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Tisza MJ, Pastrana DV, Welch NL, Stewart B, Peretti A, Starrett GJ, Pang YYS, Krishnamurthy SR, Pesavento PA, McDermott DH, Murphy PM, Whited JL, Miller B, Brenchley J, Rosshart SP, Rehermann B, Doorbar J, Ta'ala BA, Pletnikova O, Troncoso JC, Resnick SM, Bolduc B, Sullivan MB, Varsani A, Segall AM, Buck CB. Discovery of several thousand highly diverse circular DNA viruses. eLife 2020; 9:51971. [PMID: 32014111 PMCID: PMC7000223 DOI: 10.7554/elife.51971] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 01/06/2020] [Indexed: 12/18/2022] Open
Abstract
Although millions of distinct virus species likely exist, only approximately 9000 are catalogued in GenBank's RefSeq database. We selectively enriched for the genomes of circular DNA viruses in over 70 animal samples, ranging from nematodes to human tissue specimens. A bioinformatics pipeline, Cenote-Taker, was developed to automatically annotate over 2500 complete genomes in a GenBank-compliant format. The new genomes belong to dozens of established and emerging viral families. Some appear to be the result of previously undescribed recombination events between ssDNA and ssRNA viruses. In addition, hundreds of circular DNA elements that do not encode any discernable similarities to previously characterized sequences were identified. To characterize these ‘dark matter’ sequences, we used an artificial neural network to identify candidate viral capsid proteins, several of which formed virus-like particles when expressed in culture. These data further the understanding of viral sequence diversity and allow for high throughput documentation of the virosphere. When scientists hunt for new DNA sequences, sometimes they get a lot more than they bargained for. Such is the case in metagenomic surveys, which analyze not just DNA of a particular organism, but all the DNA in an environment at large. A vexing problem with these surveys is the overwhelming number of DNA sequences detected that are so different from any known microbe that they cannot be classified using traditional approaches. However, some of these “known unknowns” are undoubtedly viral sequences, because only a fraction of the enormous diversity of viruses has been characterized. This “viral dark matter” is a major obstacle for those studying viruses. This led Tisza et al. to attempt to classify some of the unknown viral sequences in their metagenomic surveys. The search, which specifically focused on viruses with circular DNA genomes, detected over 2,500 circular viral genomes. Intensive analysis revealed that many of these genomes had similar makeup to previously discovered viruses, but hundreds of them were totally different from any known virus, based on typical methods of comparison. Computational analysis of genes that were conserved among some of these brand-new circular sequences often revealed virus-like features. Experiments on a few of these genes showed that they encoded proteins capable of forming particles reminiscent of characteristic viral shells, implying that these new sequences are indeed viruses. Tisza et al. have added the 2,500 newly characterized viral sequences to the publicly accessible GenBank database, and the sequences are being considered for the more authoritative RefSeq database, which currently contains around 9,000 complete viral genomes. The expanded databases will hopefully now better equip scientists to explore the enormous diversity of viruses and help medics and veterinarians to detect disease-causing viruses in humans and other animals.
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Affiliation(s)
- Michael J Tisza
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Diana V Pastrana
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Nicole L Welch
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Brittany Stewart
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Alberto Peretti
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Gabriel J Starrett
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Yuk-Ying S Pang
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Siddharth R Krishnamurthy
- Metaorganism Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, United States
| | - Patricia A Pesavento
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, Davis, United States
| | - David H McDermott
- Molecular Signaling Section, Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, United States
| | - Philip M Murphy
- Molecular Signaling Section, Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, United States
| | - Jessica L Whited
- Department of Orthopedic Surgery, Harvard Medical School, The Harvard Stem Cell Institute, Brigham and Women's Hospital, Boston, United States.,Broad Institute of MIT and Harvard, Cambridge, United States.,Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Bess Miller
- Department of Orthopedic Surgery, Harvard Medical School, The Harvard Stem Cell Institute, Brigham and Women's Hospital, Boston, United States.,Broad Institute of MIT and Harvard, Cambridge, United States
| | - Jason Brenchley
- Barrier Immunity Section, Lab of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Cambridge, United States
| | - Stephan P Rosshart
- Immunology Section, Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Barbara Rehermann
- Immunology Section, Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - John Doorbar
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Olga Pletnikova
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, United States
| | - Juan C Troncoso
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, United States
| | - Susan M Resnick
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, United States
| | - Ben Bolduc
- Department of Microbiology, Ohio State University, Columbus, United States
| | - Matthew B Sullivan
- Department of Microbiology, Ohio State University, Columbus, United States.,Civil Environmental and Geodetic Engineering, Ohio State University, Columbus, United States
| | - Arvind Varsani
- The Biodesign Center of Fundamental and Applied Microbiomics, School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, United States.,Structural Biology Research Unit, Department of Clinical Laboratory Sciences, University of Cape Town, Rondebosch, South Africa
| | - Anca M Segall
- Viral Information Institute and Department of Biology, San Diego State University, San Diego, United States
| | - Christopher B Buck
- Lab of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, United States
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2
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Loh B, Kuhn A, Leptihn S. The fascinating biology behind phage display: filamentous phage assembly. Mol Microbiol 2019; 111:1132-1138. [PMID: 30556628 DOI: 10.1111/mmi.14187] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
With the recently awarded Nobel Prize to the inventor of Phage Display, George Smith, the technique has once more gained attention. However, one should not forget about the biology behind the method. Almost always ignored is how the structure of this bacterial virus is assembled. In contrast to lytic phages, filamentous phages are constantly being extruded through the bacterial membranes without lysis. Such filamentous phages are found in all aquatic environments, such as rivers and lakes, in the deep sea, in arctic ice, in hot springs and, associated with their hosts, in plants and animals including humans. While most filamentous phages infect Gram-negative hosts, inoviruses of Gram-positive hosts have also been described. Despite being among the minority within the phage family with an estimate of less than 5%, filamentous phages are real parasites as they exist at the expense of the host, but do not kill it. In contrast to lytic bacteriophages, filamentous phages are assembled in the host's membrane and extruded across the cellular envelope while the bacterium continues to grow. In this review, we focus on this complex and yet poorly understood process of assembly and secretion of filamentous phages.
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Affiliation(s)
- Belinda Loh
- Zhejiang University School of Medicine, Zhejiang University-Edinburgh University (ZJU-UoE) Institute, International Campus, Zhejiang University, 718 East Haizhou Road, Haining, Zhejiang, 314400, P.R. China
| | - Andreas Kuhn
- Institute of Microbiology, University of Hohenheim, Garbenstrasse 30, Stuttgart, 70599, Germany
| | - Sebastian Leptihn
- Zhejiang University School of Medicine, Zhejiang University-Edinburgh University (ZJU-UoE) Institute, International Campus, Zhejiang University, 718 East Haizhou Road, Haining, Zhejiang, 314400, P.R. China
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A novel, broad-range, CTXΦ-derived stable integrative expression vector for functional studies. J Bacteriol 2014; 196:4071-80. [PMID: 25225263 DOI: 10.1128/jb.01966-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CTXΦ, a filamentous vibriophage encoding cholera toxin, uses a unique strategy for its lysogeny. The single-stranded phage genome forms intramolecular base-pairing interactions between two inversely oriented XerC and XerD binding sites (XBS) and generates a functional phage attachment site, attP(+), for integration. The attP(+) structure is recognized by the host-encoded tyrosine recombinases XerC and XerD (XerCD), which enables irreversible integration of CTXΦ into the chromosome dimer resolution site (dif) of Vibrio cholerae. The dif site and the XerCD recombinases are widely conserved in bacteria. We took advantage of these conserved attributes to develop a broad-host-range integrative expression vector that could irreversibly integrate into the host chromosome using XerCD recombinases without altering the function of any known open reading frame (ORF). In this study, we engineered two different arabinose-inducible expression vectors, pBD62 and pBD66, using XBS of CTXΦ. pBD62 replicates conditionally and integrates efficiently into the dif of the bacterial chromosome by site-specific recombination using host-encoded XerCD recombinases. The expression level of the gene of interest could be controlled through the PBAD promoter by modulating the functions of the vector-encoded transcriptional factor AraC. We validated the irreversible integration of pBD62 into a wide range of pathogenic and nonpathogenic bacteria, such as V. cholerae, Vibrio fluvialis, Vibrio parahaemolyticus, Escherichia coli, Salmonella enterica, and Klebsiella pneumoniae. Gene expression from the PBAD promoter of integrated vectors was confirmed in V. cholerae using the well-studied reporter genes mCherry, eGFP, and lacZ.
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Falero A, Marrero K, Trigueros S, Fando R. Characterization of the RstB2 protein, the DNA-binding protein of CTXϕ phage from Vibrio cholerae. Virus Genes 2014; 48:518-27. [PMID: 24643345 DOI: 10.1007/s11262-014-1053-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 02/28/2014] [Indexed: 11/25/2022]
Abstract
The low abundant protein RstB2, encoded in the RS2 region of CTXϕ, is essential for prophage formation. However, the only biochemical activity so far described is the single/double-stranded DNA-binding capacity of that protein. In this paper, a recombinant RstB2 (rRstB2) protein was overexpressed in E. coli with a yield of 58.4 mg l(-1) in shaken cultures, LB broth. The protein, purified to homogeneity, showed an identity with rRstB2 by peptide mass fingerprinting. The apparent molecular weight of the RstB2 native protein suggests that occurs mostly as a monomer in solution. The monomers were able of reacting immediately upon exposure to DNA molecules. After a year of storage at -20 °C, the protein remains biologically active. Bioinformatics analysis of the amino acid sequence of RstB2 predicts the C-end of this protein to be disordered and highly flexible, like in many other single-stranded DNA-binding proteins. When compared with the gVp of M13, conserved amino acids are found at structurally or functionally important relative positions. These results pave the way for additional studies of structure and molecular function of RstB2 for the biology of CTXϕ.
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Affiliation(s)
- Alina Falero
- National Center for Scientific Research, Ave 25 and 158, Cubanacán, Playa, PO Box 6214, Havana, Cuba,
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Falero A, Caballero A, Trigueros S, Pérez C, Campos J, Marrero K, Fando R. Characterization of the single-stranded DNA binding protein pV(VGJΦ) of VGJΦ phage from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1814:1107-12. [PMID: 21586349 DOI: 10.1016/j.bbapap.2011.04.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 03/22/2011] [Accepted: 04/21/2011] [Indexed: 01/01/2023]
Abstract
pV(VGJΦ), a single-stranded DNA binding protein of the vibriophage VGJΦ was subject to biochemical analysis. Here, we show that this protein has a general affinity for single-stranded DNA (ssDNA) as documented by Electrophoretic Mobility Shift Assay (EMSA). The apparent molecular weight of the monomer is about 12.7kDa as measured by HPLC-SEC. Moreover, isoelectrofocusing showed an isoelectric point for pV(VGJΦ) of 6.82 pH units. Size exclusion chromatography in 150mM NaCl, 50mM sodium phosphate buffer, pH 7.0 revealed a major protein species of 27.0kDa, suggesting homodimeric protein architecture. Furthermore, pV(VGJΦ) binds ssDNA at extreme temperatures and the complex was stable after extended incubation times. Upon frozen storage at -20°C for a year the protein retained its integrity, biological activity and oligomericity. On the other hand, bioinformatics analysis predicted that pV(VGJΦ) protein has a disordered C-terminal, which might be involved in its functional activity. All the aforementioned features make pV(VGJΦ) interesting for biotechnological applications.
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Affiliation(s)
- Alina Falero
- Department of Molecular Biology, National Center for Scientific Research, Havana, Cuba.
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Das B, Bischerour J, Barre FX. Molecular mechanism of acquisition of the cholera toxin genes. Indian J Med Res 2011; 133:195-200. [PMID: 21415494 PMCID: PMC3089051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One of the major pathogenic determinants of Vibrio cholerae, the cholera toxin, is encoded in the genome of a filamentous phage, CTXφ. CTXφ makes use of the chromosome dimer resolution system of V. cholerae to integrate its single stranded genome into one, the other, or both V. cholerae chromosomes. Here, we review current knowledge about this smart integration process.
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Affiliation(s)
- Bhabatosh Das
- CNRS, Centre de Génétique Moléculaire, Gif-sur-Yvette & Université Paris-Sud, Orsay, France
| | - Julien Bischerour
- CNRS, Centre de Génétique Moléculaire, Gif-sur-Yvette & Université Paris-Sud, Orsay, France
| | - François-Xavier Barre
- CNRS, Centre de Génétique Moléculaire, Gif-sur-Yvette & Université Paris-Sud, Orsay, France,Reprint requests: Dr François-Xavier Barre, CNRS, Centre de Génétique Moléculaire, 91198 Gif-sur-Yvette, France e-mail:
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Campos J, Martínez E, Izquierdo Y, Fando R. VEJ{phi}, a novel filamentous phage of Vibrio cholerae able to transduce the cholera toxin genes. MICROBIOLOGY-SGM 2009; 156:108-115. [PMID: 19833774 DOI: 10.1099/mic.0.032235-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A novel filamentous bacteriophage, designated VEJphi, was isolated from strain MO45 of Vibrio cholerae of the O139 serogroup. A molecular characterization of the phage was carried out, which included sequencing of its whole genome, study of the genomic structure, identification of the phage receptor, and determination of the function of some of the genes, such as those encoding the major capsid protein and the single-stranded DNA-binding protein. The genome nucleotide sequence of VEJphi, which consists of 6842 bp, revealed that it is organized in modules of functionally related genes in an array that is characteristic of the genus Inovirus (filamentous phages). VEJphi is closely related to other previously described filamentous phages of V. cholerae, including VGJphi, VSK and fs1. Like these phages, VEJphi uses as a cellular receptor the type IV fimbria called the mannose-sensitive haemagglutinin (MSHA). It was also demonstrated that VEJphi, like phage VGJphi, is able to transmit the genome of phage CTXphi, and therefore the genes encoding the cholera toxin (CT), horizontally among populations of V. cholerae expressing the MSHA receptor fimbria. This suggests that the variety of phages implicated in the horizontal transmission of the CT genes could be more diverse than formerly thought.
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Affiliation(s)
- Javier Campos
- Department of Molecular Biology, National Center for Scientific Research, Ave 25 y 158 no. 15202, Cubanacán, Playa, Ciudad de la Habana 12100, PO Box 6990, Cuba
| | - Eriel Martínez
- Department of Molecular Biology, National Center for Scientific Research, Ave 25 y 158 no. 15202, Cubanacán, Playa, Ciudad de la Habana 12100, PO Box 6990, Cuba
| | - Yovanny Izquierdo
- Department of Molecular Biology, National Center for Scientific Research, Ave 25 y 158 no. 15202, Cubanacán, Playa, Ciudad de la Habana 12100, PO Box 6990, Cuba
| | - Rafael Fando
- Department of Molecular Biology, National Center for Scientific Research, Ave 25 y 158 no. 15202, Cubanacán, Playa, Ciudad de la Habana 12100, PO Box 6990, Cuba
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