1
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Edwards KF, Steward GF, Schvarcz CR. Making sense of virus size and the tradeoffs shaping viral fitness. Ecol Lett 2020; 24:363-373. [PMID: 33146939 DOI: 10.1111/ele.13630] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/26/2020] [Accepted: 09/27/2020] [Indexed: 12/18/2022]
Abstract
Viruses span an impressive size range, with genome length varying a thousandfold and virion volume nearly a millionfold. For cellular organisms the scaling of traits with size is a pervasive influence on ecological processes, but whether size plays a central role in viral ecology is unknown. Here, we focus on viruses of aquatic unicellular organisms, which exhibit the greatest known range of virus size. We outline hypotheses within a quantitative framework, and analyse data where available, to consider how size affects the primary components of viral fitness. We argue that larger viruses have fewer offspring per infection and slower contact rates with host cells, but a larger genome tends to increase infection efficiency, broaden host range, and potentially increase attachment success and decrease decay rate. These countervailing selective pressures may explain why a breadth of sizes exist and even coexist when infecting the same host populations. Oligotrophic ecosystems may be enriched in "giant" viruses, because environments with resource-limited phagotrophs at low concentrations may select for broader host range, better control of host metabolism, lower decay rate and a physical size that mimics bacterial prey. Finally, we describe where further research is needed to understand the ecology and evolution of viral size diversity.
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Affiliation(s)
- Kyle F Edwards
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Grieg F Steward
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
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2
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Coy SR, Gann ER, Papoulis SE, Holder ME, Ajami NJ, Petrosino JF, Zinser ER, Van Etten JL, Wilhelm SW. SMRT Sequencing of Paramecium Bursaria Chlorella Virus-1 Reveals Diverse Methylation Stability in Adenines Targeted by Restriction Modification Systems. Front Microbiol 2020; 11:887. [PMID: 32508769 PMCID: PMC7248222 DOI: 10.3389/fmicb.2020.00887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/16/2020] [Indexed: 12/31/2022] Open
Abstract
Chloroviruses (family Phycodnaviridae) infect eukaryotic, freshwater, unicellular green algae. A unique feature of these viruses is an abundance of DNA methyltransferases, with isolates dedicating up to 4.5% of their protein coding potential to these genes. This diversity highlights just one of the long-standing values of the chlorovirus model system; where group-wide epigenomic characterization might begin to elucidate the function(s) of DNA methylation in large dsDNA viruses. We characterized DNA modifications in the prototype chlorovirus, PBCV-1, using single-molecule real time (SMRT) sequencing (aka PacBio). Results were compared to total available sites predicted in silico based on DNA sequence alone. SMRT-software detected N6-methyl-adenine (m6A) at GATC and CATG recognition sites, motifs previously shown to be targeted by PBCV-1 DNA methyltransferases M.CviAI and M. CviAII, respectively. At the same time, PacBio analyses indicated that 10.9% of the PBCV-1 genome had large interpulse duration ratio (ipdRatio) values, the primary metric for DNA modification identification. These events represent 20.6x more sites than can be accounted for by all available adenines in GATC and CATG motifs, suggesting base or backbone modifications other than methylation might be present. To define methylation stability, we cross-compared methylation status of each GATC and CATG sequence in three biological replicates and found ∼81% of sites were stably methylated, while ∼2% consistently lack methylation. The remaining 17% of sites were stochastically methylated. When methylation status was analyzed for both strands of each target, we show that palindromes existed in completely non-methylated states, fully-methylated states, or hemi-methylated states, though GATC sites more often lack methylation than CATG sequences. Given that both sequences are targeted by not just methyltransferases, but by restriction endonucleases that are together encoded by PBCV-1 as virus-originating restriction modification (RM) systems, there is strong selective pressure to modify all target sites. The finding that most instances of non-methylation are associated with hemi-methylation is congruent with observations that hemi-methylated palindromes are resistant to cleavage by restriction endonucleases. However, sites where hemi-methylation is conserved might represent a unique regulatory function for PBCV-1. This study serves as a baseline for future investigation into the epigenomics of chloroviruses and their giant virus relatives.
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Affiliation(s)
- Samantha R. Coy
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
- BioSciences at Rice, Rice University, Houston, TX, United States
| | - Eric R. Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Spiridon E. Papoulis
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Michael E. Holder
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Nadim J. Ajami
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Joseph F. Petrosino
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Erik R. Zinser
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - James L. Van Etten
- Department of Plant Pathology and the Nebraska Center for Virology, University of Nebraska, Lincoln, NE, United States
| | - Steven W. Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
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3
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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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4
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Martín-González N, Hernando-Pérez M, Condezo GN, Pérez-Illana M, Šiber A, Reguera D, Ostapchuk P, Hearing P, San Martín C, de Pablo PJ. Adenovirus major core protein condenses DNA in clusters and bundles, modulating genome release and capsid internal pressure. Nucleic Acids Res 2019; 47:9231-9242. [PMID: 31396624 PMCID: PMC6755088 DOI: 10.1093/nar/gkz687] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/10/2019] [Accepted: 08/06/2019] [Indexed: 11/23/2022] Open
Abstract
Some viruses package dsDNA together with large amounts of positively charged proteins, thought to help condense the genome inside the capsid with no evidence. Further, this role is not clear because these viruses have typically lower packing fractions than viruses encapsidating naked dsDNA. In addition, it has recently been shown that the major adenovirus condensing protein (polypeptide VII) is dispensable for genome encapsidation. Here, we study the morphology and mechanics of adenovirus particles with (Ad5-wt) and without (Ad5-VII-) protein VII. Ad5-VII- particles are stiffer than Ad5-wt, but DNA-counterions revert this difference, indicating that VII screens repulsive DNA-DNA interactions. Consequently, its absence results in increased internal pressure. The core is slightly more ordered in the absence of VII and diffuses faster out of Ad5-VII– than Ad5-wt fractured particles. In Ad5-wt unpacked cores, dsDNA associates in bundles interspersed with VII-DNA clusters. These results indicate that protein VII condenses the adenovirus genome by combining direct clustering and promotion of bridging by other core proteins. This condensation modulates the virion internal pressure and DNA release from disrupted particles, which could be crucial to keep the genome protected inside the semi-disrupted capsid while traveling to the nuclear pore.
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Affiliation(s)
| | - Mercedes Hernando-Pérez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | - Gabriela N Condezo
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | - Marta Pérez-Illana
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | | | - David Reguera
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain.,Universitat de Barcelona Institute of Complex Systems (UBICS), 08028 Barcelona, Spain
| | - Philomena Ostapchuk
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Patrick Hearing
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Carmen San Martín
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | - Pedro J de Pablo
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid 28049, Spain.,Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain
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5
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Chloroviruses Lure Hosts through Long-Distance Chemical Signaling. J Virol 2019; 93:JVI.01688-18. [PMID: 30626679 DOI: 10.1128/jvi.01688-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022] Open
Abstract
Chloroviruses exist in aquatic systems around the planet and they infect certain eukaryotic green algae that are mutualistic endosymbionts in a variety of protists and metazoans. Natural chlorovirus populations are seasonally dynamic, but the precise temporal changes in these populations and the mechanisms that underlie them have heretofore been unclear. We recently reported the novel concept that predator/prey-mediated virus activation regulates chlorovirus population dynamics, and in the current study, we demonstrate virus-packaged chemotactic modulation of prey behavior.IMPORTANCE Viruses have not previously been reported to act as chemotactic/chemoattractive agents. Rather, viruses as extracellular entities are generally viewed as non-metabolically active spore-like agents that await further infection events upon collision with appropriate host cells. That a virus might actively contribute to its fate via chemotaxis and change the behavior of an organism independent of infection is unprecedented.
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6
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Cryopreservation of Paramecium bursaria Chlorella Virus-1 during an active infection cycle of its host. PLoS One 2019; 14:e0211755. [PMID: 30870463 PMCID: PMC6417706 DOI: 10.1371/journal.pone.0211755] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 03/01/2019] [Indexed: 02/02/2023] Open
Abstract
Best practices in laboratory culture management often include cryopreservation of microbiota, but this can be challenging with some virus particles. By preserving viral isolates researchers can mitigate genetic drift and laboratory-induced selection, thereby maintaining genetically consistent strains between experiments. To this end, we developed a method to cryopreserve the model, green-alga infecting virus, Paramecium bursaria Chlorella virus 1 (PBCV-1). We explored cryotolerance of the infectivity of this virus particle, whereby freezing without cryoprotectants was found to maintain the highest infectivity (~2.5%). We then assessed the cryopreservation potential of PBCV-1 during an active infection cycle in its Chlorella variabilis NC64A host, and found that virus survivorship was highest (69.5 ± 16.5%) when the infected host is cryopreserved during mid-late stages of infection (i.e., coinciding with virion assembly). The most optimal condition for cryopreservation was observed at 240 minutes post-infection. Overall, utilizing the cell as a vehicle for viral cryopreservation resulted in 24.9–30.1 fold increases in PBCV-1 survival based on 95% confidence intervals of frozen virus particles and virus cryopreserved at 240 minutes post-infection. Given that cryoprotectants are often naturally produced by psychrophilic organisms, we suspect that cryopreservation of infected hosts may be a reliable mechanism for virus persistence in non-growth permitting circumstances in the environment, such as ancient permafrosts.
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7
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Different forms of African cassava mosaic virus capsid protein within plants and virions. Virology 2019; 529:81-90. [PMID: 30684693 DOI: 10.1016/j.virol.2019.01.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/14/2019] [Accepted: 01/16/2019] [Indexed: 01/04/2023]
Abstract
One geminiviral gene encodes the capsid protein (CP), which can appear as several bands after electrophoresis depending on virus and plant. African cassava mosaic virus-Nigeria CP in Nicotiana benthamiana, however, yielded one band (~ 30 kDa) in total protein extracts and purified virions, although its expression in yeast yielded two bands (~ 30, 32 kDa). Mass spectrometry of the complete protein and its tryptic fragments from virions is consistent with a cleaved start M1, acetylated S2, and partial phosphorylation at T12, S25 and S62. Mutants for additional potentially modified sites (N223A; C235A) were fully infectious and formed geminiparticles. Separation in triton acetic acid urea gels confirmed charge changes of the CP between plants and yeast indicating differential phosphorylation. If the CP gene alone was expressed in plants, multiple bands were observed like in yeast. A high turnover rate indicates that post-translational modifications promote CP decay probably via the ubiquitin-triggered proteasomal pathway.
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8
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Evans CT, Payton O, Picco L, Allen MJ. Algal Viruses: The (Atomic) Shape of Things to Come. Viruses 2018; 10:E490. [PMID: 30213102 PMCID: PMC6165301 DOI: 10.3390/v10090490] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 08/30/2018] [Accepted: 09/07/2018] [Indexed: 01/15/2023] Open
Abstract
Visualization of algal viruses has been paramount to their study and understanding. The direct observation of the morphological dynamics of infection is a highly desired capability and the focus of instrument development across a variety of microscopy technologies. However, the high temporal (ms) and spatial resolution (nm) required, combined with the need to operate in physiologically relevant conditions presents a significant challenge. Here we present a short history of virus structure study and its relation to algal viruses and highlight current work, concentrating on electron microscopy and atomic force microscopy, towards the direct observation of individual algae⁻virus interactions. Finally, we make predictions towards future algal virus study direction with particular focus on the exciting opportunities offered by modern high-speed atomic force microscopy methods and instrumentation.
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Affiliation(s)
- Christopher T Evans
- Plymouth Marine Laboratory, Plymouth PL1 3DH, UK.
- Interface Analysis Centre, Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
| | - Oliver Payton
- Interface Analysis Centre, Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
| | - Loren Picco
- Interface Analysis Centre, Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Michael J Allen
- Plymouth Marine Laboratory, Plymouth PL1 3DH, UK.
- College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
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9
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Larkin J, Henley RY, Jadhav V, Korlach J, Wanunu M. Length-independent DNA packing into nanopore zero-mode waveguides for low-input DNA sequencing. NATURE NANOTECHNOLOGY 2017; 12:1169-1175. [PMID: 28892102 PMCID: PMC5718969 DOI: 10.1038/nnano.2017.176] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 07/26/2017] [Indexed: 05/03/2023]
Abstract
Compared with conventional methods, single-molecule real-time (SMRT) DNA sequencing exhibits longer read lengths than conventional methods, less GC bias, and the ability to read DNA base modifications. However, reading DNA sequence from sub-nanogram quantities is impractical owing to inefficient delivery of DNA molecules into the confines of zero-mode waveguides-zeptolitre optical cavities in which DNA sequencing proceeds. Here, we show that the efficiency of voltage-induced DNA loading into waveguides equipped with nanopores at their floors is five orders of magnitude greater than existing methods. In addition, we find that DNA loading is nearly length-independent, unlike diffusive loading, which is biased towards shorter fragments. We demonstrate here loading and proof-of-principle four-colour sequence readout of a polymerase-bound 20,000-base-pair-long DNA template within seconds from a sub-nanogram input quantity, a step towards low-input DNA sequencing and mammalian epigenomic mapping of native DNA samples.
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Affiliation(s)
- Joseph Larkin
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Robert Y Henley
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Vivek Jadhav
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Jonas Korlach
- Pacific Biosciences, Menlo Park, California 94025, USA
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA
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10
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Marion S, San Martín C, Šiber A. Role of Condensing Particles in Polymer Confinement: A Model for Virus-Packed "Minichromosomes". Biophys J 2017; 113:1643-1653. [PMID: 29045859 PMCID: PMC5647577 DOI: 10.1016/j.bpj.2017.08.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/18/2017] [Accepted: 08/14/2017] [Indexed: 12/22/2022] Open
Abstract
Confined mixtures of a polymer and nonspecifically binding particles (condensers) are studied as models for viruses containing double-stranded DNA (polymer) and condensing proteins (particles). We explore a model in which all interactions between the packed content (polymer and particles) and its confinement are purely repulsive, with only a short-range attraction between the condensers and polymer to simulate binding. In the range of physical parameters applicable to viruses, the model predicts reduction of pressure in the system effected by the condensers, despite the reduction in free volume. Condensers are found to be interspersed throughout the spherical confinement and only partially wrapped in the polymer, which acts as an effective medium for the condenser interactions. Crowding of the viral interior influences the DNA and protein organization, producing a picture inconsistent with a chromatin-like, beads-on-a-string structure. The model predicts an organization of the confined interior compatible with experimental data on unperturbed adenoviruses and polyomaviruses, at the same time providing insight into the role of condensing proteins in the viral infectious cycles of related viral families.
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Affiliation(s)
- Sanjin Marion
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Zagreb, Croatia; Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Carmen San Martín
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Antonio Šiber
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Zagreb, Croatia.
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11
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Milrot E, Shimoni E, Dadosh T, Rechav K, Unger T, Van Etten JL, Minsky A. Structural studies demonstrating a bacteriophage-like replication cycle of the eukaryote-infecting Paramecium bursaria chlorella virus-1. PLoS Pathog 2017; 13:e1006562. [PMID: 28850602 PMCID: PMC5593192 DOI: 10.1371/journal.ppat.1006562] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 09/11/2017] [Accepted: 07/31/2017] [Indexed: 11/18/2022] Open
Abstract
A fundamental stage in viral infection is the internalization of viral genomes in host cells. Although extensively studied, the mechanisms and factors responsible for the genome internalization process remain poorly understood. Here we report our observations, derived from diverse imaging methods on genome internalization of the large dsDNA Paramecium bursaria chlorella virus-1 (PBCV-1). Our studies reveal that early infection stages of this eukaryotic-infecting virus occurs by a bacteriophage-like pathway, whereby PBCV-1 generates a hole in the host cell wall and ejects its dsDNA genome in a linear, base-pair-by-base-pair process, through a membrane tunnel generated by the fusion of the virus internal membrane with the host membrane. Furthermore, our results imply that PBCV-1 DNA condensation that occurs shortly after infection probably plays a role in genome internalization, as hypothesized for the infection of some bacteriophages. The subsequent perforation of the host photosynthetic membranes presumably enables trafficking of viral genomes towards host nuclei. Previous studies established that at late infection stages PBCV-1 generates cytoplasmic organelles, termed viral factories, where viral assembly takes place, a feature characteristic of many large dsDNA viruses that infect eukaryotic organisms. PBCV-1 thus appears to combine a bacteriophage-like mechanism during early infection stages with a eukaryotic-like infection pathway in its late replication cycle. Although extensively studied, the mechanisms responsible for internalization of viral genomes into their host cells remain unclear. A particularly interesting case of genome release and internalization is provided by the large Paramecium bursaria chlorella virus-1 (PBCV-1), which infects unicellular eukaryotic photosynthetic chlorella cells. In order to release its long dsDNA genome and to enable its translocation to the host nucleus, PBCV-1 must overcome multiple hurdles, including a thick host cell wall and multilayered chloroplast membranes that surround the host cytoplasm. Our observations indicate that these obstacles are dealt with perforations of the host wall, the host cellular membrane, and the host photosynthetic membranes by viral-encoded proteins. Furthermore, our results highlight a bacteriophage-like nature of early PBCV-1 infection stages, thus implying that this virus uniquely combines bacteriophage-like and eukaryotic-like pathways to accomplish its replication cycle.
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Affiliation(s)
- Elad Milrot
- Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (EM); (AM)
| | - Eyal Shimoni
- Chemical Research Support, The Weizmann Institute of Science, Rehovot, Israel
| | - Tali Dadosh
- Chemical Research Support, The Weizmann Institute of Science, Rehovot, Israel
| | - Katya Rechav
- Chemical Research Support, The Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Unger
- Proteomics, The Weizmann Institute of Science, Rehovot, Israel
| | - James L. Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, United States of America
| | - Abraham Minsky
- Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (EM); (AM)
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12
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Sajjan DB, Hinchigeri SB. Structural Organization of Baculovirus Occlusion Bodies and Protective Role of Multilayered Polyhedron Envelope Protein. FOOD AND ENVIRONMENTAL VIROLOGY 2016; 8:86-100. [PMID: 26787118 DOI: 10.1007/s12560-016-9227-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/09/2016] [Indexed: 06/05/2023]
Abstract
Baculoviruses are the ingenious insect pathogens. Outside the host, baculovirus occlusion bodies (OB) provide stability to occlusion-derived viruses (ODV) embedded within. The OB is an organized structure, chiefly composed of proteins namely polyhedrin, polyhedron envelope protein (PEP) and P10. Currently, the structural organization of OB is poorly understood and the role of OB proteins in conferring the stability to ODV is unknown. Here we have shown that the assembly of polyhedrin unit cells into an OB is a rapid process; the PEP forms in multiple layers; the PEP layers predominantly contribute to ODV viability. Full-grown OBs (n = 36) were found to be 4.0 ± 1.0 µm in diameter and possessed a peculiar geometry of a truncated rhombic dodecahedron. The atomic force microscopy (AFM) study on the structure of OBs at different stages of growth in insect cells revealed polyhedrin assembly and thickness of PEP layers. The thickness of PEP layers at 53 h post-transfection (hpt) ranged from 56 to 80 nm. Mature PEP layers filled up approximately one third of the OB volume. The size of ODV nucleocapsid was found to be 433 ± 10 nm in length. The zeta potential and particle size distribution study of viruses revealed the protective role of PEP layers. The presence of a multilayered PEP confers a viable advantage to the baculoviruses compared to single-layered PEP. Thus, these findings may help in developing PEP layer-based biopolymers for protein-based nanodevices, nanoelectrodes and more stable biopesticides.
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Affiliation(s)
- Dayanand B Sajjan
- Department of Biochemistry, Karnatak University, Dharwad, Karnataka, 580 003, India
| | - Shivayogeppa B Hinchigeri
- Department of Biochemistry, Karnatak University, Dharwad, Karnataka, 580 003, India.
- REVA University, Rukmini Knowledge Park, Adminstrative Block, Kattigenahalli, Yelahanka, Bangalore, Karnataka, 560064, India.
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13
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Arutyunov D, Szymanski CM. A novel DNA-binding protein from Campylobacter jejuni bacteriophage NCTC12673. FEMS Microbiol Lett 2015; 362:fnv160. [PMID: 26363017 DOI: 10.1093/femsle/fnv160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2015] [Indexed: 12/21/2022] Open
Abstract
We previously suggested that the double-stranded genomic DNA of Campylobacter jejuni bacteriophage NCTC12673 was complexed with proteins. Mass spectrometry of peptides obtained from tryptic digests of purified phage DNA indicated that phage protein Gp001 co-purified with the DNA. Gp001 is an acidic protein that lacks any obvious homology or conserved domains found in known DNA-binding proteins. The DNA-binding ability of recombinant Gp001 was examined using an electrophoretic mobility shift assay. Slow DNA-Gp001 complex formation was observed at pH 5.5, but not at neutral or basic pH. This nucleoprotein complex had difficulty entering agarose gels used in the assay while proteinase K pretreatment released the DNA from the complex. No mobility shift was observed when the DNA was immediately subjected to electrophoresis after mixing with Gp001, even if both components were separately pre-incubated at pH 5.5. The complexed DNA was unable to transform chemically competent Escherichia coli cells and was less susceptible to degradation by nucleases. The formation of Gp001-DNA complexes at low pH may provide a mechanism for maintaining DNA integrity while the phage pursues its host through the gastrointestinal tract. Also, this feature can potentially be used to improve DNA delivery protocols applied in gene therapy.
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Affiliation(s)
- Denis Arutyunov
- Department of Biological Sciences and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Christine M Szymanski
- Department of Biological Sciences and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta, Canada
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Milrot E, Mutsafi Y, Fridmann-Sirkis Y, Shimoni E, Rechav K, Gurnon JR, Van Etten JL, Minsky A. Virus-host interactions: insights from the replication cycle of the large Paramecium bursaria chlorella virus. Cell Microbiol 2015; 18:3-16. [PMID: 26248343 DOI: 10.1111/cmi.12486] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/09/2015] [Accepted: 07/15/2015] [Indexed: 12/20/2022]
Abstract
The increasing interest in cytoplasmic factories generated by eukaryotic-infecting viruses stems from the realization that these highly ordered assemblies may contribute fundamental novel insights to the functional significance of order in cellular biology. Here, we report the formation process and structural features of the cytoplasmic factories of the large dsDNA virus Paramecium bursaria chlorella virus 1 (PBCV-1). By combining diverse imaging techniques, including scanning transmission electron microscopy tomography and focused ion beam technologies, we show that the architecture and mode of formation of PBCV-1 factories are significantly different from those generated by their evolutionary relatives Vaccinia and Mimivirus. Specifically, PBCV-1 factories consist of a network of single membrane bilayers acting as capsid templates in the central region, and viral genomes spread throughout the host cytoplasm but excluded from the membrane-containing sites. In sharp contrast, factories generated by Mimivirus have viral genomes in their core, with membrane biogenesis region located at their periphery. Yet, all viral factories appear to share structural features that are essential for their function. In addition, our studies support the notion that PBCV-1 infection, which was recently reported to result in significant pathological outcomes in humans and mice, proceeds through a bacteriophage-like infection pathway.
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Affiliation(s)
- Elad Milrot
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Mutsafi
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Fridmann-Sirkis
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Katya Rechav
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - James R Gurnon
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, 68583-0900, USA
| | - James L Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, 68583-0900, USA
| | - Abraham Minsky
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
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Kellner JN, Reinstein J, Meinhart A. Synergistic effects of ATP and RNA binding to human DEAD-box protein DDX1. Nucleic Acids Res 2015; 43:2813-28. [PMID: 25690890 PMCID: PMC4357711 DOI: 10.1093/nar/gkv106] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
RNA helicases of the DEAD-box protein family form the largest group of helicases. The human DEAD-box protein 1 (DDX1) plays an important role in tRNA and mRNA processing, is involved in tumor progression and is also hijacked by several virus families such as HIV-1 for replication and nuclear export. Although important in many cellular processes, the mechanism of DDX1′s enzymatic function is unknown. We have performed equilibrium titrations and transient kinetics to determine affinities for nucleotides and RNA. We find an exceptional tight binding of DDX1 to adenosine diphosphate (ADP), one of the strongest affinities observed for DEAD-box helicases. ADP binds tighter by three orders of magnitude when compared to adenosine triphosphate (ATP), arresting the enzyme in a potential dead-end ADP conformation under physiological conditions. We thus suggest that a nucleotide exchange factor leads to DDX1 recycling. Furthermore, we find a strong cooperativity in binding of RNA and ATP to DDX1 that is also reflected in ATP hydrolysis. We present a model in which either ATP or RNA binding alone can partially shift the equilibrium from an ‘open’ to a ‘closed’-state; this shift appears to be not further pronounced substantially even in the presence of both RNA and ATP as the low rate of ATP hydrolysis does not change.
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Affiliation(s)
- Julian N Kellner
- Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Jochen Reinstein
- Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Anton Meinhart
- Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
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Infection cycles of large DNA viruses: Emerging themes and underlying questions. Virology 2014; 466-467:3-14. [DOI: 10.1016/j.virol.2014.05.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 11/20/2022]
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Sirotkin S, Mermet A, Bergoin M, Ward V, Van Etten JL. Viruses as nanoparticles: structure versus collective dynamics. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:022718. [PMID: 25215769 DOI: 10.1103/physreve.90.022718] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Indexed: 06/03/2023]
Abstract
In order to test the application of the "nanoparticle" concept to viruses in terms of low-frequency dynamics, large viruses (140-190 nm) were compared to similar-sized polymer colloids using ultra-small-angle x-ray scattering and very-low-frequency Raman or Brillouin scattering. While both viruses and polymer colloids show comparable highly defined morphologies, with comparable abilities of forming self-assembled structures, their respective abilities to confine detectable acoustic vibrations, as expected for such monodisperse systems, differed. Possible reasons for these different behaviors are discussed.
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Affiliation(s)
- S Sirotkin
- Institut Lumière Matière, Université de Lyon, Université Claude Bernard Lyon 1, UMR CNRS 5306, 69622 Villeurbanne, France
| | - A Mermet
- Institut Lumière Matière, Université de Lyon, Université Claude Bernard Lyon 1, UMR CNRS 5306, 69622 Villeurbanne, France
| | - M Bergoin
- Laboratoire de Virologie Comparé des Invertébrés, E.P.H.E., Université Montpellier 2, France
| | - V Ward
- University of Otago, Department of Microbology and Immunology, New Zealand
| | - J L Van Etten
- Department of Plant Pathology and the Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska USA
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Paramecium bursaria chlorella virus 1 proteome reveals novel architectural and regulatory features of a giant virus. J Virol 2012; 86:8821-34. [PMID: 22696644 DOI: 10.1128/jvi.00907-12] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 331-kbp chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) genome was resequenced and annotated to correct errors in the original 15-year-old sequence; 40 codons was considered the minimum protein size of an open reading frame. PBCV-1 has 416 predicted protein-encoding sequences and 11 tRNAs. A proteome analysis was also conducted on highly purified PBCV-1 virions using two mass spectrometry-based protocols. The mass spectrometry-derived data were compared to PBCV-1 and its host Chlorella variabilis NC64A predicted proteomes. Combined, these analyses revealed 148 unique virus-encoded proteins associated with the virion (about 35% of the coding capacity of the virus) and 1 host protein. Some of these proteins appear to be structural/architectural, whereas others have enzymatic, chromatin modification, and signal transduction functions. Most (106) of the proteins have no known function or homologs in the existing gene databases except as orthologs with proteins of other chloroviruses, phycodnaviruses, and nuclear-cytoplasmic large DNA viruses. The genes encoding these proteins are dispersed throughout the virus genome, and most are transcribed late or early-late in the infection cycle, which is consistent with virion morphogenesis.
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