1
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Watanabe R, Song C, Takemura M, Murata K. Subnanometer structure of medusavirus capsid during maturation using cryo-electron microscopy. J Virol 2024:e0043624. [PMID: 39194243 DOI: 10.1128/jvi.00436-24] [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: 03/07/2024] [Accepted: 07/15/2024] [Indexed: 08/29/2024] Open
Abstract
Medusavirus is a giant virus classified into an independent family of Mamonoviridae. Amoebae infected with medusavirus release immature particles in addition to virions. These particles were suggested to exhibit the maturation process of this virus, but the structure of these capsids during maturation remains unknown. Here, we apply a block-based reconstruction method in cryo-electron microscopy (cryo-EM) single particle analysis to these viral capsids, extending the resolution to 7-10 Å. The maps reveal a novel network composed of minor capsid proteins (mCPs) supporting major capsid proteins (MCPs). A predicted molecular model of the MCP fitted into the cryo-EM maps clarified the boundaries between the MCP and the underlining mCPs, as well as between the MCP and the outer spikes, and identified molecular interactions between the MCP and these components. Several structural changes of the mCPs under the fivefold vertices of the immature particles were observed, depending on the presence or absence of the underlying internal membrane. In addition, the lower part of the penton proteins on the fivefold vertices was also missing in mature virions. These dynamic conformational changes of mCPs indicate an important function in the maturation process of medusavirus.IMPORTANCEThe structural changes of giant virus capsids during maturation have not thus far been well clarified. Medusavirus is a unique giant virus in which infected amoebae release immature particles in addition to mature virus particles. In this study, we used cryo-electron microscopy to investigate immature and mature medusavirus particles and elucidate the structural changes of the viral capsid during the maturation process. In DNA-empty particles, the conformation of the minor capsid proteins changed dynamically depending on the presence or absence of the underlying internal membranes. In DNA-full particles, the lower part of the penton proteins was lost. This is the first report of structural changes of the viral capsid during the maturation process of giant viruses.
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Affiliation(s)
- Ryoto Watanabe
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Chihong Song
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Masaharu Takemura
- Institute of Arts and Sciences, Tokyo University of Science, Shinjuku, Tokyo, Japan
| | - Kazuyoshi Murata
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
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2
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Yang Y, Shao Q, Guo M, Han L, Zhao X, Wang A, Li X, Wang B, Pan JA, Chen Z, Fokine A, Sun L, Fang Q. Capsid structure of bacteriophage ΦKZ provides insights into assembly and stabilization of jumbo phages. Nat Commun 2024; 15:6551. [PMID: 39095371 PMCID: PMC11297242 DOI: 10.1038/s41467-024-50811-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 07/22/2024] [Indexed: 08/04/2024] Open
Abstract
Jumbo phages are a group of tailed bacteriophages with large genomes and capsids. As a prototype of jumbo phage, ΦKZ infects Pseudomonas aeruginosa, a multi-drug-resistant (MDR) opportunistic pathogen leading to acute or chronic infection in immunocompromised individuals. It holds potential to be used as an antimicrobial agent and as a model for uncovering basic phage biology. Although previous low-resolution structural studies have indicated that jumbo phages may have more complicated capsid structures than smaller phages such as HK97, the detailed structures and the assembly mechanism of their capsids remain largely unknown. Here, we report a 3.5-Å-resolution cryo-EM structure of the ΦKZ capsid. The structure unveiled ten minor capsid proteins, with some decorating the outer surface of the capsid and the others forming a complex network attached to the capsid's inner surface. This network seems to play roles in driving capsid assembly and capsid stabilization. Similar mechanisms of capsid assembly and stabilization are probably employed by many other jumbo viruses.
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Affiliation(s)
- Yashan Yang
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Qianqian Shao
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Mingcheng Guo
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Lin Han
- Shanghai Fifth People's Hospital, Shanghai Institute of Infectious Disease and Biosecurity, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Xinyue Zhao
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Aohan Wang
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Xiangyun Li
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Bo Wang
- The Center for Infection and Immunity Study and Molecular Cancer Research Center, School of Medicine, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Ji-An Pan
- The Center for Infection and Immunity Study and Molecular Cancer Research Center, School of Medicine, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Zhenguo Chen
- Shanghai Fifth People's Hospital, Shanghai Institute of Infectious Disease and Biosecurity, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Andrei Fokine
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Lei Sun
- Shanghai Fifth People's Hospital, Shanghai Institute of Infectious Disease and Biosecurity, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Qianglin Fang
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China.
- Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, China.
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3
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Liu Y, van den Ent F, Löwe J. Filament structure and subcellular organization of the bacterial intermediate filament-like protein crescentin. Proc Natl Acad Sci U S A 2024; 121:e2309984121. [PMID: 38324567 PMCID: PMC10873595 DOI: 10.1073/pnas.2309984121] [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: 06/16/2023] [Accepted: 12/28/2023] [Indexed: 02/09/2024] Open
Abstract
The protein crescentin is required for the crescent shape of the freshwater bacterium Caulobacter crescentus (vibrioides). Crescentin forms a filamentous structure on the inner, concave side of the curved cells. It shares features with eukaryotic intermediate filament (IF) proteins, including the formation of static filaments based on long and parallel coiled coils, the protein's length, structural roles in cell and organelle shape determination and the presence of a coiled coil discontinuity called the "stutter." Here, we have used electron cryomicroscopy (cryo-EM) to determine the structure of the full-length protein and its filament, exploiting a crescentin-specific nanobody. The filament is formed by two strands, related by twofold symmetry, that each consist of two dimers, resulting in an octameric assembly. Crescentin subunits form longitudinal contacts head-to-head and tail-to-tail, making the entire filament non-polar. Using in vivo site-directed cysteine cross-linking, we demonstrated that contacts observed in the in vitro filament structure exist in cells. Electron cryotomography (cryo-ET) of cells expressing crescentin showed filaments on the concave side of the curved cells, close to the inner membrane, where they form a band. When comparing with current models of IF proteins and their filaments, which are also built from parallel coiled coil dimers and lack overall polarity, it emerges that IF proteins form head-to-tail longitudinal contacts in contrast to crescentin and hence several inter-dimer contacts in IFs have no equivalents in crescentin filaments. Our work supports the idea that intermediate filament-like proteins achieve their shared polymerization and mechanical properties through a variety of filament architectures.
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Affiliation(s)
- Yue Liu
- Medical Research Council Laboratory of Molecular Biology, Structural Studies Division, Cambridge Biomedical Campus, CambridgeCB2 0QH, United Kingdom
| | - Fusinita van den Ent
- Medical Research Council Laboratory of Molecular Biology, Structural Studies Division, Cambridge Biomedical Campus, CambridgeCB2 0QH, United Kingdom
| | - Jan Löwe
- Medical Research Council Laboratory of Molecular Biology, Structural Studies Division, Cambridge Biomedical Campus, CambridgeCB2 0QH, United Kingdom
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4
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Oltrogge LM, Chen AW, Chaijarasphong T, Turnšek JB, Savage DF. α-Carboxysome Size Is Controlled by the Disordered Scaffold Protein CsoS2. Biochemistry 2024; 63:219-229. [PMID: 38085650 PMCID: PMC10795168 DOI: 10.1021/acs.biochem.3c00403] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 01/17/2024]
Abstract
Carboxysomes are protein microcompartments that function in the bacterial CO2 concentrating mechanism (CCM) to facilitate CO2 assimilation. To do so, carboxysomes assemble from thousands of constituent proteins into an icosahedral shell, which encapsulates the enzymes Rubisco and carbonic anhydrase to form structures typically > 100 nm and > 300 megadaltons. Although many of the protein interactions driving the assembly process have been determined, it remains unknown how size and composition are precisely controlled. Here, we show that the size of α-carboxysomes is controlled by the disordered scaffolding protein CsoS2. CsoS2 contains two classes of related peptide repeats that bind to the shell in a distinct fashion, and our data indicate that size is controlled by the relative number of these interactions. We propose an energetic and structural model wherein the two repeat classes bind at the junction of shell hexamers but differ in their preferences for the shell contact angles, and thus the local curvature. In total, this model suggests that a set of specific and repeated interactions between CsoS2 and shell proteins collectively achieve the large size and monodispersity of α-carboxysomes.
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Affiliation(s)
- Luke M. Oltrogge
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of California, Berkeley, California 94720, United States
| | - Allen W. Chen
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | | | - Julia B. Turnšek
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
| | - David F. Savage
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of California, Berkeley, California 94720, United States
- Innovative
Genomics Institute, University of California, Berkeley, California 94720, United States
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5
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de Aquino ILM, Barcelos MG, Machado TB, Serafim MSM, Abrahão JS. Surface fibrils on the particles of nucleocytoviruses: A review. Exp Biol Med (Maywood) 2023; 248:2045-2052. [PMID: 37955170 PMCID: PMC10800130 DOI: 10.1177/15353702231208410] [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] [Indexed: 11/14/2023] Open
Abstract
The capsid has a central role in viruses' life cycle. Although one of its major functions is to protect the viral genome, the capsid may be composed of elements that, at some point, promote interaction with host cells and trigger infection. Considering the scenario of multiple origins of viruses along the viral evolution, a substantial number of capsid shapes, sizes, and symmetries have been described. In this context, capsids of giant viruses (GV) that infect protists have drawn the attention of the scientific community, especially in the last 20 years, specifically for having bacterial-like dimensions with hundreds of different proteins and exclusive features. For instance, the surface fibrils present on the mimivirus capsid are one of the most intriguing features of the known virosphere. They are 150-nm-long structures attached to a 450-nm capsid, resulting in a particle with a hairy appearance. Surface fibrils have also been described in the capsids of other nucleocytoviruses, although they may differ substantially among them. In this mini review for non-experts, we compile the most important available information on surface fibrils of nucleocytoviruses, discussing their putative functions, composition, length, organization, and origins.
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Affiliation(s)
- Isabella Luiza Martins de Aquino
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Matheus Gomes Barcelos
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Talita Bastos Machado
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Mateus Sá Magalhães Serafim
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Jônatas Santos Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
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6
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Zhao C, Lu D, Zhao Q, Ren C, Zhang H, Zhai J, Gou J, Zhu S, Zhang Y, Gong X. Computational methods for in situ structural studies with cryogenic electron tomography. Front Cell Infect Microbiol 2023; 13:1135013. [PMID: 37868346 PMCID: PMC10586593 DOI: 10.3389/fcimb.2023.1135013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 08/29/2023] [Indexed: 10/24/2023] Open
Abstract
Cryo-electron tomography (cryo-ET) plays a critical role in imaging microorganisms in situ in terms of further analyzing the working mechanisms of viruses and drug exploitation, among others. A data processing workflow for cryo-ET has been developed to reconstruct three-dimensional density maps and further build atomic models from a tilt series of two-dimensional projections. Low signal-to-noise ratio (SNR) and missing wedge are two major factors that make the reconstruction procedure challenging. Because only few near-atomic resolution structures have been reconstructed in cryo-ET, there is still much room to design new approaches to improve universal reconstruction resolutions. This review summarizes classical mathematical models and deep learning methods among general reconstruction steps. Moreover, we also discuss current limitations and prospects. This review can provide software and methods for each step of the entire procedure from tilt series by cryo-ET to 3D atomic structures. In addition, it can also help more experts in various fields comprehend a recent research trend in cryo-ET. Furthermore, we hope that more researchers can collaborate in developing computational methods and mathematical models for high-resolution three-dimensional structures from cryo-ET datasets.
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Affiliation(s)
- Cuicui Zhao
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Da Lu
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Qian Zhao
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Chongjiao Ren
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Huangtao Zhang
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Jiaqi Zhai
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Jiaxin Gou
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Shilin Zhu
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Yaqi Zhang
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
| | - Xinqi Gong
- Mathematical Intelligence Application LAB, Institute for Mathematical Sciences, Renmin University of China, Beijing, China
- Beijing Academy of Intelligence, Beijing, China
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7
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Lata K, Charles S, Mangala Prasad V. Advances in computational approaches to structure determination of alphaviruses and flaviviruses using cryo-electron microscopy. J Struct Biol 2023; 215:107993. [PMID: 37414374 DOI: 10.1016/j.jsb.2023.107993] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/15/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Advancements in the field of cryo-electron microscopy (cryo-EM) have greatly contributed to our current understanding of virus structures and life cycles. In this review, we discuss the application of single particle cryo-electron microscopy (EM) for the structure elucidation of small enveloped icosahedral viruses, namely, alpha- and flaviviruses. We focus on technical advances in cryo-EM data collection, image processing, three-dimensional reconstruction, and refinement strategies for obtaining high-resolution structures of these viruses. Each of these developments enabled new insights into the alpha- and flavivirus architecture, leading to a better understanding of their biology, pathogenesis, immune response, immunogen design, and therapeutic development.
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Affiliation(s)
- Kiran Lata
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Sylvia Charles
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Vidya Mangala Prasad
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India; Center for Infectious Disease Research, Indian Institute of Science, Bengaluru, Karnataka 560012, India
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8
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Burton-Smith RN, Murata K. Cryo-electron Microscopy of Protein Cages. Methods Mol Biol 2023; 2671:173-210. [PMID: 37308646 DOI: 10.1007/978-1-0716-3222-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Protein cages are one of the most widely studied objects in the field of cryogenic electron microscopy-encompassing natural and synthetic constructs, from enzymes assisting protein folding such as chaperonin to virus capsids. Tremendous diversity of morphology and function is demonstrated by the structure and role of proteins, some of which are nearly ubiquitous, while others are present in few organisms. Protein cages are often highly symmetrical, which helps improve the resolution obtained by cryo-electron microscopy (cryo-EM). Cryo-EM is the study of vitrified samples using an electron probe to image the subject. A sample is rapidly frozen in a thin layer on a porous grid, attempting to keep the sample as close to a native state as possible. This grid is kept at cryogenic temperatures throughout imaging in an electron microscope. Once image acquisition is complete, a variety of software packages may be employed to carry out analysis and reconstruction of three-dimensional structures from the two-dimensional micrograph images. Cryo-EM can be used on samples that are too large or too heterogeneous to be amenable to other structural biology techniques like NMR or X-ray crystallography. In recent years, advances in both hardware and software have provided significant improvements to the results obtained using cryo-EM, recently demonstrating true atomic resolution from vitrified aqueous samples. Here, we review these advances in cryo-EM, especially in that of protein cages, and introduce several tips for situations we have experienced.
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Affiliation(s)
- Raymond N Burton-Smith
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute for Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences (NIPS), National Institute for Natural Sciences, Okazaki, Aichi, Japan
| | - Kazuyoshi Murata
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute for Natural Sciences, Okazaki, Aichi, Japan.
- National Institute for Physiological Sciences (NIPS), National Institute for Natural Sciences, Okazaki, Aichi, Japan.
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan.
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9
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Juhas M. The World of Microorganisms. BRIEF LESSONS IN MICROBIOLOGY 2023:1-16. [DOI: 10.1007/978-3-031-29544-7_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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10
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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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Affiliation(s)
- J. Bernard Heymann
- National Cryo-EM Program, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
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11
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A novel capsid protein network allows the characteristic internal membrane structure of Marseilleviridae giant viruses. Sci Rep 2022; 12:21428. [PMID: 36504202 PMCID: PMC9742146 DOI: 10.1038/s41598-022-24651-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
Marseilleviridae is a family of giant viruses, showing a characteristic internal membrane with extrusions underneath the icosahedral vertices. However, such large objects, with a maximum diameter of 250 nm are technically difficult to examine at sub-nanometre resolution by cryo-electron microscopy. Here, we tested the utility of 1 MV high-voltage cryo-EM (cryo-HVEM) for single particle structural analysis (SPA) of giant viruses using tokyovirus, a species of Marseilleviridae, and revealed the capsid structure at 7.7 Å resolution. The capsid enclosing the viral DNA consisted primarily of four layers: (1) major capsid proteins (MCPs) and penton proteins, (2) minor capsid proteins (mCPs), (3) scaffold protein components (ScPCs), and (4) internal membrane. The mCPs showed a novel capsid lattice consisting of eight protein components. ScPCs connecting the icosahedral vertices supported the formation of the membrane extrusions, and possibly act like tape measure proteins reported in other giant viruses. The density on top of the MCP trimer was suggested to include glycoproteins. This is the first attempt at cryo-HVEM SPA. We found the primary limitations to be the lack of automated data acquisition and software support for collection and processing and thus achievable resolution. However, the results pave the way for using cryo-HVEM for structural analysis of larger biological specimens.
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12
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Shao Q, Agarkova IV, Noel EA, Dunigan DD, Liu Y, Wang A, Guo M, Xie L, Zhao X, Rossmann MG, Van Etten JL, Klose T, Fang Q. Near-atomic, non-icosahedrally averaged structure of giant virus Paramecium bursaria chlorella virus 1. Nat Commun 2022; 13:6476. [PMID: 36309542 PMCID: PMC9617893 DOI: 10.1038/s41467-022-34218-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/18/2022] [Indexed: 12/25/2022] Open
Abstract
Giant viruses are a large group of viruses that infect many eukaryotes. Although components that do not obey the overall icosahedral symmetry of their capsids have been observed and found to play critical roles in the viral life cycles, identities and high-resolution structures of these components remain unknown. Here, by determining a near-atomic-resolution, five-fold averaged structure of Paramecium bursaria chlorella virus 1, we unexpectedly found the viral capsid possesses up to five major capsid protein variants and a penton protein variant. These variants create varied capsid microenvironments for the associations of fibers, a vesicle, and previously unresolved minor capsid proteins. Our structure reveals the identities and atomic models of the capsid components that do not obey the overall icosahedral symmetry and leads to a model for how these components are assembled and initiate capsid assembly, and this model might be applicable to many other giant viruses.
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Affiliation(s)
- Qianqian Shao
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Irina V Agarkova
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - Eric A Noel
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - David D Dunigan
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - Yunshu Liu
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Aohan Wang
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Mingcheng Guo
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Linlin Xie
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Xinyue Zhao
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - James L Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA.
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
| | - Qianglin Fang
- Scholl of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, 518107, China.
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
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13
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Speciale I, Notaro A, Abergel C, Lanzetta R, Lowary TL, Molinaro A, Tonetti M, Van Etten JL, De Castro C. The Astounding World of Glycans from Giant Viruses. Chem Rev 2022; 122:15717-15766. [PMID: 35820164 PMCID: PMC9614988 DOI: 10.1021/acs.chemrev.2c00118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Indexed: 12/12/2022]
Abstract
Viruses are a heterogeneous ensemble of entities, all sharing the need for a suitable host to replicate. They are extremely diverse, varying in morphology, size, nature, and complexity of their genomic content. Typically, viruses use host-encoded glycosyltransferases and glycosidases to add and remove sugar residues from their glycoproteins. Thus, the structure of the glycans on the viral proteins have, to date, typically been considered to mimick those of the host. However, the more recently discovered large and giant viruses differ from this paradigm. At least some of these viruses code for an (almost) autonomous glycosylation pathway. These viral genes include those that encode the production of activated sugars, glycosyltransferases, and other enzymes able to manipulate sugars at various levels. This review focuses on large and giant viruses that produce carbohydrate-processing enzymes. A brief description of those harboring these features at the genomic level will be discussed, followed by the achievements reached with regard to the elucidation of the glycan structures, the activity of the proteins able to manipulate sugars, and the organic synthesis of some of these virus-encoded glycans. During this progression, we will also comment on many of the challenging questions on this subject that remain to be addressed.
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Affiliation(s)
- Immacolata Speciale
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
| | - Anna Notaro
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
- Centre
National de la Recherche Scientifique, Information Génomique
& Structurale, Aix-Marseille University, Unité Mixte de Recherche
7256, IMM, IM2B, 13288 Marseille, Cedex 9, France
| | - Chantal Abergel
- Centre
National de la Recherche Scientifique, Information Génomique
& Structurale, Aix-Marseille University, Unité Mixte de Recherche
7256, IMM, IM2B, 13288 Marseille, Cedex 9, France
| | - Rosa Lanzetta
- Department
of Chemical Sciences, University of Napoli, Via Cintia 4, 80126 Napoli, Italy
| | - Todd L. Lowary
- Institute
of Biological Chemistry, Academia Sinica, Academia Road, Section 2, Nangang 11529, Taipei, Taiwan
| | - Antonio Molinaro
- Department
of Chemical Sciences, University of Napoli, Via Cintia 4, 80126 Napoli, Italy
| | - Michela Tonetti
- Department
of Experimental Medicine and Center of Excellence for Biomedical Research, University of Genova, 16132 Genova, Italy
| | - James L. Van Etten
- Nebraska
Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900, United States
- Department
of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, United States
| | - Cristina De Castro
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
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14
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Schulz F, Abergel C, Woyke T. Giant virus biology and diversity in the era of genome-resolved metagenomics. Nat Rev Microbiol 2022; 20:721-736. [PMID: 35902763 DOI: 10.1038/s41579-022-00754-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2022] [Indexed: 11/09/2022]
Abstract
The discovery of giant viruses, with capsids as large as some bacteria, megabase-range genomes and a variety of traits typically found only in cellular organisms, was one of the most remarkable breakthroughs in biology. Until recently, most of our knowledge of giant viruses came from ~100 species-level isolates for which genome sequences were available. However, these isolates were primarily derived from laboratory-based co-cultivation with few cultured protists and algae and, thus, did not reflect the true diversity of giant viruses. Although virus co-cultures enabled valuable insights into giant virus biology, many questions regarding their origin, evolution and ecological importance remain unanswered. With advances in sequencing technologies and bioinformatics, our understanding of giant viruses has drastically expanded. In this Review, we summarize our understanding of giant virus diversity and biology based on viral isolates as laboratory cultivation has enabled extensive insights into viral morphology and infection strategies. We then explore how cultivation-independent approaches have heightened our understanding of the coding potential and diversity of the Nucleocytoviricota. We discuss how metagenomics has revolutionized our perspective of giant viruses by revealing their distribution across our planet's biomes, where they impact the biology and ecology of a wide range of eukaryotic hosts and ultimately affect global nutrient cycles.
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Affiliation(s)
- Frederik Schulz
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Chantal Abergel
- Aix Marseille University, CNRS, IGS UMR7256, IMM FR3479, IM2B, IO, Marseille, France
| | - Tanja Woyke
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,University of California Merced, Merced, CA, USA.
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15
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Watanabe R, Song C, Kayama Y, Takemura M, Murata K. Particle Morphology of Medusavirus Inside and Outside the Cells Reveals a New Maturation Process of Giant Viruses. J Virol 2022; 96:e0185321. [PMID: 35297671 PMCID: PMC9006890 DOI: 10.1128/jvi.01853-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/14/2022] [Indexed: 01/01/2023] Open
Abstract
Medusavirus, a giant virus, is phylogenetically closer to eukaryotes than the other giant viruses and has been recently classified as an independent species. However, details of its morphology and maturation process in host cells remain unclear. Here, we investigated the particle morphology of medusavirus inside and outside infected cells using conventional transmission electron microscopy (C-TEM) and cryo-electron microscopy (cryo-EM). The C-TEM of amoebae infected with the medusavirus showed four types of particles, i.e., pseudo-DNA-empty (p-Empty), DNA-empty (Empty), semi-DNA-full (s-Full), and DNA-full (Full). Time-dependent changes in the four types of particles and their intracellular localization suggested a new maturation process for the medusavirus. Viral capsids and viral DNAs are produced independently in the cytoplasm and nucleus, respectively, and only the empty particles located near the host nucleus can incorporate the viral DNA into the capsid. Therefore, all four types of particles were found outside the cells. The cryo-EM of these particles showed that the intact virus structure, covered with three different types of spikes, was preserved among all particle types, although with minor size-related differences. The internal membrane exhibited a structural array similar to that of the capsid, interacted closely with the capsid, and displayed open membrane structures in the Empty and p-Empty particles. The results suggest that these open structures in the internal membrane are used for an exchange of scaffold proteins and viral DNA during the maturation process. This new model of the maturation process of medusavirus provides insight into the structural and behavioral diversity of giant viruses. IMPORTANCE Giant viruses exhibit diverse morphologies and maturation processes. In this study, medusavirus showed four types of particle morphologies, both inside and outside the infected cells, when propagated in amoeba culture. Time-course analysis and intracellular localization of the medusavirus in the infected cells suggested a new maturation process via the four types of particles. Like the previously reported pandoravirus, the viral DNA of medusavirus is replicated in the host's nucleus. However, viral capsids are produced independently in the host cytoplasm, and only empty capsids near the nucleus can take up viral DNA. As a result, many immature particles were released from the host cell along with the mature particles. The capsid structure is well conserved among the four types of particles, except for the open membrane structures in the empty particles, suggesting that they are used to exchange scaffold proteins for viral DNAs. These findings indicate that medusavirus has a unique maturation process.
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Affiliation(s)
- Ryoto Watanabe
- School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Chihong Song
- School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Yoko Kayama
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Terabase, Inc., Okazaki, Aichi, Japan
| | - Masaharu Takemura
- Institute of Arts and Sciences, Tokyo University of Science, Shinjuku, Tokyo, Japan
| | - Kazuyoshi Murata
- School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
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16
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Edwardson TGW, Levasseur MD, Tetter S, Steinauer A, Hori M, Hilvert D. Protein Cages: From Fundamentals to Advanced Applications. Chem Rev 2022; 122:9145-9197. [PMID: 35394752 DOI: 10.1021/acs.chemrev.1c00877] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.
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Affiliation(s)
| | | | - Stephan Tetter
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Angela Steinauer
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Mao Hori
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
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17
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Hyun J, Matsunami H, Kim TG, Wolf M. Assembly mechanism of the pleomorphic immature poxvirus scaffold. Nat Commun 2022; 13:1704. [PMID: 35361762 PMCID: PMC8971458 DOI: 10.1038/s41467-022-29305-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 03/04/2022] [Indexed: 11/26/2022] Open
Abstract
In Vaccinia virus (VACV), the prototype poxvirus, scaffold protein D13 forms a honeycomb-like lattice on the viral membrane that results in formation of the pleomorphic immature virion (IV). The structure of D13 is similar to those of major capsid proteins that readily form icosahedral capsids in nucleocytoplasmic large DNA viruses (NCLDVs). However, the detailed assembly mechanism of the nonicosahedral poxvirus scaffold has never been understood. Here we show the cryo-EM structures of the D13 trimer and scaffold intermediates produced in vitro. The structures reveal that the displacement of the short N-terminal α-helix is critical for initiation of D13 self-assembly. The continuous curvature of the IV is mediated by electrostatic interactions that induce torsion between trimers. The assembly mechanism explains the semiordered capsid-like arrangement of D13 that is distinct from icosahedral NCLDVs. Our structures explain how a single protein can self-assemble into different capsid morphologies and represent a local exception to the universal Caspar-Klug theory of quasi-equivalence. Immature poxviruses are characterized by nonicosahedral semiordered protein scaffolds critical for morphogenesis. Here, the authors use cryo-EM structures of Vaccinia virus D13 scaffold intermediates to explain their assembly mechanism.
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Affiliation(s)
- Jaekyung Hyun
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, 904-0495, Onna-son, Okinawa, Japan. .,Department of Convergence Medicine, School of Medicine, Pusan National University, 50612, Yangsan-si, Gyeongsangnamdo, Republic of Korea.
| | - Hideyuki Matsunami
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, 904-0495, Onna-son, Okinawa, Japan
| | - Tae Gyun Kim
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, 904-0495, Onna-son, Okinawa, Japan.,Center for Vaccine Commercialization, R&D Planning Team, Gyeongbuk Institute for Bio Industry, 36618, Andong-si, Gyeongsanbukdo, Republic of Korea
| | - Matthias Wolf
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, 904-0495, Onna-son, Okinawa, Japan. .,Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, 115, Taipei, Taiwan.
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18
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Retel C, Kowallik V, Becks L, Feulner PGD. Strong Selection and High Mutation Supply Characterize Experimental Chlorovirus Evolution. Virus Evol 2022; 8:veac003. [PMID: 35169490 PMCID: PMC8838748 DOI: 10.1093/ve/veac003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/14/2022] [Accepted: 01/25/2022] [Indexed: 11/24/2022] Open
Abstract
Characterizing how viruses evolve expands our understanding of the underlying fundamental processes, such as mutation, selection and drift. One group of viruses whose evolution has not yet been extensively studied is the Phycodnaviridae, a globally abundant family of aquatic large double-stranded (ds) DNA viruses. Here we studied the evolutionary change of Paramecium bursaria chlorella virus 1 during experimental coevolution with its algal host. We used pooled genome sequencing of six independently evolved populations to characterize genomic change over five time points. Across six experimental replicates involving either strong or weak demographic fluctuations, we found single nucleotide polymorphisms (SNPs) at sixty-seven sites. The occurrence of genetic variants was highly repeatable, with just two of the SNPs found in only a single experimental replicate. Three genes A122/123R, A140/145R and A540L showed an excess of variable sites, providing new information about potential targets of selection during Chlorella–Chlorovirus coevolution. Our data indicated that the studied populations were not mutation-limited and experienced strong positive selection. Our investigation highlighted relevant processes governing the evolution of aquatic large dsDNA viruses, which ultimately contributes to a better understanding of the functioning of natural aquatic ecosystems.
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Affiliation(s)
- Cas Retel
- Department of Fish Ecology and Evolution, Center for Ecology, Evolution and Bio-geochemistry, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, Kastanienbaum 6047, Switzerland
- Division of Aquatic Ecology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
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19
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Wang L, Liang K, Tang L, Gong H, Chen C, Cai C. Photonic and Magnetic Dual-Responsive Molecularly Imprinted Sensor for Highly Specific Recognition of Enterovirus 71. ACS Sens 2021; 6:3715-3723. [PMID: 34641672 DOI: 10.1021/acssensors.1c01487] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The specific identification and detection of a virus are the critical factors to identify and control an epidemic situation. In this study, a novel photonic-magnetic responsive virus-molecularly imprinted photochemical sensor was constructed for recognition of enterovirus 71. As designed, the double-bond-modified magnetic metal organic framework and 4-(4'-acryloyloxyazo) benzoic acid were used as a magnetic carrier and light-responsive functional monomer, respectively. The structure of the recognition site of the virus-molecularly imprinted nanospheres can be photo-switched between two different structures to achieve rapid release and specific binding to the target virus. Additionally, the introduction of a magnetic core enables a rapid separation and recycling of imprinted particles. The device achieves a performance with high-specificity recognition (imprinting factor = 5.1) and an ultrahigh sensitivity with a detection limit of 9.5 × 10-3 U/mL (3.9 fM). Moreover, it has good reproducibility and can be stored for as long as 6 months. Thus, the approach used in this work opens a new avenue for the construction of multiresponsive virus sensors.
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Affiliation(s)
- Lingyun Wang
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
- School of Materials Science and Engineering, Hunan Institute of Technology, Hengyang 421002, China
| | - Kunsong Liang
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
| | - Li Tang
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
| | - Hang Gong
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
| | - Chunyan Chen
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
| | - Changqun Cai
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
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20
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Functional genomic analyses reveal an open pan-genome for the chloroviruses and a potential for genetic innovation in new isolates. J Virol 2021; 96:e0136721. [PMID: 34669449 DOI: 10.1128/jvi.01367-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chloroviruses (family Phycodnaviridae) are large dsDNA viruses that infect unicellular green algae present in inland waters. These viruses have been isolated using three main chlorella-like green algal host cells, traditionally called NC64A, SAG and Pbi, revealing extensive genetic diversity. In this study, we performed a functional genomic analysis on 36 chloroviruses that infected the three different hosts. Phylogenetic reconstruction based on the DNA polymerase B family gene clustered the chloroviruses into three distinct clades. The viral pan-genome consists of 1,345 clusters of orthologous groups of genes (COGs), with 126 COGs conserved in all viruses. 368, 268 and 265 COGs are found exclusively in viruses that infect NC64A, SAG, and Pbi algal hosts, respectively. Two-thirds of the COGs have no known function, constituting the "dark pan-genome" of chloroviruses, and further studies focusing on these genes may identify important novelties. The proportion of functionally characterized COGs composing the pan- and the core-genome are similar, but those related to transcription and RNA processing, protein metabolism, and virion morphogenesis are at least 4-fold more represented in the core-genome. Bipartite network construction evidencing the COG-sharing among host-specific viruses identified 270 COGs shared by at least one virus from each of the different host groups. Finally, our results reveal an open pan-genome for chloroviruses and a well-established core-genome, indicating that the isolation of new chloroviruses can be a valuable source of genetic discovery. Importance Chloroviruses are large dsDNA viruses that infect unicellular green algae distributed worldwide in freshwater environments. They comprise a genetically diverse group of viruses; however, a comprehensive investigation of the genomic evolution of these viruses is still missing. Here we performed a functional pan-genome analysis comprising 36 chloroviruses associated with three different algal hosts in the family Chlorellaceae, referred to as zoochlorellae because of their endosymbiotic lifestyle. We identified a set of 126 highly conserved genes, most of which are related to essential functions in the viral replicative cycle. Several genes are unique to distinct isolates, resulting in an open pan-genome for chloroviruses. This profile is associated with generalist organisms, and new insights into the evolution and ecology of chloroviruses are presented. Ultimately, our results highlight the potential for genetic diversity in new isolates.
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21
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Burton-Smith RN, Murata K. Cryo-Electron Microscopy of the Giant Viruses. Microscopy (Oxf) 2021; 70:477-486. [PMID: 34490462 DOI: 10.1093/jmicro/dfab036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/12/2022] Open
Abstract
High resolution study of the giant viruses presents one of the latest challenges in cryo-electron microscopy of viruses. Too small for light microscopy, but too large for easy study at high resolution by electron microscopy, they range in size from ~0.2-2 μm, from high symmetry icosahedral viruses such as Paramecium burseria Chlorella virus 1 to asymmetric forms like Tupanvirus or Pithovirus. To attain high resolution, two strategies exist to study these large viruses by cryo-EM: firstly, increasing the acceleration voltage of the electron microscope to improve sample penetration and overcome the limitations imposed by electro-optical physics at lower voltages, and secondly the method of "block-based reconstruction" pioneered by Michael G. Rossmann and his collaborators, which resolves the latter limitation through an elegant leveraging of high symmetry, but cannot overcome sample penetration limitations. In addition, more recent advances in both computational capacity and image processing also yield assistance in studying the giant viruses. Especially, the inclusion of Ewald sphere correction can provide large improvements in attainable resolutions for 300 kV electron microscopes. Despite this, the study of giant viruses remains a significant challenge.
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Affiliation(s)
- Raymond N Burton-Smith
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Kazuyoshi Murata
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
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22
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Navikas V, Leitao SM, Grussmayer KS, Descloux A, Drake B, Yserentant K, Werther P, Herten DP, Wombacher R, Radenovic A, Fantner GE. Correlative 3D microscopy of single cells using super-resolution and scanning ion-conductance microscopy. Nat Commun 2021; 12:4565. [PMID: 34315910 PMCID: PMC8316521 DOI: 10.1038/s41467-021-24901-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 07/14/2021] [Indexed: 02/07/2023] Open
Abstract
High-resolution live-cell imaging is necessary to study complex biological phenomena. Modern fluorescence microscopy methods are increasingly combined with complementary, label-free techniques to put the fluorescence information into the cellular context. The most common high-resolution imaging approaches used in combination with fluorescence imaging are electron microscopy and atomic-force microscopy (AFM), originally developed for solid-state material characterization. AFM routinely resolves atomic steps, however on soft biological samples, the forces between the tip and the sample deform the fragile membrane, thereby distorting the otherwise high axial resolution of the technique. Here we present scanning ion-conductance microscopy (SICM) as an alternative approach for topographical imaging of soft biological samples, preserving high axial resolution on cells. SICM is complemented with live-cell compatible super-resolution optical fluctuation imaging (SOFI). To demonstrate the capabilities of our method we show correlative 3D cellular maps with SOFI implementation in both 2D and 3D with self-blinking dyes for two-color high-order SOFI imaging. Finally, we employ correlative SICM/SOFI microscopy for visualizing actin dynamics in live COS-7 cells with subdiffraction-resolution.
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Affiliation(s)
- Vytautas Navikas
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, Swiss Federal InstSIitute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Samuel M Leitao
- Laboratory for Bio- and Nano-Instrumentation, Institute of Bioengineering, School of Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Kristin S Grussmayer
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, Swiss Federal InstSIitute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Grussmayer Lab, Department of Bionanoscience, Faculty of Applied Science and Kavli Institute for Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Adrien Descloux
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, Swiss Federal InstSIitute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Barney Drake
- Laboratory for Bio- and Nano-Instrumentation, Institute of Bioengineering, School of Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Klaus Yserentant
- College of Medical and Dental Sciences, Medical School & School of Chemistry, University of Birmingham, Birmingham, United Kingdom
| | - Philipp Werther
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Dirk-Peter Herten
- College of Medical and Dental Sciences, Medical School & School of Chemistry, University of Birmingham, Birmingham, United Kingdom
| | - Richard Wombacher
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Aleksandra Radenovic
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, Swiss Federal InstSIitute of Technology Lausanne (EPFL), Lausanne, Switzerland.
| | - Georg E Fantner
- Laboratory for Bio- and Nano-Instrumentation, Institute of Bioengineering, School of Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
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23
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Dos Santos Oliveira J, Lavell AA, Essus VA, Souza G, Nunes GHP, Benício E, Guimarães AJ, Parent KN, Cortines JR. Structure and physiology of giant DNA viruses. Curr Opin Virol 2021; 49:58-67. [PMID: 34051592 DOI: 10.1016/j.coviro.2021.04.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/27/2021] [Accepted: 04/29/2021] [Indexed: 02/02/2023]
Abstract
Although giant viruses have existed for millennia and possibly exerted great evolutionary influence in their environment. Their presence has only been noticed by virologists recently with the discovery of Acanthamoeba polyphaga mimivirus in 2003. Its virion with a diameter of 500 nm and its genome larger than 1 Mpb shattered preconceived standards of what a virus is and triggered world-wide prospection studies. Thanks to these investigations many giant virus families were discovered, each with its own morphological peculiarities and genomes ranging from 0.4 to 2.5 Mpb that possibly encode more than 400 viral proteins. This review aims to present the morphological diversity, the different aspects observed in host-virus interactions during replication, as well as the techniques utilized during their investigation.
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Affiliation(s)
- Juliana Dos Santos Oliveira
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil
| | - Anastasiya A Lavell
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Victor Alejandro Essus
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil
| | - Getúlio Souza
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil
| | - Gabriel Henrique Pereira Nunes
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil
| | - Eduarda Benício
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil
| | - Allan Jefferson Guimarães
- Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói, Brazil
| | - Kristin N Parent
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
| | - Juliana R Cortines
- Departamento de Virologia, Instituto de Mcirobiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21590-902, Rio de Janeiro, Brazil.
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Krupovic M, Yutin N, Koonin E. Evolution of a major virion protein of the giant pandoraviruses from an inactivated bacterial glycoside hydrolase. Virus Evol 2020; 6:veaa059. [PMID: 33686356 DOI: 10.1093/ve/veaa059] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The diverse viruses in the phylum Nucleocytoviricota (also known as NLCDVs, Nucleo-cytoplasmic Large DNA Viruses) typically possess large icosahedral virions. However, in several families of Nucleocytoviricota, the icosahedral capsid was replaced by irregular particle shapes, most notably, the amphora-like virions of pandoraviruses and pithoviruses, the largest known virus particles in the entire virosphere. Pandoraviruses appear to be the most highly derived viruses in this phylum because their evolution involved not only the change in the virion shape, but also, the actual loss of the gene encoding double-jelly roll major capsid protein (DJR MCP), the main building block of icosahedral capsids in this virus assemblage. Instead, pandoravirus virions are built of unrelated abundant proteins. Here we show that the second most abundant virion protein of pandoraviruses, major virion protein 2 (MVP2), evolved from an inactivated derivative of a bacterial glycoside hydrolase of the GH16 family. The ancestral form of MVP2 was apparently acquired early in the evolution of the Nucleocytoviricota, to become a minor virion protein. After a duplication in the common ancestor of pandoraviruses and molliviruses, one of the paralogs displaces DJR MCP in pandoraviruses, conceivably, opening the way for a major increase in the size of the virion and the genome. Exaptation of a carbohydrate-binding protein for the function of the MVP is a general trend in virus evolution and might underlie the transformation of the virion shape in other groups of the Nucleocytoviricota as well.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Archaeal Virology Unit, Institut Pasteur, Paris 75015, France
| | - Natalya Yutin
- National Library of Medicine, National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894, USA
| | - Eugene Koonin
- National Library of Medicine, National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894, USA
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Structure-Based Deep Mining Reveals First-Time Annotations for 46 Percent of the Dark Annotation Space of the 9,671-Member Superproteome of the Nucleocytoplasmic Large DNA Viruses. J Virol 2020; 94:JVI.00854-20. [PMID: 32999026 DOI: 10.1128/jvi.00854-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/16/2020] [Indexed: 12/20/2022] Open
Abstract
We conducted an exhaustive search for three-dimensional structural homologs to the proteins of 20 key phylogenetically distinct nucleocytoplasmic DNA viruses (NCLDV). Structural matches covered 429 known protein domain superfamilies, with the most highly represented being ankyrin repeat, P-loop NTPase, F-box, protein kinase, and membrane occupation and recognition nexus (MORN) repeat. Domain superfamily diversity correlated with genome size, but a diversity of around 200 superfamilies appeared to correlate with an abrupt switch to paralogization. Extensive structural homology was found across the range of eukaryotic RNA polymerase II subunits and their associated basal transcription factors, with the coordinated gain and loss of clusters of subunits on a virus-by-virus basis. The total number of predicted endonucleases across the 20 NCLDV was nearly quadrupled from 36 to 132, covering much of the structural and functional diversity of endonucleases throughout the biosphere in DNA restriction, repair, and homing. Unexpected findings included capsid protein-transcription factor chimeras; endonuclease chimeras; enzymes for detoxification; antimicrobial peptides and toxin-antitoxin systems associated with symbiosis, immunity, and addiction; and novel proteins for membrane abscission and protein turnover.IMPORTANCE We extended the known annotation space for the NCLDV by 46%, revealing high-probability structural matches for fully 45% of the 9,671 query proteins and confirming up to 98% of existing annotations per virus. The most prevalent protein families included ankyrin repeat- and MORN repeat-containing proteins, many of which included an F-box, suggesting extensive host cell modulation among the NCLDV. Regression suggested a minimum requirement for around 36 protein structural superfamilies for a viable NCLDV, and beyond around 200 superfamilies, genome expansion by the acquisition of new functions was abruptly replaced by paralogization. We found homologs to herpesvirus surface glycoprotein gB in cytoplasmic viruses. This study provided the first prediction of an endonuclease in 10 of the 20 viruses examined; the first report in a virus of a phenolic acid decarboxylase, proteasomal subunit, or cysteine knot (defensin) protein; and the first report of a prokaryotic-type ribosomal protein in a eukaryotic virus.
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Xian Y, Avila R, Pant A, Yang Z, Xiao C. The Role of Tape Measure Protein in Nucleocytoplasmic Large DNA Virus Capsid Assembly. Viral Immunol 2020; 34:41-48. [PMID: 33074779 DOI: 10.1089/vim.2020.0038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nucleocytoplasmic large DNA viruses (NCLDVs) are a group of large viruses that infect a wide range of hosts, from animals to protists. These viruses are grouped together in NCLDV based on genomic sequence analyses. They share a set of essential genes for virion morphogenesis and replication. Most NCLDVs generally have large physical sizes while their morphologies vary in different families, such as icosahedral, brick, or oval shape, raising the question of the possible regulatory factor on their morphogenesis. The capsids of icosahedral NCLDVs are assembled from small building blocks, named capsomers, which are the trimeric form of the major capsid proteins. Note that the capsids of immature poxvirus are spherical even though they are assembled from capsomers that share high structural conservation with those icosahedral NCLDVs. The recently published high resolution structure of NCLDVs, Paramecium bursaria Chlorella virus 1 and African swine fever virus, described the intensive network of minor capsid proteins that are located underneath the capsomers. Among these minor proteins is the elongated tape measure protein (TmP) that spans from one icosahedral fivefold vertex to another. In this study, we focused on the critical roles that TmP plays in the assembly of icosahedral NCLDV capsids, answering a question raised in a previously proposed spiral mechanism. Interestingly, basic local alignment search on the TmPs showed no significant hits in poxviruses, which might be the factor that differentiates poxviruses and icosahedral NCLDVs in their morphogenesis.
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Affiliation(s)
- Yuejiao Xian
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas, USA
| | - Ricardo Avila
- Bioinformatics Program, University of Texas at El Paso, El Paso, Texas, USA
| | - Anil Pant
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Zhilong Yang
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas, USA
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Dedeo CL, Teschke CM, Alexandrescu AT. Keeping It Together: Structures, Functions, and Applications of Viral Decoration Proteins. Viruses 2020; 12:v12101163. [PMID: 33066635 PMCID: PMC7602432 DOI: 10.3390/v12101163] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [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: 10/09/2020] [Accepted: 10/11/2020] [Indexed: 12/14/2022] Open
Abstract
Decoration proteins are viral accessory gene products that adorn the surfaces of some phages and viral capsids, particularly tailed dsDNA phages. These proteins often play a "cementing" role, reinforcing capsids against accumulating internal pressure due to genome packaging, or environmental insults such as extremes of temperature or pH. Many decoration proteins serve alternative functions, including target cell recognition, participation in viral assembly, capsid size determination, or modulation of host gene expression. Examples that currently have structures characterized to high-resolution fall into five main folding motifs: β-tulip, β-tadpole, OB-fold, Ig-like, and a rare knotted α-helical fold. Most of these folding motifs have structure homologs in virus and target cell proteins, suggesting horizontal gene transfer was important in their evolution. Oligomerization states of decoration proteins range from monomers to trimers, with the latter most typical. Decoration proteins bind to a variety of loci on capsids that include icosahedral 2-, 3-, and 5-fold symmetry axes, as well as pseudo-symmetry sites. These binding sites often correspond to "weak points" on the capsid lattice. Because of their unique abilities to bind virus surfaces noncovalently, decoration proteins are increasingly exploited for technology, with uses including phage display, viral functionalization, vaccination, and improved nanoparticle design for imaging and drug delivery. These applications will undoubtedly benefit from further advances in our understanding of these versatile augmenters of viral functions.
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Ravantti JJ, Martinez-Castillo A, Abrescia NG. Superimposition of Viral Protein Structures: A Means to Decipher the Phylogenies of Viruses. Viruses 2020; 12:v12101146. [PMID: 33050291 PMCID: PMC7600307 DOI: 10.3390/v12101146] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/02/2020] [Accepted: 10/02/2020] [Indexed: 02/07/2023] Open
Abstract
Superimposition of protein structures is key in unravelling structural homology across proteins whose sequence similarity is lost. Structural comparison provides insights into protein function and evolution. Here, we review some of the original findings and thoughts that have led to the current established structure-based phylogeny of viruses: starting from the original observation that the major capsid proteins of plant and animal viruses possess similar folds, to the idea that each virus has an innate “self”. This latter idea fueled the conceptualization of the PRD1-adenovirus lineage whose members possess a major capsid protein (innate “self”) with a double jelly roll fold. Based on this approach, long-range viral evolutionary relationships can be detected allowing the virosphere to be classified in four structure-based lineages. However, this process is not without its challenges or limitations. As an example of these hurdles, we finally touch on the difficulty of establishing structural “self” traits for enveloped viruses showcasing the coronaviruses but also the power of structure-based analysis in the understanding of emerging viruses
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Affiliation(s)
- Janne J. Ravantti
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland;
| | - Ane Martinez-Castillo
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain;
| | - Nicola G.A. Abrescia
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain;
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-946572502
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Xian Y, Xiao C. Current capsid assembly models of icosahedral nucleocytoviricota viruses. Adv Virus Res 2020; 108:275-313. [PMID: 33837719 PMCID: PMC8328511 DOI: 10.1016/bs.aivir.2020.09.006] [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] [Indexed: 10/23/2022]
Abstract
Nucleocytoviricota viruses (NCVs) belong to a newly established phylum originally grouped as Nucleocytoplasmic large DNA viruses. NCVs are unique because of their large and complicated genomes that contain cellular genes with homologs from all kingdoms of life, raising intensive debates on their evolutional origins. Many NCVs pack their genomes inside massive icosahedral capsids assembled from thousands of proteins. Studying the assembly mechanism of such capsids has been challenging until breakthroughs from structural studies. Subsequently, several models of the capsid assembly were proposed, which provided some interesting insights on this elaborate process. In this review, we discuss three of the most recent assembly models as well as supporting experimental observations. Furthermore, we propose a new model that combines research developments from multiple sources. Investigation of the assembly process of these vast NCV capsids will facilitate future deciphering of the molecular mechanisms driving the formation of similar supramolecular complexes.
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Affiliation(s)
- Yuejiao Xian
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, Texas, United States
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, Texas, United States.
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Solid-State NMR for Studying the Structure and Dynamics of Viral Assemblies. Viruses 2020; 12:v12101069. [PMID: 32987909 PMCID: PMC7599928 DOI: 10.3390/v12101069] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/21/2020] [Accepted: 09/21/2020] [Indexed: 12/14/2022] Open
Abstract
Structural virology reveals the architecture underlying infection. While notably electron microscopy images have provided an atomic view on viruses which profoundly changed our understanding of these assemblies incapable of independent life, spectroscopic techniques like NMR enter the field with their strengths in detailed conformational analysis and investigation of dynamic behavior. Typically, the large assemblies represented by viral particles fall in the regime of biological high-resolution solid-state NMR, able to follow with high sensitivity the path of the viral proteins through their interactions and maturation steps during the viral life cycle. We here trace the way from first solid-state NMR investigations to the state-of-the-art approaches currently developing, including applications focused on HIV, HBV, HCV and influenza, and an outlook to the possibilities opening in the coming years.
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Gann ER, Xian Y, Abraham PE, Hettich RL, Reynolds TB, Xiao C, Wilhelm SW. Structural and Proteomic Studies of the Aureococcus anophagefferens Virus Demonstrate a Global Distribution of Virus-Encoded Carbohydrate Processing. Front Microbiol 2020; 11:2047. [PMID: 33013751 PMCID: PMC7507832 DOI: 10.3389/fmicb.2020.02047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/04/2020] [Indexed: 01/28/2023] Open
Abstract
Viruses modulate the function(s) of environmentally relevant microbial populations, yet considerations of the metabolic capabilities of individual virus particles themselves are rare. We used shotgun proteomics to quantitatively identify 43 virus-encoded proteins packaged within purified Aureococcus anophagefferens Virus (AaV) particles, normalizing data to the per-virion level using a 9.5-Å-resolution molecular reconstruction of the 1900-Å (AaV) particle that we generated with cryogenic electron microscopy. This packaged proteome was used to determine similarities and differences between members of different giant virus families. We noted that proteins involved in sugar degradation and binding (e.g., carbohydrate lyases) were unique to AaV among characterized giant viruses. To determine the extent to which this virally encoded metabolic capability was ecologically relevant, we examined the TARA Oceans dataset and identified genes and transcripts of viral origin. Our analyses demonstrated that putative giant virus carbohydrate lyases represented up to 17% of the marine pool for this function. In total, our observations suggest that the AaV particle has potential prepackaged metabolic capabilities and that these may be found in other giant viruses that are widespread and abundant in global oceans.
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Affiliation(s)
- Eric R. Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Yuejiao Xian
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, TX, United States
| | - Paul E. Abraham
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Robert L. Hettich
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Todd B. Reynolds
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, TX, United States
| | - Steven W. Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
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The structures of two archaeal type IV pili illuminate evolutionary relationships. Nat Commun 2020; 11:3424. [PMID: 32647180 PMCID: PMC7347861 DOI: 10.1038/s41467-020-17268-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/22/2020] [Indexed: 12/14/2022] Open
Abstract
We have determined the cryo-electron microscopic (cryo-EM) structures of two archaeal type IV pili (T4P), from Pyrobaculum arsenaticum and Saccharolobus solfataricus, at 3.8 Å and 3.4 Å resolution, respectively. This triples the number of high resolution archaeal T4P structures, and allows us to pinpoint the evolutionary divergence of bacterial T4P, archaeal T4P and archaeal flagellar filaments. We suggest that extensive glycosylation previously observed in T4P of Sulfolobus islandicus is a response to an acidic environment, as at even higher temperatures in a neutral environment much less glycosylation is present for Pyrobaculum than for Sulfolobus and Saccharolobus pili. Consequently, the Pyrobaculum filaments do not display the remarkable stability of the Sulfolobus filaments in vitro. We identify the Saccharolobus and Pyrobaculum T4P as host receptors recognized by rudivirus SSRV1 and tristromavirus PFV2, respectively. Our results illuminate the evolutionary relationships among bacterial and archaeal T4P filaments and provide insights into archaeal virus-host interactions. Archaeal type IV pili (T4P) mediate adhesion to surfaces and are receptors for hyperthermophilic archaeal viruses. Here, the authors present the cryo-EM structures of two archaeal T4P from Pyrobaculum arsenaticum and Saccharolobus solfataricus and discuss evolutionary relationships between bacterial T4P, archaeal T4P and archaeal flagellar filaments.
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Sun C, Gonzalez B, Vago FS, Jiang W. High resolution single particle Cryo-EM refinement using JSPR. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 160:37-42. [PMID: 32622834 DOI: 10.1016/j.pbiomolbio.2020.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 05/06/2020] [Accepted: 05/09/2020] [Indexed: 11/30/2022]
Abstract
JSPR is a single particle cryo-EM image processing and 3D reconstruction software developed in the Jiang laboratory at Purdue University. It began as a few refinement scripts for symmetric and asymmetric reconstructions of icosahedral viruses, but has grown into a comprehensive suite of tools for building ab initio reconstructions, high resolution refinements of viruses, protein complexes of arbitrary symmetries including helical tubes/filaments, and image file handling utilities. In this review, we will present examples achieved using JSPR and demonstrate recently implemented features of JSPR such as multi-aberration "alignments" and automatic optimization of masking for the assessment of map resolution using "true" FSC.
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Affiliation(s)
- Chen Sun
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, 47906, USA
| | - Brenda Gonzalez
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, 47906, USA
| | - Frank S Vago
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, 47906, USA
| | - Wen Jiang
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, 47906, USA.
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Koonin EV, Dolja VV, Krupovic M, Varsani A, Wolf YI, Yutin N, Zerbini FM, Kuhn JH. Global Organization and Proposed Megataxonomy of the Virus World. Microbiol Mol Biol Rev 2020; 84:e00061-19. [PMID: 32132243 PMCID: PMC7062200 DOI: 10.1128/mmbr.00061-19] [Citation(s) in RCA: 324] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Viruses and mobile genetic elements are molecular parasites or symbionts that coevolve with nearly all forms of cellular life. The route of virus replication and protein expression is determined by the viral genome type. Comparison of these routes led to the classification of viruses into seven "Baltimore classes" (BCs) that define the major features of virus reproduction. However, recent phylogenomic studies identified multiple evolutionary connections among viruses within each of the BCs as well as between different classes. Due to the modular organization of virus genomes, these relationships defy simple representation as lines of descent but rather form complex networks. Phylogenetic analyses of virus hallmark genes combined with analyses of gene-sharing networks show that replication modules of five BCs (three classes of RNA viruses and two classes of reverse-transcribing viruses) evolved from a common ancestor that encoded an RNA-directed RNA polymerase or a reverse transcriptase. Bona fide viruses evolved from this ancestor on multiple, independent occasions via the recruitment of distinct cellular proteins as capsid subunits and other structural components of virions. The single-stranded DNA (ssDNA) viruses are a polyphyletic class, with different groups evolving by recombination between rolling-circle-replicating plasmids, which contributed the replication protein, and positive-sense RNA viruses, which contributed the capsid protein. The double-stranded DNA (dsDNA) viruses are distributed among several large monophyletic groups and arose via the combination of distinct structural modules with equally diverse replication modules. Phylogenomic analyses reveal the finer structure of evolutionary connections among RNA viruses and reverse-transcribing viruses, ssDNA viruses, and large subsets of dsDNA viruses. Taken together, these analyses allow us to outline the global organization of the virus world. Here, we describe the key aspects of this organization and propose a comprehensive hierarchical taxonomy of viruses.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Valerian V Dolja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Mart Krupovic
- Institut Pasteur, Archaeal Virology Unit, Department of Microbiology, Paris, France
| | - Arvind Varsani
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Structural Biology Research Unit, Department of Clinical Laboratory Sciences, University of Cape Town, Observatory, Cape Town, South Africa
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - F Murilo Zerbini
- Departamento de Fitopatologia/Bioagro, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, USA
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Capsid Structure of a Marine Algal Virus of the Order Picornavirales. J Virol 2020; 94:JVI.01855-19. [PMID: 32024776 DOI: 10.1128/jvi.01855-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/29/2020] [Indexed: 12/17/2022] Open
Abstract
The order Picornavirales includes viruses that infect different kinds of eukaryotes and that share similar properties. The capsid proteins (CPs) of viruses in the order that infect unicellular organisms, such as algae, presumably possess certain characteristics that have changed little over the course of evolution, and thus these viruses may resemble the Picornavirales ancestor in some respects. Herein, we present the capsid structure of Chaetoceros tenuissimus RNA virus type II (CtenRNAV-II) determined using cryo-electron microscopy at a resolution of 3.1 Å, the first alga virus belonging to the family Marnaviridae of the order Picornavirales A structural comparison to related invertebrate and vertebrate viruses revealed a unique surface loop of the major CP VP1 that had not been observed previously, and further, revealed that another VP1 loop obscures the so-called canyon, which is a host-receptor binding site for many of the mammalian Picornavirales viruses. VP2 has an N-terminal tail, which has previously been reported as a primordial feature of Picornavirales viruses. The above-mentioned and other critical structural features provide new insights on three long-standing theories about Picornavirales: (i) the canyon hypothesis, (ii) the primordial VP2 domain swap, and (iii) the hypothesis that alga Picornavirales viruses could share characteristics with the Picornavirales ancestor.IMPORTANCE Identifying the acquired structural traits in virus capsids is important for elucidating what functions are essential among viruses that infect different hosts. The Picornavirales viruses infect a broad spectrum of hosts, ranging from unicellular algae to insects and mammals and include many human pathogens. Those viruses that infect unicellular protists, such as algae, are likely to have undergone fewer structural changes during the course of evolution compared to those viruses that infect multicellular eukaryotes and thus still share some characteristics with the Picornavirales ancestor. This article describes the first atomic capsid structure of an alga Marnavirus, CtenRNAV-II. A comparison to capsid structures of the related invertebrate and vertebrate viruses identified a number of structural traits that have been functionally acquired or lost during the course of evolution. These observations provide new insights on past theories on the viability and evolution of Picornavirales viruses.
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Gann ER, Hughes BJ, Reynolds TB, Wilhelm SW. Internal Nitrogen Pools Shape the Infection of Aureococcus anophagefferens CCMP 1984 by a Giant Virus. Front Microbiol 2020; 11:492. [PMID: 32269558 PMCID: PMC7109300 DOI: 10.3389/fmicb.2020.00492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/06/2020] [Indexed: 11/13/2022] Open
Abstract
The pelagophyte Aureococcus anophagefferens blooms annually in shallow bays around the world, where it is hypothesized to outcompete other phytoplankton in part by using alternative nitrogen sources. The high proportion of natural populations that are infected during the late stages of the bloom suggest viruses cause bloom collapse. We hypothesized that the Aureococcus anophagefferens Virus (AaV) infection cycle would be negatively influenced in cultures acclimated to decreasing external nitrogen conditions, but that the real-time external nitrogen concentration would not influence the infection cycle. Cultures acclimated in NO 3 - concentrations (0.0147 mM; N:P = 0.1225) that showed reduced end point cell abundances, forward scatter (a proxy for size) and red fluorescence (a proxy for chlorophyll a), also produced fewer viruses per cell at a slower rate. Decreasing the external concentration of nitrogen post infection did not alter burst size or time to lysis. These data suggest that the nitrogen used for new viral progeny is present within host cells at the time of infection. Flow cytometric data of an infection cycle showed a reduction in red fluorescence around twelve hours post infection, consistent with degradation of nitrogen-rich chloroplasts during the infection cycle. Using cell and virus quota estimates, we determined that A. anophagefferens cells had sufficient nitrogen and carbon for the lower ranges of burst sizes determined but did not contain enough phosphorous. Consistent with this observation, expression of nitrate and sugar transporters did not increase in the publicly available transcriptome data of the infection cycle, while several phosphorus transporters were. Our data demonstrate that dynamics of viruses infecting Aureococcus over the course of a bloom is dictated by the host cell state upon infection, which is set a priori by external nutrient supplies.
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Affiliation(s)
- Eric R Gann
- Department of Microbiology, College of Arts and Sciences, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Brennan J Hughes
- Department of Microbiology, College of Arts and Sciences, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Todd B Reynolds
- Department of Microbiology, College of Arts and Sciences, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Steven W Wilhelm
- Department of Microbiology, College of Arts and Sciences, The University of Tennessee, Knoxville, Knoxville, TN, United States
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Icosadeltahedral Geometry of Geodesic Domes, Fullerenes and Viruses: A Tutorial on the T-Number. Symmetry (Basel) 2020. [DOI: 10.3390/sym12040556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Caspar–Klug (CK) classification of viruses is discussed by parallel examination of geometry of icosahedral geodesic domes, fullerenes, and viruses. The underlying symmetry of all structures is explained and thoroughly visually represented. Euler’s theorem on polyhedra is used to calculate the number of vertices, edges, and faces in domes, number of atoms, bonds, and pentagonal and hexagonal rings in fullerenes, and number of proteins and protein–protein contacts in viruses. The T-number, the characteristic for the CK classification, is defined and discussed. The superposition of fullerene and dome designs is used to obtain a representation of a CK virus with all the proteins indicated. Some modifications of the CK classifications are sketched, including elongation of the CK blueprint, fusion of two CK blueprints, dodecahedral view of the CK shapes, and generalized CK designs without a clearly visible geometry of the icosahedron. These are compared to cases of existing viruses.
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Xian Y, Xiao C. The Structure of ASFV Advances the Fight against the Disease. Trends Biochem Sci 2020; 45:276-278. [PMID: 32169172 DOI: 10.1016/j.tibs.2020.01.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 11/25/2022]
Abstract
African swine fever virus (ASFV) is the causative pathogen of the recent African swine fever epidemic, with devastating impacts on economy. A recent study by Wang et al. reveals the multilayer structural details of ASFV at near-atomic resolution, which provides interesting insights about giant virus assembly and paves the way for vaccine development.
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Affiliation(s)
- Yuejiao Xian
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, TX 79968, USA
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, TX 79968, USA.
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40
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Luque D, Castón JR. Cryo-electron microscopy for the study of virus assembly. Nat Chem Biol 2020; 16:231-239. [PMID: 32080621 DOI: 10.1038/s41589-020-0477-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 01/13/2020] [Indexed: 12/11/2022]
Abstract
Although viruses are extremely diverse in shape and size, evolution has led to a limited number of viral classes or lineages, which is probably linked to the assembly constraints of a viable capsid. Viral assembly mechanisms are restricted to two general pathways, (i) co-assembly of capsid proteins and single-stranded nucleic acids and (ii) a sequential mechanism in which scaffolding-mediated capsid precursor assembly is followed by genome packaging. Cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET), which are revolutionizing structural biology, are central to determining the high-resolution structures of many viral assemblies as well as those of assembly intermediates. This wealth of cryo-EM data has also led to the development and redesign of virus-based platforms for biomedical and biotechnological applications. In this Review, we will discuss recent viral assembly analyses by cryo-EM and cryo-ET showing how natural assembly mechanisms are used to encapsulate heterologous cargos including chemicals, enzymes, and/or nucleic acids for a variety of nanotechnological applications.
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Affiliation(s)
- Daniel Luque
- Centro Nacional de Microbiología/ISCIII, Majadahonda, Madrid, Spain
| | - José R Castón
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus Cantoblanco, Madrid, Spain.
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41
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Andrés G, Charro D, Matamoros T, Dillard RS, Abrescia NGA. The cryo-EM structure of African swine fever virus unravels a unique architecture comprising two icosahedral protein capsids and two lipoprotein membranes. J Biol Chem 2020; 295:1-12. [PMID: 31649031 PMCID: PMC6952596 DOI: 10.1074/jbc.ac119.011196] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/22/2019] [Indexed: 11/06/2022] Open
Abstract
African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) that causes a devastating swine disease currently present in many countries of Africa, Europe, and Asia. Despite intense research efforts, relevant gaps in the architecture of the infectious virus particle remain. Here, we used single-particle cryo-EM to analyze the three-dimensional structure of the mature ASFV particle. Our results show that the ASFV virion, with a radial diameter of ∼2,080 Å, encloses a genome-containing nucleoid surrounded by two distinct icosahedral protein capsids and two lipoprotein membranes. The outer capsid forms a hexagonal lattice (triangulation number T = 277) composed of 8,280 copies of the double jelly-roll major capsid protein (MCP) p72, arranged in trimers displaying a pseudo-hexameric morphology, and of 60 copies of a penton protein at the vertices. The inner protein layer, organized as a T = 19 capsid, confines the core shell, and it is composed of the mature products derived from the ASFV polyproteins pp220 and pp62. Also, an icosahedral membrane lies between the two protein layers, whereas a pleomorphic envelope wraps the outer capsid. This high-level organization confers to ASFV a unique architecture among the NCLDVs that likely reflects the complexity of its infection process and may help explain current challenges in controlling it.
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Affiliation(s)
- German Andrés
- Centro de Biología Molecular Severo Ochoa, CSIC and Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Diego Charro
- Molecular Recognition and Host-Pathogen Interactions Programme, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain
| | - Tania Matamoros
- Centro de Biología Molecular Severo Ochoa, CSIC and Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Rebecca S Dillard
- NeCEN, Institute of Biology Leiden, Leiden University, 2333_CC Leiden, Netherlands
| | - Nicola G A Abrescia
- Molecular Recognition and Host-Pathogen Interactions Programme, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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42
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Van Etten JL, Agarkova IV, Dunigan DD. Chloroviruses. Viruses 2019; 12:E20. [PMID: 31878033 PMCID: PMC7019647 DOI: 10.3390/v12010020] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/13/2019] [Accepted: 12/15/2019] [Indexed: 12/20/2022] Open
Abstract
Chloroviruses are large dsDNA, plaque-forming viruses that infect certain chlorella-like green algae; the algae are normally mutualistic endosymbionts of protists and metazoans and are often referred to as zoochlorellae. The viruses are ubiquitous in inland aqueous environments throughout the world and occasionally single types reach titers of thousands of plaque-forming units per ml of native water. The viruses are icosahedral in shape with a spike structure located at one of the vertices. They contain an internal membrane that is required for infectivity. The viral genomes are 290 to 370 kb in size, which encode up to 16 tRNAs and 330 to ~415 proteins, including many not previously seen in viruses. Examples include genes encoding DNA restriction and modification enzymes, hyaluronan and chitin biosynthetic enzymes, polyamine biosynthetic enzymes, ion channel and transport proteins, and enzymes involved in the glycan synthesis of the virus major capsid glycoproteins. The proteins encoded by many of these viruses are often the smallest or among the smallest proteins of their class. Consequently, some of the viral proteins are the subject of intensive biochemical and structural investigation.
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Affiliation(s)
- James L. Van Etten
- Department of Plant Pathology, Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, USA; (I.V.A.); (D.D.D.)
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Liu S, Luo Y, Wang Y, Li S, Zhao Z, Bi Y, Sun J, Peng R, Song H, Zhu D, Sun Y, Li S, Zhang L, Wang W, Sun Y, Qi J, Yan J, Shi Y, Zhang X, Wang P, Qiu HJ, Gao GF. Cryo-EM Structure of the African Swine Fever Virus. Cell Host Microbe 2019; 26:836-843.e3. [PMID: 31787524 DOI: 10.1016/j.chom.2019.11.004] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/01/2019] [Accepted: 11/07/2019] [Indexed: 11/18/2022]
Abstract
African swine fever virus (ASFV) is a large double-stranded DNA virus with an icosahedral multilayered structure. ASFV causes a lethal swine hemorrhagic disease and is currently responsible for widespread damage to the pork industry in Asia. Neither vaccines nor antivirals are available and the molecular characterization of the ASFV particle is outstanding. Here, we describe the cryogenic electron microscopy (cryo-EM) structure of the icosahedral capsid of ASFV at 4.6-Å. The ASFV particle consists of 8,280 copies of the major capsid protein p72, 60 copies of the penton protein, and at least 8,340 minor capsid proteins, of which there might be 3 different types. Like other nucleocytoplasmic large DNA viruses, the minor capsid proteins form a hexagonal network below the outer capsid shell, functioning as stabilizers by "gluing" neighboring capsomers together. Our findings provide a comprehensive molecular model of the ASFV capsid architecture that will contribute to the future development of countermeasures, including vaccines.
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Affiliation(s)
- Sheng Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuzi Luo
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Yajuan Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shihua Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhennan Zhao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuhai Bi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Center for Influenza Research and Early-warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Diseases (CEEID), Chinese Academy of Sciences, Beijing 100101, China
| | - Junqing Sun
- Shanxi Academy of Advanced Research and Innovation, Taiyuan 030032, China
| | - Ruchao Peng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hao Song
- Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Dongjie Zhu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuan Sun
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Su Li
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Li Zhang
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Wei Wang
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Yeping Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jinghua Yan
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yi Shi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Center for Influenza Research and Early-warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Diseases (CEEID), Chinese Academy of Sciences, Beijing 100101, China; Shanxi Academy of Advanced Research and Innovation, Taiyuan 030032, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Peiyi Wang
- Shanxi Academy of Advanced Research and Innovation, Taiyuan 030032, China; SUSTech Cryo-EM Centre, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Hua-Ji Qiu
- State Key Laboratory of Veterinary Biotechnology and National High-Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
| | - George F Gao
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Center for Influenza Research and Early-warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Diseases (CEEID), Chinese Academy of Sciences, Beijing 100101, China; Shanxi Academy of Advanced Research and Innovation, Taiyuan 030032, China; Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC), Beijing 102206, China.
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44
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Wang N, Zhao D, Wang J, Zhang Y, Wang M, Gao Y, Li F, Wang J, Bu Z, Rao Z, Wang X. Architecture of African swine fever virus and implications for viral assembly. Science 2019; 366:640-644. [PMID: 31624094 DOI: 10.1126/science.aaz1439] [Citation(s) in RCA: 207] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/09/2019] [Indexed: 01/27/2023]
Abstract
African swine fever virus (ASFV) is a giant and complex DNA virus that causes a highly contagious and often lethal swine disease for which no vaccine is available. Using an optimized image reconstruction strategy, we solved the ASFV capsid structure up to 4.1 angstroms, which is built from 17,280 proteins, including one major (p72) and four minor (M1249L, p17, p49, and H240R) capsid proteins organized into pentasymmetrons and trisymmetrons. The atomic structure of the p72 protein informs putative conformational epitopes, distinguishing ASFV from other nucleocytoplasmic large DNA viruses. The minor capsid proteins form a complicated network below the outer capsid shell, stabilizing the capsid by holding adjacent capsomers together. Acting as core organizers, 100-nanometer-long M1249L proteins run along each edge of the trisymmetrons that bridge two neighboring pentasymmetrons and form extensive intermolecular networks with other capsid proteins, driving the formation of the capsid framework. These structural details unveil the basis of capsid stability and assembly, opening up new avenues for African swine fever vaccine development.
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Affiliation(s)
- Nan Wang
- CAS Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongming Zhao
- State Key Laboratory of Veterinary Biotechnology and National High Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Jialing Wang
- CAS Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yangling Zhang
- CAS Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ming Wang
- State Key Laboratory of Veterinary Biotechnology and National High Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Yan Gao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Laboratory of Structural Biology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Fang Li
- State Key Laboratory of Veterinary Biotechnology and National High Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Jingfei Wang
- State Key Laboratory of Veterinary Biotechnology and National High Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Zhigao Bu
- State Key Laboratory of Veterinary Biotechnology and National High Containment Laboratory for Animal Diseases Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
| | - Zihe Rao
- CAS Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. .,Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Laboratory of Structural Biology, School of Medicine, Tsinghua University, Beijing 100084, China.,State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
| | - Xiangxi Wang
- CAS Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. .,University of Chinese Academy of Sciences, Beijing 100049, China
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45
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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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46
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Xian Y, Karki CB, Silva SM, Li L, Xiao C. The Roles of Electrostatic Interactions in Capsid Assembly Mechanisms of Giant Viruses. Int J Mol Sci 2019; 20:ijms20081876. [PMID: 30995716 PMCID: PMC6514965 DOI: 10.3390/ijms20081876] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 11/16/2022] Open
Abstract
In the last three decades, many giant DNA viruses have been discovered. Giant viruses present a unique and essential research frontier for studies of self-assembly and regulation of supramolecular assemblies. The question on how these giant DNA viruses assemble thousands of proteins so accurately to form their protein shells, the capsids, remains largely unanswered. Revealing the mechanisms of giant virus assembly will help to discover the mysteries of many self-assembly biology problems. Paramecium bursaria Chlorella virus-1 (PBCV-1) is one of the most intensively studied giant viruses. Here, we implemented a multi-scale approach to investigate the interactions among PBCV-1 capsid building units called capsomers. Three binding modes with different strengths are found between capsomers around the relatively flat area of the virion surface at the icosahedral 2-fold axis. Furthermore, a capsomer structure manipulation package is developed to simulate the capsid assembly process. Using these tools, binding forces among capsomers were investigated and binding funnels were observed that were consistent with the final assembled capsid. In addition, total binding free energies of each binding mode were calculated. The results helped to explain previous experimental observations. Results and tools generated in this work established an initial computational approach to answer current unresolved questions regarding giant virus assembly mechanisms. Results will pave the way for studying more complicated process in other biomolecular structures.
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Affiliation(s)
- Yuejiao Xian
- Department of Chemistry, University of Texas, 500 West University Ave, El Paso, TX 79902, USA.
| | - Chitra B Karki
- Department of Physics, University of Texas, 500 West University Ave, El Paso, TX 79902, USA.
| | - Sebastian Miki Silva
- Department of Physics, University of Texas, 500 West University Ave, El Paso, TX 79902, USA.
| | - Lin Li
- Department of Physics, University of Texas, 500 West University Ave, El Paso, TX 79902, USA.
| | - Chuan Xiao
- Department of Chemistry, University of Texas, 500 West University Ave, El Paso, TX 79902, USA.
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