1
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Hale VL, Hooker J, Russo CJ, Löwe J. Honeycomb gold specimen supports enabling orthogonal focussed ion beam-milling of elongated cells for cryo-ET. J Struct Biol 2024; 216:108097. [PMID: 38772448 DOI: 10.1016/j.jsb.2024.108097] [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: 12/29/2023] [Revised: 05/11/2024] [Accepted: 05/18/2024] [Indexed: 05/23/2024]
Abstract
Cryo-focussed ion beam (FIB)-milling is a powerful technique that opens up thick, cellular specimens to high-resolution structural analysis by electron cryotomography (cryo-ET). FIB-milled lamellae can be produced from cells on grids, or cut from thicker, high-pressure frozen specimens. However, these approaches can put geometrical constraints on the specimen that may be unhelpful, particularly when imaging structures within the cell that have a very defined orientation. For example, plunge frozen rod-shaped bacteria orient parallel to the plane of the grid, yet the Z-ring, a filamentous structure of the tubulin-like protein FtsZ and the key organiser of bacterial division, runs around the circumference of the cell such that it is perpendicular to the imaging plane. It is therefore difficult or impractical to image many complete rings with current technologies. To circumvent this problem, we have fabricated monolithic gold specimen supports with a regular array of cylindrical wells in a honeycomb geometry, which trap bacteria in a vertical orientation. These supports, which we call "honeycomb gold discs", replace standard EM grids and when combined with FIB-milling enable the production of lamellae containing cross-sections through cells. The resulting lamellae are more stable and resistant to breakage and charging than conventional lamellae. The design of the honeycomb discs can be modified according to need and so will also enable cryo-ET and cryo-EM imaging of other specimens in otherwise difficult to obtain orientations.
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Affiliation(s)
| | - James Hooker
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | - Jan Löwe
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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2
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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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3
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Tuijtel MW, Cruz-León S, Kreysing JP, Welsch S, Hummer G, Beck M, Turoňová B. Thinner is not always better: Optimizing cryo-lamellae for subtomogram averaging. SCIENCE ADVANCES 2024; 10:eadk6285. [PMID: 38669330 PMCID: PMC11051657 DOI: 10.1126/sciadv.adk6285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 03/26/2024] [Indexed: 04/28/2024]
Abstract
Cryo-electron tomography (cryo-ET) is a powerful method to elucidate subcellular architecture and to structurally analyze biomolecules in situ by subtomogram averaging, yet data quality critically depends on specimen thickness. Cells that are too thick for transmission imaging can be thinned into lamellae by cryo-focused ion beam (cryo-FIB) milling. Despite being a crucial parameter directly affecting attainable resolution, optimal lamella thickness has not been systematically investigated nor the extent of structural damage caused by gallium ions used for FIB milling. We thus systematically determined how resolution is affected by these parameters. We find that ion-induced damage does not affect regions more than 30 nanometers from either lamella surface and that up to ~180-nanometer lamella thickness does not negatively affect resolution. This shows that there is no need to generate very thin lamellae and lamella thickness can be chosen such that it captures cellular features of interest, thereby opening cryo-ET also for studies of large complexes.
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Affiliation(s)
- Maarten W. Tuijtel
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Sergio Cruz-León
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Jan Philipp Kreysing
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
- IMPRS on Cellular Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Martin Beck
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
- Institute of Biochemistry, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Beata Turoňová
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany
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4
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Liu YT, Fan H, Hu JJ, Zhou ZH. Overcoming the preferred orientation problem in cryoEM with self-supervised deep-learning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.11.588921. [PMID: 38645074 PMCID: PMC11030451 DOI: 10.1101/2024.04.11.588921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
While advances in single-particle cryoEM have enabled the structural determination of macromolecular complexes at atomic resolution, particle orientation bias (the so-called "preferred" orientation problem) remains a complication for most specimens. Existing solutions have relied on biochemical and physical strategies applied to the specimen and are often complex and challenging. Here, we develop spIsoNet, an end-to-end self-supervised deep-learning-based software to address the preferred orientation problem. Using preferred-orientation views to recover molecular information in under-sampled views, spIsoNet improves both angular isotropy and particle alignment accuracy during 3D reconstruction. We demonstrate spIsoNet's capability of generating near-isotropic reconstructions from representative biological systems with limited views, including ribosomes, β-galactosidases, and a previously intractable hemagglutinin trimer dataset. spIsoNet can also be generalized to improve map isotropy and particle alignment of preferentially oriented molecules in subtomogram averaging. Therefore, without additional specimen-preparation procedures, spIsoNet provides a general computational solution to the preferred orientation problem.
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5
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Warmack RA, Wenke BB, Spatzal T, Rees DC. Anaerobic cryoEM protocols for air-sensitive nitrogenase proteins. Nat Protoc 2024:10.1038/s41596-024-00973-5. [PMID: 38575747 DOI: 10.1038/s41596-024-00973-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 01/11/2024] [Indexed: 04/06/2024]
Abstract
Single-particle cryo-electron microscopy (cryoEM) provides an attractive avenue for advancing our atomic resolution understanding of materials, molecules and living systems. However, the vast majority of published cryoEM methodologies focus on the characterization of aerobically purified samples. Air-sensitive enzymes and microorganisms represent important yet understudied systems in structural biology. We have recently demonstrated the success of an anaerobic single-particle cryoEM workflow applied to the air-sensitive nitrogenase enzymes. In this protocol, we detail the use of Schlenk lines and anaerobic chambers to prepare samples, including a protein tag for monitoring sample exposure to oxygen in air. We describe how to use a plunge freezing apparatus inside of a soft-sided vinyl chamber of the type we routinely use for anaerobic biochemistry and crystallography of oxygen-sensitive proteins. Manual control of the airlock allows for introduction of liquid cryogens into the tent. A custom vacuum port provides slow, continuous evacuation of the tent atmosphere to avoid accumulation of flammable vapors within the enclosed chamber. These methods allowed us to obtain high-resolution structures of both nitrogenase proteins using single-particle cryoEM. The procedures involved can be generally subdivided into a 4 d anaerobic sample generation procedure, and a 1 d anaerobic cryoEM sample preparation step, followed by conventional cryoEM imaging and processing steps. As nitrogen is a substrate for nitrogenase, the Schlenk lines and anaerobic chambers described in this procedure are operated under an argon atmosphere; however, the system and these procedures are compatible with other controlled gas environments.
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Affiliation(s)
- Rebeccah A Warmack
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.
| | - Belinda B Wenke
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Thomas Spatzal
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.
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6
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Sanchez-Garcia R, Gaullier G, Cuadra-Troncoso JM, Vargas J. Cryo-EM Map Anisotropy Can Be Attenuated by Map Post-Processing and a New Method for Its Estimation. Int J Mol Sci 2024; 25:3959. [PMID: 38612769 PMCID: PMC11012471 DOI: 10.3390/ijms25073959] [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: 02/22/2024] [Revised: 03/22/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
One of the most important challenges in cryogenic electron microscopy (cryo-EM) is the substantial number of samples that exhibit preferred orientations, which leads to an uneven coverage of the projection sphere. As a result, the overall quality of the reconstructed maps can be severely affected, as manifested by the presence of anisotropy in the map resolution. Several methods have been proposed to measure the directional resolution of maps in tandem with experimental protocols to address the problem of preferential orientations in cryo-EM. Following these works, in this manuscript we identified one potential limitation that may affect most of the existing methods and we proposed an alternative approach to evaluate the presence of preferential orientations in cryo-EM reconstructions. In addition, we also showed that some of the most recently proposed cryo-EM map post-processing algorithms can attenuate map anisotropy, thus offering alternative visualization opportunities for cases affected by moderate levels of preferential orientations.
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Affiliation(s)
- Ruben Sanchez-Garcia
- Department of Statistics, University of Oxford, 24–29 St Giles’, Oxford OX1 3LB, UK
| | - Guillaume Gaullier
- Department of Chemistry—Ångström, Uppsala University, Box 523, SE 751 20 Uppsala, Sweden;
| | - Jose Manuel Cuadra-Troncoso
- Departamento de Inteligencia Artificial, Universidad Nacional de Educación a Distancia, C. Juan del Rosal 16, 28040 Madrid, Spain;
| | - Javier Vargas
- Departamento de Óptica, Universidad Complutense de Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain
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7
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Bagde SR, Kim CY. Architecture of full-length type I modular polyketide synthases revealed by X-ray crystallography, cryo-electron microscopy, and AlphaFold2. Nat Prod Rep 2024. [PMID: 38501175 DOI: 10.1039/d3np00060e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Covering: up to the end of 2023Type I modular polyketide synthases construct polyketide natural products in an assembly line-like fashion, where the growing polyketide chain attached to an acyl carrier protein is passed from catalytic domain to catalytic domain. These enzymes have immense potential in drug development since they can be engineered to produce non-natural polyketides by strategically adding, exchanging, and deleting individual catalytic domains. In practice, however, this approach frequently results in complete failures or dramatically reduced product yields. A comprehensive understanding of modular polyketide synthase architecture is expected to resolve these issues. We summarize the three-dimensional structures and the proposed mechanisms of three full-length modular polyketide synthases, Lsd14, DEBS module 1, and PikAIII. We also describe the advantages and limitations of using X-ray crystallography, cryo-electron microscopy, and AlphaFold2 to study intact type I polyketide synthases.
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Affiliation(s)
- Saket R Bagde
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Chu-Young Kim
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
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8
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Cebi E, Lee J, Subramani VK, Bak N, Oh C, Kim KK. Cryo-electron microscopy-based drug design. Front Mol Biosci 2024; 11:1342179. [PMID: 38501110 PMCID: PMC10945328 DOI: 10.3389/fmolb.2024.1342179] [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: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 03/20/2024] Open
Abstract
Structure-based drug design (SBDD) has gained popularity owing to its ability to develop more potent drugs compared to conventional drug-discovery methods. The success of SBDD relies heavily on obtaining the three-dimensional structures of drug targets. X-ray crystallography is the primary method used for solving structures and aiding the SBDD workflow; however, it is not suitable for all targets. With the resolution revolution, enabling routine high-resolution reconstruction of structures, cryogenic electron microscopy (cryo-EM) has emerged as a promising alternative and has attracted increasing attention in SBDD. Cryo-EM offers various advantages over X-ray crystallography and can potentially replace X-ray crystallography in SBDD. To fully utilize cryo-EM in drug discovery, understanding the strengths and weaknesses of this technique and noting the key advancements in the field are crucial. This review provides an overview of the general workflow of cryo-EM in SBDD and highlights technical innovations that enable its application in drug design. Furthermore, the most recent achievements in the cryo-EM methodology for drug discovery are discussed, demonstrating the potential of this technique for advancing drug development. By understanding the capabilities and advancements of cryo-EM, researchers can leverage the benefits of designing more effective drugs. This review concludes with a discussion of the future perspectives of cryo-EM-based SBDD, emphasizing the role of this technique in driving innovations in drug discovery and development. The integration of cryo-EM into the drug design process holds great promise for accelerating the discovery of new and improved therapeutic agents to combat various diseases.
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Affiliation(s)
| | | | | | | | - Changsuk Oh
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
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9
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Xu D, Ando N. Miffi: Improving the accuracy of CNN-based cryo-EM micrograph filtering with fine-tuning and Fourier space information. J Struct Biol 2024; 216:108072. [PMID: 38431179 DOI: 10.1016/j.jsb.2024.108072] [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: 12/11/2023] [Revised: 02/11/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
Efficient and high-accuracy filtering of cryo-electron microscopy (cryo-EM) micrographs is an emerging challenge with the growing speed of data collection and sizes of datasets. Convolutional neural networks (CNNs) are machine learning models that have been proven successful in many computer vision tasks, and have been previously applied to cryo-EM micrograph filtering. In this work, we demonstrate that two strategies, fine-tuning models from pretrained weights and including the power spectrum of micrographs as input, can greatly improve the attainable prediction accuracy of CNN models. The resulting software package, Miffi, is open-source and freely available for public use (https://github.com/ando-lab/miffi).
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Affiliation(s)
- Da Xu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nozomi Ando
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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10
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Xu D, Ando N. Miffi: Improving the accuracy of CNN-based cryo-EM micrograph filtering with fine-tuning and Fourier space information. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.08.570849. [PMID: 38405773 PMCID: PMC10888874 DOI: 10.1101/2023.12.08.570849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Efficient and high-accuracy filtering of cryo-electron microscopy (cryo-EM) micrographs is an emerging challenge with the growing speed of data collection and sizes of datasets. Convolutional neural networks (CNNs) are machine learning models that have been proven successful in many computer vision tasks, and have been previously applied to cryo-EM micrograph filtering. In this work, we demonstrate that two strategies, fine-tuning models from pretrained weights and including the power spectrum of micrographs as input, can greatly improve the attainable prediction accuracy of CNN models. The resulting software package, Miffi, is open-source and freely available for public use (https://github.com/ando-lab/miffi).
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Affiliation(s)
- Da Xu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Nozomi Ando
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
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11
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Bhattacharjee S, Feng X, Maji S, Dadhwal P, Zhang Z, Brown ZP, Frank J. Time resolution in cryo-EM using a PDMS-based microfluidic chip assembly and its application to the study of HflX-mediated ribosome recycling. Cell 2024; 187:782-796.e23. [PMID: 38244547 PMCID: PMC10872292 DOI: 10.1016/j.cell.2023.12.027] [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: 04/27/2023] [Revised: 10/13/2023] [Accepted: 12/19/2023] [Indexed: 01/22/2024]
Abstract
The rapid kinetics of biological processes and associated short-lived conformational changes pose a significant challenge in attempts to structurally visualize biomolecules during a reaction in real time. Conventionally, on-pathway intermediates have been trapped using chemical modifications or reduced temperature, giving limited insights. Here, we introduce a time-resolved cryo-EM method using a reusable PDMS-based microfluidic chip assembly with high reactant mixing efficiency. Coating of PDMS walls with SiO2 virtually eliminates non-specific sample adsorption and ensures maintenance of the stoichiometry of the reaction, rendering it highly reproducible. In an operating range from 10 to 1,000 ms, the device allows us to follow in vitro reactions of biological molecules at resolution levels in the range of 3 Å. By employing this method, we show the mechanism of progressive HflX-mediated splitting of the 70S E. coli ribosome in the presence of the GTP via capture of three high-resolution reaction intermediates within 140 ms.
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Affiliation(s)
- Sayan Bhattacharjee
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Xiangsong Feng
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA.
| | - Suvrajit Maji
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Prikshat Dadhwal
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Zhening Zhang
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Zuben P Brown
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10027, USA; Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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12
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González-Rodríguez N, Areán-Ulloa E, Fernández-Leiro R. A web-based dashboard for RELION metadata visualization. Acta Crystallogr D Struct Biol 2024; 80:93-100. [PMID: 38265874 PMCID: PMC10836394 DOI: 10.1107/s2059798323010902] [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: 10/31/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024] Open
Abstract
Cryo-electron microscopy (cryo-EM) has witnessed radical progress in the past decade, driven by developments in hardware and software. While current software packages include processing pipelines that simplify the image-processing workflow, they do not prioritize the in-depth analysis of crucial metadata, limiting troubleshooting for challenging data sets. The widely used RELION software package lacks a graphical native representation of the underlying metadata. Here, two web-based tools are introduced: relion_live.py, which offers real-time feedback on data collection, aiding swift decision-making during data acquisition, and relion_analyse.py, a graphical interface to represent RELION projects by plotting essential metadata including interactive data filtration and analysis. A useful script for estimating ice thickness and data quality during movie pre-processing is also presented. These tools empower researchers to analyse data efficiently and allow informed decisions during data collection and processing.
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Affiliation(s)
- Nayim González-Rodríguez
- Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Emma Areán-Ulloa
- Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rafael Fernández-Leiro
- Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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13
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Esfahani BG, Randolph PS, Peng R, Grant T, Stroupe ME, Stagg SM. SPOT-RASTR - a cryo-EM specimen preparation technique that overcomes problems with preferred orientation and the air/water interface. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.24.577038. [PMID: 38501120 PMCID: PMC10945588 DOI: 10.1101/2024.01.24.577038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
In cryogenic electron microscopy (cryo-EM), specimen preparation remains a bottleneck despite recent advancements. Classical plunge freezing methods often result in issues like aggregation and preferred orientations at the air/water interface. Many alternative methods have been proposed, but there remains a lack a universal solution, and multiple techniques are often required for challenging samples. Here, we demonstrate the use of lipid nanotubes with nickel NTA headgroups as a platform for cryo-EM sample preparation. His-tagged specimens of interest are added to the tubules, and they can be frozen by conventional plunge freezing. We show that the nanotubes protect samples from the air/water interface and promote a wider range of orientations. The reconstruction of average subtracted tubular regions (RASTR) method allows for the removal of the nanotubule signal from the cryo-EM images resulting in isolated images of specimens of interest. Testing with β-galactosidase validates the method's ability to capture particles at lower concentrations, overcome preferred orientations, and achieve near-atomic resolution reconstructions. Since the nanotubules can be identified and targeted automatically at low magnification, the method enables fully automated data collection. Furthermore, the particles on the tubes can be automatically identified and centered using 2D classification enabling particle picking without requiring prior information. Altogether, our approach that we call specimen preparation on a tube RASTR (SPOT-RASTR) holds promise for overcoming air-water interface and preferred orientation challenges and offers the potential for fully automated cryo-EM data collection and structure determination.
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14
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Aiyer S, Baldwin PR, Tan SM, Shan Z, Oh J, Mehrani A, Bowman ME, Louie G, Passos DO, Đorđević-Marquardt S, Mietzsch M, Hull JA, Hoshika S, Barad BA, Grotjahn DA, McKenna R, Agbandje-McKenna M, Benner SA, Noel JAP, Wang D, Tan YZ, Lyumkis D. Overcoming resolution attenuation during tilted cryo-EM data collection. Nat Commun 2024; 15:389. [PMID: 38195598 PMCID: PMC10776679 DOI: 10.1038/s41467-023-44555-7] [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: 07/14/2023] [Accepted: 12/15/2023] [Indexed: 01/11/2024] Open
Abstract
Structural biology efforts using cryogenic electron microscopy are frequently stifled by specimens adopting "preferred orientations" on grids, leading to anisotropic map resolution and impeding structure determination. Tilting the specimen stage during data collection is a generalizable solution but has historically led to substantial resolution attenuation. Here, we develop updated data collection and image processing workflows and demonstrate, using multiple specimens, that resolution attenuation is negligible or significantly reduced across tilt angles. Reconstructions with and without the stage tilted as high as 60° are virtually indistinguishable. These strategies allowed the reconstruction to 3 Å resolution of a bacterial RNA polymerase with preferred orientation, containing an unnatural nucleotide for studying novel base pair recognition. Furthermore, we present a quantitative framework that allows cryo-EM practitioners to define an optimal tilt angle during data acquisition. These results reinforce the utility of employing stage tilt for data collection and provide quantitative metrics to obtain isotropic maps.
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Affiliation(s)
- Sriram Aiyer
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Philip R Baldwin
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Shi Min Tan
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Zelin Shan
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Juntaek Oh
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
- College of Pharmacy, Kyung Hee University, Seoul, 02247, Republic of Korea
| | - Atousa Mehrani
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Marianne E Bowman
- Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Gordon Louie
- Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Dario Oliveira Passos
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | | | - Mario Mietzsch
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Joshua A Hull
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution, 13709 Progress Blvd Box 7, Alachua, FL, 32615, USA
| | - Benjamin A Barad
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Danielle A Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, 13709 Progress Blvd Box 7, Alachua, FL, 32615, USA
| | - Joseph A P Noel
- Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093, USA
| | - Dong Wang
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Yong Zi Tan
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore.
- Disease Intervention Technology Laboratory (DITL), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Singapore, 138648, Singapore.
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore.
| | - Dmitry Lyumkis
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
- Graduate School of Biological Sciences, Section of Molecular Biology, University of California San Diego, La Jolla, CA, 92093, USA.
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15
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Xu Y, Qin Y, Wang L, Zhang Y, Wang Y, Dang S. Metallo-supramolecular branched polymer protects particles from air-water interface in single-particle cryo-electron microscopy. Commun Biol 2024; 7:65. [PMID: 38195919 PMCID: PMC10776832 DOI: 10.1038/s42003-023-05752-8] [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: 07/26/2023] [Accepted: 12/28/2023] [Indexed: 01/11/2024] Open
Abstract
Recent technological breakthroughs in single-particle cryo-electron microscopy (cryo-EM) enable rapid atomic structure determination of biological macromolecules. A major bottleneck in the current single particle cryo-EM pipeline is the preparation of good quality frozen cryo-EM grids, which is mostly a trial-and-error process. Among many issues, preferred particle orientation and sample damage by air-water interface (AWI) are common practical problems. Here we report a method of applying metallo-supramolecular branched polymer (MSBP) in the cryo-sample preparation for high-resolution single-particle cryo-EM. Our data shows that MSBP keeps a majority of particles away from air-water interface and mitigates preferred orientation as verified by the analyses of apoferritin, hemagglutinin) trimer and various sample proteins. The use of MSBP is a simple method to improve particle distribution for high-resolution structure determination in single-particle cryo-EM.
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Affiliation(s)
- Yixin Xu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Yuqi Qin
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Lang Wang
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
| | - Yingyi Zhang
- Biological Cryo-EM Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yufeng Wang
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Shangyu Dang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.
- HKUST-Shenzhen Research Institute, Nanshan, Shenzhen, China.
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16
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Li T, Kambanis J, Sorenson TL, Sunde M, Shen Y. From Fundamental Amyloid Protein Self-Assembly to Development of Bioplastics. Biomacromolecules 2024; 25:5-23. [PMID: 38147506 PMCID: PMC10777412 DOI: 10.1021/acs.biomac.3c01129] [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: 10/18/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 12/28/2023]
Abstract
Proteins can self-assemble into a range of nanostructures as a result of molecular interactions. Amyloid nanofibrils, as one of them, were first discovered with regard to the relevance of neurodegenerative diseases but now have been exploited as building blocks to generate multiscale materials with designed functions for versatile applications. This review interconnects the mechanism of amyloid fibrillation, the current approaches to synthesizing amyloid protein-based materials, and the application in bioplastic development. We focus on the fundamental structures of self-assembled amyloid fibrils and how external factors can affect protein aggregation to optimize the process. Protein self-assembly is essentially the autonomous congregation of smaller protein units into larger, organized structures. Since the properties of the self-assembly can be manipulated by changing intrinsic factors and external conditions, protein self-assembly serves as an excellent building block for bioplastic development. Building on these principles, general processing methods and pathways from raw protein sources to mature state materials are proposed, providing a guide for the development of large-scale production. Additionally, this review discusses the diverse properties of protein-based amyloid nanofibrils and how they can be utilized as bioplastics. The economic feasibility of the protein bioplastics is also compared to conventional plastics in large-scale production scenarios, supporting their potential as sustainable bioplastics for future applications.
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Affiliation(s)
- Tianchen Li
- School
of Chemical and Biomolecular Engineering and Sydney Nano, The University of Sydney, PNR Building, Darlington NSW 2008, Australia
| | - Jordan Kambanis
- School
of Chemical and Biomolecular Engineering and Sydney Nano, The University of Sydney, PNR Building, Darlington NSW 2008, Australia
| | - Timothy L. Sorenson
- School
of Chemical and Biomolecular Engineering and Sydney Nano, The University of Sydney, PNR Building, Darlington NSW 2008, Australia
| | - Margaret Sunde
- School
of Medical Sciences and Sydney Nano, The
University of Sydney, Sydney NSW 2006, Australia
| | - Yi Shen
- School
of Chemical and Biomolecular Engineering and Sydney Nano, The University of Sydney, PNR Building, Darlington NSW 2008, Australia
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17
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Gobet A, Moissonnier L, Chaptal V. CryoEM Data Analysis of Membrane Proteins. Practical Considerations on Amphipathic Belts, Ligands, and Variability Analysis. Methods Mol Biol 2024; 2715:471-483. [PMID: 37930545 DOI: 10.1007/978-1-0716-3445-5_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Membrane proteins data analysis by cryoEM shows some specificities, as can be found in other typical investigations such as biochemistry, biophysics, or X-ray crystallography. Membrane proteins are typically surrounded by an amphipathic belt that will have some degree of influence on the 3D reconstruction and analysis. In this chapter, we review our experience with the ABC transporter BmrA, as well as our statistical analysis of amphipathic belts around membrane proteins, to bring awareness on some particular features of membrane protein investigations by cryoEM.
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Affiliation(s)
- Alexia Gobet
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS University Lyon 1, Lyon, France
| | - Loïck Moissonnier
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS University Lyon 1, Lyon, France
| | - Vincent Chaptal
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS University Lyon 1, Lyon, France.
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18
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Mazal H, Wieser FF, Sandoghdar V. Insights into protein structure using cryogenic light microscopy. Biochem Soc Trans 2023; 51:2041-2059. [PMID: 38015555 PMCID: PMC10754291 DOI: 10.1042/bst20221246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/29/2023]
Abstract
Fluorescence microscopy has witnessed many clever innovations in the last two decades, leading to new methods such as structured illumination and super-resolution microscopies. The attainable resolution in biological samples is, however, ultimately limited by residual motion within the sample or in the microscope setup. Thus, such experiments are typically performed on chemically fixed samples. Cryogenic light microscopy (Cryo-LM) has been investigated as an alternative, drawing on various preservation techniques developed for cryogenic electron microscopy (Cryo-EM). Moreover, this approach offers a powerful platform for correlative microscopy. Another key advantage of Cryo-LM is the strong reduction in photobleaching at low temperatures, facilitating the collection of orders of magnitude more photons from a single fluorophore. This results in much higher localization precision, leading to Angstrom resolution. In this review, we discuss the general development and progress of Cryo-LM with an emphasis on its application in harnessing structural information on proteins and protein complexes.
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Affiliation(s)
- Hisham Mazal
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91058 Erlangen, Germany
| | - Franz-Ferdinand Wieser
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91058 Erlangen, Germany
- Friedrich-Alexander University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Vahid Sandoghdar
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91058 Erlangen, Germany
- Friedrich-Alexander University of Erlangen-Nürnberg, 91058 Erlangen, Germany
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19
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Lewis JS, van Oijen AM, Spenkelink LM. Embracing Heterogeneity: Challenging the Paradigm of Replisomes as Deterministic Machines. Chem Rev 2023; 123:13419-13440. [PMID: 37971892 PMCID: PMC10790245 DOI: 10.1021/acs.chemrev.3c00436] [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: 06/25/2023] [Revised: 10/15/2023] [Accepted: 10/20/2023] [Indexed: 11/19/2023]
Abstract
The paradigm of cellular systems as deterministic machines has long guided our understanding of biology. Advancements in technology and methodology, however, have revealed a world of stochasticity, challenging the notion of determinism. Here, we explore the stochastic behavior of multi-protein complexes, using the DNA replication system (replisome) as a prime example. The faithful and timely copying of DNA depends on the simultaneous action of a large set of enzymes and scaffolding factors. This fundamental cellular process is underpinned by dynamic protein-nucleic acid assemblies that must transition between distinct conformations and compositional states. Traditionally viewed as a well-orchestrated molecular machine, recent experimental evidence has unveiled significant variability and heterogeneity in the replication process. In this review, we discuss recent advances in single-molecule approaches and single-particle cryo-EM, which have provided insights into the dynamic processes of DNA replication. We comment on the new challenges faced by structural biologists and biophysicists as they attempt to describe the dynamic cascade of events leading to replisome assembly, activation, and progression. The fundamental principles uncovered and yet to be discovered through the study of DNA replication will inform on similar operating principles for other multi-protein complexes.
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Affiliation(s)
- Jacob S. Lewis
- Macromolecular
Machines Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Antoine M. van Oijen
- Molecular
Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Lisanne M. Spenkelink
- Molecular
Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
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20
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Mendez JH, Chua EYD, Paraan M, Potter CS, Carragher B. Automated pipelines for rapid evaluation during cryoEM data acquisition. Curr Opin Struct Biol 2023; 83:102729. [PMID: 37988815 DOI: 10.1016/j.sbi.2023.102729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 10/14/2023] [Accepted: 10/16/2023] [Indexed: 11/23/2023]
Abstract
Cryo-electron microscopy (cryoEM) has become a popular method for determining high-resolution structures of biomolecules. However, data processing can be time-consuming, particularly for new researchers entering the field. To improve data quality and increase data collection efficiency, several software packages have been developed for on-the-fly data processing with various degrees of automation. These software packages allow researchers to perform tasks such as motion correction, CTF estimation, 2D classification, and 3D reconstruction in real-time, with minimal human input. On-the-fly data processing can not only improve data collection efficiency but also increase the productivity of instrumentation in high demand. However, the various software packages available differ in their performance, computational requirements, and levels of automation. In this review, we describe the minimal metrics used to assess data quality during data collection, outline the features of an ideal on-the-fly data processing software systems, and provide results from using three of these systems.
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Affiliation(s)
- Joshua H Mendez
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Eugene Y D Chua
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Mohammadreza Paraan
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Clinton S Potter
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Bridget Carragher
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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21
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Klebl DP, Aspinall L, Muench SP. Time resolved applications for Cryo-EM; approaches, challenges and future directions. Curr Opin Struct Biol 2023; 83:102696. [PMID: 37716094 DOI: 10.1016/j.sbi.2023.102696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 06/14/2023] [Accepted: 08/14/2023] [Indexed: 09/18/2023]
Abstract
Developments within the cryo-EM field have allowed us to generate higher-resolution "static" structures and pull out different conformational states which exist at equilibrium within the sample. Moreover, to trap non-equilibrium states and determine conformations that are present after a defined period of time (typically in the ms time frame) new approaches have been developed for the application of time-resolved cryo-EM. Here we give an overview of these different approaches and the limitations and strengths of each whilst identifying some of the current challenges to achieve higher resolutions and trap states within faster time frames. Time-resolved applications may play an important role in the ever-expanding toolkit of cryo-EM and open up new possibilities in both single particle and tomographic studies.
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Affiliation(s)
- David P Klebl
- School of Biomedical Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, UK
| | - Louie Aspinall
- School of Molecular and Cellular Biology, University of Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, UK.
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22
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Westphall MS, Lee KW, Salome AZ, Coon JJ, Grant T. Mass spectrometers as cryoEM grid preparation instruments. Curr Opin Struct Biol 2023; 83:102699. [PMID: 37703606 PMCID: PMC11019453 DOI: 10.1016/j.sbi.2023.102699] [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: 05/21/2023] [Revised: 07/18/2023] [Accepted: 08/15/2023] [Indexed: 09/15/2023]
Abstract
Structure determination by single-particle cryoEM has matured into a core structural biology technique. Despite many methodological advancements, most cryoEM grids are still prepared using the plunge-freezing method developed ∼40 years ago. Embedding samples in thin films and exposing them to the air-water interface often leads to sample damage and preferential orientation of the particles. Using native mass spectrometry to create cryoEM samples, potentially avoids these problems and allows the use of mass spectrometry sample isolation techniques during EM grid creation. We review the recent publications that have demonstrated protein complexes can be ionized, flown through the mass spectrometer, gently landed onto EM grids, imaged, and reconstructed in 3D. Although many uncertainties and challenges remain, the combination of cryoEM and MS has great potential.
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Affiliation(s)
- Michael S Westphall
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Kenneth W Lee
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Austin Z Salome
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Joshua J Coon
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States; Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States; Morgridge Institute for Research, 330 N Orchard Street, Madison, WI 53706, United States.
| | - Timothy Grant
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States; Morgridge Institute for Research, 330 N Orchard Street, Madison, WI 53706, United States.
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23
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Kang JS, Zhou X, Liu YT, Wang K, Zhou ZH. Theoretical framework and experimental solution for the air-water interface adsorption problem in cryoEM. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.23.541984. [PMID: 37961330 PMCID: PMC10634880 DOI: 10.1101/2023.05.23.541984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
As cryogenic electron microscopy (cryoEM) gains traction in the structural biology community as a method of choice for determining atomic structures of biological complexes, it has been increasingly recognized that many complexes that behave well under conventional negative-stain electron microscopy tend to have preferential orientation, aggregate or simply mysteriously "disappear" on cryoEM grids, but the reasons for such misbehavior are not well understood, limiting systematic approaches to solving the problem. Here, we have developed a theoretical formulation that explains these observations. Our formulation predicts that all particles migrate to the air-water interface (AWI) to lower the total potential surface energy - rationalizing the use of surfactant, which is a direct solution to reducing the surface tension of the aqueous solution. By conducting cryogenic electron tomography (cryoET) with the widely-tested sample, GroEL, we demonstrate that, in a standard buffer solution, nearly all particles migrate to the AWI. Gradual reduction of the surface tension by introducing surfactants decreased the percentage of particles exposed to the surface. By conducting single-particle cryoEM, we confirm that applicable surfactants do not damage the biological complex, thus suggesting that they might offer a practical, simple, and general solution to the problem for high-resolution cryoEM. Application of this solution to a real-world AWI adsorption problem with a more challenging membrane protein, namely, the ClC-1 channel, has led to its first near-atomic structure using cryoEM.
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24
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Kang JS, Zhou X, Liu YT, Wang K, Zhou ZH. Theoretical framework and experimental solution for the air-water interface adsorption problem in cryoEM. BIOPHYSICS REPORTS 2023; 9:215-229. [PMID: 38516618 PMCID: PMC10951471 DOI: 10.52601/bpr.2023.230008] [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: 10/07/2023] [Accepted: 10/31/2023] [Indexed: 03/23/2024] Open
Abstract
As cryogenic electron microscopy (cryoEM) gains traction in the structural biology community as a method of choice for determining atomic structures of biological complexes, it has been increasingly recognized that many complexes that behave well under conventional negative-stain electron microscopy tend to have preferential orientation, aggregate or simply mysteriously "disappear" on cryoEM grids. However, the reasons for such misbehavior are not well understood, which limits systematic approaches to solving the problem. Here, we have developed a theoretical formulation that explains these observations. Our formulation predicts that all particles migrate to the air-water interface (AWI) to lower the total potential surface energy-rationalizing the use of surfactant, which is a direct solution to reduce the surface tension of the aqueous solution. By performing cryogenic electron tomography (cryoET) on the widely-tested sample, GroEL, we demonstrate that, in a standard buffer solution, nearly all particles migrate to the AWI. Gradually reducing the surface tension by introducing surfactants decreased the percentage of particles exposed to the surface. By conducting single-particle cryoEM, we confirm that suitable surfactants do not damage the biological complex, thus suggesting that they might provide a practical, simple, and general solution to the problem for high-resolution cryoEM. Applying this solution to a real-world AWI adsorption problem involving a more challenging membrane protein, namely, the ClC-1 channel, has resulted in its near-atomic structure determination using cryoEM.
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Affiliation(s)
- Joon S. Kang
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Molecular Biology Institute, UCLA, Los Angeles, CA 90095, USA
| | - Xueting Zhou
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Yun-Tao Liu
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Kaituo Wang
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Z. Hong Zhou
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Molecular Biology Institute, UCLA, Los Angeles, CA 90095, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
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25
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Han BG, Avila-Sakar A, Remis J, Glaeser RM. Challenges in making ideal cryo-EM samples. Curr Opin Struct Biol 2023; 81:102646. [PMID: 37392555 DOI: 10.1016/j.sbi.2023.102646] [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: 12/27/2022] [Revised: 06/02/2023] [Accepted: 06/02/2023] [Indexed: 07/03/2023]
Abstract
Recognizing that interaction with the air-water interface (AWI) is a major challenge for cryo-EM, we first review current approaches designed to avoid it. Of these, immobilizing particles on affinity grids is arguably the most promising. In addition, we review efforts to gain more reliable control of the sample thicknesses, not the least important reason being to prevent immobilized particles from coming in contact with the AWI of the remaining buffer. It is emphasized that avoiding such a contact is as important for cryo-ET as for single-particle cryo-EM. Finally, looking to the future, it is proposed that immobilized samples might be used to perform time-resolved biochemical experiments directly on EM grids rather than just in test tubes or cuvettes.
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Affiliation(s)
- Bong-Gyoon Han
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
| | - Agustin Avila-Sakar
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
| | - Jonathan Remis
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Robert M Glaeser
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
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26
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Tan ZY, Cai S, Noble AJ, Chen JK, Shi J, Gan L. Heterogeneous non-canonical nucleosomes predominate in yeast cells in situ. eLife 2023; 12:RP87672. [PMID: 37503920 PMCID: PMC10382156 DOI: 10.7554/elife.87672] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023] Open
Abstract
Nuclear processes depend on the organization of chromatin, whose basic units are cylinder-shaped complexes called nucleosomes. A subset of mammalian nucleosomes in situ (inside cells) resembles the canonical structure determined in vitro 25 years ago. Nucleosome structure in situ is otherwise poorly understood. Using cryo-electron tomography (cryo-ET) and 3D classification analysis of budding yeast cells, here we find that canonical nucleosomes account for less than 10% of total nucleosomes expected in situ. In a strain in which H2A-GFP is the sole source of histone H2A, class averages that resemble canonical nucleosomes both with and without GFP densities are found ex vivo (in nuclear lysates), but not in situ. These data suggest that the budding yeast intranuclear environment favors multiple non-canonical nucleosome conformations. Using the structural observations here and the results of previous genomics and biochemical studies, we propose a model in which the average budding yeast nucleosome's DNA is partially detached in situ.
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Affiliation(s)
- Zhi Yang Tan
- Department of Biological Sciences and Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shujun Cai
- Department of Biological Sciences and Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Alex J Noble
- National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, United States
| | - Jon K Chen
- Department of Biological Sciences and Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jian Shi
- Department of Biological Sciences and Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Lu Gan
- Department of Biological Sciences and Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
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27
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Liu YT, Hu J, Zhou ZH. Resolving the Preferred Orientation Problem in CryoEM Reconstruction with Self-Supervised Deep Learning. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1918-1919. [PMID: 37612958 DOI: 10.1093/micmic/ozad067.991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Yun-Tao Liu
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California, United States
| | - Jason Hu
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California, United States
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California, United States
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California, United States
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28
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Chua EYD, Neselu K, Wang B, Rice WJ, Potter CS, Carragher B. Measuring the Effect of Ice Thickness and Microscope Configuration on Resolution in Single Particle Cryo-EM. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1040. [PMID: 37613233 DOI: 10.1093/micmic/ozad067.531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Eugene Y D Chua
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Kasahun Neselu
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Bing Wang
- Cryo-Electron Microscopy Core, New York University Grossman School of Medicine, New York, NYUSA
| | - William J Rice
- Cryo-Electron Microscopy Core, New York University Grossman School of Medicine, New York, NYUSA
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
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29
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Aiyer S, Baldwin PR, Tan SM, Shan Z, Oh J, Mehrani A, Bowman ME, Louie G, Passos DO, Đorđević-Marquardt S, Mietzsch M, Hull JA, Hoshika S, Barad BA, Grotjahn DA, McKenna R, Agbandje-McKenna M, Benner SA, Noel JAP, Wang D, Tan YZ, Lyumkis D. Overcoming Resolution Attenuation During Tilted Cryo-EM Data Collection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.14.548955. [PMID: 37503021 PMCID: PMC10369999 DOI: 10.1101/2023.07.14.548955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Structural biology efforts using cryogenic electron microscopy are frequently stifled by specimens adopting "preferred orientations" on grids, leading to anisotropic map resolution and impeding structure determination. Tilting the specimen stage during data collection is a generalizable solution but has historically led to substantial resolution attenuation. Here, we develop updated data collection and image processing workflows and demonstrate, using multiple specimens, that resolution attenuation is negligible or significantly reduced across tilt angles. Reconstructions with and without the stage tilted as high as 60° are virtually indistinguishable. These strategies allowed the reconstruction to 3 Å resolution of a bacterial RNA polymerase with preferred orientation. Furthermore, we present a quantitative framework that allows cryo-EM practitioners to define an optimal tilt angle for dataset acquisition. These data reinforce the utility of employing stage tilt for data collection and provide quantitative metrics to obtain isotropic maps.
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30
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Dhakal A, Gyawali R, Wang L, Cheng J. A large expert-curated cryo-EM image dataset for machine learning protein particle picking. Sci Data 2023; 10:392. [PMID: 37349345 PMCID: PMC10287764 DOI: 10.1038/s41597-023-02280-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/30/2023] [Indexed: 06/24/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) is a powerful technique for determining the structures of biological macromolecular complexes. Picking single-protein particles from cryo-EM micrographs is a crucial step in reconstructing protein structures. However, the widely used template-based particle picking process is labor-intensive and time-consuming. Though machine learning and artificial intelligence (AI) based particle picking can potentially automate the process, its development is hindered by lack of large, high-quality labelled training data. To address this bottleneck, we present CryoPPP, a large, diverse, expert-curated cryo-EM image dataset for protein particle picking and analysis. It consists of labelled cryo-EM micrographs (images) of 34 representative protein datasets selected from the Electron Microscopy Public Image Archive (EMPIAR). The dataset is 2.6 terabytes and includes 9,893 high-resolution micrographs with labelled protein particle coordinates. The labelling process was rigorously validated through 2D particle class validation and 3D density map validation with the gold standard. The dataset is expected to greatly facilitate the development of both AI and classical methods for automated cryo-EM protein particle picking.
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Affiliation(s)
- Ashwin Dhakal
- Department of Electrical Engineering and Computer Science, NextGen Precision Health, University of Missouri, Columbia, MO, 65211, USA
| | - Rajan Gyawali
- Department of Electrical Engineering and Computer Science, NextGen Precision Health, University of Missouri, Columbia, MO, 65211, USA
| | - Liguo Wang
- Laboratory for BioMolecular Structure (LBMS), Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Jianlin Cheng
- Department of Electrical Engineering and Computer Science, NextGen Precision Health, University of Missouri, Columbia, MO, 65211, USA.
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31
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Chari A, Stark H. Prospects and Limitations of High-Resolution Single-Particle Cryo-Electron Microscopy. Annu Rev Biophys 2023; 52:391-411. [PMID: 37159297 DOI: 10.1146/annurev-biophys-111622-091300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Single particle cryo-electron microscopy (cryo-EM) has matured into a robust method for the determination of biological macromolecule structures in the past decade, complementing X-ray crystallography and nuclear magnetic resonance. Constant methodological improvements in both cryo-EM hardware and image processing software continue to contribute to an exponential growth in the number of structures solved annually. In this review, we provide a historical view of the many steps that were required to make cryo-EM a successful method for the determination of high-resolution protein complex structures. We further discuss aspects of cryo-EM methodology that are the greatest pitfalls challenging successful structure determination to date. Lastly, we highlight and propose potential future developments that would improve the method even further in the near future.
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Affiliation(s)
- Ashwin Chari
- Research Group for Structural Biochemistry and Mechanisms, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Holger Stark
- Department of Structural Dynamics, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany;
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32
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Are extraordinary nucleosome structures more ordinary than we thought? Chromosoma 2023:10.1007/s00412-023-00791-w. [PMID: 36917245 DOI: 10.1007/s00412-023-00791-w] [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: 01/23/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/16/2023]
Abstract
The nucleosome is a DNA-protein assembly that is the basic unit of chromatin. A nucleosome can adopt various structures. In the canonical nucleosome structure, 145-147 bp of DNA is wrapped around a histone heterooctamer. The strong histone-DNA interactions cause the DNA to be inaccessible for nuclear processes such as transcription. Therefore, the canonical nucleosome structure has to be altered into different, non-canonical structures to increase DNA accessibility. While it is recognised that non-canonical structures do exist, these structures are not well understood. In this review, we discuss both the evidence for various non-canonical nucleosome structures in the nucleus and the factors that are believed to induce these structures. The wide range of non-canonical structures is likely to regulate the amount of accessible DNA, and thus have important nuclear functions.
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33
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Faille A, Dent KC, Pellegrino S, Jaako P, Warren AJ. The chemical landscape of the human ribosome at 1.67 Å resolution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.28.530191. [PMID: 36909531 PMCID: PMC10002709 DOI: 10.1101/2023.02.28.530191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The ability of ribosomes to translate the genetic code into protein requires a finely tuned ion and solvent ecosystem. However, the lack of high-resolution structures has precluded accurate positioning of all the functional elements of the ribosome and limited our understanding of the specific role of ribosomal RNA chemical modifications in modulating ribosome function in health and disease. Here, using a new sample preparation methodology based on functionalised pristine graphene-coated grids, we solve the cryo-EM structure of the human large ribosomal subunit to a resolution of 1.67 Å. The accurate assignment of water molecules, magnesium and potassium ions in our model highlights the fundamental biological role of ribosomal RNA methylation in harnessing unconventional carbon-oxygen hydrogen bonds to establish chemical interactions with the environment and fine-tune the functional interplay with tRNA. In addition, the structures of three translational inhibitors bound to the human large ribosomal subunit at better than 2 Å resolution provide mechanistic insights into how three key druggable pockets of the ribosome are targeted and illustrate the potential of this methodology to accelerate high-throughput structure-based design of anti-cancer therapeutics.
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34
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Warmack RA, Maggiolo AO, Orta A, Wenke BB, Howard JB, Rees DC. Structural consequences of turnover-induced homocitrate loss in nitrogenase. Nat Commun 2023; 14:1091. [PMID: 36841829 PMCID: PMC9968304 DOI: 10.1038/s41467-023-36636-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/09/2023] [Indexed: 02/26/2023] Open
Abstract
Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The active site FeMo-cofactor contains a [7Fe:1Mo:9S:1C] metallocluster coordinated with an R-homocitrate (HCA) molecule. Here, we establish through single particle cryoEM and chemical analysis of two forms of the Azotobacter vinelandii MoFe-protein - a high pH turnover inactivated species and a ∆NifV variant that cannot synthesize HCA - that loss of HCA is coupled to α-subunit domain and FeMo-cofactor disordering, and formation of a histidine coordination site. We further find a population of the ∆NifV variant complexed to an endogenous protein identified through structural and proteomic approaches as the uncharacterized protein NafT. Recognition by endogenous NafT demonstrates the physiological relevance of the HCA-compromised form, perhaps for cofactor insertion or repair. Our results point towards a dynamic active site in which HCA plays a role in enabling nitrogenase catalysis by facilitating activation of the FeMo-cofactor from a relatively stable form to a state capable of reducing dinitrogen under ambient conditions.
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Affiliation(s)
- Rebeccah A Warmack
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA.
| | - Ailiena O Maggiolo
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Andres Orta
- Biochemistry and Molecular Biophysics Graduate Program, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Belinda B Wenke
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA
| | - James B Howard
- Department of Biochemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA.
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.
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35
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Shi H, Wu C, Zhang X. Addressing compressive deformation of proteins embedded in crystalline ice. Structure 2023; 31:213-220.e3. [PMID: 36586403 DOI: 10.1016/j.str.2022.12.001] [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: 04/20/2022] [Revised: 08/09/2022] [Accepted: 11/29/2022] [Indexed: 12/31/2022]
Abstract
For cryoelectron microscopy (cryo-EM), high cooling rates have been required for preparation of protein samples to vitrify the surrounding water and avoid formation of damaging crystalline ice. Whether and how crystalline ice affects single-particle cryo-EM is still unclear. Here, single-particle cryo-EM was used to analyze three-dimensional structures of various proteins and viruses embedded in crystalline ice formed at various cooling rates. Low cooling rates led to shrinkage deformation and density distortions on samples having loose structures. Higher cooling rates reduced deformations. Deformation-free proteins in crystalline ice were obtained by modifying the freezing conditions, and reconstructions from these samples revealed a marked improvement over vitreous ice. This procedure also increased the efficiency of cryo-EM structure determinations and was essential for high-resolution reconstructions.
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Affiliation(s)
- Huigang Shi
- 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; University of Chinese Academy of Sciences, Beijing 100049, 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; University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
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36
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Nickl P, Hilal T, Olal D, Donskyi IS, Radnik J, Ludwig K, Haag R. A New Support Film for Cryo Electron Microscopy Protein Structure Analysis Based on Covalently Functionalized Graphene. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205932. [PMID: 36507556 DOI: 10.1002/smll.202205932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/25/2022] [Indexed: 06/18/2023]
Abstract
Protein adsorption at the air-water interface is a serious problem in cryogenic electron microscopy (cryoEM) as it restricts particle orientations in the vitrified ice-film and promotes protein denaturation. To address this issue, the preparation of a graphene-based modified support film for coverage of conventional holey carbon transmission electron microscopy (TEM) grids is presented. The chemical modification of graphene sheets enables the universal covalent anchoring of unmodified proteins via inherent surface-exposed lysine or cysteine residues in a one-step reaction. Langmuir-Blodgett (LB) trough approach is applied for deposition of functionalized graphene sheets onto commercially available holey carbon TEM grids. The application of the modified TEM grids in single particle analysis (SPA) shows high protein binding to the surface of the graphene-based support film. Suitability for high resolution structure determination is confirmed by SPA of apoferritin. Prevention of protein denaturation at the air-water interface and improvement of particle orientations is shown using human 20S proteasome, demonstrating the potential of the support film for structural biology.
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Affiliation(s)
- Philip Nickl
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
- Forschungszentrum für Elektronenmikroskopie und Core Facility BioSupraMol, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 36a, 14195, Berlin, Germany
- Division 6.1 - Surface Analysis and Interfacial Chemistry, BAM - Federal Institute for Material Science and Testing, Unter den Eichen 44-46, 12205, Berlin, Germany
| | - Tarek Hilal
- Forschungszentrum für Elektronenmikroskopie und Core Facility BioSupraMol, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 36a, 14195, Berlin, Germany
| | - Daniel Olal
- Forschungszentrum für Elektronenmikroskopie und Core Facility BioSupraMol, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 36a, 14195, Berlin, Germany
| | - Ievgen Sergeevitch Donskyi
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
- Division 6.1 - Surface Analysis and Interfacial Chemistry, BAM - Federal Institute for Material Science and Testing, Unter den Eichen 44-46, 12205, Berlin, Germany
| | - Jörg Radnik
- Division 6.1 - Surface Analysis and Interfacial Chemistry, BAM - Federal Institute for Material Science and Testing, Unter den Eichen 44-46, 12205, Berlin, Germany
| | - Kai Ludwig
- Forschungszentrum für Elektronenmikroskopie und Core Facility BioSupraMol, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 36a, 14195, Berlin, Germany
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
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37
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Neselu K, Wang B, Rice WJ, Potter CS, Carragher B, Chua EY. Measuring the effects of ice thickness on resolution in single particle cryo-EM. J Struct Biol X 2023; 7:100085. [PMID: 36742017 PMCID: PMC9894782 DOI: 10.1016/j.yjsbx.2023.100085] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
Ice thickness is a critical parameter in single particle cryo-EM - too thin ice can break during imaging or exclude the sample of interest, while ice that is too thick contributes to more inelastic scattering that precludes obtaining high resolution reconstructions. Here we present the practical effects of ice thickness on resolution, and the influence of energy filters, accelerating voltage, or detector mode. We collected apoferritin data with a wide range of ice thicknesses on three microscopes with different instrumentation and settings. We show that on a 300 kV microscope, using a 20 eV energy filter slit has a greater effect on improving resolution in thicker ice; that operating at 300 kV instead of 200 kV accelerating voltage provides significant resolution improvements at an ice thickness above 150 nm; and that on a 200 kV microscope using a detector operating in super resolution mode enables good reconstructions for up to 200 nm ice thickness, while collecting in counting instead of linear mode leads to improvements in resolution for ice of 50-150 nm thickness. Our findings can serve as a guide for users seeking to optimize data collection or sample preparation routines for both single particle and in situ cryo-EM. We note that most in situ data collection is done on samples in a range of ice thickness above 150 nm so these results may be especially relevant to that community.
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Affiliation(s)
- Kasahun Neselu
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Bing Wang
- Cryo-Electron Microscopy Core, New York University Grossman School of Medicine, New York, NY, USA
| | - William J. Rice
- Cryo-Electron Microscopy Core, New York University Grossman School of Medicine, New York, NY, USA,Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
| | - Clinton S. Potter
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Bridget Carragher
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA,Corresponding authors.
| | - Eugene Y.D. Chua
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA,Corresponding authors.
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38
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Amann SJ, Keihsler D, Bodrug T, Brown NG, Haselbach D. Frozen in time: analyzing molecular dynamics with time-resolved cryo-EM. Structure 2023; 31:4-19. [PMID: 36584678 PMCID: PMC9825670 DOI: 10.1016/j.str.2022.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 10/10/2022] [Accepted: 11/25/2022] [Indexed: 12/30/2022]
Abstract
Molecular machines, such as polymerases, ribosomes, or proteasomes, fulfill complex tasks requiring the thermal energy of their environment. They achieve this by restricting random motion along a path of possible conformational changes. These changes are often directed through engagement with different cofactors, which can best be compared to a Brownian ratchet. Many molecular machines undergo three major steps throughout their functional cycles, including initialization, repetitive processing, and termination. Several of these major states have been elucidated by cryogenic electron microscopy (cryo-EM). However, the individual steps for these machines are unique and multistep processes themselves, and their coordination in time is still elusive. To measure these short-lived intermediate events by cryo-EM, the total reaction time needs to be shortened to enrich for the respective pre-equilibrium states. This approach is termed time-resolved cryo-EM (trEM). In this review, we sum up the methodological development of trEM and its application to a range of biological questions.
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Affiliation(s)
- Sascha Josef Amann
- IMP - Research Institute of Molecular Pathology, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria; Vienna BioCenter PhD Program, a Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Demian Keihsler
- IMP - Research Institute of Molecular Pathology, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria
| | - Tatyana Bodrug
- IMP - Research Institute of Molecular Pathology, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria; Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nicholas G Brown
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - David Haselbach
- IMP - Research Institute of Molecular Pathology, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria; Institute for Physical Chemistry, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
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39
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Cheng A, Kim PT, Kuang H, Mendez JH, Chua EYD, Maruthi K, Wei H, Sawh A, Aragon MF, Serbynovskyi V, Neselu K, Eng ET, Potter CS, Carragher B, Bepler T, Noble AJ. Fully automated multi-grid cryoEM screening using Smart Leginon. IUCRJ 2023; 10:77-89. [PMID: 36598504 PMCID: PMC9812217 DOI: 10.1107/s2052252522010624] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023]
Abstract
Single-particle cryo-electron microscopy (cryoEM) is a swiftly growing method for understanding protein structure. With increasing demand for high-throughput, high-resolution cryoEM services comes greater demand for rapid and automated cryoEM grid and sample screening. During screening, optimal grids and sample conditions are identified for subsequent high-resolution data collection. Screening is a major bottleneck for new cryoEM projects because grids must be optimized for several factors, including grid type, grid hole size, sample concentration, buffer conditions, ice thickness and particle behavior. Even for mature projects, multiple grids are commonly screened to select a subset for high-resolution data collection. Here, machine learning and novel purpose-built image-processing and microscope-handling algorithms are incorporated into the automated data-collection software Leginon, to provide an open-source solution for fully automated high-throughput grid screening. This new version, broadly called Smart Leginon, emulates the actions of an operator in identifying areas on the grid to explore as potentially useful for data collection. Smart Leginon Autoscreen sequentially loads and examines grids from an automated specimen-exchange system to provide completely unattended grid screening across a set of grids. Comparisons between a multi-grid autoscreen session and conventional manual screening by 5 expert microscope operators are presented. On average, Autoscreen reduces operator time from ∼6 h to <10 min and provides a percentage of suitable images for evaluation comparable to the best operator. The ability of Smart Leginon to target holes that are particularly difficult to identify is analyzed. Finally, the utility of Smart Leginon is illustrated with three real-world multi-grid user screening/collection sessions, demonstrating the efficiency and flexibility of the software package. The fully automated functionality of Smart Leginon significantly reduces the burden on operator screening time, improves the throughput of screening and recovers idle microscope time, thereby improving availability of cryoEM services.
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Affiliation(s)
- Anchi Cheng
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Paul T. Kim
- Simons Machine Learning Center, New York Structural Biology Center, New York, NY, USA
| | - Huihui Kuang
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Joshua H. Mendez
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Eugene Y. D. Chua
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Kashyap Maruthi
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Hui Wei
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Anjelique Sawh
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Mahira F. Aragon
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | | | - Kasahun Neselu
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Edward T. Eng
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Clinton S. Potter
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Bridget Carragher
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Tristan Bepler
- Simons Machine Learning Center, New York Structural Biology Center, New York, NY, USA
| | - Alex J. Noble
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
- Simons Machine Learning Center, New York Structural Biology Center, New York, NY, USA
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40
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Niebling S, Burastero O, García-Alai M. Biophysical Characterization of Membrane Proteins. Methods Mol Biol 2023; 2652:215-230. [PMID: 37093478 DOI: 10.1007/978-1-0716-3147-8_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Membrane proteins are responsible for a large variety of tasks in organisms and of particular interesting as drug targets. At the same time, they are notoriously difficult to work with and require a thorough characterization before proceeding with structural studies. Here, we present a biophysical pipeline to characterize membrane proteins focusing on the optimization of stability, aggregation behavior, and homogeneity. The pipeline shown here is built on three biophysical techniques: differential scanning fluorimetry using native protein fluorescence (nano differential scanning fluorimetry), dynamic light scattering, and mass photometry. For each of these techniques, we provide detailed protocols for performing experiments and data analysis.
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Affiliation(s)
- Stephan Niebling
- European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
| | - Osvaldo Burastero
- European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
| | - María García-Alai
- European Molecular Biology Laboratory Hamburg, Hamburg, Germany.
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany.
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41
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Kim PT, Noble AJ, Cheng A, Bepler T. Learning to automate cryo-electron microscopy data collection with Ptolemy. IUCRJ 2023; 10:90-102. [PMID: 36598505 PMCID: PMC9812219 DOI: 10.1107/s2052252522010612] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023]
Abstract
Over the past decade, cryo-electron microscopy (cryoEM) has emerged as an important method for determining near-native, near-atomic resolution 3D structures of biological macromolecules. To meet the increasing demand for cryoEM, automated methods that improve throughput and efficiency of microscope operation are needed. Currently, the targeting algorithms provided by most data-collection software require time-consuming manual tuning of parameters for each grid, and, in some cases, operators must select targets completely manually. However, the development of fully automated targeting algorithms is non-trivial, because images often have low signal-to-noise ratios and optimal targeting strategies depend on a range of experimental parameters and macromolecule behaviors that vary between projects and collection sessions. To address this, Ptolemy provides a pipeline to automate low- and medium-magnification targeting using a suite of purpose-built computer vision and machine-learning algorithms, including mixture models, convolutional neural networks and U-Nets. Learned models in this pipeline are trained on a large set of images from real-world cryoEM data-collection sessions, labeled with locations selected by human operators. These models accurately detect and classify regions of interest in low- and medium-magnification images, and generalize to unseen sessions, as well as to images collected on different microscopes at another facility. This open-source, modular pipeline can be integrated with existing microscope control software to enable automation of cryoEM data collection and can serve as a foundation for future cryoEM automation software.
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Affiliation(s)
- Paul T. Kim
- Simons Machine Learning Center, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY USA
| | - Alex J. Noble
- Simons Machine Learning Center, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY USA
| | - Anchi Cheng
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY USA
| | - Tristan Bepler
- Simons Machine Learning Center, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY USA
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42
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Dienemann C. Towards automating single-particle cryo-EM data acquisition. IUCRJ 2023; 10:4-5. [PMID: 36598497 PMCID: PMC9812215 DOI: 10.1107/s2052252522012039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Target selection for single-particle cryo-EM data acquisition sessions is mostly done manually by human operators, which is time consuming and leads to the inefficient use of instruments. The software toolbox Ptolemy [Kim et al. (2023). IUCrJ, 10, 90–102] provides solutions for automated target selection for cryo-EM imaging.
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Affiliation(s)
- Christian Dienemann
- Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
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43
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Schreiber MT, Maigné A, Beleggia M, Shibata S, Wolf M. Temporal dynamics of charge buildup in cryo-electron microscopy. J Struct Biol X 2022; 7:100081. [PMID: 36632442 PMCID: PMC9826809 DOI: 10.1016/j.yjsbx.2022.100081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
It is well known that insulating samples can accumulate electric charges from exposure to an electron beam. How the accumulation of charge affects imaging parameters and sample stability in transmission electron microscopy is poorly understood. To quantify these effects, it is important to know how the charge is distributed within the sample and how it builds up over time. In the present study, we determine the spatial distribution and temporal dynamics of charge accumulation on vitreous ice samples with embedded proteins through a combination of modeling and Fresnel diffraction experiments. Our data reveal a rapid evolution of the charge state on ice upon initial exposure to the electron beam accompanied by charge gradients at the interfaces between ice and carbon films. We demonstrate that ice film movement and charge state variations occur upon electron beam exposure and are dose-rate dependent. Both affect the image defocus through a combination of sample height changes and lensing effects. Our results may be used as a guide to improve sample preparation, data collection, and data processing for imaging of dose-sensitive samples.
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Affiliation(s)
- Makoto Tokoro Schreiber
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Alan Maigné
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Marco Beleggia
- DTU Nanolab, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Satoshi Shibata
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, Japan
| | - Matthias Wolf
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, Japan,Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan,Corresponding author at: Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, Japan.
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44
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Liu N, Wang HW. Better Cryo-EM Specimen Preparation: How to Deal with the Air-Water Interface? J Mol Biol 2022; 435:167926. [PMID: 36563741 DOI: 10.1016/j.jmb.2022.167926] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/08/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) is now one of the most powerful and widely used methods to determine high-resolution structures of macromolecules. A major bottleneck of cryo-EM is to prepare high-quality vitrified specimen, which still faces many practical challenges. During the conventional vitrification process, macromolecules tend to adsorb at the air-water interface (AWI), which is known unfriendly to biological samples. In this review, we outline the nature of AWI and the problems caused by it, such as unpredictable or uneven particle distribution, protein denaturation, dissociation of complex and preferential orientation. We review and discuss the approaches and underlying mechanisms to deal with AWI: 1) Additives, exemplified by detergents, forming a protective layer at AWI and thus preserving the native folds of target macromolecules. 2) Fast vitrification devices based on the idea to freeze in-solution macromolecules before their touching of AWI. 3) Thin layer of continuous supporting films to adsorb macromolecules, and when functionalized with affinity ligands, to specifically anchor the target particles away from the AWI. Among these supporting films, graphene, together with its derivatives, with negligible background noise and mechanical robustness, has emerged as a new generation of support. These strategies have been proven successful in various cases and enable us a better handling of the problems caused by the AWI in cryo-EM specimen preparation.
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Affiliation(s)
- Nan Liu
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structures, School of Life Sciences, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.
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45
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Bepler T, Borst AJ, Bouvette J, Cannone G, Chen S, Cheng A, Cheng A, Fan Q, Grollios F, Gupta H, Gupta M, Humphreys T, Kim PT, Kuang H, Li Y, Noble AJ, Punjani A, Rice WJ, Oscar S Sorzano C, Stagg SM, Strauss J, Yu L, Carragher B, Potter CS. Smart data collection for CryoEM. J Struct Biol 2022; 214:107913. [PMID: 36341954 DOI: 10.1016/j.jsb.2022.107913] [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: 08/02/2022] [Revised: 09/29/2022] [Accepted: 10/23/2022] [Indexed: 11/06/2022]
Abstract
This report provides an overview of the discussions, presentations, and consensus thinking from the Workshop on Smart Data Collection for CryoEM held at the New York Structural Biology Center on April 6-7, 2022. The goal of the workshop was to address next generation data collection strategies that integrate machine learning and real-time processing into the workflow to reduce or eliminate the need for operator intervention.
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Affiliation(s)
| | - Andrew J Borst
- University of Washington, Institute for Protein Design, Seattle, WA, USA
| | - Jonathan Bouvette
- National Institute of Environmental Health Sciences, NIH, Durham, NC, USA
| | - Giuseppe Cannone
- Laboratory for Molecular Biology, Medical Research Council, Cambridge, England
| | - Songye Chen
- California Institute of Technology, Pasadena, CA, USA
| | - Anchi Cheng
- New York Structural Biology Center, New York, NY, USA
| | - Ao Cheng
- Northwestern University, Evanston, IL, USA
| | - Quanfu Fan
- MIT-IBM Watson AI Lab, Cambridge, MA, USA
| | | | - Harshit Gupta
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Meghna Gupta
- University of California at San Francisco, San Francisco, CA, USA
| | | | - Paul T Kim
- New York Structural Biology Center, New York, NY, USA
| | - Huihui Kuang
- New York Structural Biology Center, New York, NY, USA
| | - Yilai Li
- University of Michigan, Ann Arbor, MI, USA
| | - Alex J Noble
- New York Structural Biology Center, New York, NY, USA
| | | | - William J Rice
- New York University School of Medicine, New York, NY, USA
| | | | | | - Joshua Strauss
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lingbo Yu
- ThermoFisher Scientific, Eindhoven, The Netherlands
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46
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Halfon Y, Aspinall L, White J, Jackson Hirst I, Wang Y, Darrow MC, Muench SP, Thompson RF. Maintaining the momentum in cryoEM for biological discovery. Faraday Discuss 2022; 240:18-32. [PMID: 36172917 DOI: 10.1039/d2fd00129b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cryo-electron microscopy (cryoEM) has been transformed over the last decade, with continual new hardware and software tools coming online, pushing the boundaries of what is possible and the nature and complexity of projects that can be undertaken. Here we discuss some recent trends and new tools which are creating opportunities to make more effective use of the resources available within facilities (both staff and equipment). We present approaches for the stratification of projects based on risk and known information about the projects, and the impacts this might have on the allocation of microscope time. We show that allocating different resources (microscope time) based on this information can lead to a significant increase in 'successful' use of the microscope, and reduce lead time by enabling projects to 'fail faster'. This model results in more efficient and sustainable cryoEM facility operation.
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Affiliation(s)
- Yehuda Halfon
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Louie Aspinall
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Joshua White
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Isobel Jackson Hirst
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Yiheng Wang
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Michele C Darrow
- The Rosalind Franklin Institute, Harwell Campus, Didcot, OX11 0QS, UK.,SPT Labtech Ltd, Melbourn Science Park, Melbourn, SG8 6HB, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Rebecca F Thompson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
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47
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Klebl DP, Kay RW, Sobott F, Kapur N, Muench SP. Towards sub-millisecond cryo-EM grid preparation. Faraday Discuss 2022; 240:33-43. [PMID: 35920384 PMCID: PMC9642037 DOI: 10.1039/d2fd00079b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 06/15/2022] [Indexed: 02/06/2023]
Abstract
Sample preparation is still a significant problem for many single particle cryo-EM workflows and our understanding and developments in the area lag behind that of image processing and microscope design. Over the last few years there has been growing evidence that many of the problems which occur during sample preparation are during the time the sample resides within the thin film created during the conventional blotting process. In parallel, faster grid preparation approaches have been developed for time-resolved cryo-EM experiments allowing for non-equilibrium intermediates to be captured on the ms timescale. Therefore, an important question is how fast can we prepare suitable grids for imaging by cryo-EM and how much does this mitigate the problems observed in sample preparation? Here we use a novel approach which has been developed for time-resolved studies to produce grids on an estimated sub-1 ms timescale. While the method comes with its own challenges, a 3.8 Å reconstruction of apoferritin prepared with the ultrafast method shows that good resolutions can be achieved. Although several orders of magnitude faster than conventional approaches we show using a ribosome sample, that interactions with the air-water interface cannot be avoided with preferred orientations still present. Therefore, the work shows that faster reactions can be captured but poses the question whether speed is the answer to problems with sample preparation.
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Affiliation(s)
- David P Klebl
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, UK.
| | - Robert W Kay
- School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Frank Sobott
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, UK
| | - Nikil Kapur
- School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, UK.
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48
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Isotropic reconstruction for electron tomography with deep learning. Nat Commun 2022; 13:6482. [PMID: 36309499 PMCID: PMC9617606 DOI: 10.1038/s41467-022-33957-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/05/2022] [Indexed: 12/25/2022] Open
Abstract
Cryogenic electron tomography (cryoET) allows visualization of cellular structures in situ. However, anisotropic resolution arising from the intrinsic "missing-wedge" problem has presented major challenges in visualization and interpretation of tomograms. Here, we have developed IsoNet, a deep learning-based software package that iteratively reconstructs the missing-wedge information and increases signal-to-noise ratio, using the knowledge learned from raw tomograms. Without the need for sub-tomogram averaging, IsoNet generates tomograms with significantly reduced resolution anisotropy. Applications of IsoNet to three representative types of cryoET data demonstrate greatly improved structural interpretability: resolving lattice defects in immature HIV particles, establishing architecture of the paraflagellar rod in Eukaryotic flagella, and identifying heptagon-containing clathrin cages inside a neuronal synapse of cultured cells. Therefore, by overcoming two fundamental limitations of cryoET, IsoNet enables functional interpretation of cellular tomograms without sub-tomogram averaging. Its application to high-resolution cellular tomograms should also help identify differently oriented complexes of the same kind for sub-tomogram averaging.
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49
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Bromberg R, Cai K, Guo Y, Plymire D, Emde T, Puzio M, Borek D, Otwinowski Z. The His-tag as a decoy modulating preferred orientation in cryoEM. Front Mol Biosci 2022; 9:912072. [PMID: 36325274 PMCID: PMC9619061 DOI: 10.3389/fmolb.2022.912072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 08/19/2022] [Indexed: 12/02/2022] Open
Abstract
The His-tag is a widely used affinity tag that facilitates purification by means of affinity chromatography of recombinant proteins for functional and structural studies. We show here that His-tag presence affects how coproheme decarboxylase interacts with the air-water interface during grid preparation for cryoEM. Depending on His-tag presence or absence, we observe significant changes in patterns of preferred orientation. Our analysis of particle orientations suggests that His-tag presence can mask the hydrophobic and hydrophilic patches on a protein’s surface that mediate the interactions with the air-water interface, while the hydrophobic linker between a His-tag and the coding sequence of the protein may enhance other interactions with the air-water interface. Our observations suggest that tagging, including rational design of the linkers between an affinity tag and a protein of interest, offer a promising approach to modulating interactions with the air-water interface.
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Affiliation(s)
- Raquel Bromberg
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Ligo Analytics, Dallas, TX, United States
| | - Kai Cai
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Yirui Guo
- Ligo Analytics, Dallas, TX, United States
| | - Daniel Plymire
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Ligo Analytics, Dallas, TX, United States
| | - Tabitha Emde
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Maciej Puzio
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Dominika Borek
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Center for Structural Genomics of Infectious Diseases, Dallas, TX, United States
- *Correspondence: Dominika Borek, ; Zbyszek Otwinowski,
| | - Zbyszek Otwinowski
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Center for Structural Genomics of Infectious Diseases, Dallas, TX, United States
- *Correspondence: Dominika Borek, ; Zbyszek Otwinowski,
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50
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Wang T, Li B, Zhang J, Zeng X, Uddin MR, Wu W, Xu M. DEEP ACTIVE LEARNING FOR CRYO-ELECTRON TOMOGRAPHY CLASSIFICATION. PROCEEDINGS. INTERNATIONAL CONFERENCE ON IMAGE PROCESSING 2022; 2022:1611-1615. [PMID: 37021115 PMCID: PMC10072314 DOI: 10.1109/icip46576.2022.9898002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Cryo-Electron Tomography (cryo-ET) is an emerging 3D imaging technique which shows great potentials in structural biology research. One of the main challenges is to perform classification of macromolecules captured by cryo-ET. Recent efforts exploit deep learning to address this challenge. However, training reliable deep models usually requires a huge amount of labeled data in supervised fashion. Annotating cryo-ET data is arguably very expensive. Deep Active Learning (DAL) can be used to reduce labeling cost while not sacrificing the task performance too much. Nevertheless, most existing methods resort to auxiliary models or complex fashions (e.g. adversarial learning) for uncertainty estimation, the core of DAL. These models need to be highly customized for cryo-ET tasks which require 3D networks, and extra efforts are also indispensable for tuning these models, rendering a difficulty of deployment on cryo-ET tasks. To address these challenges, we propose a novel metric for data selection in DAL, which can also be leveraged as a regularizer of the empirical loss, further boosting the task model. We demonstrate the superiority of our method via extensive experiments on both simulated and real cryo-ET datasets. Our source Code and Appendix can be found at this URL.
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Affiliation(s)
| | - Bo Li
- University of Southern Mississippi
| | | | | | | | - Wei Wu
- University of Southern Mississippi
| | - Min Xu
- Carnegie Mellon University
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