obtained by direct methods with the cryo-EM method microelectron diffraction (MicroED), just as in X-ray diffraction. The success of these four experiments dispels the concern that dynamical scattering is an obstacle to ab initio phasing by MicroED and suggests that structures of novel macromolecules can also be determined by direct methods.
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23
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KOECK P, KARSHIKOFF A. Limitations of the linear and the projection approximations in three-dimensional transmission electron microscopy of fully hydrated proteins. J Microsc 2015; 259:197-209. [DOI: 10.1111/jmi.12253] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 03/09/2015] [Indexed: 11/29/2022]
Affiliation(s)
- P.J.B. KOECK
- Royal Institute of Technology; School of Technology and Health; Handen Sweden
- Department of Biosciences and Nutrition; Karolinska Institutet; Huddinge Sweden
| | - A. KARSHIKOFF
- Department of Biosciences and Nutrition; Karolinska Institutet; Huddinge Sweden
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24
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Wisedchaisri G, Reichow SL, Gonen T. Advances in structural and functional analysis of membrane proteins by electron crystallography. Structure 2012; 19:1381-93. [PMID: 22000511 DOI: 10.1016/j.str.2011.09.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 12/27/2022]
Abstract
Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography.
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Affiliation(s)
- Goragot Wisedchaisri
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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25
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Wisedchaisri G, Gonen T. Fragment-based phase extension for three-dimensional structure determination of membrane proteins by electron crystallography. Structure 2011; 19:976-87. [PMID: 21742264 DOI: 10.1016/j.str.2011.04.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/18/2011] [Accepted: 04/09/2011] [Indexed: 10/18/2022]
Abstract
In electron crystallography, membrane protein structure is determined from two-dimensional crystals where the protein is embedded in a membrane. Once large and well-ordered 2D crystals are grown, one of the bottlenecks in electron crystallography is the collection of image data to directly provide experimental phases to high resolution. Here, we describe an approach to bypass this bottleneck, eliminating the need for high-resolution imaging. We use the strengths of electron crystallography in rapidly obtaining accurate experimental phase information from low-resolution images and accurate high-resolution amplitude information from electron diffraction. The low-resolution experimental phases were used for the placement of α helix fragments and extended to high resolution using phases from the fragments. Phases were further improved by density modifications followed by fragment expansion and structure refinement against the high-resolution diffraction data. Using this approach, structures of three membrane proteins were determined rapidly and accurately to atomic resolution without high-resolution image data.
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26
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Zhang X, Zhou ZH. Limiting factors in atomic resolution cryo electron microscopy: no simple tricks. J Struct Biol 2011; 175:253-63. [PMID: 21627992 PMCID: PMC3710782 DOI: 10.1016/j.jsb.2011.05.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 01/25/2023]
Abstract
To bring cryo electron microscopy (cryoEM) of large biological complexes to atomic resolution, several factors--in both cryoEM image acquisition and 3D reconstruction--that may be neglected at low resolution become significantly limiting. Here we present thorough analyses of four limiting factors: (a) electron-beam tilt, (b) inaccurate determination of defocus values, (c) focus gradient through particles, and (d) particularly for large particles, dynamic (multiple) scattering of electrons. We also propose strategies to cope with these factors: (a) the divergence and direction tilt components of electron-beam tilt could be reduced by maintaining parallel illumination and by using a coma-free alignment procedure, respectively. Moreover, the effect of all beam tilt components, including spiral tilt, could be eliminated by use of a spherical aberration corrector. (b) More accurate measurement of defocus value could be obtained by imaging areas adjacent to the target area at high electron dose and by measuring the image shift induced by tilting the electron beam. (c) Each known Fourier coefficient in the Fourier transform of a cryoEM image is the sum of two Fourier coefficients of the 3D structure, one on each of two curved 'characteristic surfaces' in 3D Fourier space. We describe a simple model-based iterative method that could recover these two Fourier coefficients on the two characteristic surfaces. (d) The effect of dynamic scattering could be corrected by deconvolution of a transfer function. These analyses and our proposed strategies offer useful guidance for future experimental designs targeting atomic resolution cryoEM reconstruction.
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Affiliation(s)
- Xing Zhang
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, 237 BSRB, 615 Charles E. Young Dr. S., Los Angeles, CA 90095-7364, USA California NanoSystems Institute, University of California, Los Angeles, Box 957227, 570 Westwood Plaza, Bldg 114, Los Angeles, CA 90095-7227, USA
| | - Z. Hong Zhou
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, 237 BSRB, 615 Charles E. Young Dr. S., Los Angeles, CA 90095-7364, USA California NanoSystems Institute, University of California, Los Angeles, Box 957227, 570 Westwood Plaza, Bldg 114, Los Angeles, CA 90095-7227, USA
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27
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Abstract
For solving the atomic structure of organic molecules such as small proteins which are difficult to crystallize, the use of a jet of doped liquid helium droplets traversing a continuous high energy electron beam is proposed as a means of obtaining electron diffraction patterns (serial crystallography). Organic molecules (such as small proteins) within the droplet (and within a vitreous ice jacket) may be aligned by use of a polarized laser beam. Iterative methods for solving the phase problem are indicated. Comparisons with a related plan for pulsed x-ray diffraction from single proteins in a molecular beam are provided.
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Affiliation(s)
- J C H Spence
- Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85287-1504, USA
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28
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Abstract
We present a refined model of the alpha beta-tubulin dimer to 3.5 A resolution. An improved experimental density for the zinc-induced tubulin sheets was obtained by adding 114 electron diffraction patterns at 40-60 degrees tilt and increasing the completeness of structure factor amplitudes to 84.7 %. The refined structure was obtained using maximum-likelihood including phase information from experimental images, and simulated annealing Cartesian refinement to an R-factor of 23.2 and free R-factor of 29.7. The current model includes residues alpha:2-34, alpha:61-439, beta:2-437, one molecule of GTP, one of GDP, and one of taxol, as well as one magnesium ion at the non-exchangeable nucleotide site, and one putative zinc ion near the M-loop in the alpha-tubulin subunit. The acidic C-terminal tails could not be traced accurately, neither could the N-terminal loop including residues 35-60 in the alpha-subunit. There are no major changes in the overall fold of tubulin with respect to the previous structure, testifying to the quality of the initial experimental phases. The overall geometry of the model is, however, greatly improved, and the position of side-chains, especially those of exposed polar/charged groups, is much better defined. Three short protein sequence frame shifts were detected with respect to the non-refined structure. In light of the new model we discuss details of the tubulin structure such as nucleotide and taxol binding sites, lateral contacts in zinc-sheets, and the significance of the location of highly conserved residues.
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Affiliation(s)
- J Löwe
- MRC Laboratory of Molecular Biology, Cambridge, UK
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29
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Wille H, Prusiner SB. Ultrastructural studies on scrapie prion protein crystals obtained from reverse micellar solutions. Biophys J 1999; 76:1048-62. [PMID: 9916037 PMCID: PMC1300055 DOI: 10.1016/s0006-3495(99)77270-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The structural transition from the cellular prion protein (PrPC) that is rich in alpha-helices to the pathological form (PrPSc) that has a high beta-sheet content seems to be the fundamental event underlying the prion diseases. Determination of the structure of PrPSc and the N-terminally truncated PrP 27-30 has been complicated by their insolubility. Here we report the solubilization of PrP 27-30 through a system of reverse micelles that yields monomeric and dimeric PrP. Although solubilization of PrP 27-30 was not accompanied by any recognizable change in secondary structure as measured by FTIR spectroscopy, it did result in a loss of prion infectivity. The formation of small two- and three-dimensional crystals upon exposure to uranyl salts argues that soluble PrP 27-30 possesses considerable tertiary structure. The crystals of PrP 27-30 grown from reverse micellar solutions suggest a novel crystallization mechanism that might be applicable for other membrane proteins. A variety of different crystal lattices diffracted up to 1.85 nm by electron microscopy. Despite the lack of measurable biological activity, the structure of PrP 27-30 in these crystals may provide insight into the structural transition that occurs during PrPSc formation.
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Affiliation(s)
- H Wille
- Department of Neurology, University of California, San Francisco, California 94143 USA
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30
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Oostergetel G, Keegstra W, Brisson A. Automation of specimen selection and data acquisition for protein electron crystallography. Ultramicroscopy 1998. [DOI: 10.1016/s0304-3991(98)00022-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Walz T, Grigorieff N. Electron Crystallography of Two-Dimensional Crystals of Membrane Proteins. J Struct Biol 1998; 121:142-61. [PMID: 9618341 DOI: 10.1006/jsbi.1998.3945] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electron microscopy has become a powerful technique, along with X-ray crystallography and nuclear magnetic resonance spectroscopy, to study the three-dimensional structure of biological molecules. It has evolved into a number of methods dealing with a wide range of biological samples, with electron crystallography of two-dimensional crystals being so far the only method allowing data collection at near-atomic resolution. In this paper, we review the methodology of electron crystallography and its application to membrane proteins, starting with the pioneering work on bacteriorhodopsin, which led to the first visualization of the secondary structure of a membrane protein in 1975. Since then, improvements in instrumentation, sample preparation, and data analysis have led to atomic models for bacteriorhodopsin and light-harvesting complex II from higher plants. The structures of many more membrane proteins have been studied by electron crystallography and in this review examples are included where a resolution of better than 10 Å has been achieved. Indeed, in some of the given examples an atomic model can be expected in the near future. Finally, a brief outlook is given on current and future developments of electron crystallographic methods. Copyright 1998 Academic Press.
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Affiliation(s)
- T Walz
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, United Kingdom
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32
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33
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Grigorieff N, Henderson R. Comparison of calculated and observed dynamical diffraction from purple membrane: implications. Ultramicroscopy 1996. [DOI: 10.1016/s0304-3991(96)00061-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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34
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Winkler H, Taylor KA. Three-dimensional distortion correction applied to tomographic reconstructions of sectioned crystals. Ultramicroscopy 1996; 63:125-32. [PMID: 8875811 DOI: 10.1016/0304-3991(96)00024-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Unaveraged tomograms of embedded and sectioned insect flight muscle show not only structural variation within the individual unit cells but also defects in the filament lattice such as lack of straightness of the filaments and wrinkling of the sections. Adaptation of conventional 2D crystal image processing methods usually average out these structural variations and lattice defects thereby reducing the resolution and information content of the 3D reconstructions. We present here a computational method to correct the reconstructed 3D object for these distortions to make it suitable for further analysis. The correction is an extension of conventional 2D cross-correlation techniques applied to a 3D image. These procedures determine the unit cell positions of the distorted crystal and use a spline-fitting approach to calculate a mapping function from the observed positions that is subsequently used to reinterpolate the image onto a regular grid. The resulting reinterpolated image is corrected for both filament straightening as well as section wrinkling.
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Affiliation(s)
- H Winkler
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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35
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Beniac DR, Harauz G. Structures of small subunit ribosomal RNAs in situ from Escherichia coli and Thermomyces lanuginosus. Mol Cell Biochem 1995; 148:165-81. [PMID: 8594421 DOI: 10.1007/bf00928154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Small ribosomal subunits from the prokaryote Escherichia coli and the eukaryote Thermomyces lanuginosus were imaged electron spectroscopically, and single particle analysis used to yield three-dimensional reconstructions of the net phosphorus distribution representing the nucleic acid (RNA) backbone. This direct approach showed both ribosomal RNAs to have a three domain structure and other characteristic morphological features. The eukaryotic small ribosomal subunit had a prominent bill present in the head domain, while the prokaryotic subunit had a small vestigial bill. Both ribosomal subunits contained a thick 'collar' central domain which correlates to the site of the evolutionarily conserved ribosomal RNA core, and the location of the majority of ribosomal RNA bases that have been implicated in translation. The reconstruction of the prokaryotic subunit had a prominent protrusion extending from the collar, forming a channel approximately 1.5 nm wide and potentially representing a 'bridge' to the large subunit in the intact monosome. The basal domain of the prokaryotic ribosomal subunit was protein free. In this region of the eukaryotic subunit, there were two basal lobes composed of ribosomal RNA, consistent with previous hypotheses that this is a site for the 'non-conserved core' ribosomal RNA.
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Affiliation(s)
- D R Beniac
- Department of Molecular Biology and Genetics, University of Guelph, Ontario, Canada
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