1
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Yeo J, Daurer BJ, Kimanius D, Balakrishnan D, Bepler T, Tan YZ, Loh ND. Ghostbuster: A phase retrieval diffraction tomography algorithm for cryo-EM. Ultramicroscopy 2024; 262:113962. [PMID: 38642481 DOI: 10.1016/j.ultramic.2024.113962] [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: 12/20/2023] [Revised: 03/16/2024] [Accepted: 04/01/2024] [Indexed: 04/22/2024]
Abstract
Ewald sphere curvature correction, which extends beyond the projection approximation, stretches the shallow depth of field in cryo-EM reconstructions of thick particles. Here we show that even for previously assumed thin particles, reconstruction artifacts which we refer to as ghosts can appear. By retrieving the lost phases of the electron exitwaves and accounting for the first Born approximation scattering within the particle, we show that these ghosts can be effectively eliminated. Our simulations demonstrate how such ghostbusting can improve reconstructions as compared to existing state-of-the-art software. Like ptychographic cryo-EM, our Ghostbuster algorithm uses phase retrieval to improve reconstructions, but unlike the former, we do not need to modify the existing data acquisition pipelines.
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Affiliation(s)
- Joel Yeo
- NUS Graduate School for Integrative Sciences and Engineering Programme, National University of Singapore, 119077 Singapore, Singapore; Department of Physics, National University of Singapore, 117551 Singapore, Singapore; Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, 138634 Singapore, Singapore
| | - Benedikt J Daurer
- Center for Bio-Imaging Sciences, National University of Singapore, 117557 Singapore, Singapore; Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - Dari Kimanius
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; CZ Imaging Institute, 3400 Bridge Parkway, Redwood City, CA 94065, USA
| | - Deepan Balakrishnan
- Department of Biological Sciences, National University of Singapore, 117558 Singapore, Singapore; Center for Bio-Imaging Sciences, National University of Singapore, 117557 Singapore, Singapore
| | - Tristan Bepler
- Simons Machine Learning Center, New York Structural Biology Center, New York, NY, USA
| | - Yong Zi Tan
- Department of Biological Sciences, National University of Singapore, 117558 Singapore, Singapore; Center for Bio-Imaging Sciences, National University of Singapore, 117557 Singapore, Singapore; Disease Intervention Technology Laboratory (DITL), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, 138648 Singapore, Singapore; Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, 138673 Singapore, Singapore
| | - N Duane Loh
- NUS Graduate School for Integrative Sciences and Engineering Programme, National University of Singapore, 119077 Singapore, Singapore; Department of Physics, National University of Singapore, 117551 Singapore, Singapore; Department of Biological Sciences, National University of Singapore, 117558 Singapore, Singapore; Center for Bio-Imaging Sciences, National University of Singapore, 117557 Singapore, Singapore.
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2
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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 PMCID: PMC11162944 DOI: 10.1016/j.jsb.2024.108072] [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: 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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3
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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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4
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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: 2] [Impact Index Per Article: 2.0] [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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5
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Zhu D, Cao D, Zhang X. Virus structures revealed by advanced cryoelectron microscopy methods. Structure 2023; 31:1348-1359. [PMID: 37797619 DOI: 10.1016/j.str.2023.09.008] [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: 06/27/2023] [Revised: 08/25/2023] [Accepted: 09/11/2023] [Indexed: 10/07/2023]
Abstract
Before the resolution revolution, cryoelectron microscopy (cryo-EM) single-particle analysis (SPA) already achieved resolutions beyond 4 Å for certain icosahedral viruses, enabling ab initio atomic model building of these viruses. As the only samples that achieved such high resolution at that time, cryo-EM method development was closely intertwined with the improvement of reconstructions of symmetrical viruses. Viral morphology exhibits significant diversity, ranging from small to large, uniform to non-uniform, and from containing single symmetry to multiple symmetries. Furthermore, viruses undergo conformational changes during their life cycle. Several methods, such as asymmetric reconstruction, Ewald sphere correction, cryoelectron tomography (cryo-ET), and sub-tomogram averaging (STA), have been developed and applied to determine virus structures in vivo and in vitro. This review outlines current advanced cryo-EM methods for high-resolution structure determination of viruses and summarizes accomplishments obtained with these approaches. Moreover, persisting challenges in comprehending virus structures are discussed and we propose potential solutions.
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Affiliation(s)
- Dongjie Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Duanfang Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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6
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Hsi J, Mietzsch M, Chipman P, Afione S, Zeher A, Huang R, Chiorini J, McKenna R. Structural and antigenic characterization of the avian adeno-associated virus capsid. J Virol 2023; 97:e0078023. [PMID: 37702486 PMCID: PMC10617571 DOI: 10.1128/jvi.00780-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 07/19/2023] [Indexed: 09/14/2023] Open
Abstract
IMPORTANCE AAVs are extensively studied as promising therapeutic gene delivery vectors. In order to circumvent pre-existing antibodies targeting primate-based AAV capsids, the AAAV capsid was evaluated as an alternative to primate-based therapeutic vectors. Despite the high sequence diversity, the AAAV capsid was found to bind to a common glycan receptor, terminal galactose, which is also utilized by other AAVs already being utilized in gene therapy trials. However, contrary to the initial hypothesis, AAAV was recognized by approximately 30% of human sera tested. Structural and sequence comparisons point to conserved epitopes in the fivefold region of the capsid as the reason determinant for the observed cross-reactivity.
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Affiliation(s)
- Jane Hsi
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mario Mietzsch
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Sandra Afione
- National Institute of Dental and Craniofacial Research, NIH, Bethesda, Maryland, USA
| | - Allison Zeher
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, USA
- Department of Epidemiology, Bloomberg School for Public Health, Johns Hopkins University, Baltimore, Maryland, USA
| | - Rick Huang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, USA
| | - John Chiorini
- National Institute of Dental and Craniofacial Research, NIH, Bethesda, Maryland, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
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7
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Luque D, Ortega-Esteban A, Valbuena A, Luis Vilas J, Rodríguez-Huete A, Mateu MG, Castón JR. Equilibrium Dynamics of a Biomolecular Complex Analyzed at Single-amino Acid Resolution by Cryo-electron Microscopy. J Mol Biol 2023; 435:168024. [PMID: 36828271 DOI: 10.1016/j.jmb.2023.168024] [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: 11/14/2022] [Revised: 02/10/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023]
Abstract
The biological function of macromolecular complexes depends not only on large-scale transitions between conformations, but also on small-scale conformational fluctuations at equilibrium. Information on the equilibrium dynamics of biomolecular complexes could, in principle, be obtained from local resolution (LR) data in cryo-electron microscopy (cryo-EM) maps. However, this possibility had not been validated by comparing, for a same biomolecular complex, LR data with quantitative information on equilibrium dynamics obtained by an established solution technique. In this study we determined the cryo-EM structure of the minute virus of mice (MVM) capsid as a model biomolecular complex. The LR values obtained correlated with crystallographic B factors and with hydrogen/deuterium exchange (HDX) rates obtained by mass spectrometry (HDX-MS), a gold standard for determining equilibrium dynamics in solution. This result validated a LR-based cryo-EM approach to investigate, with high spatial resolution, the equilibrium dynamics of biomolecular complexes. As an application of this approach, we determined the cryo-EM structure of two mutant MVM capsids and compared their equilibrium dynamics with that of the wild-type MVM capsid. The results supported a previously suggested linkage between mechanical stiffening and impaired equilibrium dynamics of a virus particle. Cryo-EM is emerging as a powerful approach for simultaneously acquiring information on the atomic structure and local equilibrium dynamics of biomolecular complexes.
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Affiliation(s)
- Daniel Luque
- Spanish National Microbiology Centre, Institute of Health Carlos III, Madrid, Spain
| | - Alvaro Ortega-Esteban
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain
| | - Alejandro Valbuena
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Jose Luis Vilas
- Biocomputing Unit, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain
| | - Alicia Rodríguez-Huete
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Mauricio G Mateu
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain.
| | - José R Castón
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain.
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8
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Zane G, Silveria M, Meyer N, White T, Duan R, Zou X, Chapman M. Cryo-EM structure of adeno-associated virus 4 at 2.2 Å resolution. Acta Crystallogr D Struct Biol 2023; 79:140-153. [PMID: 36762860 PMCID: PMC9912921 DOI: 10.1107/s2059798322012190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 12/26/2022] [Indexed: 01/21/2023] Open
Abstract
Adeno-associated virus (AAV) is the vector of choice for several approved gene-therapy treatments and is the basis for many ongoing clinical trials. Various strains of AAV exist (referred to as serotypes), each with their own transfection characteristics. Here, a high-resolution cryo-electron microscopy structure (2.2 Å) of AAV serotype 4 (AAV4) is presented. The receptor responsible for transduction of the AAV4 clade of AAV viruses (including AAV11, AAV12 and AAVrh32.33) is unknown. Other AAVs interact with the same cell receptor, adeno-associated virus receptor (AAVR), in one of two different ways. AAV5-like viruses interact exclusively with the polycystic kidney disease-like 1 (PKD1) domain of AAVR, while most other AAVs interact primarily with the PKD2 domain. A comparison of the present AAV4 structure with prior corresponding structures of AAV5, AAV2 and AAV1 in complex with AAVR provides a foundation for understanding why the AAV4-like clade is unable to interact with either PKD1 or PKD2 of AAVR. The conformation of the AAV4 capsid in variable regions I, III, IV and V on the viral surface appears to be sufficiently different from AAV2 to ablate binding with PKD2. Differences between AAV4 and AAV5 in variable region VII appear to be sufficient to exclude binding with PKD1.
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Affiliation(s)
- Grant Zane
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Mark Silveria
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Nancy Meyer
- Center for Spatial Systems Biomedicine, Oregon Health Sciences University, Portland, Oregon, USA
| | - Tommi White
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
- Bayer Crop Science, Bayer (United States), Chesterfield, MO 63017, USA
- Electron Microscopy Core, University of Missouri, Columbia, MO 65211, USA
| | - Rui Duan
- Dalton Cardiovascular Center, University of Missouri, Columbia, MO 65211, USA
| | - Xiaoqin Zou
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
- Dalton Cardiovascular Center, University of Missouri, Columbia, MO 65211, USA
- Department of Physics, University of Missouri, Columbia, MO 65211, USA
- Institute for Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA
| | - Michael Chapman
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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9
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Heymann JB. The Ewald sphere/focus gradient does not limit the resolution of cryoEM reconstructions. J Struct Biol X 2022; 7:100083. [PMID: 36632443 PMCID: PMC9826812 DOI: 10.1016/j.yjsbx.2022.100083] [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] [Received: 11/02/2022] [Revised: 12/09/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022] Open
Abstract
In our quest to solve biomolecular structures to higher resolutions in cryoEM, care must be taken to deal with all aspects of image formation in the electron microscope. One of these is the Ewald sphere/focus gradient that derives from the scattering geometry in the microscope and its implications for recovering high resolution and handedness information. While several methods to deal with it has been proposed and implemented, there are still questions as to the correct approach. At the high acceleration voltages used for cryoEM, the traditional projection approximation that ignores the Ewald sphere breaks down around 2-3 Å and with large particles. This is likely not crucial for most biologically interesting molecules, but is required to understand detail about catalytic events, molecular orbitals, orientation of bound water molecules, etc. Through simulation I show that integration along the Ewald spheres in frequency space during reconstruction, the "simple insertion method" is adequate to reach resolutions to the Nyquist frequency. Both theory and simulations indicate that the handedness information encoded in such phases is irretrievably lost in the formation of real space images. The conclusion is that correct reconstruction along the Ewald spheres avoids the limitations of the projection approximation.
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10
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Lakshmanan R, Mietzsch M, Jimenez Ybargollin A, Chipman P, Fu X, Qiu J, Söderlund-Venermo M, McKenna R. Capsid Structure of Aleutian Mink Disease Virus and Human Parvovirus 4: New Faces in the Parvovirus Family Portrait. Viruses 2022; 14:2219. [PMID: 36298773 PMCID: PMC9612331 DOI: 10.3390/v14102219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/07/2022] Open
Abstract
Parvoviruses are small, single-stranded DNA viruses with non-enveloped capsids. Determining the capsid structures provides a framework for annotating regions important to the viral life cycle. Aleutian mink disease virus (AMDV), a pathogen in minks, and human parvovirus 4 (PARV4), infecting humans, are parvoviruses belonging to the genera Amdoparvovirus and Tetraparvovirus, respectively. While Aleutian mink disease caused by AMDV is a major threat to mink farming, no clear clinical manifestations have been established following infection with PARV4 in humans. Here, the capsid structures of AMDV and PARV4 were determined via cryo-electron microscopy at 2.37 and 3.12 Å resolutions, respectively. Despite low amino acid sequence identities (10-30%) both viruses share the icosahedral nature of parvovirus capsids, with 60 viral proteins (VPs) assembling the capsid via two-, three-, and five-fold symmetry VP-related interactions, but display major structural variabilities in the surface loops when the capsid structures are superposed onto other parvoviruses. The capsid structures of AMDV and PARV4 will add to current knowledge of the structural platform for parvoviruses and permit future functional annotation of these viruses, which will help in understanding their infection mechanisms at a molecular level for the development of diagnostics and therapeutics.
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Affiliation(s)
- Renuk Lakshmanan
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32603, USA
| | - Mario Mietzsch
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32603, USA
| | - Alberto Jimenez Ybargollin
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32603, USA
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32603, USA
| | - Xiaofeng Fu
- Biological Science Imaging Resource, Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Jianming Qiu
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | | | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32603, USA
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11
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Abstract
While the application of cryogenic electron microscopy (cryo-EM) to helical polymers in biology has a long history, due to the huge number of helical macromolecular assemblies in viruses, bacteria, archaea, and eukaryotes, the use of cryo-EM to study synthetic soft matter noncovalent polymers has been much more limited. This has mainly been due to the lack of familiarity with cryo-EM in the materials science and chemistry communities, in contrast to the fact that cryo-EM was developed as a biological technique. Nevertheless, the relatively few structures of self-assembled peptide nanotubes and ribbons solved at near-atomic resolution by cryo-EM have demonstrated that cryo-EM should be the method of choice for a structural analysis of synthetic helical filaments. In addition, cryo-EM has also demonstrated that the self-assembly of soft matter polymers has enormous potential for polymorphism, something that may be obscured by techniques such as scattering and spectroscopy. These cryo-EM structures have revealed how far we currently are from being able to predict the structure of these polymers due to their chaotic self-assembly behavior.
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Affiliation(s)
- Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908, United States
| | - Ordy Gnewou
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Armin Solemanifar
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- School of Chemical Engineering, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Vincent P Conticello
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908, United States
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12
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Abstract
Adeno-associated virus (AAV) has a single-stranded DNA genome encapsidated in a small icosahedrally symmetric protein shell with 60 subunits. AAV is the leading delivery vector in emerging gene therapy treatments for inherited disorders, so its structure and molecular interactions with human hosts are of intense interest. A wide array of electron microscopic approaches have been used to visualize the virus and its complexes, depending on the scientific question, technology available, and amenability of the sample. Approaches range from subvolume tomographic analyses of complexes with large and flexible host proteins to detailed analysis of atomic interactions within the virus and with small ligands at resolutions as high as 1.6 Å. Analyses have led to the reclassification of glycan receptors as attachment factors, to structures with a new-found receptor protein, to identification of the epitopes of antibodies, and a new understanding of possible neutralization mechanisms. AAV is now well-enough characterized that it has also become a model system for EM methods development. Heralding a new era, cryo-EM is now also being deployed as an analytic tool in the process development and production quality control of high value pharmaceutical biologics, namely AAV vectors.
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Affiliation(s)
- Scott
M. Stagg
- Department
of Biological Sciences, Florida State University, Tallahassee, Florida 32306, United States
- Institute
of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
| | - Craig Yoshioka
- Department
of Biomedical Engineering, Oregon Health
& Science University, Portland Oregon 97239, United States
| | - Omar Davulcu
- Environmental
Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354, United States
| | - Michael S. Chapman
- Department
of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
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13
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Vilas JL, Carazo JM, Sorzano COS. Emerging Themes in CryoEM─Single Particle Analysis Image Processing. Chem Rev 2022; 122:13915-13951. [PMID: 35785962 PMCID: PMC9479088 DOI: 10.1021/acs.chemrev.1c00850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cryo-electron microscopy (CryoEM) has become a vital technique in structural biology. It is an interdisciplinary field that takes advantage of advances in biochemistry, physics, and image processing, among other disciplines. Innovations in these three basic pillars have contributed to the boosting of CryoEM in the past decade. This work reviews the main contributions in image processing to the current reconstruction workflow of single particle analysis (SPA) by CryoEM. Our review emphasizes the time evolution of the algorithms across the different steps of the workflow differentiating between two groups of approaches: analytical methods and deep learning algorithms. We present an analysis of the current state of the art. Finally, we discuss the emerging problems and challenges still to be addressed in the evolution of CryoEM image processing methods in SPA.
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Affiliation(s)
- Jose Luis Vilas
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - Jose Maria Carazo
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - Carlos Oscar S Sorzano
- Biocomputing Unit, Centro Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
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14
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Chua EYD, Mendez JH, Rapp M, Ilca SL, Tan YZ, Maruthi K, Kuang H, Zimanyi CM, Cheng A, Eng ET, Noble AJ, Potter CS, Carragher B. Better, Faster, Cheaper: Recent Advances in Cryo-Electron Microscopy. Annu Rev Biochem 2022; 91:1-32. [PMID: 35320683 PMCID: PMC10393189 DOI: 10.1146/annurev-biochem-032620-110705] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cryo-electron microscopy (cryo-EM) continues its remarkable growth as a method for visualizing biological objects, which has been driven by advances across the entire pipeline. Developments in both single-particle analysis and in situ tomography have enabled more structures to be imaged and determined to better resolutions, at faster speeds, and with more scientists having improved access. This review highlights recent advances at each stageof the cryo-EM pipeline and provides examples of how these techniques have been used to investigate real-world problems, including antibody development against the SARS-CoV-2 spike during the recent COVID-19 pandemic.
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Affiliation(s)
- Eugene Y D Chua
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
| | - Joshua H Mendez
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
| | - Micah Rapp
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
| | - Serban L Ilca
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
| | - Yong Zi Tan
- Department of Biological Sciences, National University of Singapore, Singapore;
- Disease Intervention Technology Laboratory, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Kashyap Maruthi
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
| | - Huihui Kuang
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
| | - Christina M Zimanyi
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
| | - Anchi Cheng
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
| | - Edward T Eng
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
| | - Alex J Noble
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
- National Center for In-Situ Tomographic Ultramicroscopy, New York, NY, USA
- Simons Machine Learning Center, New York, NY, USA
| | - Clinton S Potter
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
- National Center for In-Situ Tomographic Ultramicroscopy, New York, NY, USA
- Simons Machine Learning Center, New York, NY, USA
| | - Bridget Carragher
- New York Structural Biology Center, New York, NY, USA; , , , , , , , , , , ,
- Simons Electron Microscopy Center, New York, NY, USA
- National Center for CryoEM Access and Training, New York, NY, USA
- National Resource for Automated Molecular Microscopy, New York, NY, USA
- National Center for In-Situ Tomographic Ultramicroscopy, New York, NY, USA
- Simons Machine Learning Center, New York, NY, USA
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15
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Characterization of the Serpentine Adeno-Associated Virus (SAAV) Capsid Structure: Receptor Interactions and Antigenicity. J Virol 2022; 96:e0033522. [DOI: 10.1128/jvi.00335-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AAVs are widely studied therapeutic gene delivery vectors. However, preexisting antibodies and their detrimental effect on therapeutic efficacy are a primary challenge encountered during clinical trials.
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16
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Rabuck-Gibbons JN, Lyumkis D, Williamson JR. Quantitative mining of compositional heterogeneity in cryo-EM datasets of ribosome assembly intermediates. Structure 2022; 30:498-509.e4. [PMID: 34990602 PMCID: PMC9891661 DOI: 10.1016/j.str.2021.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 09/02/2021] [Accepted: 12/09/2021] [Indexed: 02/03/2023]
Abstract
Single-particle cryoelectron microscopy (cryo-EM) offers a unique opportunity to characterize macromolecular structural heterogeneity by virtue of its ability to place distinct particle populations into different groups through computational classification. However, there is a dearth of tools for surveying the heterogeneity landscape, quantitatively analyzing heterogeneous particle populations after classification, deciding how many unique classes are represented by the data, and accurately cross-comparing reconstructions. Here, we develop a workflow that contains discovery and analysis modules to quantitatively mine cryo-EM data for sets of structures with maximal diversity. This workflow was applied to a dataset of E. coli 50S ribosome assembly intermediates, which are characterized by significant structural heterogeneity. We identified more detailed branchpoints in the assembly process and characterized the interactions of an assembly factor with immature intermediates. While the tools described here were developed for ribosome assembly, they should be broadly applicable to the analysis of other heterogeneous cryo-EM datasets.
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Affiliation(s)
- Jessica N Rabuck-Gibbons
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Dmitry Lyumkis
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Laboratory of Genetics and Helmsley Center for Genomic Medicine, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - James R Williamson
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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17
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Ma H, Jia X, Zhang K, Su Z. Cryo-EM advances in RNA structure determination. Signal Transduct Target Ther 2022; 7:58. [PMID: 35197441 PMCID: PMC8864457 DOI: 10.1038/s41392-022-00916-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/27/2022] [Accepted: 01/30/2022] [Indexed: 02/08/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) has emerged as an unprecedented tool to resolve protein structures at atomic resolution. Structural insights of biological samples not accessible by conventional X-ray crystallography and NMR can be explored with cryo-EM because measurements are carried out under near-native crystal-free conditions, and large protein complexes with conformational and compositional heterogeneity are readily resolved. RNA has remained underexplored in cryo-EM, despite its essential role in various biological processes. This review highlights current challenges and recent progress in using cryo-EM single-particle analysis to determine protein-free RNA structures, enabled by improvement in sample preparation and integration of multiple structural and biochemical methods.
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Affiliation(s)
- Haiyun Ma
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, 610044, China
| | - Xinyu Jia
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, 610044, China
| | - Kaiming Zhang
- MOE Key Laboratory for Cellular Dynamics and Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - Zhaoming Su
- The State Key Laboratory of Biotherapy, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, 610044, China.
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18
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Zhao Z, Anselmo AC, Mitragotri S. Viral vector-based gene therapies in the clinic. Bioeng Transl Med 2022; 7:e10258. [PMID: 35079633 PMCID: PMC8780015 DOI: 10.1002/btm2.10258] [Citation(s) in RCA: 86] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/04/2021] [Accepted: 08/11/2021] [Indexed: 02/06/2023] Open
Abstract
Gene therapies are currently one of the most investigated therapeutic modalities in both the preclinical and clinical settings and have shown promise in treating a diverse spectrum of diseases. Gene therapies aim at introducing a gene material in target cells and represent a promising approach to cure diseases that were thought to be incurable by conventional modalities. In many cases, a gene therapy requires a vector to deliver gene therapeutics into target cells; viral vectors are among the most widely studied vectors owing to their distinguished advantages such as outstanding transduction efficiency. With decades of development, viral vector-based gene therapies have achieved promising clinical outcomes with many products approved for treating a range of diseases including cancer, infectious diseases and monogenic diseases. In addition, a number of active clinical trials are underway to further expand their therapeutic potential. In this review, we highlight the diversity of viral vectors, review approved products, and discuss the current clinical landscape of in vivo viral vector-based gene therapies. We have reviewed 13 approved products and their clinical applications. We have also analyzed more than 200 active trials based on various viral vectors and discussed their respective therapeutic applications. Moreover, we provide a critical analysis of the major translational challenges for in vivo viral vector-based gene therapies and discuss possible strategies to address the same.
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Affiliation(s)
- Zongmin Zhao
- Department of Pharmaceutical Sciences, College of PharmacyUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Aaron C. Anselmo
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of PharmacyUniversity of North Carolina at Chapel HillChapel HillNorth CarolinaUSA
| | - Samir Mitragotri
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired EngineeringHarvard UniversityBostonMassachusettsUSA
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19
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Wigge C, Stefanovic A, Radjainia M. The rapidly evolving role of cryo-EM in drug design. DRUG DISCOVERY TODAY. TECHNOLOGIES 2021; 38:91-102. [PMID: 34895645 DOI: 10.1016/j.ddtec.2020.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/09/2020] [Accepted: 12/22/2020] [Indexed: 01/18/2023]
Abstract
Since the early 2010s, cryo-electron microscopy (cryo-EM) has evolved to a mainstream structural biology method in what has been dubbed the "resolution revolution". Pharma companies also began to use cryo-EM in drug discovery, evidenced by a growing number of industry publications. Hitherto limited in resolution, throughput and attainable molecular weight, cryo-EM is rapidly overcoming its main limitations for more widespread use through a new wave of technological advances. This review discusses how cryo-EM has already impacted drug discovery, and how the state-of-the-art is poised to further revolutionize its application to previously intractable proteins as well as new use cases.
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Affiliation(s)
- Christoph Wigge
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands
| | | | - Mazdak Radjainia
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands.
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20
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Galibert L, Hyvönen A, Eriksson RAE, Mattola S, Aho V, Salminen S, Albers JD, Peltola SK, Weman S, Nieminen T, Ylä-Herttuala S, Lesch HP, Vihinen-Ranta M, Airenne KJ. Functional roles of the membrane-associated AAV protein MAAP. Sci Rep 2021; 11:21698. [PMID: 34737404 PMCID: PMC8568889 DOI: 10.1038/s41598-021-01220-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/25/2021] [Indexed: 12/23/2022] Open
Abstract
With a limited coding capacity of 4.7 kb, adeno-associated virus (AAV) genome has evolved over-lapping genes to maximise the usage of its genome. An example is the recently found ORF in the cap gene, encoding membrane-associated accessory protein (MAAP), located in the same genomic region as the VP1/2 unique domain, but in a different reading frame. This 13 KDa protein, unique to the dependovirus genus, is not homologous to any known protein. Our studies confirm that MAAP translation initiates from the first CTG codon found in the VP1 ORF2. We have further observed MAAP localised in the plasma membrane, in the membranous structures in close proximity to the nucleus and to the nuclear envelope by co-transfecting with plasmids encoding the wild-type AAV (wt-AAV) genome and adenovirus (Ad) helper genes. While keeping VP1/2 protein sequence identical, both inactivation and truncation of MAAP translation affected the emergence and intracellular distribution of the AAV capsid proteins. We have demonstrated that MAAP facilitates AAV replication and has a role in controlling Ad infection. Additionally, we were able to improve virus production and capsid integrity through a C-terminal truncation of MAAP while other modifications led to increased packaging of contaminating, non-viral DNA. Our results show that MAAP plays a significant role in AAV infection, with profound implications for the production of therapeutic AAV vectors.
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Affiliation(s)
| | - Amira Hyvönen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.511728.8FinVector, Kuopio, Finland
| | - Reetta A. E. Eriksson
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.9668.10000 0001 0726 2490A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Salla Mattola
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | - Vesa Aho
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | - Sami Salminen
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | | | | | - Saija Weman
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Tiina Nieminen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.9668.10000 0001 0726 2490A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland ,grid.410705.70000 0004 0628 207XGene Therapy Unit and Research Center, Kuopio University Hospital, Kuopio, Finland
| | - Hanna P. Lesch
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Maija Vihinen-Ranta
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
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21
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Abstract
We introduce Viral Phrenology, a new scheme for understanding the genomic composition of spherical viruses based on the locations of their structural protrusions. We used icosahedral point arrays to classify 135 distinct viral capsids collected from over 600 capsids available in the VIPERdb. Using gauge points of point arrays, we found 149 unique structural protrusions. We then show how to use the locations of these protrusions to determine the genetic composition of the virus. We then show that ssDNA, dsDNA, dsRNA and ssRNA viruses use different arrangements for distributing their protrusions. We also found that Triangulation number is also partially dependent on the structural protrusions. This analysis begins to tie together Baltimore Classification and Triangulation number using point arrays.
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22
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Abstract
The saying "It takes a village to raise a child" has never been truer than in my case. This autobiographical article documents my growing up and working on three different continents and my influencers along the way. Born in a village in Nigeria, West Africa, I spent the first 12 years of life with my grandmother living in a mud house and attending a village primary school. I walked barefoot to school every day, learned to read, and wrote on a chalk slate. At the age of 13, I moved to my second "village," London, England. In secondary school my love of science began to blossom. I attained a double major in chemistry and human biology from the University of Hertfordshire and a PhD in biophysics from the University of London, with a research project aimed at designing anticancer agents. I was mentored by Terence Jenkins and Stephen Neidle. For my postdoctoral training, I crossed the ocean again, to the United States, my third "village." In Michael Rossmann's group at Purdue University, my love for viruses was ignited. My independent career in structural virology began at Warwick University, England, working on pathogenic single-stranded DNA packaging viruses. In 2020, I am a full professor at the University of Florida. Most of my research is focused on the adeno-associated viruses, gene delivery vectors. My list of mentors has grown and includes Nick Muzyczka. Here, the mentee has become the mentor, and along the way, we attained a number of firsts in the field of structural virology and contributed to the field at the national and international stages.
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Affiliation(s)
- Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, College of Medicine, Gainesville, Florida 32610, USA
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23
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Monobac System-A Single Baculovirus for the Production of rAAV. Microorganisms 2021; 9:microorganisms9091799. [PMID: 34576695 PMCID: PMC8465638 DOI: 10.3390/microorganisms9091799] [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] [Received: 07/07/2021] [Revised: 08/09/2021] [Accepted: 08/13/2021] [Indexed: 11/28/2022] Open
Abstract
Large-scale manufacturing of rAAV is a bottleneck for the development of genetic disease treatments. The baculovirus/Sf9 cell system underpins the first rAAV treatment approved by EMA and remains one of the most advanced platforms for rAAV manufacturing. Despite early successes, rAAV is still a complex biomaterial to produce. Efficient production of the recombinant viral vector requires that AAV replicase and capsid genes be co-located with the recombinant AAV genome. Here, we present the Monobac system, a singular, modified baculovirus genome that contains all of these functions. To assess the relative yields between the dual baculovirus and Monobac systems, we prepared each system with a transgene encoding γSGC and evaluated vectors’ potency in vivo. Our results show that rAAV production using the Monobac system not only yields higher titers of rAAV vector but also a lower amount of DNA contamination from baculovirus.
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24
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Abstract
In the recent years, the protein databank has been fueled by the exponential growth of high-resolution electron cryo-microscopy (cryo-EM) structures. This trend will be further accelerated through the continuous software and method developments and the increasing availability of imaging centers, which will open cryo-EM to a wide array of researchers with their diverse scientific goals and questions. Especially for structural biology of membrane proteins, cryo-EM offers significant advantages as it can overcome multiple limitations of classical methods. Most importantly, in cryo-EM, the sample is prepared as a vitrified suspension, which abolishes the need for crystallization, reduces the required sample amount and allows usage of a wide arsenal of hydrophobic environments. Despite recent improvements, high-resolution cryo-EM still poses some significant challenges, and standardized procedures, especially for the characterization of membrane proteins, are missing. While there can be no ultimate recipe toward a high-resolution cryo-EM structure for every membrane protein, certain factors seem to be universally relevant. Here, we share the protocols that have been successfully used in our laboratory. We hope that this may be a useful resource to other researchers in the field and may increase their chances of success.
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Affiliation(s)
- Dovile Januliene
- Max-Planck Institute of Biophysics, Frankfurt, Germany.,Department of Structural Biology, University of Osnabrück, Osnabrück, Germany
| | - Arne Moeller
- Max-Planck Institute of Biophysics, Frankfurt, Germany. .,Department of Structural Biology, University of Osnabrück, Osnabrück, Germany.
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25
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Gijsbers A, Zhang Y, Gao Y, Peters PJ, Ravelli RBG. Mycobacterium tuberculosis ferritin: a suitable workhorse protein for cryo-EM development. Acta Crystallogr D Struct Biol 2021; 77:1077-1083. [PMID: 34342280 PMCID: PMC8329864 DOI: 10.1107/s2059798321007233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 07/13/2021] [Indexed: 11/10/2022] Open
Abstract
The use of cryo-EM continues to expand worldwide and calls for good-quality standard proteins with simple protocols for their production. Here, a straightforward expression and purification protocol is presented that provides an apoferritin, bacterioferritin B (BfrB), from Mycobacterium tuberculosis with high yield and purity. A 2.12 Å resolution cryo-EM structure of BfrB is reported, showing the typical cage-like oligomer constituting of 24 monomers related by 432 symmetry. However, it also contains a unique C-terminal extension (164-181), which loops into the cage region of the shell and provides extra stability to the protein. Part of this region was ambiguous in previous crystal structures but could be built within the cryo-EM map. These findings and this protocol could serve the growing cryo-EM community in characterizing and pushing the limits of their electron microscopes and workflows.
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Affiliation(s)
- Abril Gijsbers
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Yue Zhang
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Ye Gao
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Peter J. Peters
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Raimond B. G. Ravelli
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
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26
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Sub-3 Å Cryo-EM Structures of Necrosis Virus Particles via the Use of Multipurpose TEM with Electron Counting Camera. Int J Mol Sci 2021; 22:ijms22136859. [PMID: 34202259 PMCID: PMC8268952 DOI: 10.3390/ijms22136859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/31/2021] [Accepted: 06/22/2021] [Indexed: 11/17/2022] Open
Abstract
During this global pandemic, cryo-EM has made a great impact on the structure determination of COVID-19 proteins. However, nearly all high-resolution results are based on data acquired on state-of-the-art microscopes where their availability is restricted to a number of centers across the globe with the studies on infectious viruses being further regulated or forbidden. One potential remedy is to employ multipurpose microscopes. Here, we investigated the capability of 200 kV multipurpose microscopes equipped with a direct electron camera in determining the structures of infectious particles. We used 30 nm particles of the grouper nerve necrosis virus as a test sample and obtained the cryo-EM structure with a resolution as high as ∼2.7 Å from a setting that used electron counting. For comparison, we tested a high-end cryo-EM (Talos Arctica) using a similar virus (Macrobrachium rosenbergii nodavirus) to obtain virtually the same resolution. Those results revealed that the resolution is ultimately limited by the depth of field. Our work updates the density maps of these viruses at the sub-3Å level to allow for building accurate atomic models from de novo to provide structural insights into the assembly of the capsids. Importantly, this study demonstrated that multipurpose TEMs are capable of the high-resolution cryo-EM structure determination of infectious particles and is thus germane to the research on pandemics.
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Weissenberger G, Henderikx RJM, Peters PJ. Understanding the invisible hands of sample preparation for cryo-EM. Nat Methods 2021; 18:463-471. [PMID: 33963356 DOI: 10.1038/s41592-021-01130-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 03/30/2021] [Indexed: 02/03/2023]
Abstract
Cryo-electron microscopy (cryo-EM) is rapidly becoming an attractive method in the field of structural biology. With the exploding popularity of cryo-EM, sample preparation must evolve to prevent congestion in the workflow. The dire need for improved microscopy samples has led to a diversification of methods. This Review aims to categorize and explain the principles behind various techniques in the preparation of vitrified samples for the electron microscope. Various aspects and challenges in the workflow are discussed, from sample optimization and carriers to deposition and vitrification. Reliable and versatile specimen preparation remains a challenge, and we hope to give guidelines and posit future directions for improvement.
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Affiliation(s)
- Giulia Weissenberger
- CryoSol-World, Maastricht, the Netherlands.,Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands
| | - Rene J M Henderikx
- CryoSol-World, Maastricht, the Netherlands.,Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands
| | - Peter J Peters
- Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands.
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28
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Johnson JE, Olson AJ. Icosahedral virus structures and the protein data bank. J Biol Chem 2021; 296:100554. [PMID: 33744290 PMCID: PMC8081926 DOI: 10.1016/j.jbc.2021.100554] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/12/2021] [Accepted: 03/16/2021] [Indexed: 11/30/2022] Open
Abstract
The structural study of icosahedral viruses has a long and impactful history in both crystallographic methodology and molecular biology. The evolution of the Protein Data Bank has paralleled and supported these studies providing readily accessible formats dealing with novel features associated with viral particle symmetries and subunit interactions. This overview describes the growth in size and complexity of icosahedral viruses from the first early studies of small RNA plant viruses and human picornaviruses up to the larger and more complex bacterial phage, insect, and human disease viruses such as Zika, hepatitis B, Adeno and Polyoma virus. The analysis of icosahedral viral capsid protein domain folds has shown striking similarities, with the beta jelly roll motif observed across multiple evolutionarily divergent species. The icosahedral symmetry of viruses drove the development of noncrystallographic symmetry averaging as a powerful phasing method, and the constraints of maintaining this symmetry resulted in the concept of quasi-equivalence in viral structures. Symmetry also played an important early role in demonstrating the power of cryo-electron microscopy as an alternative to crystallography in generating atomic resolution structures of these viruses. The Protein Data Bank has been a critical resource for assembling and disseminating these structures to a wide community, and the virus particle explorer (VIPER) was developed to enable users to easily generate and view complete viral capsid structures from their asymmetric building blocks. Finally, we share a personal perspective on the early use of computer graphics to communicate the intricacies, interactions, and beauty of these virus structures.
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Affiliation(s)
- John E Johnson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA.
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
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Beckers M, Mann D, Sachse C. Structural interpretation of cryo-EM image reconstructions. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 160:26-36. [PMID: 32735944 DOI: 10.1016/j.pbiomolbio.2020.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/03/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
The productivity of single-particle cryo-EM as a structure determination method has rapidly increased as many novel biological structures are being elucidated. The ultimate result of the cryo-EM experiment is an atomic model that should faithfully represent the computed image reconstruction. Although the principal approach of atomic model building and refinement from maps resembles that of the X-ray crystallographic methods, there are important differences due to the unique properties resulting from the 3D image reconstructions. In this review, we discuss the practiced work-flow from the cryo-EM image reconstruction to the atomic model. We give an overview of (i) resolution determination methods in cryo-EM including local and directional resolution variation, (ii) cryo-EM map contrast optimization including complementary map types that can help in identifying ambiguous density features, (iii) atomic model building and (iv) refinement in various resolution regimes including (v) their validation and (vi) discuss differences between X-ray and cryo-EM maps. Based on the methods originally developed for X-ray crystallography, the path from 3D image reconstruction to atomic coordinates has become an integral and important part of the cryo-EM structure determination work-flow that routinely delivers atomic models.
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Affiliation(s)
- Maximilian Beckers
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117, Heidelberg, Germany; Candidate for Joint PhD Degree from EMBL and Heidelberg University, Faculty of Biosciences, Germany; Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Daniel Mann
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Carsten Sachse
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425, Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425, Jülich, Germany; Chemistry Department, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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Zhang J, Wang Z, Liu Z, Zhang F. Improve the Resolution and Parallel Performance of the Three-Dimensional Refine Algorithm in RELION Using CUDA and MPI. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2021; 18:583-595. [PMID: 31329127 DOI: 10.1109/tcbb.2019.2929171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In cryo-electron microscopy, RELION is a powerful tool for high-resolution reconstruction. Due to the complicated imaging procedure and the heterogeneity of particles, some of the selected particle images offer more disturbing information than others. However, in the current RELION, all these particle images are treated equally. In our work, we extend RELION's model with one scalar parameter to score the contribution of a particle depending on the error between the experimental particle and the corresponding reprojection. This scores down weight potentially poor particles, hence accelerating the convergence. Besides, by now there is no sophisticated memory management system for RELION, fragmentation on GPU will increase with iterations, eventually crashing the program. In our work, we designed the stack-based memory management system to guarantee the stability of RELION and to optimize the memory usage condition. Also, to reduce memory usage, we developed a customized compressed data structure for the memory-demanding weight array. In addition, to speed up the GPU version of RELION, we proposed two highly efficient parallel algorithms for weight calculation algorithm and weight selection algorithm. Experiments show that compared with RELION, the optimized three-dimensional refine algorithm can speed up the converge procedure, the memory system can avoid memory fragmentation, and a better speed-up ratio can be obtained.
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31
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Greber BJ, Remis J, Ali S, Nogales E. 2.5 Å-resolution structure of human CDK-activating kinase bound to the clinical inhibitor ICEC0942. Biophys J 2021; 120:677-686. [PMID: 33476598 PMCID: PMC7896097 DOI: 10.1016/j.bpj.2020.12.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/11/2020] [Accepted: 12/21/2020] [Indexed: 12/22/2022] Open
Abstract
The human CDK-activating kinase (CAK), composed of CDK7, cyclin H, and MAT1, is involved in the control of transcription initiation and the cell cycle. Because of these activities, it has been identified as a promising target for cancer chemotherapy. A number of CDK7 inhibitors have entered clinical trials, among them ICEC0942 (also known as CT7001). Structural information can aid in improving the affinity and specificity of such drugs or drug candidates, reducing side effects in patients. Here, we have determined the structure of the human CAK in complex with ICEC0942 at 2.5 Å-resolution using cryogenic electron microscopy. Our structure reveals conformational differences of ICEC0942 compared with previous X-ray crystal structures of the CDK2-bound complex, and highlights the critical ability of cryogenic electron microscopy to resolve structures of drug-bound protein complexes without the need to crystalize the protein target.
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Affiliation(s)
- Basil J Greber
- Division of Structural Biology, The Institute of Cancer Research, London, United Kingdom; California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, California; Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California.
| | - Jonathan Remis
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, California
| | - Simak Ali
- Division of Cancer, Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Eva Nogales
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, California; Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, University of California, Berkeley, Berkeley, California; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California
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32
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Completion of the AAV Structural Atlas: Serotype Capsid Structures Reveals Clade-Specific Features. Viruses 2021; 13:v13010101. [PMID: 33450892 PMCID: PMC7828300 DOI: 10.3390/v13010101] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/07/2021] [Indexed: 12/13/2022] Open
Abstract
The capsid structures of most Adeno-associated virus (AAV) serotypes, already assigned to an antigenic clade, have been previously determined. This study reports the remaining capsid structures of AAV7, AAV11, AAV12, and AAV13 determined by cryo-electron microscopy and three-dimensional image reconstruction to 2.96, 2.86, 2.54, and 2.76 Å resolution, respectively. These structures complete the structural atlas of the AAV serotype capsids. AAV7 represents the first clade D capsid structure; AAV11 and AAV12 are of a currently unassigned clade that would include AAV4; and AAV13 represents the first AAV2-AAV3 hybrid clade C capsid structure. These newly determined capsid structures all exhibit the AAV capsid features including 5-fold channels, 3-fold protrusions, 2-fold depressions, and a nucleotide binding pocket with an ordered nucleotide in genome-containing capsids. However, these structures have viral proteins that display clade-specific loop conformations. This structural characterization completes our three-dimensional library of the current AAV serotypes to provide an atlas of surface loop configurations compatible with capsid assembly and amenable for future vector engineering efforts. Derived vectors could improve gene delivery success with respect to specific tissue targeting, transduction efficiency, antigenicity or receptor retargeting.
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33
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Aiyer S, Zhang C, Baldwin PR, Lyumkis D. Evaluating Local and Directional Resolution of Cryo-EM Density Maps. Methods Mol Biol 2021; 2215:161-187. [PMID: 33368004 PMCID: PMC8294179 DOI: 10.1007/978-1-0716-0966-8_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A systematic and quantitative evaluation of cryo-EM maps is necessary to judge their quality and to capture all possible sources of error. A single value for global resolution is insufficient to accurately describe the quality of a reconstructed density. We describe the estimation and evaluation of two additional resolution measures, local and directional resolution, using methods based on the Fourier shell correlation (FSC). We apply the protocol to samples that encompass different types of pathologies a user is expected to encounter and provide analyses on how to interpret the output files and resulting maps. Implementation of these tools will facilitate density interpretation and can guide the user in adapting their experiments to improve the quality of cryo-EM maps, and by extension atomic models.
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Affiliation(s)
- Sriram Aiyer
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Cheng Zhang
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Philp R Baldwin
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, La Jolla, CA, USA.
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Behkamal B, Naghibzadeh M, Pagnani A, Saberi MR, Al Nasr K. Solving the α-helix correspondence problem at medium-resolution Cryo-EM maps through modeling and 3D matching. J Mol Graph Model 2020; 103:107815. [PMID: 33338845 DOI: 10.1016/j.jmgm.2020.107815] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 11/30/2022]
Abstract
Cryo-electron microscopy (cryo-EM) has recently emerged as a prominent biophysical method for macromolecular structure determination. Many research efforts have been devoted to produce cryo-EM images, density maps, at near-atomic resolution. Despite many advances in technology, the resolution of the generated density maps may not be sufficiently adequate and informative to directly construct the atomic structure of proteins. At medium-resolution (∼4-10 Å), secondary structure elements (α-helices and β-sheets) are discernible, whereas finding the correspondence of secondary structure elements detected in the density map with those on the sequence remains a challenging problem. In this paper, an automatic framework is proposed to solve α-helix correspondence problem in three-dimensional space. Through modeling of the sequence with the aid of a novel strategy, the α-helix correspondence problem is initially transformed into a complete weighted bipartite graph matching problem. An innovative correlation-based scoring function based on a well-known and robust statistical method is proposed for weighting the graph. Moreover, two local optimization algorithms, which are Greedy and Improved Greedy algorithms, have been presented to find α-helix correspondence. A widely used data set including 16 reconstructed and 4 experimental cryo-EM maps were chosen to verify the accuracy and reliability of the proposed automatic method. The experimental results demonstrate that the automatic method is highly efficient (86.25% accuracy), robust (11.3% error rate), fast (∼1.4 s), and works independently from cryo-EM skeleton.
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Affiliation(s)
- Bahareh Behkamal
- Department of Computer Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, 9177948944, Iran.
| | - Mahmoud Naghibzadeh
- Department of Computer Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, 9177948944, Iran.
| | - Andrea Pagnani
- Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy; Italian Institute for Genomic Medicine (IIGM), IRCC-Candiolo, Candiolo, TO, Italy; INFN Sezione di Torino, Via P. Giuria 1, Torino, Italy
| | - Mohammad Reza Saberi
- Medicinal Chemistry Department, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran; Bioinformatics Research group, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Kamal Al Nasr
- Department of Computer Science, Tennessee State University, Nashville, TN, 37209, USA
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35
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Naydenova K, Jia P, Russo CJ. Cryo-EM with sub-1 Å specimen movement. Science 2020; 370:223-226. [PMID: 33033219 DOI: 10.1126/science.abb7927] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022]
Abstract
Most information loss in cryogenic electron microscopy (cryo-EM) stems from particle movement during imaging, which remains poorly understood. We show that this movement is caused by buckling and subsequent deformation of the suspended ice, with a threshold that depends directly on the shape of the frozen water layer set by the support foil. We describe a specimen support design that eliminates buckling and reduces electron beam-induced particle movement to less than 1 angstrom. The design allows precise foil tracking during imaging with high-speed detectors, thereby lessening demands on cryostage precision and stability. It includes a maximal density of holes, which increases throughput in automated cryo-EM without degrading data quality. Movement-free imaging allows extrapolation to a three-dimensional map of the specimen at zero electron exposure, before the onset of radiation damage.
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Affiliation(s)
| | - Peipei Jia
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.,ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide 5005, Australia
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36
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Xie Q, Yoshioka CK, Chapman MS. Adeno-Associated Virus (AAV-DJ)-Cryo-EM Structure at 1.56 Å Resolution. Viruses 2020; 12:E1194. [PMID: 33092282 PMCID: PMC7589773 DOI: 10.3390/v12101194] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 01/12/2023] Open
Abstract
Adeno-associated virus is the leading viral vector for gene therapy. AAV-DJ is a recombinant variant developed for tropism to the liver. The AAV-DJ structure has been determined to 1.56 Å resolution through cryo-electron microscopy (cryo-EM). Only apoferritin is reported in preprints at 1.6 Å or higher resolution, and AAV-DJ nearly matches the highest resolutions ever attained through X-ray diffraction of virus crystals. However, cryo-EM has the advantage that most of the hydrogens are clear, improving the accuracy of atomic refinement, and removing ambiguity in hydrogen bond identification. Outside of secondary structures where hydrogen bonding was predictable a priori, the networks of hydrogen bonds coming from direct observation of hydrogens and acceptor atoms are quite different from those inferred even at 2.8 Å resolution. The implications for understanding viral assembly mean that cryo-EM will likely become the favored approach for high resolution structural virology.
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Affiliation(s)
- Qing Xie
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, OR 97239, USA;
| | - Craig K. Yoshioka
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA;
| | - Michael S. Chapman
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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Mietzsch M, Smith JK, Yu JC, Banala V, Emmanuel SN, Jose A, Chipman P, Bhattacharya N, McKenna R, Agbandje-McKenna M. Characterization of AAV-Specific Affinity Ligands: Consequences for Vector Purification and Development Strategies. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 19:362-373. [PMID: 33145372 PMCID: PMC7591348 DOI: 10.1016/j.omtm.2020.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023]
Abstract
Affinity-based purification of adeno-associated virus (AAV) vectors has replaced density-based methods for vectors used in clinical settings. This method utilizes camelid single-domain antibodies recognizing AAV capsids. These include AVB Sepharose (AVB) and POROS CaptureSelect affinity ligand for AAV8 (CSAL8) and AAV9 (CSAL9). In this study, we utilized cryo-electron microscopy and 3D image reconstruction to map the binding sites of these affinity ligands on the capsids of several AAV serotypes, including AAV1, AAV2, AAV5, AAV8, and AAV9, representing the range of sequence and structure diversity among AAVs. The AAV-ligand complex structures showed that AVB and CSAL9 bound to the 5-fold capsid region, although in different orientations, and CSAL8 bound to the side of the 3-fold protrusion. The AAV contact residues required for ligand binding, and thus AAV purification, and the ability of the ligands to neutralize infection were analyzed. The data show that only a few residues within the epitopes served to block affinity ligand binding. Neutralization was observed for AAV1 and AAV5 with AVB, for AAV1 with CSAL8, and for AAV9 with CSAL9, associated with regions that overlap with epitopes for neutralizing monoclonal antibodies against these capsids. This information is critical and could be generally applicable in the development of novel AAV vectors amenable to affinity column purification.
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Affiliation(s)
- Mario Mietzsch
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - J Kennon Smith
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jennifer C Yu
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Vibhu Banala
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Shanan N Emmanuel
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Ariana Jose
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nilakshee Bhattacharya
- Biological Science Imaging Resource, Department of Biological Sciences, Florida State University, Tallahassee, FL, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, USA
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Moscoso CG, Steer CJ. The Evolution of Gene Therapy in the Treatment of Metabolic Liver Diseases. Genes (Basel) 2020; 11:genes11080915. [PMID: 32785089 PMCID: PMC7463482 DOI: 10.3390/genes11080915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 08/02/2020] [Accepted: 08/06/2020] [Indexed: 12/12/2022] Open
Abstract
Monogenic metabolic disorders of hepatic origin number in the hundreds, and for many, liver transplantation remains the only cure. Liver-targeted gene therapy is an attractive treatment modality for many of these conditions, and there have been significant advances at both the preclinical and clinical stages. Viral vectors, including retroviruses, lentiviruses, adenovirus-based vectors, adeno-associated viruses and simian virus 40, have differing safety, efficacy and immunogenic profiles, and several of these have been used in clinical trials with variable success. In this review, we profile viral vectors and non-viral vectors, together with various payloads, including emerging therapies based on RNA, that are entering clinical trials. Genome editing technologies are explored, from earlier to more recent novel approaches that are more efficient, specific and safe in reaching their target sites. The various curative approaches for the multitude of monogenic hepatic metabolic disorders currently at the clinical development stage portend a favorable outlook for this class of genetic disorders.
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Affiliation(s)
- Carlos G. Moscoso
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Minnesota Medical School, Minneapolis, MN 55455, USA
- Correspondence: (C.G.M.); (C.J.S.); Tel.: +1-612-625-8999 (C.G.M. & C.J.S.); Fax: +1-612-625-5620 (C.G.M. & C.J.S.)
| | - Clifford J. Steer
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Minnesota Medical School, Minneapolis, MN 55455, USA
- Department of Genetics, Cell Biology and Development, University of Minnesota Medical School, Minneapolis, MN 55455, USA
- Correspondence: (C.G.M.); (C.J.S.); Tel.: +1-612-625-8999 (C.G.M. & C.J.S.); Fax: +1-612-625-5620 (C.G.M. & C.J.S.)
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Weis F, Hagen WJH. Combining high throughput and high quality for cryo-electron microscopy data collection. Acta Crystallogr D Struct Biol 2020; 76:724-728. [PMID: 32744254 PMCID: PMC7397495 DOI: 10.1107/s2059798320008347] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/23/2020] [Indexed: 01/24/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) can be used to elucidate the 3D structure of macromolecular complexes. Driven by technological breakthroughs in electron-microscope and electron-detector development, coupled with improved image-processing procedures, it is now possible to reach high resolution both in single-particle analysis and in cryo-electron tomography and subtomogram-averaging approaches. As a consequence, the way in which cryo-EM data are collected has changed and new challenges have arisen in terms of microscope alignment, aberration correction and imaging parameters. This review describes how high-end data collection is performed at the EMBL Heidelberg cryo-EM platform, presenting recent microscope implementations that allow an increase in throughput while maintaining aberration-free imaging and the optimization of acquisition parameters to collect high-resolution data.
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Affiliation(s)
- Felix Weis
- The Cryo-Electron Microscopy Service Platform, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Wim J. H. Hagen
- The Cryo-Electron Microscopy Service Platform, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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40
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Mietzsch M, Li Y, Kurian J, Smith JK, Chipman P, McKenna R, Yang L, Agbandje-McKenna M. Structural characterization of a bat Adeno-associated virus capsid. J Struct Biol 2020; 211:107547. [PMID: 32522552 PMCID: PMC9744130 DOI: 10.1016/j.jsb.2020.107547] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/04/2020] [Indexed: 02/08/2023]
Abstract
Adeno-associated viruses (AAVs) are widespread among vertebrates. AAVs isolated from bats display low capsid protein sequence identities (<60%) to AAV2, AAV5, and other primate AAVs. Here we report the first capsid structure of a non-primate AAV which was isolated from bats. The capsid structure of BtAAV-10HB (10HB) was determined by cryo-electron microscopy and three-dimensional image reconstruction to 3.03 Å resolution. Comparison of empty and genome-containing capsids showed that the capsid structures are almost identical except for an ordered nucleotide in a previously described nucleotide-binding pocket, the density in the 5-fold channel, and several amino acids with altered side chain conformations. Compared to other dependoparvoviruses, for example AAV2 and AAV5, 10HB displays unique structural features including insertions and deletions in capsid surface loops. Overall, the 10HB capsid structure superposes with an RMSD of 1.7 Å and 1.8 Å to AAV2 and AAV5, respectively. Currently all approved AAV human gene therapy biologics and vectors in clinical trials are based on primate isolates. However, pre-existing neutralizing antibodies in the human population represents a hurdle to their use. 10HB capsids are capable of packaging AAV2 vector genomes and thus have potential as gene delivery vectors. Significantly, a screen with human sera showed lack of recognition by the 10HB capsid. Thus, the different capsid surface of 10HB vectors likely renders it "invisible" to potential pre-existing neutralizing human anti-AAV antibodies especially because this virus or similar variants do not exist in primate populations.
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Affiliation(s)
- Mario Mietzsch
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Ya Li
- Department of Cardiology and Laboratory of Gene Therapy for Heart Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, China
| | - Justin Kurian
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - James Kennon Smith
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Lin Yang
- Department of Cardiology and Laboratory of Gene Therapy for Heart Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, China
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, The McKnight Brain Institute, University of Florida, Gainesville, Florida, USA,Address correspondence to Mavis Agbandje-McKenna,
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41
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Merk A, Fukumura T, Zhu X, Darling JE, Grisshammer R, Ognjenovic J, Subramaniam S. 1.8 Å resolution structure of β-galactosidase with a 200 kV CRYO ARM electron microscope. IUCRJ 2020; 7:639-643. [PMID: 32695410 PMCID: PMC7340270 DOI: 10.1107/s2052252520006855] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/20/2020] [Indexed: 05/26/2023]
Abstract
We report the determination of the structure of Escherichia coli β-galactosidase at a resolution of ∼1.8 Å using data collected on a 200 kV CRYO ARM microscope equipped with a K3 direct electron detector. The data were collected in a single 24 h session by recording images from an array of 7 × 7 holes at each stage position using the automated data collection program SerialEM. In addition to the expected features such as holes in the densities of aromatic residues, the map also shows density bumps corresponding to the locations of hydrogen atoms. The hydrogen densities are useful in assigning absolute orientations for residues such as glutamine or asparagine by removing the uncertainty in the fitting of the amide groups, and are likely to be especially relevant in the context of structure-guided drug design. These findings validate the use of electron microscopes operating at 200 kV for imaging protein complexes at atomic resolution using cryo-EM.
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Affiliation(s)
- Alan Merk
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | | | - Xing Zhu
- University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Joseph E. Darling
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Reinhard Grisshammer
- National Cancer Institute Frederick Office of Scientific Operations, Frederick, MD 21701, USA
| | - Jana Ognjenovic
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Sriram Subramaniam
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
- University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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42
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43
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Zhang Y, Tammaro R, Peters P, Ravelli R. Could Egg White Lysozyme be Solved by Single Particle Cryo-EM? J Chem Inf Model 2020; 60:2605-2613. [PMID: 32202786 PMCID: PMC7254834 DOI: 10.1021/acs.jcim.9b01176] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Indexed: 12/29/2022]
Abstract
The combination of high-end cryogenic transmission electron microscopes (cryo-EM), direct electron detectors, and advanced image algorithms allows researchers to obtain the 3D structures of much smaller macromolecules than years ago. However, there are still major challenges for the single-particle cryo-EM method to achieve routine structure determinations for macromolecules much smaller than 100 kDa, which are the majority of all plant and animal proteins. These challenges include sample characteristics such as sample heterogeneity, beam damage, ice layer thickness, stability, and quality, as well as hardware limitations such as detector performance, beam, and phase plate quality. Here, single particle data sets were simulated for samples that were ideal in terms of homogeneity, distribution, and stability, but with realistic parameters for ice layer, dose, detector performance, and beam characteristics. Reference data were calculated for human apo-ferritin using identical parameters reported for an experimental data set downloaded from EMPIAR. Processing of the simulated data set resulted in a value of 1.86 Å from 20 214 particles, similar to a 2 Å density map obtained from 29 224 particles selected from real micrographs. Simulated data sets were then generated for a 14 kDa protein, hen egg white lysozyme (HEWL), with and without an ideal phase plate (PP). Whereas we could not obtain a high-resolution 3D reconstruction of HEWL for the data set without PP, the one with PP resulted in a 2.78 Å resolution density map from 225 751 particles. Our simulator and simulations could help in pushing the size limits of cryo-EM.
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Affiliation(s)
- Y. Zhang
- The Maastricht Multimodal
Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, 6229ER, Maastricht, The Netherlands
| | - R. Tammaro
- The Maastricht Multimodal
Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, 6229ER, Maastricht, The Netherlands
| | - P.J. Peters
- The Maastricht Multimodal
Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, 6229ER, Maastricht, The Netherlands
| | - R.B.G. Ravelli
- The Maastricht Multimodal
Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, 6229ER, Maastricht, The Netherlands
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44
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Cabanes-Creus M, Westhaus A, Navarro RG, Baltazar G, Zhu E, Amaya AK, Liao SHY, Scott S, Sallard E, Dilworth KL, Rybicki A, Drouyer M, Hallwirth CV, Bennett A, Santilli G, Thrasher AJ, Agbandje-McKenna M, Alexander IE, Lisowski L. Attenuation of Heparan Sulfate Proteoglycan Binding Enhances In Vivo Transduction of Human Primary Hepatocytes with AAV2. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 17:1139-1154. [PMID: 32490035 PMCID: PMC7260615 DOI: 10.1016/j.omtm.2020.05.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/07/2020] [Indexed: 12/19/2022]
Abstract
Use of the prototypical adeno-associated virus type 2 (AAV2) capsid delivered unexpectedly modest efficacy in an early liver-targeted gene therapy trial for hemophilia B. This result is consistent with subsequent data generated in chimeric mouse-human livers showing that the AAV2 capsid transduces primary human hepatocytes in vivo with low efficiency. In contrast, novel variants generated by directed evolution in the same model, such as AAV-NP59, transduce primary human hepatocytes with high efficiency. While these empirical data have immense translational implications, the mechanisms underpinning this enhanced AAV capsid transduction performance in primary human hepatocytes are yet to be fully elucidated. Remarkably, AAV-NP59 differs from the prototypical AAV2 capsid by only 11 aa and can serve as a tool to study the correlation between capsid sequence/structure and vector function. Using two orthogonal vectorological approaches, we have determined that just 2 of the 11 changes present in AAV-NP59 (T503A and N596D) account for the enhanced transduction performance of this capsid variant in primary human hepatocytes in vivo, an effect that we have associated with attenuation of heparan sulfate proteoglycan (HSPG) binding affinity. In support of this hypothesis, we have identified, using directed evolution, two additional single amino acid substitution AAV2 variants, N496D and N582S, which are highly functional in vivo. Both substitution mutations reduce AAV2's affinity for HSPG. Finally, we have modulated the ability of AAV8, a highly murine-hepatotropic serotype, to interact with HSPG. The results support our hypothesis that enhanced HSPG binding can negatively affect the in vivo function of otherwise strongly hepatotropic variants and that modulation of the interaction with HSPG is critical to ensure maximum efficiency in vivo. The insights gained through this study can have powerful implications for studies into AAV biology and capsid development for preclinical and clinical applications targeting liver and other organs.
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Affiliation(s)
- Marti Cabanes-Creus
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Adrian Westhaus
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia.,Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Renina Gale Navarro
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Grober Baltazar
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Erhua Zhu
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia.,Gene Therapy Research Unit, Children's Medical Research Institute & The Children's Hospital at Westmead, University of Sydney, Westmead, NSW 2145, Australia
| | - Anais K Amaya
- Gene Therapy Research Unit, Children's Medical Research Institute & The Children's Hospital at Westmead, University of Sydney, Westmead, NSW 2145, Australia
| | - Sophia H Y Liao
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Suzanne Scott
- Gene Therapy Research Unit, Children's Medical Research Institute & The Children's Hospital at Westmead, University of Sydney, Westmead, NSW 2145, Australia.,Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW 2113, Australia
| | - Erwan Sallard
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Kimberley L Dilworth
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Arkadiusz Rybicki
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Matthieu Drouyer
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia
| | - Claus V Hallwirth
- Gene Therapy Research Unit, Children's Medical Research Institute & The Children's Hospital at Westmead, University of Sydney, Westmead, NSW 2145, Australia
| | - Antonette Bennett
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, University of Florida, Gainesville, FL 32610, USA
| | - Giorgia Santilli
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Adrian J Thrasher
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, University of Florida, Gainesville, FL 32610, USA
| | - Ian E Alexander
- Gene Therapy Research Unit, Children's Medical Research Institute & The Children's Hospital at Westmead, University of Sydney, Westmead, NSW 2145, Australia.,Discipline of Child and Adolescent Health, The University of Sydney, Sydney, NSW 2006, Australia
| | - Leszek Lisowski
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia.,Vector and Genome Engineering Facility, Children's Medical Research Institute, The University of Sydney, Westmead, NSW 2145, Australia.,Military Institute of Hygiene and Epidemiology, Biological Threats Identification and Countermeasure Center, 24-100 Puławy, Poland
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45
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Wu M, Lander GC, Herzik MA. Sub-2 Angstrom resolution structure determination using single-particle cryo-EM at 200 keV. J Struct Biol X 2020; 4:100020. [PMID: 32647824 PMCID: PMC7337053 DOI: 10.1016/j.yjsbx.2020.100020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 11/30/2022] Open
Abstract
Although the advent of direct electron detectors (DEDs) and software developments have enabled the routine use of single-particle cryogenic electron microscopy (cryo-EM) for structure determination of well-behaved specimens to high-resolution, there nonetheless remains a discrepancy between the resolutions attained for biological specimens and the information limits of modern transmission electron microscopes (TEMs). Instruments operating at 300 kV equipped with DEDs are the current paradigm for high-resolution single-particle cryo-EM, while 200 kV TEMs remain comparatively underutilized for purposes beyond sample screening. Here, we expand upon our prior work and demonstrate that one such 200 kV microscope, the Talos Arctica, equipped with a K2 DED is capable of determining structures of macromolecules to as high as ∼1.7 Å resolution. At this resolution, ordered water molecules are readily assigned and holes in aromatic residues can be clearly distinguished in the reconstructions. This work emphasizes the utility of 200 kV electrons for high-resolution single-particle cryo-EM and applications such as structure-based drug design.
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Affiliation(s)
- Mengyu Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Gabriel C. Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Mark A. Herzik
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, United States
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46
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Comparative Analysis of the Capsid Structures of AAVrh.10, AAVrh.39, and AAV8. J Virol 2020; 94:JVI.01769-19. [PMID: 31826994 DOI: 10.1128/jvi.01769-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/27/2019] [Indexed: 12/17/2022] Open
Abstract
Adeno-associated viruses (AAVs) from clade E are often used as vectors in gene delivery applications. This clade includes rhesus isolate 10 (AAVrh.10) and 39 (AAVrh.39) which, unlike representative AAV8, are capable of crossing the blood-brain barrier (BBB), thereby enabling the delivery of therapeutic genes to the central nervous system. Here, the capsid structures of AAV8, AAVrh.10 and AAVrh.39 have been determined by cryo-electron microscopy and three-dimensional image reconstruction to 3.08-, 2.75-, and 3.39-Å resolution, respectively, to enable a direct structural comparison. AAVrh.10 and AAVrh.39 are 98% identical in amino acid sequence but only ∼93.5% identical to AAV8. However, the capsid structures of all three viruses are similar, with only minor differences observed in the previously described surface variable regions, suggesting that specific residues S269 and N472, absent in AAV8, may confer the ability to cross the BBB in AAVrh.10 and AAVrh.39. Head-to-head comparison of empty and genome-containing particles showed DNA ordered in the previously described nucleotide-binding pocket, supporting the suggested role of this pocket in DNA packaging for the Dependoparvovirus The structural characterization of these viruses provides a platform for future vector engineering efforts toward improved gene delivery success with respect to specific tissue targeting, transduction efficiency, antigenicity, or receptor retargeting.IMPORTANCE Recombinant adeno-associated virus vectors (rAAVs), based on AAV8 and AAVrh.10, have been utilized in multiple clinical trials to treat different monogenetic diseases. The closely related AAVrh.39 has also shown promise in vivo As recently attained for other AAV biologics, e.g., Luxturna and Zolgensma, based on AAV2 and AAV9, respectively, the vectors in this study will likely gain U.S. Food and Drug Administration approval for commercialization in the near future. This study characterized the capsid structures of these clinical vectors at atomic resolution using cryo-electron microscopy and image reconstruction for comparative analysis. The analysis suggested two key residues, S269 and N472, as determinants of BBB crossing for AAVrh.10 and AAVrh.39, a feature utilized for central nervous system delivery of therapeutic genes. The structure information thus provides a platform for engineering to improve receptor retargeting or tissue specificity. These are important challenges in the field that need attention. Capsid structure information also provides knowledge potentially applicable for regulatory product approval.
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47
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Shigematsu H. Electron cryo-microscopy for elucidating the dynamic nature of live-protein complexes. Biochim Biophys Acta Gen Subj 2020; 1864:129436. [DOI: 10.1016/j.bbagen.2019.129436] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 08/31/2019] [Accepted: 09/11/2019] [Indexed: 12/30/2022]
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48
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Structure comparison of the chimeric AAV2.7m8 vector with parental AAV2. J Struct Biol 2019; 209:107433. [PMID: 31859208 DOI: 10.1016/j.jsb.2019.107433] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/28/2019] [Accepted: 12/03/2019] [Indexed: 12/26/2022]
Abstract
The AAV2.7m8 vector is an engineered capsid with a 10-amino acid insertion in adeno-associated virus (AAV) surface variable region VIII (VR-VIII) resulting in the alteration of an antigenic region of AAV2 and the ability to efficiently transduce retina cells following intravitreal administration. Directed evolution and in vivo screening in the mouse retina isolated this vector. In the present study, we sought to identify the structural differences between a recombinant AAV2.7m8 (rAAV2.7m8) vector packaging a GFP genome and its parental serotype, AAV2, by cryo-electron microscopy (cryo-EM) and image reconstruction. The structures of rAAV2.7m8 and AAV2 were determined to 2.91 and 3.02 Å resolution, respectively. The rAAV2.7m8 amino acid side-chains for residues 219-745 (the last C-terminal residue) were interpretable in the density map with the exception of the 10 inserted amino acids. While observable in a low sigma threshold density, side-chains were only resolved at the base of the insertion, likely due to flexibility at the top of the loop. A comparison to parental AAV2 (ordered from residues 217-735) showed the structures to be similar, except at some side-chains that had different orientations and, in VR-VIII containing the 10 amino acid insertion. VR-VIII is part of an AAV2 antigenic epitope, and the difference is consistent with rAAV2.7m8's escape from a known AAV2 monoclonal antibody, C37-B. The observations provide valuable insight into the configuration of inserted surface peptides on the AAV capsid and structural differences to be leveraged for future AAV vector rational design, especially for retargeted tropism and antibody escape.
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Non-uniformity of projection distributions attenuates resolution in Cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:160-183. [PMID: 31525386 DOI: 10.1016/j.pbiomolbio.2019.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 09/02/2019] [Accepted: 09/07/2019] [Indexed: 11/23/2022]
Abstract
Virtually all single-particle cryo-EM experiments currently suffer from specimen adherence to the air-water interface, leading to a non-uniform distribution in the set of projection views. Whereas it is well accepted that uniform projection distributions can lead to high-resolution reconstructions, non-uniform (anisotropic) distributions can negatively affect map quality, elongate structural features, and in some cases, prohibit interpretation altogether. Although some consequences of non-uniform sampling have been described qualitatively, we know little about how sampling quantitatively affects resolution in cryo-EM. Here, we show how inhomogeneity in any projection distribution scheme attenuates the global Fourier Shell Correlation (FSC) in relation to the number of particles and a single geometrical parameter, which we term the sampling compensation factor (SCF). The reciprocal of the SCF is defined as the average over Fourier shells of the reciprocal of the per-particle sampling and normalized to unity for uniform distributions. The SCF therefore ranges from one to zero, with values close to the latter implying large regions of poorly sampled or completely missing data in Fourier space. Using two synthetic test cases, influenza hemagglutinin and human apoferritin, we demonstrate how any amount of sampling inhomogeneity always attenuates the FSC compared to a uniform distribution. We advocate quantitative evaluation of the SCF criterion to approximate the effect of non-uniform sampling on resolution within experimental single-particle cryo-EM reconstructions.
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50
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Casañal A, Shakeel S, Passmore LA. Interpretation of medium resolution cryoEM maps of multi-protein complexes. Curr Opin Struct Biol 2019; 58:166-174. [PMID: 31362190 PMCID: PMC6863432 DOI: 10.1016/j.sbi.2019.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/14/2019] [Accepted: 06/18/2019] [Indexed: 12/20/2022]
Abstract
CryoEM maps at medium (3.5–6 Å) resolution can be challenging to interpret. Integration of multiple methods can inform cryoEM studies. Mass spectrometry and biochemistry facilitate map interpretation and model building.
Electron cryo-microscopy (cryoEM) is used to determine structures of biological molecules, including multi-protein complexes. Maps at better than 3.0 Å resolution are relatively straightforward to interpret since atomic models of proteins and nucleic acids can be built directly. Still, these resolutions are often difficult to achieve, and map quality frequently varies within a structure. This results in data that are challenging to interpret, especially when crystal structures or suitable homology models are not available. Recent advances in mass spectrometry techniques, computational methods and model building tools facilitate subunit/domain fitting into maps, elucidation of protein contacts, and de novo generation of atomic models. Here, we review techniques for map interpretation and provide examples from recent studies of multi-protein complexes.
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Affiliation(s)
- Ana Casañal
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom.
| | - Shabih Shakeel
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Lori A Passmore
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom.
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