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Zhao Q, Hong X, Wang Y, Zhang S, Ding Z, Meng X, Song Q, Hong Q, Jiang W, Shi X, Cai T, Cong Y. An immobilized antibody-based affinity grid strategy for on-grid purification of target proteins enables high-resolution cryo-EM. Commun Biol 2024; 7:715. [PMID: 38858498 PMCID: PMC11164986 DOI: 10.1038/s42003-024-06406-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 05/31/2024] [Indexed: 06/12/2024] Open
Abstract
In cryo-electron microscopy (cryo-EM), sample preparation poses a critical bottleneck, particularly for rare or fragile macromolecular assemblies and those suffering from denaturation and particle orientation distribution issues related to air-water interface. In this study, we develop and characterize an immobilized antibody-based affinity grid (IAAG) strategy based on the high-affinity PA tag/NZ-1 antibody epitope tag system. We employ Pyr-NHS as a linker to immobilize NZ-1 Fab on the graphene oxide or carbon-covered grid surface. Our results demonstrate that the IAAG grid effectively enriches PA-tagged target proteins and overcomes preferred orientation issues. Furthermore, we demonstrate the utility of our IAAG strategy for on-grid purification of low-abundance target complexes from cell lysates, enabling atomic resolution cryo-EM. This approach greatly streamlines the purification process, reduces the need for large quantities of biological samples, and addresses common challenges encountered in cryo-EM sample preparation. Collectively, our IAAG strategy provides an efficient and robust means for combined sample purification and vitrification, feasible for high-resolution cryo-EM. This approach holds potential for broader applicability in both cryo-EM and cryo-electron tomography (cryo-ET).
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Affiliation(s)
- Qiaoyu Zhao
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Xiaoyu Hong
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Yanxing Wang
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Shaoning Zhang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 200050, Shanghai, China
| | - Zhanyu Ding
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Xueming Meng
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Qianqian Song
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Qin Hong
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China
| | - Wanying Jiang
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Xiangyi Shi
- Shanghai Nanoport, Thermo Fisher Scientific, Shanghai, China
| | - Tianxun Cai
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 200050, Shanghai, China
| | - Yao Cong
- Key Laboratory of RNA Innovation, Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 200031, Shanghai, China.
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
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Deniaud A, Kabasakal BV, Bufton JC, Schaffitzel C. Sample Preparation for Electron Cryo-Microscopy of Macromolecular Machines. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 3234:173-190. [PMID: 38507207 DOI: 10.1007/978-3-031-52193-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
High-resolution structure determination by electron cryo-microscopy underwent a step change in recent years. This now allows study of challenging samples which previously were inaccessible for structure determination, including membrane proteins. These developments shift the focus in the field to the next bottlenecks which are high-quality sample preparations. While the amounts of sample required for cryo-EM are relatively small, sample quality is the key challenge. Sample quality is influenced by the stability of complexes which depends on buffer composition, inherent flexibility of the sample, and the method of solubilization from the membrane for membrane proteins. It further depends on the choice of sample support, grid pre-treatment and cryo-grid freezing protocol. Here, we discuss various widely applicable approaches to improve sample quality for structural analysis by cryo-EM.
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Affiliation(s)
- Aurélien Deniaud
- Univ. Grenoble Alpes, CNRS, CEA, IRIG - Laboratoire de Chimie et Biologie des Métaux, Grenoble, France
| | - Burak V Kabasakal
- School of Biochemistry, University of Bristol, Bristol, UK
- Turkish Accelerator and Radiation Laboratory, Gölbaşı, Ankara, Türkiye
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Ramlaul K, Feng Z, Canavan C, de Martín Garrido N, Carreño D, Crone M, Jensen KE, Li B, Barnett H, Riglar DT, Freemont PS, Miller D, Aylett CHS. A 3D-printed flow-cell for on-grid purification of electron microscopy samples directly from lysate. J Struct Biol 2023; 215:107999. [PMID: 37451560 DOI: 10.1016/j.jsb.2023.107999] [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: 05/30/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
While recent advances in cryo-EM, coupled with single particle analysis, have the potential to allow structure determination in a near-native state from vanishingly few individual particles, this vision has yet to be realised in practise. Requirements for particle numbers that currently far exceed the theoretical lower limits, challenges with the practicalities of achieving high concentrations for difficult-to-produce samples, and inadequate sample-dependent imaging conditions, all result in significant bottlenecks preventing routine structure determination using cryo-EM. Therefore, considerable efforts are being made to circumvent these bottlenecks by developing affinity purification of samples on-grid; at once obviating the need to produce large amounts of protein, as well as more directly controlling the variable, and sample-dependent, process of grid preparation. In this proof-of-concept study, we demonstrate a further practical step towards this paradigm, developing a 3D-printable flow-cell device to allow on-grid affinity purification from raw inputs such as whole cell lysates, using graphene oxide-based affinity grids. Our flow-cell device can be interfaced directly with routinely-used laboratory equipment such as liquid chromatographs, or peristaltic pumps, fitted with standard chromatographic (1/16") connectors, and can be used to allow binding of samples to affinity grids in a controlled environment prior to the extensive washing required to remove impurities. Furthermore, by designing a device which can be 3D printed and coupled to routinely used laboratory equipment, we hope to increase the accessibility of the techniques presented herein to researchers working towards single-particle macromolecular structures.
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Affiliation(s)
- Kailash Ramlaul
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Ziyi Feng
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Caoimhe Canavan
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Natàlia de Martín Garrido
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - David Carreño
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Michael Crone
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Kirsten E Jensen
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Bing Li
- Hamlyn Centre, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Harry Barnett
- Imperial College Advanced Hackspace, Imperial College London, London, United Kingdom
| | - David T Riglar
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom; The Francis Crick Institute, London, United Kingdom
| | - Paul S Freemont
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - David Miller
- Imperial College Advanced Hackspace, Imperial College London, London, United Kingdom.
| | - Christopher H S Aylett
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom.
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Ma Y, Wu Z, Steinmetz NF. In Vitro and Ex Planta Gold-Bonded and Gold-Mineralized Tobacco Mosaic Virus. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11238-11244. [PMID: 37540623 DOI: 10.1021/acs.langmuir.3c00688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/06/2023]
Abstract
Biotemplated mineralization is a promising and ecofriendly approach to manufacture metal nanoparticles and composites with precise size control. Plant viruses are suitable templates for biomineralization because they are chemically robust and highly scalable through molecular farming. Here, we report a gold-nanoparticle-coated tobacco mosaic virus (TMV) synthesized in a test tube or in plant extracts making use of a TMV displaying a gold-binding peptide (GBP). The methods developed are a step toward engineered living materials, where gold nanowires could be formed in plant tissues for sensing or energy harvest applications.
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Affiliation(s)
- Yifeng Ma
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92039, United States
| | - Zhuohong Wu
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92039, United States
| | - Nicole F Steinmetz
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92039, United States
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5
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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: 13] [Impact Index Per Article: 6.5] [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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6
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Hrebík D, Gondová M, Valentová L, Füzik T, Přidal A, Nováček J, Plevka P. Polyelectrolyte coating of cryo-EM grids improves lateral distribution and prevents aggregation of macromolecules. Acta Crystallogr D Struct Biol 2022; 78:1337-1346. [DOI: 10.1107/s2059798322009299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/21/2022] [Indexed: 11/06/2022] Open
Abstract
Cryo-electron microscopy (cryo-EM) is one of the primary methods used to determine the structures of macromolecules and their complexes. With the increased availability of cryo-electron microscopes, the preparation of high-quality samples has become a bottleneck in the cryo-EM structure-determination pipeline. Macromolecules can be damaged during the purification or preparation of vitrified samples for cryo-EM, making them prone to binding to the grid support, to aggregation or to the adoption of preferential orientations at the air–water interface. Here, it is shown that coating cryo-EM grids with a negatively charged polyelectrolyte, such as single-stranded DNA, before applying the sample reduces the aggregation of macromolecules and improves their distribution. The single-stranded DNA-coated grids enabled the determination of high-resolution structures from samples that aggregated on conventional grids. The polyelectrolyte coating reduces the diffusion of macromolecules and thus may limit the negative effects of the contact of macromolecules with the grid support and blotting paper, as well as of the shear forces on macromolecules during grid blotting. Coating grids with polyelectrolytes can readily be employed in any laboratory dealing with cryo-EM sample preparation, since it is fast, simple, inexpensive and does not require specialized equipment.
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Chen S, Li J, Vinothkumar KR, Henderson R. Interaction of human erythrocyte catalase with air-water interface in cryoEM. Microscopy (Oxf) 2022; 71:i51-i59. [PMID: 35275189 PMCID: PMC8855524 DOI: 10.1093/jmicro/dfab037] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/13/2021] [Accepted: 09/16/2021] [Indexed: 11/14/2022] Open
Abstract
One of the key goals in single-particle cryo-microscopy is to obtain a uniform distribution of particle orientations, so that the three-dimensional structure has isotropic resolution in Fourier space. A common problem arises from the interaction of protein molecules with the air-water interface that exists on both surfaces of the thin film of liquid that is formed prior to plunge-freezing into liquid ethane. Some proteins and other macromolecular complexes are disrupted by interaction with the air-water interface. Other proteins or macromolecules either become concentrated through their interaction with the interface or are excluded because they bind strongly to some other part of the grid or the filter paper used in blotting. In this paper, the interaction of human erythrocyte catalase with the air-water interface is investigated and minimized by the addition of certain detergents. Detergents can form an amphipathic monolayer at the air-water interface that creates a barrier and leaves the molecules free to adopt a variety of orientations, thus facilitating the 3D structure determination. These results suggest that further characterization and development of detergents for cryo-microscopy plunge-freezing would be useful.
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Affiliation(s)
- Shaoxia Chen
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jade Li
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Kutti R Vinothkumar
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research, Bellary Road, Bengaluru 560065, India
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8
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Hoq MR, Vago FS, Li K, Kovaliov M, Nicholas RJ, Huryn DM, Wipf P, Jiang W, Thompson DH. Affinity Capture of p97 with Small-Molecule Ligand Bait Reveals a 3.6 Å Double-Hexamer Cryoelectron Microscopy Structure. ACS NANO 2021; 15:8376-8385. [PMID: 33900731 DOI: 10.1021/acsnano.0c10185] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recent progress in the development of affinity grids for cryoelectron microscopy (cryo-EM) typically employs genetic engineering of the protein sample such as histidine or Spy tagging, immobilized antibody capture, or nonselective immobilization via electrostatic interactions or Schiff base formation. We report a powerful and flexible method for the affinity capture of target proteins for cryo-EM analysis that utilizes small-molecule ligands as bait for concentrating human target proteins directly onto the grid surface for single-particle reconstruction. This approach is demonstrated for human p97, captured using two different small-molecule high-affinity ligands of this AAA+ ATPase. Four electron density maps are revealed, each representing a p97 conformational state captured from solution, including a double-hexamer structure resolved to 3.6 Å. These results demonstrate that the noncovalent capture of protein targets on EM grids modified with high-affinity ligands can enable the structure elucidation of multiple configurational states of the target and potentially inform structure-based drug design campaigns.
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Affiliation(s)
- Md Rejaul Hoq
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Frank S Vago
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Kunpeng Li
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Marina Kovaliov
- University of Pittsburgh Chemical Diversity Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Robert J Nicholas
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Donna M Huryn
- University of Pittsburgh Chemical Diversity Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Peter Wipf
- University of Pittsburgh Chemical Diversity Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Wen Jiang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Center for Cancer Research, West Lafayette, Indiana 47907, United States
| | - David H Thompson
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Center for Cancer Research, West Lafayette, Indiana 47907, United States
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Diebolder CA, Dillard RS, Renault L. From Tube to Structure: SPA Cryo-EM Workflow Using Apoferritin as an Example. Methods Mol Biol 2021; 2305:229-256. [PMID: 33950393 DOI: 10.1007/978-1-0716-1406-8_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this chapter, we present an overview of a standard protocol to achieve structure determination at high resolution by Single Particle Analysis cryogenic Electron Microscopy using apoferritin as a standard sample. The purified apoferritin is applied to a glow-discharged support and then flash frozen in liquid ethane. The prepared grids are loaded into the electron microscope and checked for particle spreading and ice thickness. The microscope alignments are performed and the data collection session is setup for an overnight data collection. The collected movies containing two-dimensional images of the apoferritin sample are then processed to obtain a high-resolution three-dimensional reconstruction.
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Affiliation(s)
- Christoph A Diebolder
- The Netherlands Centre for Electron Nanoscopy (NeCEN), Leiden University, Leiden, The Netherlands
| | - Rebecca S Dillard
- The Netherlands Centre for Electron Nanoscopy (NeCEN), Leiden University, Leiden, The Netherlands
| | - Ludovic Renault
- The Netherlands Centre for Electron Nanoscopy (NeCEN), Leiden University, Leiden, The Netherlands.
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10
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General and robust covalently linked graphene oxide affinity grids for high-resolution cryo-EM. Proc Natl Acad Sci U S A 2020; 117:24269-24273. [PMID: 32913054 PMCID: PMC7533693 DOI: 10.1073/pnas.2009707117] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Despite the increasing efforts in developing affinity grids to facilitate sample preparation for challenging systems and dynamic complexes, they are not widely used in cryo-electron microscopy (EM) owing to concerns of limiting resolution. We show that our affinity grids extract proteins through covalent bonding with 3.3-Å reconstruction. To our knowledge, no example of small proteins (<200 KDa) has been successfully tested with other affinity grids. With encouraging results further from a mixture sample, we believe that the strategy described here is highly applicable to a broad array of challenging macromolecules and thus is a method of broad interest to the cryo-EM community. The dramatic improvement in cryo-EM sample preparation outlined here paves the way to “purification on the grid.” Affinity grids have great potential to facilitate rapid preparation of even quite impure samples in single-particle cryo-electron microscopy (EM). Yet despite the promising advances of affinity grids over the past decades, no single strategy has demonstrated general utility. Here we chemically functionalize cryo-EM grids coated with mostly one or two layers of graphene oxide to facilitate affinity capture. The protein of interest is tagged using a system that rapidly forms a highly specific covalent bond to its cognate catcher linked to the grid via a polyethylene glycol (PEG) spacer. Importantly, the spacer keeps particles away from both the air–water interface and the graphene oxide surface, protecting them from potential denaturation and rendering them sufficiently flexible to avoid preferential sample orientation concerns. Furthermore, the PEG spacer successfully reduces nonspecific binding, enabling high-resolution reconstructions from a much cruder lysate sample.
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11
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Marcink TC, Wang T, des Georges A, Porotto M, Moscona A. Human parainfluenza virus fusion complex glycoproteins imaged in action on authentic viral surfaces. PLoS Pathog 2020; 16:e1008883. [PMID: 32956394 PMCID: PMC7529294 DOI: 10.1371/journal.ppat.1008883] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 10/01/2020] [Accepted: 08/13/2020] [Indexed: 01/21/2023] Open
Abstract
Infection by human parainfluenza viruses (HPIVs) causes widespread lower respiratory diseases, including croup, bronchiolitis, and pneumonia, and there are no vaccines or effective treatments for these viruses. HPIV3 is a member of the Respirovirus species of the Paramyxoviridae family. These viruses are pleomorphic, enveloped viruses with genomes composed of single-stranded negative-sense RNA. During viral entry, the first step of infection, the viral fusion complex, comprised of the receptor-binding glycoprotein hemagglutinin-neuraminidase (HN) and the fusion glycoprotein (F), mediates fusion upon receptor binding. The HPIV3 transmembrane protein HN, like the receptor-binding proteins of other related viruses that enter host cells using membrane fusion, binds to a receptor molecule on the host cell plasma membrane, which triggers the F glycoprotein to undergo major conformational rearrangements, promoting viral entry. Subsequent fusion of the viral and host membranes allows delivery of the viral genetic material into the host cell. The intermediate states in viral entry are transient and thermodynamically unstable, making it impossible to understand these transitions using standard methods, yet understanding these transition states is important for expanding our knowledge of the viral entry process. In this study, we use cryo-electron tomography (cryo-ET) to dissect the stepwise process by which the receptor-binding protein triggers F-mediated fusion, when forming a complex with receptor-bearing membranes. Using an on-grid antibody capture method that facilitates examination of fresh, biologically active strains of virus directly from supernatant fluids and a series of biological tools that permit the capture of intermediate states in the fusion process, we visualize the series of events that occur when a pristine, authentic viral particle interacts with target receptors and proceeds from the viral entry steps of receptor engagement to membrane fusion.
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Affiliation(s)
- Tara C. Marcink
- Department of Pediatrics, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Center for Host-Pathogen Interaction, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
| | - Tong Wang
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York, United States of America
| | - Amedee des Georges
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York, United States of America
- Department of Chemistry and Biochemistry, City College of New York, New York, New York, United States of America
| | - Matteo Porotto
- Department of Pediatrics, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Center for Host-Pathogen Interaction, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Anne Moscona
- Department of Pediatrics, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Center for Host-Pathogen Interaction, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Department of Microbiology & Immunology, Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
- Department of Physiology & Columbia University Vagelos College of Physicians & Surgeons, New York, New York, United States of America
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12
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Brillault L, Landsberg MJ. Preparation of Proteins and Macromolecular Assemblies for Cryo-electron Microscopy. Methods Mol Biol 2020; 2073:221-246. [PMID: 31612445 DOI: 10.1007/978-1-4939-9869-2_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cryo-electron microscopy has become popular as the penultimate step on the road to structure determination for many proteins and macromolecular assemblies. The process of obtaining high-resolution images of a purified biomolecular complex in an electron microscope often follows a long, and in many cases exhaustive screening process in which many iterative rounds of protein purification are employed and the sample preparation procedure progressively re-evaluated in order to improve the distribution of particles visualized under the electron microscope, and thus maximize the opportunity for high-resolution structure determination. Typically, negative stain electron microscopy is employed to obtain a preliminary assessment of the sample quality, followed by cryo-EM which first requires the identification of optimal vitrification conditions. The original methods for frozen-hydrated specimen preparation developed over 40 years ago still enjoy widespread use today, although recent developments have set the scene for a future where more systematic and high-throughput approaches to the preparation of vitrified biomolecular complexes may be routinely employed. Here we summarize current approaches and ongoing innovations for the preparation of frozen-hydrated single particle specimens for cryo-EM, highlighting some of the commonly encountered problems and approaches that may help overcome these.
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Affiliation(s)
- Lou Brillault
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Michael J Landsberg
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia.
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Dillard RS, Hampton CM, Strauss JD, Ke Z, Altomara D, Guerrero-Ferreira RC, Kiss G, Wright ER. Biological Applications at the Cutting Edge of Cryo-Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:406-419. [PMID: 30175702 PMCID: PMC6265046 DOI: 10.1017/s1431927618012382] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cryo-electron microscopy (cryo-EM) is a powerful tool for macromolecular to near-atomic resolution structure determination in the biological sciences. The specimen is maintained in a near-native environment within a thin film of vitreous ice and imaged in a transmission electron microscope. The images can then be processed by a number of computational methods to produce three-dimensional information. Recent advances in sample preparation, imaging, and data processing have led to tremendous growth in the field of cryo-EM by providing higher resolution structures and the ability to investigate macromolecules within the context of the cell. Here, we review developments in sample preparation methods and substrates, detectors, phase plates, and cryo-correlative light and electron microscopy that have contributed to this expansion. We also have included specific biological applications.
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Affiliation(s)
- Rebecca S Dillard
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Cheri M Hampton
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Joshua D Strauss
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Zunlong Ke
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Deanna Altomara
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Ricardo C Guerrero-Ferreira
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Gabriella Kiss
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
| | - Elizabeth R Wright
- 1Division of Pediatric Infectious Diseases,Emory University School of Medicine,Children's Healthcare of Atlanta,Atlanta,GA 30322,USA
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14
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Serwer P, Wright ET. Nanomedicine and Phage Capsids. Viruses 2018; 10:E307. [PMID: 29882754 PMCID: PMC6024614 DOI: 10.3390/v10060307] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/19/2018] [Accepted: 06/04/2018] [Indexed: 02/07/2023] Open
Abstract
Studies of phage capsids have at least three potential interfaces with nanomedicine. First, investigation of phage capsid states potentially will provide therapies targeted to similar states of pathogenic viruses. Recently detected, altered radius-states of phage T3 capsids include those probably related to intermediate states of DNA injection and DNA packaging (dynamic states). We discuss and test the idea that some T3 dynamic states include extensive α-sheet in subunits of the capsid’s shell. Second, dynamic states of pathogenic viral capsids are possible targets of innate immune systems. Specifically, α-sheet-rich innate immune proteins would interfere with dynamic viral states via inter-α-sheet co-assembly. A possible cause of neurodegenerative diseases is excessive activity of these innate immune proteins. Third, some phage capsids appear to have characteristics useful for improved drug delivery vehicles (DDVs). These characteristics include stability, uniformity and a gate-like sub-structure. Gating by DDVs is needed for (1) drug-loading only with gate opened; (2) closed gate-DDV migration through circulatory systems (no drug leakage-generated toxicity); and (3) drug release only at targets. A gate-like sub-structure is the connector ring of double-stranded DNA phage capsids. Targeting to tumors of phage capsid-DDVs can possibly be achieved via the enhanced permeability and retention effect.
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Affiliation(s)
- Philip Serwer
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
| | - Elena T Wright
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
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15
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Drulyte I, Johnson RM, Hesketh EL, Hurdiss DL, Scarff CA, Porav SA, Ranson NA, Muench SP, Thompson RF. Approaches to altering particle distributions in cryo-electron microscopy sample preparation. Acta Crystallogr D Struct Biol 2018; 74:560-571. [PMID: 29872006 PMCID: PMC6096488 DOI: 10.1107/s2059798318006496] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/26/2018] [Indexed: 11/23/2022] Open
Abstract
Cryo-electron microscopy (cryo-EM) can now be used to determine high-resolution structural information on a diverse range of biological specimens. Recent advances have been driven primarily by developments in microscopes and detectors, and through advances in image-processing software. However, for many single-particle cryo-EM projects, major bottlenecks currently remain at the sample-preparation stage; obtaining cryo-EM grids of sufficient quality for high-resolution single-particle analysis can require the careful optimization of many variables. Common hurdles to overcome include problems associated with the sample itself (buffer components, labile complexes), sample distribution (obtaining the correct concentration, affinity for the support film), preferred orientation, and poor reproducibility of the grid-making process within and between batches. This review outlines a number of methodologies used within the electron-microscopy community to address these challenges, providing a range of approaches which may aid in obtaining optimal grids for high-resolution data collection.
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Affiliation(s)
- Ieva Drulyte
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Rachel M. Johnson
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
- School of Chemistry, Faculty of Mathematics and Physical Chemistry and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Emma L. Hesketh
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Daniel L. Hurdiss
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Charlotte A. Scarff
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Sebastian A. Porav
- National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania
| | - Neil A. Ranson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Stephen P. Muench
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
| | - Rebecca F. Thompson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
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16
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Abstract
It has become clear that the standard cartoon, in which macromolecular particles prepared for electron cryo-microscopy are shown to be surrounded completely by vitreous ice, often is not accurate. In particular, the standard picture does not include the fact that diffusion to the air-water interface, followed by adsorption and possibly denaturation, can occur on the time scale that normally is required to make thin specimens. The extensive literature on interaction of proteins with the air-water interface suggests that many proteins can bind to the interface, either directly or indirectly via a sacrificial layer of already-denatured protein. In the process, the particles of interest can, in some cases, become preferentially oriented, and in other cases they can be damaged and/or aggregated at the surface. Thus, although a number of methods and recipes have evolved for dealing with protein complexes that prove to be difficult, making good cryo-grids can still be a major challenge for each new type of specimen. Recognition that the air-water interface is a very dangerous place to be has inspired work on some novel approaches for preparing cryo-grids. At the moment, two of the most promising ones appear to be: (1) thin and vitrify the specimen much faster than is done currently or (2) immobilize the particles onto a structure-friendly support film so that they cannot diffuse to the air-water interface.
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Affiliation(s)
- Robert M Glaeser
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94705
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17
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Serwer P, Wright ET, Demeler B, Jiang W. States of phage T3/T7 capsids: buoyant density centrifugation and cryo-EM. Biophys Rev 2017; 10:583-596. [PMID: 29243090 DOI: 10.1007/s12551-017-0372-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 11/20/2017] [Indexed: 12/16/2022] Open
Abstract
Mature double-stranded DNA bacteriophages have capsids with symmetrical shells that typically resist disruption, as they must to survive in the wild. However, flexibility and associated dynamism assist function. We describe biochemistry-oriented procedures used to find previously obscure flexibility for capsids of the related phages, T3 and T7. The primary procedures are hydration-based buoyant density ultracentrifugation and purified particle-based cryo-electron microscopy (cryo-EM). We review the buoyant density centrifugation in detail. The mature, stable T3/T7 capsid is a shell flexibility-derived conversion product of an initially assembled procapsid (capsid I). During DNA packaging, capsid I expands and loses a scaffolding protein to form capsid II. The following are observations made with capsid II. (1) The in vivo DNA packaging of wild type T3 generates capsid II that has a slight (1.4%), cryo-EM-detected hyper-expansion relative to the mature phage capsid. (2) DNA packaging in some altered conditions generates more extensive hyper-expansion of capsid II, initially detected by hydration-based preparative buoyant density centrifugation in Nycodenz density gradients. (3) Capsid contraction sometimes occurs, e.g., during quantized leakage of DNA from mature T3 capsids without a tail.
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Affiliation(s)
- Philip Serwer
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA.
| | - Elena T Wright
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA
| | - Borries Demeler
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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18
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Yu G, Li K, Huang P, Jiang X, Jiang W. Antibody-Based Affinity Cryoelectron Microscopy at 2.6-Å Resolution. Structure 2017; 24:1984-1990. [PMID: 27806259 DOI: 10.1016/j.str.2016.09.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/16/2016] [Accepted: 09/30/2016] [Indexed: 02/02/2023]
Abstract
The affinity cryoelectron microscopy (cryo-EM) approach has been explored in recent years to simplify and/or improve the sample preparation for cryo-EM, which can bring previously challenging specimens such as those of low abundance and/or unpurified ones within reach of the cryo-EM technique. Despite the demonstrated successes for solving structures to low to intermediate resolutions, the lack of near-atomic structures using this approach has led to a common perception of affinity cryo-EM as a niche technique incapable of reaching high resolutions. Here, we report a ∼2.6-Å structure solved using the antibody-based affinity grid approach with low-concentration Tulane virus purified from a low-yield cell-culture system that has been challenging to standard cryo-EM grid preparation. Quantitative analyses of the structure indicate data and reconstruction quality comparable with the conventional grid preparation method using samples at high concentration.
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Affiliation(s)
- Guimei Yu
- Department of Biological Science, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Kunpeng Li
- Department of Biological Science, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Pengwei Huang
- Divisions of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Xi Jiang
- Divisions of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Wen Jiang
- Department of Biological Science, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA.
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19
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Davies RB, Smits C, Wong ASW, Stock D, Christie M, Sandin S, Stewart AG. Cryo-EM analysis of a domain antibody bound rotary ATPase complex. J Struct Biol 2017; 197:350-353. [PMID: 28115258 DOI: 10.1016/j.jsb.2017.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/16/2017] [Accepted: 01/17/2017] [Indexed: 01/11/2023]
Abstract
The bacterial A/V-type ATPase/synthase rotary motor couples ATP hydrolysis/synthesis with proton translocation across biological membranes. The A/V-type ATPase/synthase from Thermus thermophilus has been extensively studied both structurally and functionally for many years. Here we provide an 8.7Å resolution cryo-electron microscopy 3D reconstruction of this complex bound to single-domain antibody fragments, small monomeric antibodies containing just the variable heavy domain. Docking of known structures into the density revealed the molecular orientation of the domain antibodies, suggesting that structure determination of co-domain antibody:protein complexes could be a useful avenue for unstable or smaller proteins. Although previous studies suggested that the presence of fluoroaluminate in this complex could change the rotary state of this enzyme, we observed no gross structural rearrangements under these conditions.
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Affiliation(s)
- Roberta B Davies
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Callum Smits
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Andrew S W Wong
- NTU Institute of Structural Biology, Nanyang Technological University, 636921, Singapore
| | - Daniela Stock
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Mary Christie
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Sara Sandin
- NTU Institute of Structural Biology, Nanyang Technological University, 636921, Singapore; School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Alastair G Stewart
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia.
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20
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Martin TG, Bharat TAM, Joerger AC, Bai XC, Praetorius F, Fersht AR, Dietz H, Scheres SHW. Design of a molecular support for cryo-EM structure determination. Proc Natl Acad Sci U S A 2016; 113:E7456-E7463. [PMID: 27821763 PMCID: PMC5127339 DOI: 10.1073/pnas.1612720113] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite the recent rapid progress in cryo-electron microscopy (cryo-EM), there still exist ample opportunities for improvement in sample preparation. Macromolecular complexes may disassociate or adopt nonrandom orientations against the extended air-water interface that exists for a short time before the sample is frozen. We designed a hollow support structure using 3D DNA origami to protect complexes from the detrimental effects of cryo-EM sample preparation. For a first proof-of-principle, we concentrated on the transcription factor p53, which binds to specific DNA sequences on double-stranded DNA. The support structures spontaneously form monolayers of preoriented particles in a thin film of water, and offer advantages in particle picking and sorting. By controlling the position of the binding sequence on a single helix that spans the hollow support structure, we also sought to control the orientation of individual p53 complexes. Although the latter did not yet yield the desired results, the support structures did provide partial information about the relative orientations of individual p53 complexes. We used this information to calculate a tomographic 3D reconstruction, and refined this structure to a final resolution of ∼15 Å. This structure settles an ongoing debate about the symmetry of the p53 tetramer bound to DNA.
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Affiliation(s)
- Thomas G Martin
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Tanmay A M Bharat
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Andreas C Joerger
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
- German Cancer Consortium (DKTK), Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany
| | - Xiao-Chen Bai
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Florian Praetorius
- Physik Department, Walter Schottky Institute, Technische Universität München, 85748 Garching near Munich, Germany
| | - Alan R Fersht
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Hendrik Dietz
- Physik Department, Walter Schottky Institute, Technische Universität München, 85748 Garching near Munich, Germany
| | - Sjors H W Scheres
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom;
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21
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Glaeser RM, Han BG. Opinion: hazards faced by macromolecules when confined to thin aqueous films. BIOPHYSICS REPORTS 2016; 3:1-7. [PMID: 28781996 PMCID: PMC5516009 DOI: 10.1007/s41048-016-0026-3] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/16/2016] [Indexed: 11/29/2022] Open
Abstract
Samples prepared for single-particle electron cryo-microscopy (cryo-EM) necessarily have a very high surface-to-volume ratio during the short period of time between thinning and vitrification. During this time, there is an obvious risk that macromolecules of interest may adsorb to the air–water interface with a preferred orientation, or that they may even become partially or fully unfolded at the interface. In addition, adsorption of macromolecules to an air–water interface may occur even before thinning. This paper addresses the question whether currently used methods of sample preparation might be improved if one could avoid such interfacial interactions. One possible way to do so might be to preemptively form a surfactant monolayer over the air–water interfaces, to serve as a structure-friendly slide and coverslip. An alternative is to immobilize particles of interest by binding them to some type of support film, which—to continue using the analogy—thus serves as a slide. In this case, the goal is not only to prevent the particles of interest from diffusing into contact with the air–water interface but also to increase the number of particles seen in each image. In this direction, it is natural to think of developing various types of affinity grids as structure-friendly alternatives to thin carbon films. Perhaps ironically, if precautions are not taken against adsorption of particles to air–water interfaces, sacrificial monolayers of denatured protein may take the roles of slide, coverslip, or even both.
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Affiliation(s)
- Robert M Glaeser
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 USA
| | - Bong-Gyoon Han
- Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 USA
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22
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Abstract
The suddenness with which single-particle cryo-electron microscopy (cryo-EM) has emerged as a method for determining high-resolution structures of biological macromolecules invites the questions, how much better can this technology get, and how fast is that likely to happen? Though we can rightly celebrate the maturation of cryo-EM as a high-resolution structure-determination tool, I believe there still are many developments to look forward to.
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23
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Yu G, Li K, Jiang W. Antibody-based affinity cryo-EM grid. Methods 2016; 100:16-24. [PMID: 26804563 DOI: 10.1016/j.ymeth.2016.01.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 12/01/2022] Open
Abstract
The Affinity Grid technique combines sample purification and cryo-Electron Microscopy (cryo-EM) grid preparation into a single step. Several types of affinity surfaces, including functionalized lipids monolayers, streptavidin 2D crystals, and covalently functionalized carbon surfaces have been reported. More recently, we presented a new affinity cryo-EM approach, cryo-SPIEM, which applies the traditional Solid Phase Immune Electron Microscopy (SPIEM) technique to cryo-EM. This approach significantly simplifies the preparation of affinity grids and directly works with native macromolecular complexes without need of target modifications. With wide availability of high affinity and high specificity antibodies, the antibody-based affinity grid would enable cryo-EM studies of the native samples directly from cell cultures, targets of low abundance, and unstable or short-lived intermediate states.
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Affiliation(s)
- Guimei Yu
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Kunpeng Li
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.
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24
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Benjamin CJ, Wright KJ, Hyun SH, Krynski K, Yu G, Bajaj R, Guo F, Stauffacher CV, Jiang W, Thompson DH. Nonfouling NTA-PEG-Based TEM Grid Coatings for Selective Capture of Histidine-Tagged Protein Targets from Cell Lysates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:551-9. [PMID: 26726866 PMCID: PMC5310270 DOI: 10.1021/acs.langmuir.5b03445] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report the preparation and performance of TEM grids bearing stabilized nonfouling lipid monolayer coatings. These films contain NTA capture ligands of controllable areal density at the distal end of a flexible poly(ethylene glycol) 2000 (PEG2000) spacer to avoid preferred orientation of surface-bound histidine-tagged (His-tag) protein targets. Langmuir-Schaefer deposition at 30 mN/m of mixed monolayers containing two novel synthetic lipids-1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(5-amido-1-carboxypentyl)iminodiacetic acid]polyethylene glycolamide 2000) (NTA-PEG2000-DSPE) and 1,2-(tricosa-10',12'-diynoyl)-sn-glycero-3-phosphoethanolamine-N-(methoxypolyethylene glycolamide 350) (mPEG350-DTPE)-in 1:99 and 5:95 molar ratios prior to treatment with a 5 min, 254 nm light exposure was used for grid fabrication. These conditions were designed to limit nonspecific protein adsorption onto the stabilized lipid coating by favoring the formation of a mPEG350 brush layer below a flexible, mushroom conformation of NTA-PEG2000 at low surface density to enable specific immobilization and random orientation of the protein target on the EM grid. These grids were then used to capture His6-T7 bacteriophage and RplL from cell lysates, as well as purified His8-green fluorescent protein (GFP) and nanodisc solubilized maltose transporter, His6-MalFGK2. Our findings indicate that TEM grid supported, polymerized NTA lipid monolayers are capable of capturing His-tag protein targets in a manner that controls their areal densities, while efficiently blocking nonspecific adsorption and limiting film degradation, even upon prolonged detergent exposure.
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Affiliation(s)
- Christopher J Benjamin
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kyle J Wright
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Seok-Hee Hyun
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kyle Krynski
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Guimei Yu
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Ruchika Bajaj
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Fei Guo
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Cynthia V Stauffacher
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Wen Jiang
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - David H Thompson
- Department of Chemistry and ‡Department of Biological Sciences, Purdue University , West Lafayette, Indiana 47907, United States
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25
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Yu G, Yan R, Zhang C, Mao C, Jiang W. Single-Particle Cryo-EM and 3D Reconstruction of Hybrid Nanoparticles with Electron-Dense Components. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5157-5163. [PMID: 26179326 DOI: 10.1002/smll.201500531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/13/2015] [Indexed: 06/04/2023]
Abstract
Single-particle cryo-electron microscopy (cryo-EM), accompanied with 3D reconstruction, is a broadly applicable tool for the structural characterization of macromolecules and nanoparticles. Recently, the cryo-EM field has pushed the limits of this technique to higher resolutions and samples of smaller molecular mass, however, some samples still present hurdles to this technique. Hybrid particles with electron-dense components, which have been studied using single-particle cryo-EM yet with limited success in 3D reconstruction due to the interference caused by electron-dense elements, constitute one group of such challenging samples. To process such hybrid particles, a masking method is developed in this work to adaptively remove pixels arising from electron-dense portions in individual projection images while maintaining maximal biomass signals for subsequent 2D alignment, 3D reconstruction, and iterative refinements. As demonstrated by the success in 3D reconstruction of an octahedron DNA/gold hybrid particle, which has been previously published without a 3D reconstruction, the devised strategy that combines adaptive masking and standard single-particle 3D reconstruction approach has overcome the hurdle of electron-dense elements interference, and is generally applicable to cryo-EM structural characterization of most, if not all, hybrid nanomaterials with electron-dense components.
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Affiliation(s)
- Guimei Yu
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, 240 S Martin Jischke Dr, West Lafayette, IN, 47907, USA
| | - Rui Yan
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, 240 S Martin Jischke Dr, West Lafayette, IN, 47907, USA
| | - Chuan Zhang
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Chengde Mao
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, 240 S Martin Jischke Dr, West Lafayette, IN, 47907, USA
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Capsid expansion mechanism of bacteriophage T7 revealed by multistate atomic models derived from cryo-EM reconstructions. Proc Natl Acad Sci U S A 2014; 111:E4606-14. [PMID: 25313071 DOI: 10.1073/pnas.1407020111] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Many dsDNA viruses first assemble a DNA-free procapsid, using a scaffolding protein-dependent process. The procapsid, then, undergoes dramatic conformational maturation while packaging DNA. For bacteriophage T7 we report the following four single-particle cryo-EM 3D reconstructions and the derived atomic models: procapsid (4.6-Å resolution), an early-stage DNA packaging intermediate (3.5 Å), a later-stage packaging intermediate (6.6 Å), and the final infectious phage (3.6 Å). In the procapsid, the N terminus of the major capsid protein, gp10, has a six-turn helix at the inner surface of the shell, where each skewed hexamer of gp10 interacts with two scaffolding proteins. With the exit of scaffolding proteins during maturation the gp10 N-terminal helix unfolds and swings through the capsid shell to the outer surface. The refolded N-terminal region has a hairpin that forms a novel noncovalent, joint-like, intercapsomeric interaction with a pocket formed during shell expansion. These large conformational changes also result in a new noncovalent, intracapsomeric topological linking. Both interactions further stabilize the capsids by interlocking all pentameric and hexameric capsomeres in both DNA packaging intermediate and phage. Although the final phage shell has nearly identical structure to the shell of the DNA-free intermediate, surprisingly we found that the icosahedral faces of the phage are slightly (∼4 Å) contracted relative to the faces of the intermediate, despite the internal pressure from the densely packaged DNA genome. These structures provide a basis for understanding the capsid maturation process during DNA packaging that is essential for large numbers of dsDNA viruses.
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