1
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Cao X, Tang L, Song J. Circular Single-Stranded DNA: Discovery, Biological Effects, and Applications. ACS Synth Biol 2024; 13:1038-1058. [PMID: 38501391 DOI: 10.1021/acssynbio.4c00040] [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: 03/20/2024]
Abstract
The field of nucleic acid therapeutics has witnessed a significant surge in recent times, as evidenced by the increasing number of approved genetic drugs. However, current platform technologies containing plasmids, lipid nanoparticle-mRNAs, and adeno-associated virus vectors encounter various limitations and challenges. Thus, we are devoted to finding a novel nucleic acid vector and have directed our efforts toward investigating circular single-stranded DNA (CssDNA), an ancient form of nucleic acid. CssDNAs are ubiquitous, but generally ignored. Accumulating evidence suggests that CssDNAs possess exceptional properties as nucleic acid vectors, exhibiting great potential for clinical applications in genetic disorders, gene editing, and immune cell therapy. Here, we comprehensively review the discovery and biological effects of CssDNAs as well as their applications in the field of biomedical research for the first time. Undoubtedly, as an ancient form of DNA, CssDNA holds immense potential and promises novel insights for biomedical research.
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Affiliation(s)
- Xisen Cao
- Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Linlin Tang
- Hangzhou Institute of Medicine, Chinese Academy of Sciences, Hangzhou 310022, China
| | - Jie Song
- Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Hangzhou Institute of Medicine, Chinese Academy of Sciences, Hangzhou 310022, China
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2
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Torralba B, Blanc S, Michalakis Y. Reassortments in single-stranded DNA multipartite viruses: Confronting expectations based on molecular constraints with field observations. Virus Evol 2024; 10:veae010. [PMID: 38384786 PMCID: PMC10880892 DOI: 10.1093/ve/veae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/23/2023] [Accepted: 01/30/2024] [Indexed: 02/23/2024] Open
Abstract
Single-stranded DNA multipartite viruses, which mostly consist of members of the genus Begomovirus, family Geminiviridae, and all members of the family Nanoviridae, partly resolve the cost of genomic integrity maintenance through two remarkable capacities. They are able to systemically infect a host even when their genomic segments are not together in the same host cell, and these segments can be separately transmitted by insect vectors from host to host. These capacities potentially allow such viruses to reassort at a much larger spatial scale, since reassortants could arise from parental genotypes that do not co-infect the same cell or even the same host. To assess the limitations affecting reassortment and their implications in genome integrity maintenance, the objective of this review is to identify putative molecular constraints influencing reassorted segments throughout the infection cycle and to confront expectations based on these constraints with empirical observations. Trans-replication of the reassorted segments emerges as the major constraint, while encapsidation, viral movement, and transmission compatibilities appear more permissive. Confronting the available molecular data and the resulting predictions on reassortments to field population surveys reveals notable discrepancies, particularly a surprising rarity of interspecific natural reassortments within the Nanoviridae family. These apparent discrepancies unveil important knowledge gaps in the biology of ssDNA multipartite viruses and call for further investigation on the role of reassortment in their biology.
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Affiliation(s)
- Babil Torralba
- PHIM, Université Montpellier, IRD, CIRAD, INRAE, Institut Agro, Avenue du Campus d’Agropolis - ZAC de Baillarguet, Montpellier 34980, France
| | - Stéphane Blanc
- PHIM, Université Montpellier, IRD, CIRAD, INRAE, Institut Agro, Avenue du Campus d’Agropolis - ZAC de Baillarguet, Montpellier 34980, France
| | - Yannis Michalakis
- MIVEGEC, Université Montpellier, CNRS, IRD, 911, Avenue Agropolis, Montpellier 34394, France
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3
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Bonnamy M, Blanc S, Michalakis Y. Replication mechanisms of circular ssDNA plant viruses and their potential implication in viral gene expression regulation. mBio 2023; 14:e0169223. [PMID: 37695133 PMCID: PMC10653810 DOI: 10.1128/mbio.01692-23] [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: 09/12/2023] Open
Abstract
The replication of members of the two circular single-stranded DNA (ssDNA) virus families Geminiviridae and Nanoviridae, the only ssDNA viruses infecting plants, is believed to be processed by rolling-circle replication (RCR) and recombination-dependent replication (RDR) mechanisms. RCR is a ubiquitous replication mode for circular ssDNA viruses and involves a virus-encoded Replication-associated protein (Rep) which fulfills multiple functions in the replication mechanism. Two key genomic elements have been identified for RCR in Geminiviridae and Nanoviridae: (i) short iterative sequences called iterons which determine the specific recognition of the viral DNA by the Rep and (ii) a sequence enabling the formation of a stem-loop structure which contains a conserved motif and constitutes the origin of replication. In addition, studies in Geminiviridae provided evidence for a second replication mode, RDR, which has also been documented in some double-stranded DNA viruses. Here, we provide a synthesis of the current understanding of the two presumed replication modes of Geminiviridae and Nanoviridae, and we identify knowledge gaps and discuss the possibility that these replication mechanisms could regulate viral gene expression through modulation of gene copy number.
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Affiliation(s)
- Mélia Bonnamy
- PHIM, Univ Montpellier, IRD, CIRAD, INRAE, Institut Agro, Montpellier, France
- MIVEGEC, CNRS, IRD, Univ Montpellier, Montpellier, France
| | - Stéphane Blanc
- PHIM, Univ Montpellier, IRD, CIRAD, INRAE, Institut Agro, Montpellier, France
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4
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Siskos L, Antoniou M, Riado J, Enciso M, Garcia C, Liberti D, Esselink D, Baranovskiy AG, Tahirov TH, Visser RGF, Kormelink R, Bai Y, Schouten HJ. DNA primase large subunit is an essential plant gene for geminiviruses, putatively priming viral ss-DNA replication. FRONTIERS IN PLANT SCIENCE 2023; 14:1130723. [PMID: 37008458 PMCID: PMC10064052 DOI: 10.3389/fpls.2023.1130723] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 03/03/2023] [Indexed: 06/19/2023]
Abstract
The family of Geminiviridae consists of more than 500 circular single-stranded (ss) DNA viral species that can infect numerous dicot and monocot plants. Geminiviruses replicate their genome in the nucleus of a plant cell, taking advantage of the host's DNA replication machinery. For converting their DNA into double-stranded DNA, and subsequent replication, these viruses rely on host DNA polymerases. However, the priming of the very first step of this process, i.e. the conversion of incoming circular ssDNA into a dsDNA molecule, has remained elusive for almost 30 years. In this study, sequencing of melon (Cucumis melo) accession K18 carrying the Tomato leaf curl New Delhi virus (ToLCNDV) recessive resistance quantitative trait locus (QTL) in chromosome 11, and analyses of DNA sequence data from 100 melon genomes, showed a conservation of a shared mutation in the DNA Primase Large subunit (PRiL) of all accessions that exhibited resistance upon a challenge with ToLCNDV. Silencing of (native) Nicotiana benthamiana PriL and subsequent challenging with three different geminiviruses showed a severe reduction in titers of all three viruses, altogether emphasizing an important role of PRiL in geminiviral replication. A model is presented explaining the role of PriL during initiation of geminiviral DNA replication, i.e. as a regulatory subunit of primase that generates an RNA primer at the onset of DNA replication in analogy to DNA Primase-mediated initiation of DNA replication in all living organisms.
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Affiliation(s)
- Lampros Siskos
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
| | - Maria Antoniou
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
| | - Jose Riado
- Sakata Vegetables Europe, Almeria, Spain
| | | | | | | | - Danny Esselink
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
| | - Andrey G. Baranovskiy
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, United States
| | - Tahir H. Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, United States
| | - Richard G. F. Visser
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
| | - Richard Kormelink
- Laboratory of Virology, Wageningen University and Research, Wageningen, Netherlands
| | - Yuling Bai
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
| | - Henk J. Schouten
- Laboratory of Plant Breeding, Wageningen University and Research, Wageningen, Netherlands
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5
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Wei H, Lozano-Durán R. The primase subunits of DNA polymerase α, PRIM1 and PRIM2, are required for the replication of the geminivirus tomato yellow leaf curl virus in the host plant. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000735. [PMID: 36685730 PMCID: PMC9853271 DOI: 10.17912/micropub.biology.000735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/01/2023] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Geminiviruses are causal agents of devastating diseases in crops. Geminiviral genomes are single-stranded (ss) circular DNA molecules that replicate in the nucleus of the infected cell through double-stranded (ds) intermediates by co-opting the plant DNA replication machinery. However, the identity of the plant DNA polymerases enabling geminiviral replication has remained largely elusive. Recently, we showed that DNA polymerase α mediates the ss-to-ds conversion of tomato yellow leaf curl virus (TYLCV), and is therefore essential for the infection. Here, we provide data indicating that the primase subunits of DNA polymerase α, PRIM1 and PRIM2, are also required for TYLCV replication.
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Affiliation(s)
- Hua Wei
- Department of Plant Biochemistry, Centre for Plant Molecular Biology (ZMBP), Eberhard Karls University, D-72076 Tübingen, Germany.
,
Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Rosa Lozano-Durán
- Department of Plant Biochemistry, Centre for Plant Molecular Biology (ZMBP), Eberhard Karls University, D-72076 Tübingen, Germany.
,
Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China.
,
Correspondence to: Rosa Lozano-Durán (
)
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6
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Voorburg CM, Bai Y, Kormelink R. Small RNA Profiling of Susceptible and Resistant Ty-1 Encoding Tomato Plants Upon Tomato Yellow Leaf Curl Virus Infection. FRONTIERS IN PLANT SCIENCE 2021; 12:757165. [PMID: 34868151 PMCID: PMC8637622 DOI: 10.3389/fpls.2021.757165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
Ty-1 presents an atypical dominant resistance gene that codes for an RNA-dependent RNA polymerase (RDR) of the gamma class and confers resistance to tomato yellow leaf curl virus (TYLCV) and other geminiviruses. Tomato lines bearing Ty-1 not only produce relatively higher amounts of viral small interfering (vsi)RNAs, but viral DNA also exhibits a higher amount of cytosine methylation. Whether Ty-1 specifically enhances posttranscriptional gene silencing (PTGS), leading to a degradation of RNA target molecules and primarily relying on 21-22 nucleotides (nts) siRNAs, and/or transcriptional gene silencing (TGS), leading to the methylation of cytosines within DNA target sequences and relying on 24-nts siRNAs, was unknown. In this study, small RNAs were isolated from systemically TYLCV-infected leaves of Ty-1 encoding tomato plants and susceptible tomato Moneymaker (MM) and sequence analyzed. While in susceptible tomato plants vsiRNAs of the 21-nt size class were predominant, their amount was drastically reduced in tomato containing Ty-1. The latter, instead, revealed elevated levels of vsiRNAs of the 22- and 24-nt size classes. In addition, the genomic distribution profiles of the vsiRNAs were changed in Ty-1 plants compared with those from susceptible MM. In MM three clear hotspots were seen, but these were less pronounced in Ty-1 plants, likely due to enhanced transitive silencing to neighboring viral genomic sequences. The largest increase in the amount of vsiRNAs was observed in the intergenic region and the V1 viral gene. The results suggest that Ty-1 enhances an antiviral TGS response. Whether the elevated levels of 22 nts vsiRNAs contribute to an enhanced PTGS response or an additional TGS response involving a noncanonical pathway of RNA dependent DNA methylation remains to be investigated.
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Affiliation(s)
- Corien M. Voorburg
- Laboratory of Virology, Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
| | - Yuling Bai
- Plant Breeding, Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
| | - Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
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7
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Ruhel R, Mazumder M, Gnanasekaran P, Kumar M, Gourinath S, Chakraborty S. Functional implications of residues of the B' motif of geminivirus replication initiator protein in its helicase activity. FEBS J 2021; 288:6492-6509. [PMID: 34092039 DOI: 10.1111/febs.16053] [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: 11/20/2020] [Revised: 04/15/2021] [Accepted: 06/04/2021] [Indexed: 01/03/2023]
Abstract
Geminivirus replication initiator protein (Rep) is a multifunctional viral protein required for replication. During the process of viral replication, Rep acts as a site- and strand-specific endonuclease, ligase, ATPase, and helicase. B' motif and β-hairpin loop of the geminivirus Rep are conserved and important for Rep-mediated helicase activity required for viral replication. To dissect the roles of various amino acid residues of the B' motif and β-hairpin loop of the geminivirus Rep helicase in its process of unwinding DNA, we investigated eight conserved residues near the ATP active site or the ssDNA contact channel. Our strategy was to mutate these residues to alanines and investigate the effects of these mutations on various biochemical activities associated with DNA unwinding. We looked into the ATP binding, ATP hydrolysis, DNA binding, and DNA unwinding activities of the wild-type and mutant Rep proteins. These investigations showed four residues (Arg279, Asp280, Tyr287, and Pro290) affecting the DNA unwinding activity. A structural model analysis confirmed the B' loop and ssDNA binding loop to be connected through a β-hairpin structure, suggesting that changes on one loop might affect the other and that these residues function by acting in concert. Viral genomes containing Rep proteins having these mutations in the B' motif did not replicate in planta. Taken together, these results indicated all four residues to be implicated in helicase activity mediated by Rep and demonstrated the significance, for viral replication, of the B' motif and β-hairpin loop of the C-terminal region of the Rep protein.
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Affiliation(s)
- Rajrani Ruhel
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mohit Mazumder
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Prabu Gnanasekaran
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Manish Kumar
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Samudrala Gourinath
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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8
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Sáez C, Flores-León A, Montero-Pau J, Sifres A, Dhillon NPS, López C, Picó B. RNA-Seq Transcriptome Analysis Provides Candidate Genes for Resistance to Tomato Leaf Curl New Delhi Virus in Melon. FRONTIERS IN PLANT SCIENCE 2021; 12:798858. [PMID: 35116050 PMCID: PMC8805612 DOI: 10.3389/fpls.2021.798858] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 11/29/2021] [Indexed: 05/10/2023]
Abstract
Tomato leaf curl New Delhi virus (ToLCNDV) emerged in the Mediterranean Basin in 2012 as the first DNA bipartite begomovirus (Geminiviridae family), causing severe yield and economic losses in cucurbit crops. A major resistance locus was identified in the wild melon accession WM-7 (Cucumis melo kachri group), but the mechanisms involved in the resistant response remained unknown. In this work, we used RNA-sequencing to identify disease-associated genes that are differentially expressed in the course of ToLCNDV infection and could contribute to resistance. Transcriptomes of the resistant WM-7 genotype and the susceptible cultivar Piñonet Piel de Sapo (PS) (C. melo ibericus group) in ToLCNDV and mock inoculated plants were compared at four time points during infection (0, 3, 6, and 12 days post inoculation). Different gene expression patterns were observed over time in the resistant and susceptible genotypes in comparison to their respective controls. Differentially expressed genes (DEGs) in ToLCNDV-infected plants were classified using gene ontology (GO) terms, and genes of the categories transcription, DNA replication, and helicase activity were downregulated in WM-7 but upregulated in PS, suggesting that reduced activity of these functions reduces ToLCNDV replication and intercellular spread and thereby contributes to resistance. DEGs involved in the jasmonic acid signaling pathway, photosynthesis, RNA silencing, transmembrane, and sugar transporters entail adverse consequences for systemic infection in the resistant genotype, and lead to susceptibility in PS. The expression levels of selected candidate genes were validated by qRT-PCR to corroborate their differential expression upon ToLCNDV infection in resistant and susceptible melon. Furthermore, single nucleotide polymorphism (SNPs) with an effect on structural functionality of DEGs linked to the main QTLs for ToLCNDV resistance have been identified. The obtained results pinpoint cellular functions and candidate genes that are differentially expressed in a resistant and susceptible melon line in response to ToLCNDV, an information of great relevance for breeding ToLCNDV-resistant melon cultivars.
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Affiliation(s)
- Cristina Sáez
- Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, Valencia, Spain
- *Correspondence: Cristina Sáez,
| | - Alejandro Flores-León
- Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, Valencia, Spain
| | - Javier Montero-Pau
- Cavanilles Institute of Biodiversity and Evolutionary Biology, Universitat de València, Valencia, Spain
| | - Alicia Sifres
- Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, Valencia, Spain
| | - Narinder P. S. Dhillon
- World Vegetable Center, East and Southeast Asia, Research and Training Station, Kasetsart University, Nakhon Pathom, Thailand
| | - Carmelo López
- Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, Valencia, Spain
- Carmelo López,
| | - Belén Picó
- Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, Valencia, Spain
- Belén Picó,
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9
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Characterization of Local and Systemic Impact of Whitefly ( Bemisia tabaci) Feeding and Whitefly-Transmitted Tomato Mottle Virus Infection on Tomato Leaves by Comprehensive Proteomics. Int J Mol Sci 2020; 21:ijms21197241. [PMID: 33008056 PMCID: PMC7583044 DOI: 10.3390/ijms21197241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/21/2020] [Accepted: 09/26/2020] [Indexed: 11/23/2022] Open
Abstract
Tomato mottle virus (ToMoV) is a single-stranded DNA (ssDNA) begomovirus transmitted to solanaceous crops by the whitefly species complex (Bemisia tabaci), causing stunted growth, leaf mottling, and reduced yield. Using a genetic repertoire of seven genes, ToMoV pathogenesis includes the manipulation of multiple plant biological processes to circumvent antiviral defenses. To further understand the effects of whitefly feeding and whitefly-transmitted ToMoV infection on tomato plants (Solanum lycopersicum ‘Florida Lanai’), we generated comprehensive protein profiles of leaves subjected to feeding by either viruliferous whiteflies harboring ToMoV, or non-viruliferous whiteflies, or a no-feeding control. The effects of whitefly feeding and ToMoV infection were measured both locally and systemically by sampling either a mature leaf directly from the site of clip-cage confined whitefly feeding, or from a newly formed leaf 10 days post feeding (dpf). At 3 dpf, tomato’s response to ToMoV included proteins associated with translation initiation and elongation as well as plasmodesmata dynamics. In contrast, systemic impacts of ToMoV on younger leaves 10 dpf were more pronounced and included a virus-specific change in plant proteins associated with mRNA maturation and export, RNA-dependent DNA methylation, and other antiviral plant processes. Our analysis supports previous findings and provides novel insight into tomato’s local and systemic response to whitefly feeding and ToMoV infection.
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10
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Jeske H. Barcoding of Plant Viruses with Circular Single-Stranded DNA Based on Rolling Circle Amplification. Viruses 2018; 10:E469. [PMID: 30200312 PMCID: PMC6164888 DOI: 10.3390/v10090469] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 01/10/2023] Open
Abstract
The experience with a diagnostic technology based on rolling circle amplification (RCA), restriction fragment length polymorphism (RFLP) analyses, and direct or deep sequencing (Circomics) over the past 15 years is surveyed for the plant infecting geminiviruses, nanoviruses and associated satellite DNAs, which have had increasing impact on agricultural and horticultural losses due to global transportation and recombination-aided diversification. Current state methods for quarantine measures are described to identify individual DNA components with great accuracy and to recognize the crucial role of the molecular viral population structure as an important factor for sustainable plant protection.
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Affiliation(s)
- Holger Jeske
- Department of Molecular Biology and Plant Virology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
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11
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Saeed ST, Samad A. Emerging threats of begomoviruses to the cultivation of medicinal and aromatic crops and their management strategies. Virusdisease 2017; 28:1-17. [PMID: 28466050 PMCID: PMC5377872 DOI: 10.1007/s13337-016-0358-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 12/30/2016] [Indexed: 12/01/2022] Open
Abstract
Begomoviruses (family Geminiviridae) are responsible for extreme yield reduction in a number of economically important crops including medicinal and aromatic plants (MAPs). Emergence of new variants of viruses due to recombination and mutations in the genomes, modern cropping systems, introduction of susceptible plant varieties, global trade in agricultural products, and changes in climatic conditions are responsible for aggravating the begomovirus problems during the last two decades. This review summaries the current research work on begomoviruses affecting MAPs and provides various traditional and advanced strategies for the management of begomoviruses and vector in MAPs.
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Affiliation(s)
- Sana Tabanda Saeed
- Department of Plant Pathology, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, 226015 India
| | - Abdul Samad
- Department of Plant Pathology, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, 226015 India
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12
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Deuschle K, Kepp G, Jeske H. Differential methylation of the circular DNA in geminiviral minichromosomes. Virology 2016; 499:243-258. [PMID: 27716464 DOI: 10.1016/j.virol.2016.09.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/22/2016] [Accepted: 09/24/2016] [Indexed: 10/20/2022]
Abstract
Geminiviral minichromosomes were purified to explore epigenetic modifications. The levels of methylation in their covalently closed circular DNA were examined with the help of methylation-dependent restriction (MdR). DNA with 12 superhelical turns was preferentially modified, indicating minichromosomes with 12 nucleosomes leaving an open gap. MdR digestion yielded a specific product of genomic length, which was cloned and Sanger-sequenced, or amplified following ligation-mediated rolling circle amplification and deep-sequenced (circomics). The conventional approach revealed a single cleavage product indicating specific methylations at the borders of the common region. The circomics approach identified considerably more MdR sites in a preferential distance to each other of ~200 nts, which is the DNA length in a nucleosome. They accumulated in regions of nucleosome-free gaps, but scattered also along the genomic components. These results may hint at a function in specific gene regulation, as well as in virus resistance.
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Affiliation(s)
- Kathrin Deuschle
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Gabi Kepp
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Holger Jeske
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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13
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Hipp K, Rau P, Schäfer B, Pfannstiel J, Jeske H. Translation, modification and cellular distribution of two AC4 variants of African cassava mosaic virus in yeast and their pathogenic potential in plants. Virology 2016; 498:136-148. [PMID: 27584591 DOI: 10.1016/j.virol.2016.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 07/05/2016] [Accepted: 07/07/2016] [Indexed: 11/29/2022]
Abstract
Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential.
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Affiliation(s)
- Katharina Hipp
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
| | - Peter Rau
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Benjamin Schäfer
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Jens Pfannstiel
- University of Hohenheim, Mass Spectrometry Core Facility, August-von-Hartmann-Straße 3, 70599 Stuttgart, Germany
| | - Holger Jeske
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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14
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Richter KS, Serra H, White CI, Jeske H. The recombination mediator RAD51D promotes geminiviral infection. Virology 2016; 493:113-27. [PMID: 27018825 DOI: 10.1016/j.virol.2016.03.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/15/2016] [Accepted: 03/18/2016] [Indexed: 11/28/2022]
Abstract
To study a possible role for homologous recombination in geminivirus replication, we challenged Arabidopsis recombination gene knockouts by Euphorbia yellow mosaic virus infection. Our results show that the RAD51 paralog RAD51D, rather than RAD51 itself, promotes viral replication at early stages of infection. Blot hybridization analyses of replicative intermediates using one- and two-dimensional gels and deep sequencing point to an unexpected facet of recombination-dependent replication, the repair by single-strand annealing (SSA) during complementary strand replication. A significant decrease of both intramolecular, yielding defective DNAs and intermolecular recombinant molecules between the two geminiviral DNA components (A, B) were observed in the absence of RAD51D. By contrast, DNA A and B reacted differentially with the generation of inversions. A model to implicate single-strand annealing recombination in geminiviral recombination-dependent replication is proposed.
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Affiliation(s)
- Kathrin S Richter
- Institute of Biomaterials and Biomolecular Systems, Department of Molecular Biology and Plant Virology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Heϊdi Serra
- Génétique, Reproduction et Développement, UMR CNRS 6293-Clermont Université- INSERM U1103 Aubière, France
| | - Charles I White
- Génétique, Reproduction et Développement, UMR CNRS 6293-Clermont Université- INSERM U1103 Aubière, France
| | - Holger Jeske
- Institute of Biomaterials and Biomolecular Systems, Department of Molecular Biology and Plant Virology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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15
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Paprotka T, Deuschle K, Pilartz M, Jeske H. Form follows function in geminiviral minichromosome architecture. Virus Res 2015; 196:44-55. [PMID: 25445344 DOI: 10.1016/j.virusres.2014.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 10/24/2022]
Abstract
A comprehensive survey on the viral minichromosomes of the begomoviruses Abutilon mosaic virus, tomato yellow leaf curl Sardinia virus, African cassava mosaic virus, Indian cassava mosaic virus (family Geminiviridae) during the course of infections in Nicotiana benthamiana is summarized. Using optimized one-dimensional and two-dimensional gel systems combined with blot hybridization and a standardized evaluation, discrete and heterogeneous virus-specific signals with different DNA forms were compared to trace functions of viral multiplication with inactive/active replication and/or transcription. A quantitative approach to compare the distantly related viruses during the course of infection with the aim to generalize the conclusions for geminiviruses has been developed. Focussing on the distribution of topoisomers of viral supercoiled DNA, which reflect minichromosomal stages, predominant minichromosomes with 12 nucleosomes, less with 13 nucleosomes and no with 11 nucleosomes were found. These results indicate that chromatin with only one open gap to bind transcription factors is the favourite form. The dynamics during infections in dependence on the experimental conditions is discussed with reference to the design of experiments for resistance breeding and molecular analyses.
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Affiliation(s)
- Tobias Paprotka
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Kathrin Deuschle
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Marcel Pilartz
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Holger Jeske
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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16
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Insights into the functional characteristics of geminivirus rolling-circle replication initiator protein and its interaction with host factors affecting viral DNA replication. Arch Virol 2014; 160:375-87. [PMID: 25449306 DOI: 10.1007/s00705-014-2297-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
Geminiviruses are DNA viruses that infect several economically important crops, resulting in a reduction in their overall yield. These plant viruses have circular, single-stranded DNA genomes that replicate mainly by a rolling-circle mechanism. Geminivirus infection results in crosstalk between viral and cellular factors to complete the viral life cycle or counteract the infection as part of defense mechanisms of host plants. The geminiviral replication initiator protein Rep is the only essential viral factor required for replication. It is multifunctional and is known to interact with a number of host factors to modulate the cellular environment or to function as a part of the replication machinery. This review provides a holistic view of the research related to the viral Rep protein and various host factors involved in geminiviral DNA replication. Studies on the promiscuous nature of geminiviral satellite DNAs are also reviewed.
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17
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Hull R. Replication of Plant Viruses. PLANT VIROLOGY 2014. [PMCID: PMC7184227 DOI: 10.1016/b978-0-12-384871-0.00007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses co-infecting cells. Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses coinfecting cells.
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18
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Hanley-Bowdoin L, Bejarano ER, Robertson D, Mansoor S. Geminiviruses: masters at redirecting and reprogramming plant processes. Nat Rev Microbiol 2013; 11:777-88. [DOI: 10.1038/nrmicro3117] [Citation(s) in RCA: 484] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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19
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Pooggin MM. How can plant DNA viruses evade siRNA-directed DNA methylation and silencing? Int J Mol Sci 2013; 14:15233-59. [PMID: 23887650 PMCID: PMC3759858 DOI: 10.3390/ijms140815233] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 07/01/2013] [Accepted: 07/01/2013] [Indexed: 11/16/2022] Open
Abstract
Plants infected with DNA viruses produce massive quantities of virus-derived, 24-nucleotide short interfering RNAs (siRNAs), which can potentially direct viral DNA methylation and transcriptional silencing. However, growing evidence indicates that the circular double-stranded DNA accumulating in the nucleus for Pol II-mediated transcription of viral genes is not methylated. Hence, DNA viruses most likely evade or suppress RNA-directed DNA methylation. This review describes the specialized mechanisms of replication and silencing evasion evolved by geminiviruses and pararetoviruses, which rescue viral DNA from repressive methylation and interfere with transcriptional and post-transcriptional silencing of viral genes.
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Affiliation(s)
- Mikhail M Pooggin
- University of Basel, Department of Environmental Sciences, Botany, Schönbeinstrasse 6, Basel 4056, Switzerland.
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20
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Cheung AK. Replicative intermediates of porcine circovirus in animal tissue cultured cells or in bacteria undergoing copy-release replication. Virology 2012; 434:38-42. [PMID: 22939286 DOI: 10.1016/j.virol.2012.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/03/2012] [Accepted: 08/14/2012] [Indexed: 10/27/2022]
Abstract
Porcine circovirus (PCV) has been assumed to replicate its genome via the rolling-circle replication (RCR) mechanism because it encodes a Rep protein that contains several amino acid motifs commonly found in other RCR biological systems. Two proteins, Rep and Rep', are essential for PCV DNA replication in mammalian cells. In this work, replicative intermediates of PCV-infected porcine kidney (PK15) cells or copy-release of PCV genomes from a head-to-tail tandem construct (without Rep') in Escherichia coli were examined. In PK15 cells, replicative intermediates consistent with complementary-strand replication which converts single-stranded circular genome to double-stranded supercoiled DNA and RCR which generates single-stranded plus strand progeny genome were observed. To a lesser extent, intermediates suggestive of recombination-dependent replication were also detected. In Escherichia coli, copy release of the single-stranded circular PCV genome with conversion to a supercoiled molecule by complementary-strand synthesis was observed. However, replicative intermediates indicative of RCR were not detected.
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Affiliation(s)
- Andrew K Cheung
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
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21
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Cheung AK. Porcine circovirus: transcription and DNA replication. Virus Res 2011; 164:46-53. [PMID: 22036834 DOI: 10.1016/j.virusres.2011.10.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 10/14/2011] [Accepted: 10/15/2011] [Indexed: 12/18/2022]
Abstract
This review summarizes the molecular studies pertaining to porcine circovirus (PCV) transcription and DNA replication. The genome of PCV is circular, single-stranded DNA and contains 1759-1768 nucleotides. Both the genome-strand (packaged in the virus particle) and the complementary-strand (synthesized in the new host) encode viral proteins. Among a multitude of RNAs synthesized by alternate splicing, only rep and rep' are essential for virus DNA replication via the rolling-circle replication (RCR) mechanism. In contrast to other RCR biological systems which utilize only one multi-functional protein, Rep, to replicate their respective genomes, PCV requires two proteins, Rep and Rep'. During DNA synthesis, the PCV origin of DNA replication (Ori), which contains a pair of inverted repeats (palindrome), exists in a destabilized four-stranded configuration (the melting-pot model) and permits both the palindromic-strand and the complementary-strand to serve as templates simultaneously for initiation and termination. Inherent in the "melting-pot" model is the template-strand-switching mechanism. This mechanism is the basis for the "correction or conversion" of any mutated nucleotide sequences engineered into either arm of the palindrome and the incorporation of "illegitimate recombination" (addition or deletion of nucleotides) events that are commonly observed at the Ori of other RCR biological systems during DNA replication.
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Affiliation(s)
- Andrew K Cheung
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
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22
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Reconstructing the history of maize streak virus strain a dispersal to reveal diversification hot spots and its origin in southern Africa. J Virol 2011; 85:9623-36. [PMID: 21715477 DOI: 10.1128/jvi.00640-11] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Maize streak virus strain A (MSV-A), the causal agent of maize streak disease, is today one of the most serious biotic threats to African food security. Determining where MSV-A originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. Similarly, determining where the major extant MSV-A lineages arose could identify geographical hot spots of MSV evolution. Here, we use model-based phylogeographic analyses of 353 fully sequenced MSV-A isolates to reconstruct a plausible history of MSV-A movements over the past 150 years. We show that since the probable emergence of MSV-A in southern Africa around 1863, the virus spread transcontinentally at an average rate of 32.5 km/year (95% highest probability density interval, 15.6 to 51.6 km/year). Using distinctive patterns of nucleotide variation caused by 20 unique intra-MSV-A recombination events, we tentatively classified the MSV-A isolates into 24 easily discernible lineages. Despite many of these lineages displaying distinct geographical distributions, it is apparent that almost all have emerged within the past 4 decades from either southern or east-central Africa. Collectively, our results suggest that regular analysis of MSV-A genomes within these diversification hot spots could be used to monitor the emergence of future MSV-A lineages that could affect maize cultivation in Africa.
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23
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Shepherd DN, Martin DP, Van Der Walt E, Dent K, Varsani A, Rybicki EP. Maize streak virus: an old and complex 'emerging' pathogen. MOLECULAR PLANT PATHOLOGY 2010; 11:1-12. [PMID: 20078771 PMCID: PMC6640477 DOI: 10.1111/j.1364-3703.2009.00568.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
UNLABELLED Maize streak virus (MSV; Genus Mastrevirus, Family Geminiviridae) occurs throughout Africa, where it causes what is probably the most serious viral crop disease on the continent. It is obligately transmitted by as many as six leafhopper species in the Genus Cicadulina, but mainly by C. mbila Naudé and C. storeyi. In addition to maize, it can infect over 80 other species in the Family Poaceae. Whereas 11 strains of MSV are currently known, only the MSV-A strain is known to cause economically significant streak disease in maize. Severe maize streak disease (MSD) manifests as pronounced, continuous parallel chlorotic streaks on leaves, with severe stunting of the affected plant and, usuallly, a failure to produce complete cobs or seed. Natural resistance to MSV in maize, and/or maize infections caused by non-maize-adapted MSV strains, can result in narrow, interrupted streaks and no obvious yield losses. MSV epidemiology is primarily governed by environmental influences on its vector species, resulting in erratic epidemics every 3-10 years. Even in epidemic years, disease incidences can vary from a few infected plants per field, with little associated yield loss, to 100% infection rates and complete yield loss. TAXONOMY The only virus species known to cause MSD is MSV, the type member of the Genus Mastrevirus in the Family Geminiviridae. In addition to the MSV-A strain, which causes the most severe form of streak disease in maize, 10 other MSV strains (MSV-B to MSV-K) are known to infect barley, wheat, oats, rye, sugarcane, millet and many wild, mostly annual, grass species. Seven other mastrevirus species, many with host and geographical ranges partially overlapping those of MSV, appear to infect primarily perennial grasses. PHYSICAL PROPERTIES MSV and all related grass mastreviruses have single-component, circular, single-stranded DNA genomes of approximately 2700 bases, encapsidated in 22 x 38-nm geminate particles comprising two incomplete T = 1 icosahedra, with 22 pentameric capsomers composed of a single 32-kDa capsid protein. Particles are generally stable in buffers of pH 4-8. DISEASE SYMPTOMS In infected maize plants, streak disease initially manifests as minute, pale, circular spots on the lowest exposed portion of the youngest leaves. The only leaves that develop symptoms are those formed after infection, with older leaves remaining healthy. As the disease progresses, newer leaves emerge containing streaks up to several millimetres in length along the leaf veins, with primary veins being less affected than secondary or tertiary veins. The streaks are often fused laterally, appearing as narrow, broken, chlorotic stripes, which may extend over the entire length of severely affected leaves. Lesion colour generally varies from white to yellow, with some virus strains causing red pigmentation on maize leaves and abnormal shoot and flower bunching in grasses. Reduced photosynthesis and increased respiration usually lead to a reduction in leaf length and plant height; thus, maize plants infected at an early stage become severely stunted, producing undersized, misshapen cobs or giving no yield at all. Yield loss in susceptible maize is directly related to the time of infection: infected seedlings produce no yield or are killed, whereas plants infected at later times are proportionately less affected. DISEASE CONTROL Disease avoidance can be practised by only planting maize during the early season when viral inoculum loads are lowest. Leafhopper vectors can also be controlled with insecticides such as carbofuran. However, the development and use of streak-resistant cultivars is probably the most effective and economically viable means of preventing streak epidemics. Naturally occurring tolerance to MSV (meaning that, although plants become systemically infected, they do not suffer serious yield losses) has been found, which has primarily been attributed to a single gene, msv-1. However, other MSV resistance genes also exist and improved resistance has been achieved by concentrating these within individual maize genotypes. Whereas true MSV immunity (meaning that plants cannot be symptomatically infected by the virus) has been achieved in lines that include multiple small-effect resistance genes together with msv-1, it has proven difficult to transfer this immunity into commercial maize genotypes. An alternative resistance strategy using genetic engineering is currently being investigated in South Africa. USEFUL WEBSITES http://www.mcb.uct.ac.za/MSV/mastrevirus.htm; http://www.danforthcenter.org/iltab/geminiviridae/geminiaccess/mastrevirus/Mastrevirus.htm.
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Affiliation(s)
- Dionne N Shepherd
- Department of Molecular and Cell Biology, University of Cape Town, PB Rondebosch, 7701, South Africa.
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24
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Faurez F, Dory D, Grasland B, Jestin A. Replication of porcine circoviruses. Virol J 2009; 6:60. [PMID: 19450240 PMCID: PMC2690592 DOI: 10.1186/1743-422x-6-60] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Accepted: 05/18/2009] [Indexed: 02/05/2023] Open
Abstract
Porcine circoviruses are circular single-stranded DNA viruses that infect swine and wild boars. Two species of porcine circoviruses exist. Porcine circovirus type 1 is non pathogenic contrary to porcine circovirus type 2 which is associated with the disease known as Post-weaning Multisystemic Wasting Syndrome. Porcine circovirus DNA has been shown to replicate by a rolling circle mechanism. Other studies have revealed similar mechanisms of rolling-circle replication in plasmids and single-stranded viruses such as Geminivirus. Three elements are important in rolling-circle replication: i) a gene encoding initiator protein, ii) a double strand origin, and iii) a single strand origin. However, differences exist between viruses and plasmids and between viruses. Porcine circovirus replication probably involves a "melting pot" rather than "cruciform" rolling-circle mechanism. This review provides a summary of current knowledge of replication in porcine circoviruses as models of the Circovirus genus. Based on various studies, the factors affecting replication are defined and the mechanisms involved in the different phases of replication are described or proposed.
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Affiliation(s)
- Florence Faurez
- French Food Safety Agency, Viral Genetics and Biosafety Unit, Ploufragan, France.
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25
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Abstract
The replication-associated protein (Rep) of geminiviruses, single-stranded DNA viruses of higher plants, is essential for virus replication. Since these viruses do not encode their own polymerases, Rep induces differentiated plant cells to reenter the cell cycle by interacting with the plant homologues of retinoblastoma proteins in order to activate the host DNA synthesis machinery. We have used fission yeast (Schizosaccharomyces pombe) as a model organism to analyze the impact of ectopically expressed African cassava mosaic virus Rep protein on the cell division cycle in closer detail. Upon expression, Rep showed its characteristic DNA cleavage activity, and about 10% of the cells exhibited morphological changes. They were elongated threefold, on average, and possessed a single but enlarged and less compact nucleus in comparison to noninduced or vector-only control cells. Flow cytometry of Rep-expressing cultures revealed a distinct subpopulation of Rep protein-containing cells with aberrant morphology. The other 90% of the cells were indistinguishable from control cells, and no Rep was detectable. Rep-expressing cells exhibited DNA contents beyond 2C, indicating ongoing replication without intervening mitosis. Because a second open reading frame (ORF), AC4, is present within the Rep gene, the role of AC4 was examined by destroying its start codon within the AC1 ORF. The results confirmed that Rep is necessary and sufficient to induce rereplication in fission yeast. The unique potential of this well-investigated model for dissecting the cell cycle control by geminiviral proteins is discussed.
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26
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Abstract
The technique described was developed for the separation of begomovirus DNA. DNA products resulting from and during geminiviral replication are characterized by the application of strand-specific separation and identification by strand-specific DNA probing of Southern blots. The mapping of the initiation site of complementary-strand DNA synthesis, by this technique is also presented.
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27
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Wu CY, Yang SH, Lai YC, Lin NS, Hsu YH, Hu CC. Unit-length, single-stranded circular DNAs of both polarity of begomoviruses are generated in Escherichia coli harboring phage M13-cloned begomovirus genome with single copy of replication origin. Virus Res 2007; 125:14-28. [PMID: 17204346 DOI: 10.1016/j.virusres.2006.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2006] [Revised: 12/04/2006] [Accepted: 12/04/2006] [Indexed: 11/25/2022]
Abstract
Replication of genomic DNAs of plant-pathogenic begomoviruses has been demonstrated in prokaryotes, which supported the possibility of analyzing DNA replication process of begomoviruses in bacteria. However, previous studies indicated that the replication of begomovirus DNAs in prokaryotes requires tandem constructs of viral genomes with at least two copies of the origin of replication (ori). In this study, phage M13 vector harboring the unit-length genome with only a single copy of ori of a mono-partite begomovirus, Ageratum yellow vein virus PD isolate (AYVV-[PD]), was constructed and used to investigate the replication of AYVV-[PD] DNAs in Escherichia coli. The generation of single-stranded, circular DNAs (sscDNAs) corresponding to the unit-length AYVV-[PD] genome of both polarity was observed and verified. Replication-associated (Rep) protein of AYVV-[PD] was detected only in bacteria generating the corresponding sscDNAs, whereas disruption of the Rep gene abolished the phenomenon. The results suggested that a single copy of ori is sufficient for the prokaryotes to support the generation of unit-length, genomic sscDNAs of begomoviruses, which requires the presence of functional Rep protein.
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Affiliation(s)
- Chia-Ying Wu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
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28
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Briddon RW, Stanley J. Subviral agents associated with plant single-stranded DNA viruses. Virology 2006; 344:198-210. [PMID: 16364750 DOI: 10.1016/j.virol.2005.09.042] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Accepted: 09/16/2005] [Indexed: 11/18/2022]
Abstract
Begomoviruses (family Geminiviridae) are responsible for many economically important crop diseases worldwide. The majority of these diseases are caused by bipartite begomovirus infections, although a rapidly growing number of diseases of the Old World are associated with monopartite begomoviruses. With the exception of several diseases of tomato, most of these are caused by a monopartite begomovirus in association with a recently discovered essential satellite component (DNA-beta). These begomovirus/satellite disease complexes are widespread and diverse and collectively infect a wide variety of crops, weeds and ornamental plants. Non-essential subviral components (DNA-1) originating from nanoviruses are frequently associated with these disease complexes, and there are tantalizing hints that further novel satellites may also be associated with some begomovirus diseases. DNA-beta components can be maintained in permissive plants by more than one distinct begomovirus, reflecting less stringent requirements for trans-replication that will undoubtedly encourage diversification and adaptation as a consequence of component exchange and recombination. In view of their impact on agriculture, there is a pressing need to develop a more comprehensive picture of the diversity and distribution of the disease complexes. A greater understanding of how they elicit the host response may provide useful information for their control as well as an insight into plant developmental processes.
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Affiliation(s)
- R W Briddon
- Plant Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
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29
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Alberter B, Ali Rezaian M, Jeske H. Replicative intermediates of Tomato leaf curl virus and its satellite DNAs. Virology 2005; 331:441-8. [PMID: 15629786 DOI: 10.1016/j.virol.2004.10.043] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 10/14/2004] [Accepted: 10/26/2004] [Indexed: 11/30/2022]
Abstract
Several plant geminiviruses have been shown recently to utilize both rolling-circle replication (RCR) and recombination-dependent replication (RDR) strategies. A highly specific binding of the viral replication-associated protein (Rep) to its cognate DNA is essential for initiation of viral DNA replication and for the recognition of DNA components of the bipartite geminiviruses of the Begomovirus genus. We have extended the replication analysis to the monopartite Australian Tomato leaf curl virus (ToLCV), its Rep binding deficient mutants, and the satellite DNAs it supports. Analyses of viral DNA by two-dimensional agarose gel electrophoresis after fractionation by single-stranded (ss) DNA-selective cellulose chromatography revealed that DNA intermediates of ToLCV and its mutant were identical. Both RCR and RDR intermediates were identified. New ToLCV DNA forms were observed and characterized as subgenomic topoisomers, heterogeneous open circular double-stranded (ds) DNA, and degradation products. A 1350-nt DNA beta satellite associated with the unrelated Cotton leaf curl Multan virus (CLCuMV) was supported by ToLCV and produced intermediates of both RCR and RDR, suggesting that replication strategies of satellites are determined by the helper virus. Replicative intermediates of the 682 nt ToLCV satellite DNA could not be resolved; however, concatemers of up to octamer were detected, together with a field of hybridizing material suggestive of complementary strand replication on heterogeneous circular ssDNA templates.
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Affiliation(s)
- Barbara Alberter
- Department of Molecular Biology and Plant Virology, Institute of Biology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
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30
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Abstract
Geminiviruses package single-stranded circular DNA and replicate via double-stranded DNA intermediates. During the past decade, increasing evidence has led to the general acceptance that their replication follows a rolling-circle replication mechanism like bacteriophages with single-stranded DNA. In a recent study, we showed that this is also true for Abutilon mosaic geminivirus (AbMV), but that this particular virus may also use a recombination-dependent replication (RDR) route in analogy to T4 phages. Because AbMV is a special case, since it has been propagated on ornamental plants for more than a hundred years, it was interesting to determine whether RDR is common among other geminiviruses. We analyzed geminiviruses from different genera and geographic origins by using BND cellulose chromatography in combination with an improved high resolution two-dimensional gel electrophoresis, and we conclude that multitasking in replication is widespread, at least for African cassava mosaic, Beet curly top, Tomato golden mosaic, and Tomato yellow leaf curl virus.
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Affiliation(s)
- Werner Preiss
- Department of Molecular Biology and Plant Virology, Institute of Biology, University of Stuttgart, D-70550 Stuttgart, Germany
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31
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Brunetti A, Tavazza R, Noris E, Lucioli A, Accotto GP, Tavazza M. Transgenically expressed T-Rep of tomato yellow leaf curl Sardinia virus acts as a trans-dominant-negative mutant, inhibiting viral transcription and replication. J Virol 2001; 75:10573-81. [PMID: 11602699 PMCID: PMC114639 DOI: 10.1128/jvi.75.22.10573-10581.2001] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously shown that transgenic expression of a truncated C1 gene of Tomato yellow leaf curl Sardinia virus (TYLCSV), expressing the first 210 amino acids of the replication-associated protein (T-Rep) and potentially coexpressing the C4 protein, confers resistance to the homologous virus in Nicotiana benthamiana plants. In the present study we have investigated the role of T-Rep and C4 proteins in the resistance mechanism, analyzing changes in virus transcription and replication. Transgenic plants and protoplasts were challenged with TYLCSV and the related TYLCSV Murcia strain (TYLCSV-ES[1]). TYLCSV-resistant plants were susceptible to TYLCSV-ES[1]; moreover, TYLCSV but not TYLCSV-ES[1] replication was strongly inhibited in transgenic protoplasts as well as in wild-type (wt) protoplasts transiently expressing T-Rep but not the C4 protein. Viral circular single-stranded DNA (cssDNA) was usually undetectable in transgenically and transiently T-Rep-expressing protoplasts, while viral DNAs migrating more slowly than the cssDNA were observed. Biochemical studies showed that these DNAs were partial duplexes with the minus strand incomplete. Interestingly, similar viral DNA forms were also found at early stages of TYLCSV replication in wt N. benthamiana protoplasts. Transgenically expressed T-Rep repressed the transcription of the GUS reporter gene up to 300-fold when fused to the homologous (TYLCSV) but not to the heterologous (TYLCSV-ES[1]) C1 promoter. Similarly, transiently expressed T-Rep but not C4 protein strongly repressed GUS transcription when fused to the C1 promoter of TYLCSV. A model of T-Rep interference with TYLCSV transcription-replication is proposed.
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Affiliation(s)
- A Brunetti
- ENEA, Divisione Biotecnologie e Agricoltura, C. R. Casaccia, 00060 Rome, Italy
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Jeske H, Lütgemeier M, Preiss W. DNA forms indicate rolling circle and recombination-dependent replication of Abutilon mosaic virus. EMBO J 2001; 20:6158-67. [PMID: 11689455 PMCID: PMC125697 DOI: 10.1093/emboj/20.21.6158] [Citation(s) in RCA: 190] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Geminiviruses have spread worldwide and have become increasingly important in crop plants during recent decades. Recombination among geminiviruses was one major source of new variants. Geminiviruses replicate via rolling circles, confirmed here by electron microscopic visualization and two-dimensional gel analysis of Abutilon mosaic virus (AbMV) DNA. However, only a minority of DNA intermediates are consistent with this model. The majority are compatible with recombination-dependent replication (RDR). During development of naturally infected leaves, viral intermediates compatible with both models appeared simultaneously, whereas agro-infection of leaf discs with AbMV led to an early appearance of RDR forms but no RCR intermediates. Inactivation of viral genes ac2 and ac3 delayed replication, but produced the same DNA types as after wild-type infection, indicating that these genes were not essential for RDR in leaf discs. In conclusion, host factors alone or in combination with the viral AC1 protein are necessary and sufficient for the production of RDR intermediates. The consequences of an inherent geminiviral recombination activity for the use of pathogen-derived resistance traits are discussed.
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Affiliation(s)
- H Jeske
- Institute of Biology, Department of Molecular Biology and Plant Virology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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Abstract
Plant cell growth and development depend on continuous cell proliferation which is restricted to small regions of the plant called meristems. Infection by geminiviruses, small DNA viruses whose replicative cycle relies on host cell factors, is excluded from those proliferating areas. Since most of the replicative factors are present, almost exclusively, in proliferating cells, geminivirus infection is believed to induce a cellular state permissive for viral DNA replication, e.g. S-phase or, at least, some specific S-phase functions. The molecular basis for this effect seems to be the interference that certain geminivirus proteins exert on the retinoblastoma-related (RBR) pathway, which analogously to that of animal cells, regulates plant cell cycle activation and G(1)-S transition. In some cases, geminiviruses induce cell proliferation and abnormal growth. Mechanisms other than sequestering plant RBR probably contribute to the multiple effects of geminivirus proteins on cellular gene expression, cell growth control and cellular DNA replication. Current efforts to understand the coupling of geminivirus DNA replication to cell cycle and growth control as well as the directions in which future research is aiming are reviewed.
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Affiliation(s)
- C Gutierrez
- Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad Autónoma de Madrid (UAM), Cantoblanco, 28049 Madrid, Spain.
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Affiliation(s)
- K E Palmer
- Department of Microbiology, University of Cape Town, Western Cape, South Africa
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Akbar Behjatnia SA, Dry IB, Ali Rezaian M. Identification of the replication-associated protein binding domain within the intergenic region of tomato leaf curl geminivirus. Nucleic Acids Res 1998; 26:925-31. [PMID: 9461449 PMCID: PMC147362 DOI: 10.1093/nar/26.4.925] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The geminiviral replication-associated protein (Rep) is the only viral protein required for viral DNA replication. Tomato leaf curl virus (TLCV) Rep was expressed in Escherichia coli as a histidine-tagged fusion protein and purified to homogeneity in non-denaturing form. The fusion protein was used in in vitro binding experiments to identify the Rep-binding elements within the origin of replication of TLCV. Electrophoretic mobility shift assays demonstrated that the Rep binds specifically to a 120 bp fragment within the TLCV intergenic region. Fine resolution of the binding regions within the 120 bp fragment, using DNase I footprinting, demonstrated two footprints covering the sequences GCAATTGGTGTCTCTCAA and TGAATCGGTGTCTGGGG containing a direct repeat of the motif GGTGTCT (underlined). Our results suggest that the repeated motif is involved in virus-specific Rep-binding, but may not constitute the entire binding element. This is the first demonstration of geminivirus sequence elements involved in Rep-binding by direct protein-DNA interaction assays.
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Affiliation(s)
- S A Akbar Behjatnia
- CSIRO, Plant Industry, Horticulture Research Unit, PO Box 350, Glen Osmond 5064, Adelaide, Australia
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Abstract
The genome of the geminivirus tomato golden mosaic virus (TGMV) consists of two single-stranded circular DNAs, A and B, that replicate through a rolling-circle mechanism in nuclei of infected plant cells. The TGMV origin of replication is located in a conserved 5' intergenic region and includes at least two functional elements: the origin recognition site of the essential viral replication protein, AL1, and a sequence motif with the potential to form a hairpin or cruciform structure. To address the role of the hairpin motif during TGMV replication, we constructed a series of B-component mutants that resolved sequence changes from structural alterations of the motif. Only those mutant B DNAs that retained the capacity to form the hairpin structure replicated to wild-type levels in tobacco protoplasts when the viral replication proteins were provided in trans from a plant expression cassette. In contrast, the same B DNAs replicated to significantly lower levels in transient assays that included replicating, wild-type TGMV A DNA. These data established that the hairpin structure is essential for TGMV replication, whereas its sequence affects the efficiency of replication. We also showed that TGMV AL1 functions as a site-specific endonuclease in vitro and mapped the cleavage site to the loop of the hairpin. In vitro cleavage analysis of two TGMV B mutants with different replication phenotypes indicated that there is a correlation between the two assays for origin activity. These results suggest that the in vivo replication results may reflect structural and sequence requirements for DNA cleavage during initiation of rolling-circle replication.
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Affiliation(s)
- B M Orozco
- Department of Biochemistry, North Carolina State University, Raleigh 27695-7622, USA
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