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Inhibition of Binding of Tomato Yellow Leaf Curl Virus Rep to its Replication Origin by Artificial Zinc-Finger Protein. Mol Biotechnol 2012; 54:198-203. [DOI: 10.1007/s12033-012-9552-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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52
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A novel class of DNA satellites associated with New World begomoviruses. Virology 2012; 426:1-6. [DOI: 10.1016/j.virol.2012.01.024] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/11/2012] [Accepted: 01/18/2012] [Indexed: 11/24/2022]
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53
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Reddy RVC, Dong W, Njock T, Rey MEC, Fondong VN. Molecular interaction between two cassava geminiviruses exhibiting cross-protection. Virus Res 2012; 163:169-77. [PMID: 21925553 DOI: 10.1016/j.virusres.2011.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 09/06/2011] [Accepted: 09/06/2011] [Indexed: 10/17/2022]
Abstract
There are increasing reports of geminivirus mixed infections of field plant hosts. These mixed infections have been suggested to result in recombinations, emergence of new viruses and new disease epidemics. We previously reported the occurrence of mixed infection between African cassava mosaic virus (ACMV) and East African cassava mosaic Cameroon virus (EACMCV) resulting in severe symptoms in cassava fields in Cameroon. Here, we show that reassortment of DNA-A and DNA-B components of ACMV and EACMCV does not form viable recombinants. However, in the presence of both components of either virus, the DNA-A component of the other virus replicated and spread in the absence of its DNA-B component. This result suggests that failure of ACMV and EACMCV to form viable recombinants is due to the inability of each DNA-A component to trans-replicate the heterologous DNA-B component. This study also shows that ACMV DNA-A induces a resistance to ACMV and EACMCV as indicated by absence or late symptom development. Moreover, this resistance enabled plants to recover from severe symptoms caused by EACMCV in Nicotiana benthamiana, suggesting that the resistance induced is not specific to ACMV and is consistent with the phenomenon of cross-protection between related viruses.
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Affiliation(s)
- R V Chowda Reddy
- Department of Biological Sciences, Delaware State University, 1200 North DuPont Highway, Dover, DE 19901, USA
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54
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Two genetically related begomoviruses causing tomato leaf curl disease in Togo and Nigeria differ in virulence and host range but do not require a betasatellite for induction of disease symptoms. Arch Virol 2011; 157:107-20. [DOI: 10.1007/s00705-011-1139-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 10/03/2011] [Indexed: 11/26/2022]
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55
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Sánchez-Durán MA, Dallas MB, Ascencio-Ibañez JT, Reyes MI, Arroyo-Mateos M, Ruiz-Albert J, Hanley-Bowdoin L, Bejarano ER. Interaction between geminivirus replication protein and the SUMO-conjugating enzyme is required for viral infection. J Virol 2011; 85:9789-800. [PMID: 21775461 PMCID: PMC3196459 DOI: 10.1128/jvi.02566-10] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 07/08/2011] [Indexed: 12/11/2022] Open
Abstract
Geminiviruses are small DNA viruses that replicate in nuclei of infected plant cells by using plant DNA polymerases. These viruses encode a protein designated AL1, Rep, or AC1 that is essential for viral replication. AL1 is an oligomeric protein that binds to double-stranded DNA, catalyzes the cleavage and ligation of single-stranded DNA, and induces the accumulation of host replication machinery. It also interacts with several host proteins, including the cell cycle regulator retinoblastoma-related protein (RBR), the DNA replication protein PCNA (proliferating cellular nuclear antigen), and the sumoylation enzyme that conjugates SUMO to target proteins (SUMO-conjugating enzyme [SCE1]). The SCE1-binding motif was mapped by deletion to a region encompassing AL1 amino acids 85 to 114. Alanine mutagenesis of lysine residues in the binding region either reduced or eliminated the interaction with SCE1, but no defects were observed for other AL1 functions, such as oligomerization, DNA binding, DNA cleavage, and interaction with AL3 or RBR. The lysine mutations reduced or abolished virus infectivity in plants and viral DNA accumulation in transient-replication assays, suggesting that the AL1-SCE1 interaction is required for viral DNA replication. Ectopic AL1 expression did not result in broad changes in the sumoylation pattern of plant cells, but specific changes were detected, indicating that AL1 modifies the sumoylation state of selected host proteins. These results established the importance of AL1-SCE1 interactions during geminivirus infection of plants and suggested that AL1 alters the sumoylation of selected host factors to create an environment suitable for viral infection.
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Affiliation(s)
- Miguel A. Sánchez-Durán
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Mary B. Dallas
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622
| | - José T. Ascencio-Ibañez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622
| | - Maria Ines Reyes
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622
| | - Manuel Arroyo-Mateos
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Javier Ruiz-Albert
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Linda Hanley-Bowdoin
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622
| | - Eduardo R. Bejarano
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
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56
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Faria JAQA, Reis PAB, Reis MTB, Rosado GL, Pinheiro GL, Mendes GC, Fontes EPB. The NAC domain-containing protein, GmNAC6, is a downstream component of the ER stress- and osmotic stress-induced NRP-mediated cell-death signaling pathway. BMC PLANT BIOLOGY 2011; 11:129. [PMID: 21943253 PMCID: PMC3193034 DOI: 10.1186/1471-2229-11-129] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 09/26/2011] [Indexed: 05/18/2023]
Abstract
BACKGROUND The endoplasmic reticulum (ER) is a major signaling organelle, which integrates a variety of responses against physiological stresses. In plants, one such stress-integrating response is the N-rich protein (NRP)-mediated cell death signaling pathway, which is synergistically activated by combined ER stress and osmotic stress signals. Despite the potential of this integrated signaling to protect plant cells against different stress conditions, mechanistic knowledge of the pathway is lacking, and downstream components have yet to be identified. RESULTS In the present investigation, we discovered an NAC domain-containing protein from soybean, GmNAC6 (Glycine max NAC6), to be a downstream component of the integrated pathway. Similar to NRP-A and NRP-B, GmNAC6 is induced by ER stress and osmotic stress individually, but requires both signals for full activation. Transient expression of GmNAC6 promoted cell death and hypersensitive-like responses in planta. GmNAC6 and NRPs also share overlapping responses to biotic signals, but the induction of NRPs peaked before the increased accumulation of GmNAC6 transcripts. Consistent with the delayed kinetics of GmNAC6 induction, increased levels of NRP-A and NRP-B transcripts induced promoter activation and the expression of the GmNAC6 gene. CONCLUSIONS Collectively, our results biochemically link GmNAC6 to the ER stress- and osmotic stress-integrating cell death response and show that GmNAC6 may act downstream of the NRPs.
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Affiliation(s)
- Jerusa AQA Faria
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Pedro AB Reis
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions. Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Marco TB Reis
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Gustavo L Rosado
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions. Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Guilherme L Pinheiro
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Giselle C Mendes
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions. Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
| | - Elizabeth PB Fontes
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions. Universidade Federal de Viçosa, 36570.000, Viçosa, Minas Gerais, Brazil
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57
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Stewart CS, Kon T, Gilbertson RL, Roye ME. First report of the complete sequence of Sida golden yellow vein virus from Jamaica. Arch Virol 2011; 156:1481-4. [DOI: 10.1007/s00705-011-1030-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 05/11/2011] [Indexed: 11/27/2022]
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58
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Nash TE, Dallas MB, Reyes MI, Buhrman GK, Ascencio-Ibañez JT, Hanley-Bowdoin L. Functional analysis of a novel motif conserved across geminivirus Rep proteins. J Virol 2011; 85:1182-92. [PMID: 21084480 PMCID: PMC3020519 DOI: 10.1128/jvi.02143-10] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 11/09/2010] [Indexed: 12/28/2022] Open
Abstract
Members of the Geminiviridae have single-stranded DNA genomes that replicate in nuclei of infected plant cells. All geminiviruses encode a conserved protein (Rep) that catalyzes initiation of rolling-circle replication. Earlier studies showed that three conserved motifs-motifs I, II, and III-in the N termini of geminivirus Rep proteins are essential for function. In this study, we identified a fourth sequence, designated GRS (geminivirus Rep sequence), in the Rep N terminus that displays high amino acid sequence conservation across all geminivirus genera. Using the Rep protein of Tomato golden mosaic virus (TGMV AL1), we show that GRS mutants are not infectious in plants and do not support viral genome replication in tobacco protoplasts. GRS mutants are competent for protein-protein interactions and for both double- and single-stranded DNA binding, indicating that the mutations did not impair its global conformation. In contrast, GRS mutants are unable to specifically cleave single-stranded DNA, which is required to initiate rolling-circle replication. Interestingly, the Rep proteins of phytoplasmal and algal plasmids also contain GRS-related sequences. Modeling of the TGMV AL1 N terminus suggested that GRS mutations alter the relative positioning of motif II, which coordinates metal ions, and motif III, which contains the tyrosine involved in DNA cleavage. Together, these results established that the GRS is a conserved, essential motif characteristic of an ancient lineage of rolling-circle initiators and support the idea that geminiviruses may have evolved from plasmids associated with phytoplasma or algae.
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Affiliation(s)
- Tara E. Nash
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Mary B. Dallas
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Maria Ines Reyes
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Gregory K. Buhrman
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - J. Trinidad Ascencio-Ibañez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Linda Hanley-Bowdoin
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
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59
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Tahir M, Haider MS, Briddon RW. Complete nucleotide sequences of a distinct bipartite begomovirus, bitter gourd yellow vein virus, infecting Momordica charantia. Arch Virol 2010; 155:1901-5. [PMID: 20924621 DOI: 10.1007/s00705-010-0819-5] [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: 05/31/2010] [Accepted: 09/21/2010] [Indexed: 11/25/2022]
Abstract
Momordica charantia (Cucurbitaceae), a vegetable crop commonly cultivated throughout Pakistan, and begomoviruses, a serious threat to crop plants, are natives of tropical and subtropical regions of the world. Leaf samples of M. charantia with yellow vein symptoms typical of begomovirus infections and samples from apparently healthy plants were collected from areas around Lahore in 2004. Full-length clones of a bipartite begomovirus were isolated from symptomatic samples. The complete nucleotide sequences of the components of one isolate were determined, and these showed the arrangement of genes typical of Old World begomoviruses. The complete nucleotides sequence of DNA A showed the highest nucleotide sequence identity (86.9%) to an isolate of Tomato leaf curl New Delhi virus (ToLCNDV), confirming it to belong to a distinct species of begomovirus, for which the name Bitter gourd yellow vein virus (BGYVV) is proposed. Sequence comparisons showed that BGYVV likely emerged as a result of inter-specific recombination between ToLCNDV and tomato leaf curl Bangladesh virus (ToLCBDV). The complete nucleotide sequence of DNA B showed 97.2% nucleotide sequence identity to that of an Indian strain of Squash leaf curl China virus.
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Affiliation(s)
- Muhammad Tahir
- NUST Centre of Virology and Immunology, National University of Sciences and Technology, Islamabad, Pakistan.
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60
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Díaz-Pendón JA, Cañizares MC, Moriones E, Bejarano ER, Czosnek H, Navas-Castillo J. Tomato yellow leaf curl viruses: ménage à trois between the virus complex, the plant and the whitefly vector. MOLECULAR PLANT PATHOLOGY 2010; 11:441-50. [PMID: 20618703 PMCID: PMC6640490 DOI: 10.1111/j.1364-3703.2010.00618.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
UNLABELLED Tomato yellow leaf curl disease (TYLCD) is one of the most devastating viral diseases affecting tomato crops in tropical, subtropical and temperate regions of the world. Here, we focus on the interactions through recombination between the different begomovirus species causing TYLCD, provide an overview of the interactions with the cellular genes involved in viral replication, and highlight recent progress on the relationships between these viruses and their vector, the whitefly Bemisia tabaci. TAXONOMY The tomato yellow leaf curl virus-like viruses (TYLCVs) are a complex of begomoviruses (family Geminiviridae, genus Begomovirus) including 10 accepted species: Tomato yellow leaf curl Axarquia virus (TYLCAxV), Tomato yellow leaf curl China virus (TYLCCNV), Tomato yellow leaf curl Guangdong virus (TYLCGuV), Tomato yellow leaf curl Indonesia virus (TYLCIDV), Tomato yellow leaf curl Kanchanaburi virus (TYLVKaV), Tomato yellow leaf curl Malaga virus (TYLCMalV), Tomato yellow leaf curl Mali virus (TYLCMLV), Tomato yellow leaf curl Sardinia virus (TYLCSV), Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato yellow leaf curl Vietnam virus (TYLCVNV) and Tomato yellow leaf curl virus(TYLCV). We follow the species demarcation criteria of the International Committee on Taxonomy of Viruses (ICTV), the most important of which is an 89% nucleotide identity threshold between full-length DNA-A component nucleotide sequences for begomovirus species. Strains of a species are defined by a 93% nucleotide identity threshold. HOST RANGE The primary host of TYLCVs is tomato (Solanum lycopersicum), but they can also naturally infect other crops [common bean (Phaseolus vulgaris), sweet pepper (Capsicum annuum), chilli pepper (C. chinense) and tobacco (Nicotiana tabacum)], a number of ornamentals [petunia (Petuniaxhybrida) and lisianthus (Eustoma grandiflora)], as well as common weeds (Solanum nigrum and Datura stramonium). TYLCVs also infect the experimental host Nicotiana benthamiana. DISEASE SYMPTOMS Infected tomato plants are stunted or dwarfed, with leaflets rolled upwards and inwards; young leaves are slightly chlorotic; in recently infected plants, fruits might not be produced or, if produced, are small and unmarketable. In common bean, some TYLCVs produce the bean leaf crumple disease, with thickening, epinasty, crumpling, blade reduction and upward curling of leaves, as well as abnormal shoot proliferation and internode reduction; the very small leaves result in a bushy appearance.
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Affiliation(s)
- Juan Antonio Díaz-Pendón
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental 'La Mayora', 29750 Algarrobo-Costa, Málaga, Spain
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Patil BL, Fauquet CM. Differential interaction between cassava mosaic geminiviruses and geminivirus satellites. J Gen Virol 2010; 91:1871-82. [PMID: 20335493 DOI: 10.1099/vir.0.019513-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Geminiviruses are often associated with subviral agents called DNA satellites that require proteins encoded by the helper virus for their replication, movement and encapsidation. Hitherto, most of the single-stranded DNA satellites reported to be associated with members of the family Geminiviridae have been associated with monopartite begomoviruses. Cassava mosaic disease is known to be caused by viruses belonging to nine different begomovirus species in the African continent and the Indian subcontinent. In addition to these species, several strains have been recognized that exhibit contrasting phenotypes and infection dynamics. It is established that Sri Lankan cassava mosaic virus can trans-replicate betasatellites and can cross host barriers. To extend these studies further, we carried out an exhaustive investigation of the ability of geminiviruses, selected to represent all cassava-infecting geminivirus species, to trans-replicate betasatellites (DNA-beta) and to interact with alphasatellites (nanovirus-like components; previously called DNA-1). Each of the cassava-infecting geminiviruses showed a contrasting and differential interaction with the DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites. These observations could be extrapolated to field situations in order to hypothesize about the possibility of acquisition of such DNA satellites currently associated with other begomoviruses. These results call for more detailed analyses of these subviral components and an investigation of their possible interaction with the cassava mosaic disease complex.
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Affiliation(s)
- Basavaprabhu L Patil
- International Laboratory for Tropical Agricultural Biotechnology (ILTAB), Danforth Plant Science Center, 975 North Warson Road, St Louis, MO 63132, USA
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Levy A, Tzfira T. Bean dwarf mosaic virus: a model system for the study of viral movement. MOLECULAR PLANT PATHOLOGY 2010; 11:451-461. [PMID: 20618704 PMCID: PMC6640244 DOI: 10.1111/j.1364-3703.2010.00619.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
TAXONOMY Bean dwarf mosaic virus-[Colombia:1987] (BDMV-[CO:87]) is a single-stranded plant DNA virus, a member of the genus Begomovirus of the family Geminiviridae. PHYSICAL PROPERTIES BDMV virions are twinned incomplete isosahedra measuring 18 x 30 nm. The viral particle is composed of 110 subunits of coat protein, organized as 22 pentameric capsomers. Each subunit has a molecular mass of approximately 29 kDa. BDMV possesses two DNA components (designated DNA-A and DNA-B), each approximately 2.6 kb in size. HOST RANGE The natural and most important host of BDMV is the common bean (Phaseolus vulgaris). Nicotiana benthamiana is often used as an experimental host. Common bean germplasm can be divided into two major gene pools: Andean materials, which are mostly susceptible to BDMV, and Middle American materials, which are mostly resistant to BDMV. DISEASE SYMPTOMS The symptom intensity in common bean plants depends on the stage of infection. Early infection of susceptible bean seedlings will result in severe stunting and dwarfing, leaf distortion and mottling or mosaic, as well as chlorotic or yellow spots or blotches. BDMV-infected plants usually abort their flowers or produce severely distorted pods. Late infection of susceptible plants or early infection of moderately resistant genotypes may show a mild mosaic, mottle and crumpling or an irregular distribution of variegated patches. BIOLOGICAL PROPERTIES: As a member of the Begomovirus group, BDMV is transmitted from plant to plant by the whitefly Bemisia tabaci. BDMV is a nonphloem-limited virus and can replicate and move in the epidermal, cortical and phloem cells. As a nonphloem-limited virus, it is sap-transmissible.
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Affiliation(s)
- Avner Levy
- Department of Molecular, Cellular and Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, USA.
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63
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Teng K, Chen H, Lai J, Zhang Z, Fang Y, Xia R, Zhou X, Guo H, Xie Q. Involvement of C4 protein of beet severe curly top virus (family Geminiviridae) in virus movement. PLoS One 2010; 5:e11280. [PMID: 20585583 PMCID: PMC2892029 DOI: 10.1371/journal.pone.0011280] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 06/01/2010] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Beet severe curly top virus (BSCTV) is a leafhopper transmitted geminivirus with a monopartite genome. C4 proteins encoded by geminivirus play an important role in virus/plant interaction. METHODS AND FINDINGS To understand the function of C4 encoded by BSCTV, two BSCTV mutants were constructed by introducing termination codons in ORF C4 without affecting the amino acids encoded by overlapping ORF Rep. BSCTV mutants containing disrupted ORF C4 retained the ability to replicate in Arabidopsis protoplasts and in the agro-inoculated leaf discs of N. benthamiana, suggesting C4 is not required for virus DNA replication. However, both mutants did not accumulate viral DNA in newly emerged leaves of inoculated N. benthamiana and Arabidopsis, and the inoculated plants were asymptomatic. We also showed that C4 expression in plant could help C4 deficient BSCTV mutants to move systemically. C4 was localized in the cytosol and the nucleus in both Arabidopsis protoplasts and N. benthamiana leaves and the protein appeared to bind viral DNA and ds/ssDNA nonspecifically, displaying novel DNA binding properties. CONCLUSIONS Our results suggest that C4 protein in BSCTV is involved in symptom production and may facilitate virus movement instead of virus replication.
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Affiliation(s)
- Kunling Teng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Hao Chen
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Jianbin Lai
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Zhonghui Zhang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yuanyuan Fang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Ran Xia
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Huishan Guo
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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Pasumarthy KK, Choudhury NR, Mukherjee SK. Tomato leaf curl Kerala virus (ToLCKeV) AC3 protein forms a higher order oligomer and enhances ATPase activity of replication initiator protein (Rep/AC1). Virol J 2010; 7:128. [PMID: 20546567 PMCID: PMC2901266 DOI: 10.1186/1743-422x-7-128] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Accepted: 06/14/2010] [Indexed: 11/30/2022] Open
Abstract
Background Geminiviruses are emerging plant viruses that infect a wide variety of vegetable crops, ornamental plants and cereal crops. They undergo recombination during co-infections by different species of geminiviruses and give rise to more virulent species. Antiviral strategies targeting a broad range of viruses necessitate a detailed understanding of the basic biology of the viruses. ToLCKeV, a virus prevalent in the tomato crop of Kerala state of India and a member of genus Begomovirus has been used as a model system in this study. Results AC3 is a geminiviral protein conserved across all the begomoviral species and is postulated to enhance viral DNA replication. In this work we have successfully expressed and purified the AC3 fusion proteins from E. coli. We demonstrated the higher order oligomerization of AC3 using sucrose gradient ultra-centrifugation and gel-filtration experiments. In addition we also established that ToLCKeV AC3 protein interacted with cognate AC1 protein and enhanced the AC1-mediated ATPase activity in vitro. Conclusions Highly hydrophobic viral protein AC3 can be purified as a fusion protein with either MBP or GST. The purification method of AC3 protein improves scope for the biochemical characterization of the viral protein. The enhancement of AC1-mediated ATPase activity might lead to increased viral DNA replication.
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Affiliation(s)
- Kalyan K Pasumarthy
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi -110067, India.
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65
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Briddon RW, Patil BL, Bagewadi B, Nawaz-ul-Rehman MS, Fauquet CM. Distinct evolutionary histories of the DNA-A and DNA-B components of bipartite begomoviruses. BMC Evol Biol 2010; 10:97. [PMID: 20377896 PMCID: PMC2858149 DOI: 10.1186/1471-2148-10-97] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 04/08/2010] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Viruses of the genus Begomovirus (family Geminiviridae) have genomes consisting of either one or two genomic components. The component of bipartite begomoviruses known as DNA-A is homologous to the genomes of all geminiviruses and encodes proteins required for replication, control of gene expression, overcoming host defenses, encapsidation and insect transmission. The second component, referred to as DNA-B, encodes two proteins with functions in intra- and intercellular movement in host plants. The origin of the DNA-B component remains unclear. The study described here was initiated to investigate the relationship between the DNA-A and DNA-B components of bipartite begomoviruses with a view to unraveling their evolutionary histories and providing information on the possible origin of the DNA-B component. RESULTS Comparative phylogenetic and exhaustive pairwise sequence comparison of all DNA-A and DNA-B components of begomoviruses demonstrates that the two molecules have very distinct molecular evolutionary histories and likely are under very different evolutionary pressures. The analysis highlights that component exchange has played a far greater role in diversification of begomoviruses than previously suspected, although there are distinct differences in the apparent ability of different groups of viruses to utilize this "sexual" mechanism of genetic exchange. Additionally we explore the hypothesis that DNA-B originated as a satellite that was captured by the monopartite progenitor of all extant bipartite begomoviruses and subsequently evolved to become the integral (essential) genome component that we recognize today. The situation with present-day satellites associated with begomoviruses provides some clues to the processes and selection pressures that may have led to the "domestication" of a wild progenitor of the DNA-B component. CONCLUSIONS The analysis has highlighted the greater genetic variation of DNA-B components, in comparison to the DNA-A components, and that component exchange is more widespread than previously demonstrated and confined to viruses from the Old World. Although the vast majority of New World and some Old World begomoviruses show near perfect co-evolution of the DNA-A and DNA-B components, this is not the case for the majority of Old World viruses. Genetic differences between Old and New World begomoviruses and the cultivation of exotic crops in the Old World are likely factors that have led to this dichotomy.
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Affiliation(s)
- Rob W Briddon
- National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Basavaprabhu L Patil
- ILTAB, Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO, USA
| | - Basavaraj Bagewadi
- ILTAB, Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO, USA
| | | | - Claude M Fauquet
- ILTAB, Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO, USA
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66
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Chen H, Zhang Z, Teng K, Lai J, Zhang Y, Huang Y, Li Y, Liang L, Wang Y, Chu C, Guo H, Xie Q. Up-regulation of LSB1/GDU3 affects geminivirus infection by activating the salicylic acid pathway. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:12-23. [PMID: 20042021 DOI: 10.1111/j.1365-313x.2009.04120.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Geminiviruses include a large number of single-stranded DNA viruses that are emerging as useful tools to dissect many fundamental processes in plant hosts. However, there have been no reports yet regarding the genetic dissection of the geminivirus-plant interaction. Here, a high-throughput approach was developed to screen Arabidopsis activation-tagged mutants which are resistant to geminivirus Beet severe curly top virus (BSCTV) infection. A mutant, lsb1 (less susceptible to BSCTV 1), was identified, in which BSCTV replication was impaired and BSCTV infectivity was reduced. We found that the three genes closest to the T-DNA were up-regulated in lsb1, and the phenotypes of lsb1 could only be recapitulated by the overexpression of GDU3 (GLUTAMINE DUMPER 3), a gene implicated in amino acid transport. We further demonstrated that activation of LSB1/GDU3 increased the expression of components in the salicylic acid (SA) pathway, which is known to counter geminivirus infection, including the upstream regulator ACD6. These data indicate that up-regulation of LSB1/GDU3 affects BSCTV infection by activating the SA pathway. This study thus provides a new approach to study of the geminivirus-host interaction.
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Affiliation(s)
- Hao Chen
- Stake Key Laboratory for Biocontrol, Sun Yat-sen (Zhongshan) University, 135 West Xin-Gang Road, Guangzhou 510275, China
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67
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Tahir M, Haider MS, Briddon RW. Chili leaf curl betasatellite is associated with a distinct recombinant begomovirus, Pepper leaf curl Lahore virus, in Capsicum in Pakistan. Virus Res 2010; 149:109-14. [DOI: 10.1016/j.virusres.2009.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 11/18/2009] [Accepted: 12/30/2009] [Indexed: 11/29/2022]
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68
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Qing L, Zhou X. Trans-replication of, and competition between, DNA beta satellites in plants inoculated with Tomato yellow leaf curl China virus and Tobacco curly shoot virus. PHYTOPATHOLOGY 2009; 99:716-20. [PMID: 19453231 DOI: 10.1094/phyto-99-6-0716] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Tomato yellow leaf curl China virus (TYLCCNV) Y10 isolate (Y10) and Tobacco curly shoot virus (TbCSV) Y35 isolate (Y35), both obtained from Yunnan Province, were each found to be associated with a distinct species of satellite DNA (DNA beta). Here, we demonstrate that both Y10 DNA beta (Y10beta) and Y35 DNA beta (Y35beta) were stably trans-replicated by the noncognate Begomovirus, although the noncognate DNA beta accumulated in plants at a lower level than did the cognate DNA beta. In Nicotiana benthamiana and N. glutinosa plants agroinoculated with Y10+Y10beta+Y35beta or with Y35+Y35beta+Y10beta, all components accumulated in the early stages of infection but, at later stages, the noncognate DNA beta decreased in relative concentration and was undetectable at 80 to 120 days after inoculation. The helper viruses and cognate DNA beta species persisted at higher levels throughout the experiments. When the initiation codon of the betaC1 gene of the cognate DNA beta was mutated, the dominance of the cognate over the noncognate DNA beta in mixed infections was unimpaired. These results imply that the cognate DNA beta competes with the noncognate DNA beta and that the ability for selective maintenance of DNA beta is not controlled by the betaC1 protein.
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Affiliation(s)
- Ling Qing
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China
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69
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Lai J, Chen H, Teng K, Zhao Q, Zhang Z, Li Y, Liang L, Xia R, Wu Y, Guo H, Xie Q. RKP, a RING finger E3 ligase induced by BSCTV C4 protein, affects geminivirus infection by regulation of the plant cell cycle. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:905-17. [PMID: 19000158 DOI: 10.1111/j.1365-313x.2008.03737.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The C4 protein from Curtovirus is known as a major symptom determinant, but the mode of action of the C4 protein remains unclear. To understand the mechanism of involvement of C4 protein in virus-plant interactions, we introduced the C4 gene from Beet severe curly top virus (BSCTV) into Arabidopsis under a conditional expression promoter; the resulting overexpression of BSCTV C4 led to abnormal host cell division. RKP, a RING finger protein, which is a homolog of the human cell cycle regulator KPC1, was discovered to be induced by BSCTV C4 protein. Mutation of RKP reduced the susceptibility to BSCTV in Arabidopsis and impaired BSCTV replication in plant cells. Callus formation is impaired in rkp mutants, indicating a role of RKP in the plant cell cycle. RKP was demonstrated to be a functional ubiquitin E3 ligase and is able to interact with cell-cycle inhibitor ICK/KRP proteins in vitro. Accumulation of the protein ICK2/KRP2 was found increased in the rkp mutant. The above results strengthen the possibility that RKP might regulate the degradation of ICK/KRP proteins. In addition, the protein level of ICK2/KRP2 was decreased upon BSCTV infection. Overexpression of ICK1/KRP1 in Arabidopsis could reduce the susceptibility to BSCTV. In conclusion, we found that RKP is induced by BSCTV C4 and may affect BSCTV infection by regulating the host cell cycle.
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Affiliation(s)
- Jianbin Lai
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen Zhongshan University, Guangzhou, China
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70
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Saunders K, Briddon RW, Stanley J. Replication promiscuity of DNA-beta satellites associated with monopartite begomoviruses; deletion mutagenesis of the Ageratum yellow vein virus DNA-beta satellite localizes sequences involved in replication. J Gen Virol 2008; 89:3165-3172. [PMID: 19008407 DOI: 10.1099/vir.0.2008/003848-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudorecombination studies in Nicotiana benthamiana demonstrate that Ageratum yellow vein virus (AYVV) and Eupatorium yellow vein virus (EpYVV) can functionally interact with DNA-beta satellites associated with AYVV, EpYVV, cotton leaf curl Multan virus (CLCuMV) and honeysuckle yellow vein virus (HYVV). In contrast, CLCuMV shows some specificity in its ability to interact with distinct satellites and HYVV is able to interact only with its own satellite. Using an N. benthamiana leaf disk assay, we have demonstrated that HYVV is unable to trans-replicate other satellites. To investigate the basis of trans-replication compatibility, deletion mutagenesis of AYVV DNA-beta has been used to localize the origin of replication to approximately 360 nt, encompassing the ubiquitous nonanucleotide/stem-loop structure, satellite conserved region (SCR) and part of the intergenic region immediately upstream of the SCR. Additional deletions within this intergenic region have identified a region that is essential for replication. The capacity for DNA-beta satellites to functionally interact with distinct geminivirus species and its implications for disease diversification are discussed.
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Affiliation(s)
| | - Rob W Briddon
- Plant Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - John Stanley
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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71
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Jin M, Li C, Shi Y, Ryabov E, Huang J, Wu Z, Fan Z, Hong Y. A single amino acid change in a geminiviral Rep protein differentiates between triggering a plant defence response and initiating viral DNA replication. J Gen Virol 2008; 89:2636-2641. [PMID: 18796734 DOI: 10.1099/vir.0.2008/001966-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have devised an in planta system for functional analysis of the replication-associated protein (Rep) of African cassava mosaic virus (ACMV). Using this assay and PCR-based random mutagenesis, we have identified an ACMV Rep mutant that failed to trigger the hypersensitive response (HR), but had an enhanced ability to initiate DNA replication. The mutant Rep-green fluorescent protein (GFP) fusion protein was localized to the nucleus. Sequence analysis showed that the mutated Rep gene had three nucleotide changes (A6-->T, T375-->G and G852-->A); only the A6-->T transversion resulted in an amino acid substitution (Arg to Ser), which is at the second residue in the 358 amino acid ACMV Rep protein. Our results indicate that a single amino acid can alter the differential ability of ACMV Rep to trigger the host-mediated HR defence mechanism and to initiate viral DNA replication. The implications of this finding are discussed in the context of plant-virus interactions.
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Affiliation(s)
- Mingfei Jin
- School of Life Science, East China Normal University, Shanghai 200062, PR China.,Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
| | - Chunyang Li
- Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
| | - Yan Shi
- Department of Plant Pathology and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.,Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
| | - Eugene Ryabov
- Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
| | - Jing Huang
- School of Life Science, East China Normal University, Shanghai 200062, PR China
| | - Zirong Wu
- School of Life Science, East China Normal University, Shanghai 200062, PR China
| | - Zaifeng Fan
- Department of Plant Pathology and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.,Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
| | - Yiguo Hong
- Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
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72
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MYMIV replication initiator protein (Rep): roles at the initiation and elongation steps of MYMIV DNA replication. Virology 2008; 380:75-83. [PMID: 18703212 DOI: 10.1016/j.virol.2008.07.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 06/06/2008] [Accepted: 07/07/2008] [Indexed: 11/21/2022]
Abstract
In order to explore the mechanism of geminivirus DNA replication, we show that the Replication initiator (Rep) protein encoded by Mungbean yellow mosaic India virus (MYMIV), a member of the family Geminiviridae, binds specifically to the iterons present in the viral DNA replication origin (CR-A) in a highly ordered manner that might be a prerequisite for the initiation of replication. MYMIV Rep also acts as a helicase during the post-initiation stage and is upregulated in presence of the RPA32 subunit of Replication Protein A. The implication of these findings on the initiation and elongation stages of MYMIV DNA replication has been discussed.
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73
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Costa MDL, Reis PAB, Valente MAS, Irsigler AST, Carvalho CM, Loureiro ME, Aragão FJL, Boston RS, Fietto LG, Fontes EPB. A new branch of endoplasmic reticulum stress signaling and the osmotic signal converge on plant-specific asparagine-rich proteins to promote cell death. J Biol Chem 2008; 283:20209-19. [PMID: 18490446 DOI: 10.1074/jbc.m802654200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NRPs (N-rich proteins) were identified as targets of a novel adaptive pathway that integrates endoplasmic reticulum (ER) and osmotic stress signals based on coordinate regulation and synergistic up-regulation by tunicamycin and polyethylene glycol treatments. This integrated pathway diverges from the molecular chaperone-inducing branch of the unfolded protein response (UPR) in several ways. While UPR-specific targets were inversely regulated by ER and osmotic stresses, NRPs required both signals for full activation. Furthermore, BiP (binding protein) overexpression in soybean prevented activation of the UPR by ER stress inducers, but did not affect activation of NRPs. We also found that this integrated pathway transduces a PCD signal generated by ER and osmotic stresses that result in the appearance of markers associated with leaf senescence. Overexpression of NRPs in soybean protoplasts induced caspase-3-like activity and promoted extensive DNA fragmentation. Furthermore, transient expression of NRPs in planta caused leaf yellowing, chlorophyll loss, malondialdehyde production, ethylene evolution, and induction of the senescence marker gene CP1. This phenotype was alleviated by the cytokinin zeatin, a potent senescence inhibitor. Collectively, these results indicate that ER stress induces leaf senescence through activation of plant-specific NRPs via a novel branch of the ER stress response.
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Affiliation(s)
- Maximiller D L Costa
- Departamento de Bioquímica e Biologia Molecular, BIOAGRO, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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74
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Cowpea golden mosaic disease in Gujarat is caused by a Mungbean yellow mosaic India virus isolate with a DNA B variant. Arch Virol 2008; 153:1359-65. [PMID: 18516489 DOI: 10.1007/s00705-008-0116-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
Abstract
It has long been assumed that cowpea golden mosaic disease (CGMD) in southern Asia is caused by a begomovirus distinct from those causing disease in other legumes. The components of a begomovirus causing CGMD in western India were isolated, cloned and sequenced. Analysis of the sequences shows the virus to be an isolate of Mungbean yellow mosaic India virus, but with a distinct DNA B component with greater similarity to components of a second legume-infecting begomovirus occurring in the region, Mungbean yellow mosaic virus. The clones of the virus were readily infectious to cowpea, mungbean, blackgram and French bean by agroinoculation. However, the wild-type isolate was shown to be easily transmissible by whiteflies between cowpea plants but not to blackgram and mugbean, suggesting that the insect vector plays a major role in determining the natural host range of these viruses.
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75
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Ha C, Coombs S, Revill P, Harding R, Vu M, Dale J. Molecular characterization of begomoviruses and DNA satellites from Vietnam: additional evidence that the New World geminiviruses were present in the Old World prior to continental separation. J Gen Virol 2008; 89:312-326. [PMID: 18089756 DOI: 10.1099/vir.0.83236-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sixteen viruses, belonging to 16 species of begomovirus, that infect crops and weeds in Vietnam were identified. Sequence analysis of the complete genomes showed that nine of the viruses (six monopartite and three bipartite) belong to novel species and five of them were identified in Vietnam for the first time. Additionally, eight DNA-beta and three nanovirus-like DNA-1 molecules were also found associated with some of the monopartite viruses. Five of the DNA-beta molecules were novel. Importantly, a second bipartite begomovirus, Corchorus golden mosaic virus, shared several features with the previously characterized virus Corchorus yellow vein virus and with other bipartite begomoviruses from the New World, supporting the hypothesis that New World-like viruses were present in the Old World. This, together with a high degree of virus diversity that included putative recombinant viruses, satellite molecules and viruses with previously undescribed variability in the putative stem-loop sequences, suggested that South-East Asia, and Vietnam in particular, is one of the origins of begomovirus diversity.
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Affiliation(s)
- Cuong Ha
- Department of Plant Pathology, Hanoi Agriculture University, Gialam, Hanoi, Vietnam.,Tropical Crops and Biocommodities Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4001, Australia
| | - Steven Coombs
- Tropical Crops and Biocommodities Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4001, Australia
| | - Peter Revill
- Tropical Crops and Biocommodities Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4001, Australia
| | - Rob Harding
- Tropical Crops and Biocommodities Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4001, Australia
| | - Man Vu
- Department of Plant Pathology, Hanoi Agriculture University, Gialam, Hanoi, Vietnam
| | - James Dale
- Tropical Crops and Biocommodities Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4001, Australia
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76
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Ferreira PDTDO, Lemos TO, Nagata T, Inoue-Nagata AK. One-step cloning approach for construction of agroinfectious begomovirus clones. J Virol Methods 2008; 147:351-4. [DOI: 10.1016/j.jviromet.2007.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 06/21/2007] [Accepted: 10/10/2007] [Indexed: 11/15/2022]
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77
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Molecular variation of satellite DNA beta molecules associated with Malvastrum yellow vein virus and their role in pathogenicity. Appl Environ Microbiol 2008; 74:1909-13. [PMID: 18245261 DOI: 10.1128/aem.02461-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have found that the diversity of begomovirus-associated DNA beta satellites is related to host and geographical origin. In this study, we have cloned and sequenced 20 different isolates of DNA beta molecules associated with Malvastrum yellow vein virus (MYVV) isolated from Malvastrum coromandelianum plants in different geographical locations of Yunnan Province, China. Analyses of their molecular variation indicate that the satellites are clustered together according to their geographical location but that they have only limited sequence diversity. Infectivity tests using infectious clones of MYVV and its associated DNA beta molecule indicate that MYVV DNA beta is indispensable for symptom induction in Nicotiana benthamiana, N. glutinosa, Petunia hybrida, and M. coromandelianum plants. Furthermore, we showed that MYVV interacts functionally with heterologous DNA beta molecules in N. benthamiana plants.
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78
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Santos AA, Florentino LH, Pires ABL, Fontes EPB. Geminivirus: biolistic inoculation and molecular diagnosis. Methods Mol Biol 2008; 451:563-579. [PMID: 18370282 DOI: 10.1007/978-1-59745-102-4_39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The Geminiviridae family is a large family of plant viruses that has single-stranded DNA genomes and infects a large variety of crop species. In this chapter, we describe a biolistic inoculation protocol that has been successfully used to propagate new species of geminivirus in permissive hosts with total DNA extracted from infected plants. This allows us to directly investigate the biological properties of uncloned and not sap-transmissible geminiviruses.
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Affiliation(s)
- Anésia A Santos
- Departamento de Bioquímica e Biologia Molecular, BIOAGRO- Universidade Federal de Viçosa-36571.000, Viçosa, MG, Brazil
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79
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Florentino LH, Santos AA, Zerbini FM, Fontes EPB. Begomoviruses: molecular cloning and identification of replication origin. Methods Mol Biol 2008; 451:145-166. [PMID: 18370254 DOI: 10.1007/978-1-59745-102-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The Begomovirus genus is the largest genus of the Geminiviridae family and comprises the whitefly transmitted geminiviruses that infect dicotyledonous plants. They can be either mono or bipartite. In this chapter, we describe the cloning of begomovirus replication modules and the subsequent functional characterization of geminivirus replication origins.
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Affiliation(s)
- Lilian H Florentino
- Departamento de Bioquímica e Biologia Molecular, BIOAGRO-Universidade, Federal de Viçosa-36571.000, Viçosa, MG, Brazil
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80
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Shung CY, Sunter G. AL1-dependent repression of transcription enhances expression of Tomato golden mosaic virus AL2 and AL3. Virology 2007; 364:112-22. [PMID: 17407785 PMCID: PMC2902176 DOI: 10.1016/j.virol.2007.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 01/03/2007] [Accepted: 03/01/2007] [Indexed: 11/22/2022]
Abstract
Studies using Nicotiana benthamiana protoplasts have determined that repression of upstream transcription by AL1 protein enhances AL2 and AL3 expression in Tomato golden mosaic virus (TGMV). Mutations resulting in the inability of TGMV AL1 protein to associate with its cognate binding site, result in a decrease in both AL2 and AL3 expression. Reduced expression correlates with an increase in transcription from the AL62 start site, and decreased transcription from downstream initiation sites (AL1935 and AL1629) present within the AL1 coding region. The results demonstrate that, in a tobacco protoplast system, repression of AL62 transcription, regulated through binding of AL1 protein to sequences in the origin of replication, is required prior to AL2 and AL3 gene expression from the AL1935 and AL1629 viral transcripts. This provides a mechanism to regulate expression of AL2, which is involved in suppression of host defense responses and is required for late gene expression.
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Affiliation(s)
- Chia-Yi Shung
- Department of Biology The University of Texas at San Antonio One UTSA Circle San Antonio, TX 78249 USA
| | - Garry Sunter
- Department of Biology The University of Texas at San Antonio One UTSA Circle San Antonio, TX 78249 USA
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81
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Li D, Behjatnia SAA, Dry IB, Randles JW, Eini O, Rezaian MA. Genomic regions of tomato leaf curl virus DNA satellite required for replication and for satellite-mediated delivery of heterologous DNAs. J Gen Virol 2007; 88:2073-2077. [PMID: 17554042 DOI: 10.1099/vir.0.82853-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tomato leaf curl virus (TLCV) satellite DNA (sat-DNA) is a 682 nt, circular, single-stranded molecule that lacks an open reading frame (ORF) or an apparent promoter. It contains binding motifs for the TLCV replication-associated protein, but these are dispensable for replication. To identify the regions of the sat-DNA critical for replication, the entire sequence was scanned by deletion/replacement mutagenesis. Transient assays using Nicotiana benthamiana revealed that sequences within nt 296-35 (through nt 682) are essential for replication. Sequence deletions and replacements between nt 35 and 296 were tolerated but with a significant loss of infectivity, indicating that genome size strongly influences replication efficiency. Within the permissible region, inserts of 100-700 nt were retained in transient assays although with a slight reduction in replication. In addition, sat-DNA constructs containing short non-viral DNAs replicated and spread in tobacco plants, indicating their potential as gene-delivery vectors.
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Affiliation(s)
- Dongmei Li
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia
- CSIRO Plant Industry, PO Box 350, Glen Osmond, SA 5064, Australia
| | - S A Akbar Behjatnia
- Plant Protection Department, College of Agriculture, Shiraz University, Shiraz, Iran
- CSIRO Plant Industry, PO Box 350, Glen Osmond, SA 5064, Australia
| | - Ian B Dry
- CSIRO Plant Industry, PO Box 350, Glen Osmond, SA 5064, Australia
| | - John W Randles
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia
| | - Omid Eini
- Department of Plant Protection, School of Agriculture, Zanjan University, Zanjan, Iran
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia
- CSIRO Plant Industry, PO Box 350, Glen Osmond, SA 5064, Australia
| | - M Ali Rezaian
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia
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82
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Qazi J, Ilyas M, Mansoor S, Briddon RW. Legume yellow mosaic viruses: genetically isolated begomoviruses. MOLECULAR PLANT PATHOLOGY 2007; 8:343-348. [PMID: 20507504 DOI: 10.1111/j.1364-3703.2007.00402.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY The yellow mosaic diseases of a number of legumes across Southern Asia are caused by four species of whitefly-transmitted geminiviruses (genus Begomovirus, family Geminiviridae): Mungbean yellow mosaic virus, Mungbean yellow mosaic India virus, Dolichos yellow mosaic virus and Horsegram yellow mosaic virus. They cause losses to a number of important pulse crops, a major source of dietary protein in the region. The viruses have host ranges limited to plants of the family Fabaceae and efforts to limit losses are hampered by limited availability of conventional resistance sources and/or the lack of durability of the resistance that has been identified. There is ample evidence for genetic interaction between these begomoviruses within the legumes, in the form of both classical recombination and component exchange, but little evidence for interaction with viruses that infect other plants. This is indicative of genetic isolation, the viruses in legumes evolving independently of the begomoviruses in plant species of other families. This has implications for the development of engineered resistance in legumes, which holds the promise of durability but has yet to be transferred to the field. TAXONOMY The viruses causing yellow mosaic diseases of legumes across southern Asia, four of which have been identified so far, are bipartite begomoviruses (genus Begomovirus, family Geminiviridae): Mungbean yellow mosaic virus, Mungbean yellow mosaic India virus, Horsegram yellow mosaic virus and Dolichos yellow mosaic virus. Physical properties: The legume yellow mosaic viruses (LYMVs), like all members of the Geminiviridae, have geminate (twinned) particles, 18-20 nm in diameter, 30 nm long, apparently consisting of two incomplete T = 1 icosahedra joined together in a structure with 22 pentameric capsomers and 110 identical protein subunits. DISEASE SYMPTOMS Symptoms caused by LYMVs are largely dependent on host species and susceptibility. Initially symptoms appear as small yellow specks along the veins and then spread over the leaf. In severe infections the entire leaf may become chlorotic. In blackgram the chlorotic areas sometimes turn necrotic. Infections of French bean usually do not produce a mosaic but instead induce a downward leaf curling. DISEASE CONTROL Control is based mainly on preventing the establishment of the whitefly vector, Bemisia tabaci, in the crop by application of insecticides. Changes in agricultural practices, such as moving the cropping period out of periods of high vector incidence (the wet period in late summer) to times of low vector incidence (dry season in early summer) have met with some, albeit short-term, benefits. The use of natural, host plant resistance is efficacious, although the available sources of resistance in most legume crops are limited. In mungbean the resistance is attributed to two recessive genes which are used effectively to control the disease. USEFUL WEBSITES http://www.danforthcentre.org/iltab/geminiviridae/, http://www.iwglvv.org/
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Affiliation(s)
- Javaria Qazi
- Plant Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
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83
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Willment JA, Martin DP, Palmer KE, Schnippenkoetter WH, Shepherd DN, Rybicki EP. Identification of long intergenic region sequences involved in maize streak virus replication. J Gen Virol 2007; 88:1831-1841. [PMID: 17485545 DOI: 10.1099/vir.0.82513-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The main cis-acting control regions for replication of the single-stranded DNA genome of maize streak virus (MSV) are believed to reside within an approximately 310 nt long intergenic region (LIR). However, neither the minimum LIR sequence required nor the sequence determinants of replication specificity have been determined experimentally. There are iterated sequences, or iterons, both within the conserved inverted-repeat sequences with the potential to form a stem-loop structure at the origin of virion-strand replication, and upstream of the rep gene TATA box (the rep-proximal iteron or RPI). Based on experimental analyses of similar iterons in viruses from other geminivirus genera and their proximity to known Rep-binding sites in the distantly related mastrevirus wheat dwarf virus, it has been hypothesized that the iterons may be Rep-binding and/or -recognition sequences. Here, a series of LIR deletion mutants was used to define the upper bounds of the LIR sequence required for replication. After identifying MSV strains and distinct mastreviruses with incompatible replication-specificity determinants (RSDs), LIR chimaeras were used to map the primary MSV RSD to a 67 nt sequence containing the RPI. Although the results generally support the prevailing hypothesis that MSV iterons are functional analogues of those found in other geminivirus genera, it is demonstrated that neither the inverted-repeat nor RPI sequences are absolute determinants of replication specificity. Moreover, widely divergent mastreviruses can trans-replicate one another. These results also suggest that sequences in the 67 nt region surrounding the RPI interact in a sequence-specific manner with those of the inverted repeat.
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Affiliation(s)
- Janet A Willment
- Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
| | - Darrin P Martin
- Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
| | - Kenneth E Palmer
- Department of Pharmacology and Toxicology, University of Louisville, 570 South Preston Street, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, 529 South Jackson Street, Louisville, KY 40202, USA
| | | | - Dionne N Shepherd
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch, Cape Town 7701, South Africa
| | - Edward P Rybicki
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch, Cape Town 7701, South Africa
- Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
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84
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Ascencio-Ibañez JT, Settlage SB. DNA abrasion onto plants is an effective method for geminivirus infection and virus-induced gene silencing. J Virol Methods 2007; 142:198-203. [PMID: 17337069 DOI: 10.1016/j.jviromet.2007.01.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 12/08/2006] [Accepted: 01/25/2007] [Indexed: 01/01/2023]
Abstract
Geminiviruses belong to a rapidly growing group of plant pathogens that contribute to crop losses in tropical and subtropical areas of the world. Geminivirus infection is a model for plant DNA replication and virus/host interactions. Geminiviruses are also used as vectors to induce silencing of endogenous genes in several plant species. A method was analyzed for inoculating geminiviruses using plasmid DNA rubbed onto leaves in the presence of an abrasive (DNA abrasion). Although the use of DNA abrasion to inoculate geminiviruses has been described previously, the technique has fallen out of favor and has not been systematically optimized. However, consistent efficiencies of 100% infection rates can be achieved by DNA abrasion. The symptoms of Tomato Golden Mosaic Virus or Cabbage Leaf Curl Virus infection on Nicotiana benthamiana were similar in timing and appearance to the symptoms observed in plants inoculated using Agrobacterium as the delivery method. More importantly, silencing of an endogenous gene was highly efficient when a geminivirus silencing vector was inoculated by the DNA abrasion method. Other plant species successfully inoculated with geminiviruses by DNA abrasion were Nicotiana tabacum, Capsicum annuum and Nicandra physalodes. Unfortunately, Arabidopsis thaliana could not be infected with Cabbage Leaf Curl Virus using leaf abrasion, demonstrating limitation of the method. However, leaf abrasion to inoculate geminiviruses is an easy and inexpensive method that should be considered as an accessible technique to the growing number of researchers using geminiviruses.
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Affiliation(s)
- Jose Trinidad Ascencio-Ibañez
- North Carolina State University, Department of Molecular and Structural Biochemistry, Viral Genomics Group, CB 7651 Partners III, Room B04, Raleigh, NC 27695, USA.
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85
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Ribeiro SG, Martin DP, Lacorte C, Simões IC, Orlandini DRS, Inoue-Nagata AK. Molecular and Biological Characterization of Tomato chlorotic mottle virus Suggests that Recombination Underlies the Evolution and Diversity of Brazilian Tomato Begomoviruses. PHYTOPATHOLOGY 2007; 97:702-711. [PMID: 18943601 DOI: 10.1094/phyto-97-6-0702] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
ABSTRACT Tomato chlorotic mottle virus (ToCMoV) is an emerging begomovirus species widely distributed throughout tomato-growing regions of Brazil. ToCMoV appears to have expanded its geographic range recently, invading tomato-growing areas that were free of begomovirus infection before 2004. We have determined the first complete genome sequence of an infectious ToCMoV genome (isolate BA-Se1), which is the first begomovirus species isolated in the northeast of Brazil. When introduced by particle bombardment into tomato, the cloned ToCMoV-[BA-Se1] DNA-A and DNA-B components caused typical chlorotic mottle symptoms. The cloned virus was whitefly-transmissible and, although it was infectious in hosts such as Nicotiana benthamiana, pepper, tobacco, and Nicandra physaloides, it was unable to infect Arabidopsis thaliana, bean, N. glutinosa, and Datura metel. Sequence and biological analyses indicate that ToCMoV-[BA-Se1] is a typical New World begomovirus sp. requiring both DNA-A and DNA-B components to establish systemic infections. Although evidence of multiple recombination events was detected within the ToCMoV-[BA-Se1] DNA-A, they apparently occurred relatively long ago, implying that recombination probably has not contributed to the recent emergence of this species.
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86
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Fontenelle MR, Luz DF, Gomes APS, Florentino LH, Zerbini FM, Fontes EPB. Functional analysis of the naturally recombinant DNA-A of the bipartite begomovirus Tomato chlorotic mottle virus. Virus Res 2007; 126:262-7. [PMID: 17367887 DOI: 10.1016/j.virusres.2007.02.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 02/08/2007] [Accepted: 02/09/2007] [Indexed: 11/18/2022]
Abstract
All geminiviruses found in Brazil belong to the Begomovirus genus with a bipartite genome that is split between two genomic components, DNA-A and DNA-B. The DNA-A of the bipartite begomovirus ToCMoV-[MG-Bt] (Tomato chlorotic mottle virus), however, possesses as a peculiar characteristic the capacity to systemically infect Nicotiana benthamiana. Here we further characterize this variant DNA-A and show that it also infects Solanum lycopersicum and other host plants, in the absence of DNA-B. The ToCMoV-[MG-Bt]-DNA-A encodes an additional ORF, designated AC5, but otherwise its genome organization is similar to other DNA-A from Western Hemisphere begomoviruses. We showed that this AC5 putative ORF is not essential for infection, as disruption of its coding capacity caused no effect on ToCMoV-[MG-Bt]-DNA-A-mediated infection process. Likewise, the ToCMoV-[MG-Bt]-DNA-A ac4 mutant was indistinguishable from its wild type counterpart in all hosts tested. In contrast, an av1 (coat protein) mutant was unable to infect systemically N. benthamiana and Chenopodium quinoa in the absence of DNA-B. However, inclusion of DNA-B in the infection assay fully rescued the movement defect of the ToCMoV-[MG-Bt]-DNA-A av1 mutant. These results suggest that at suboptimal conditions for infection the coat protein is required for ToCMoV-[MG-Bt] systemic movement.
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Affiliation(s)
- Mariana R Fontenelle
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa, 36571.000 Viçosa, MG, Brazil
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87
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Bull SE, Briddon RW, Sserubombwe WS, Ngugi K, Markham PG, Stanley J. Infectivity, pseudorecombination and mutagenesis of Kenyan cassava mosaic begomoviruses. J Gen Virol 2007; 88:1624-1633. [PMID: 17412996 DOI: 10.1099/vir.0.82662-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cloned DNA-A and DNA-B components of Kenyan isolates of East African cassava mosaic virus (EACMV, EACMV-UG and EACMV-KE2), East African cassava mosaic Kenya virus (EACMKV) and East African cassava mosaic Zanzibar virus (EACMZV) are shown to be infectious in cassava. EACMV and EACMKV genomic components have the same iteron sequence (GGGGG) and can form viable pseudorecombinants, while EACMZV components have a different sequence (GGAGA) and are incompatible with EACMV and EACMKV. Mutagenesis of EACMZV has demonstrated that open reading frames (ORFs) AV1 (encoding the coat protein), AV2 and AC4 are not essential for a symptomatic infection of cassava, although mutants of both ORF AV1 and AV2 produce attenuated symptoms in this host. Furthermore, ORF AV1 and AV2 mutants were compromised for coat protein production, suggesting a close structural and/or functional relationship between these coding regions or their protein products.
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Affiliation(s)
- Simon E Bull
- Department of Disease and Stress Biology, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK
| | - Rob W Briddon
- Department of Disease and Stress Biology, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK
| | - William S Sserubombwe
- Department of Disease and Stress Biology, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK
| | - Kahiu Ngugi
- Kenya Agricultural Research Institute, Katumani Applied Biotechnology Laboratory, PO Box 340, Machakos, Kenya
| | - Peter G Markham
- Department of Disease and Stress Biology, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK
| | - John Stanley
- Department of Disease and Stress Biology, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK
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88
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Andrade EC, Manhani GG, Alfenas PF, Calegario RF, Fontes EPB, Zerbini FM. Tomato yellow spot virus, a tomato-infecting begomovirus from Brazil with a closer relationship to viruses from Sida sp., forms pseudorecombinants with begomoviruses from tomato but not from Sida. J Gen Virol 2006; 87:3687-3696. [PMID: 17098986 DOI: 10.1099/vir.0.82279-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Geminiviruses are characterized by a circular, single-stranded DNA genome and twinned icosahedral particles. Begomoviruses (whitefly-transmitted geminiviruses) are a major constraint to crop production worldwide. In Brazil, tomato-infecting begomoviruses emerged as serious pathogens over the last 10 years, due to the introduction of a new biotype of the insect vector. Tomato yellow spot virus (ToYSV) is a newly described begomovirus originally isolated from tomato, but phylogenetically closer to viruses from Sida sp. A study was performed to determine the viability of pseudorecombinants formed between the DNA components of ToYSV and other weed- and tomato-infecting begomoviruses from Brazil. Despite its closer relationship to weed-infecting viruses, ToYSV was only capable of forming viable pseudorecombinants with tomato viruses. An infectious pseudorecombinant formed between ToYSV DNA-A and tomato crinkle leaf yellows virus (TCrLYV) DNA-B induced severe symptoms in Nicotiana benthamiana. This was attributed, at least in part, to the fact that the origins of replication of both components had identical Rep-binding sequences. However, this was not the case for another infectious pseudorecombinant formed between tomato golden mosaic virus (TGMV) DNA-A and ToYSV DNA-B, which have different Rep-binding sequences. These results reinforce the notion that pseudorecombinant formation cannot be explained solely on the basis of phylogenetic relationships and conserved iteron sequences, and suggest that the TGMV Rep protein may be more versatile in terms of recognizing heterologous DNA components than that of ToYSV.
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Affiliation(s)
- E C Andrade
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
| | - G G Manhani
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
| | - P F Alfenas
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
| | - R F Calegario
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
| | - E P B Fontes
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
| | - F M Zerbini
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil
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89
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Shung CY, Sunter J, Sirasanagandla SS, Sunter G. Distinct viral sequence elements are necessary for expression of Tomato golden mosaic virus complementary sense transcripts that direct AL2 and AL3 gene expression. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2006; 19:1394-405. [PMID: 17153924 DOI: 10.1094/mpmi-19-1394] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Transient expression studies using Nicotiana benthamiana protoplasts and plants have identified sequences important for transcription of complementary sense RNAs derived from Tomato golden mosaic virus (TGMV) DNA component A that direct expression of AL2 and AL3. Transcription of two complementary sense RNAs, initiating at nucleotides 1,935 (AL1935) and 1,629 (AL1629), is directed by unique sequences located upstream of each transcription initiation site. One element is located between 28 and 124 nucleotides (nt) upstream of the AL1935 transcription start site, which differs from a second element located 150 nt downstream, between 129 and 184 nt upstream of the AL1629 transcription start site. Transcription initiation at nucleotide 1,935 is lower than that at nucleotide 1,629 as determined by run-on transcription assays, and the resulting transcript is only capable of expressing AL3. The transcript initiating at nucleotide 1,629 is capable of directing expression of both AL2 and AL3, although expression of AL3 is up to fourfold greater than that for AL2. Nuclear factors purified from tobacco suspension cells bind to sequences upstream of both AL1935 and AL1629, correlating with the ability of these sequences to direct gene expression. Thus, in tobacco, regulatory sequences direct transcription of two unique TGMV messenger RNAs that differentially express AL2 and AL3.
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Affiliation(s)
- Chia-Yi Shung
- Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA
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90
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Herrera-Valencia VA, Dugdale B, Harding RM, Dale JL. An iterated sequence in the genome of Banana bunchy top virus is essential for efficient replication. J Gen Virol 2006; 87:3409-3412. [PMID: 17030877 DOI: 10.1099/vir.0.82166-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Banana bunchy top virus (BBTV) has a multi-component genome of circular, single-stranded DNA. BBTV replicates via a rolling-circle mechanism, probably involving sequence-specific interaction of the replication initiation protein (Rep) with iterated sequences (iterons) within the viral genome. Three putative iterons (designated F1, F2 and R), with the sequence GGGAC, have been identified in the intergenic region of each BBTV component. To investigate their role in replication, each of the iterons was mutated, singularly and in tandem, in a BBTV DNA-N 1.1mer and the ability of these molecules to be replicated by the BBTV 'master' Rep was evaluated in banana cells using transient biolistic assays. All iteron mutants were replicated less efficiently than the native DNA-N. Mutation of the F1 and R iterons caused a 42 and 62 % reduction in DNA-N replication, respectively, whereas mutation of the F2 and combined F1F2 iteron virtually abolished DNA-N replication.
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Affiliation(s)
| | - Benjamin Dugdale
- Science Research Centre, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia
| | - Robert M Harding
- Science Research Centre, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia
| | - James L Dale
- Science Research Centre, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia
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91
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Girish KR, Palanivelu S, Kumar PD, Usha R. Refolding, purification and characterization of replication-initiator protein from soybean-infecting geminivirus. J Virol Methods 2006; 136:154-9. [PMID: 16765456 DOI: 10.1016/j.jviromet.2006.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Revised: 04/22/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
The replication-initiator protein (Rep) from a soybean-infecting geminivirus was overexpressed in E. coli as a fusion protein with maltose binding protein (MBP). In spite of the presence of the highly soluble MBP as the fusion partner, the overexpressed MBP-Rep fusion protein formed insoluble inclusion bodies. The protein was solubilized from the inclusion bodies and refolded. The refolded MBP-Rep protein was purified using ion exchange and amylose affinity chromatography. The activity of the purified MBP-Rep was assessed using an in vitro cleavage assay. Soluble and stable MBP-Rep protein was obtained in high abundance, providing the feasibility of large-scale production of active Rep protein for functional characterization and X-ray crystallographic structure determination.
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Affiliation(s)
- K R Girish
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India
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92
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Lopez-Ochoa L, Ramirez-Prado J, Hanley-Bowdoin L. Peptide aptamers that bind to a geminivirus replication protein interfere with viral replication in plant cells. J Virol 2006; 80:5841-53. [PMID: 16731923 PMCID: PMC1472579 DOI: 10.1128/jvi.02698-05] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The AL1 protein of tomato golden mosaic virus (TGMV), a member of the geminivirus family, is essential for viral replication in plants. Its N terminus contains three conserved motifs that mediate origin recognition and DNA cleavage during the initiation of rolling-circle replication. We used the N-terminal domain of TGMV AL1 as bait in a yeast two-hybrid screen of a random peptide aptamer library constrained in the active site of the thioredoxin A (TrxA) gene. The screen selected 88 TrxA peptides that also bind to the full-length TGMV AL1 protein. Plant expression cassettes corresponding to the TrxA peptides and a TGMV A replicon encoding AL1 were cotransfected into tobacco protoplasts, and viral DNA replication was monitored by semiquantitative PCR. In these assays, 31 TrxA peptides negatively impacted TGMV DNA accumulation, reducing viral DNA levels to 13 to 64% of those of the wild type. All of the interfering aptamers also bound to the AL1 protein of cabbage leaf curl virus. A comparison of the 20-mer peptides revealed that their sequences are not random. The alignments detected seven potential binding motifs, five of which are more highly represented among the interfering peptides. One motif was present in 18 peptides, suggesting that these peptides interact with a hot spot in the AL1 N terminus. The peptide aptamers characterized in these studies represent new tools for studying AL1 function and can serve as the basis for the development of crops with broad-based resistance to single-stranded DNA viruses.
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Affiliation(s)
- Luisa Lopez-Ochoa
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695-7622, USA
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93
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Florentino LH, Santos AA, Fontenelle MR, Pinheiro GL, Zerbini FM, Baracat-Pereira MC, Fontes EPB. A PERK-like receptor kinase interacts with the geminivirus nuclear shuttle protein and potentiates viral infection. J Virol 2006; 80:6648-56. [PMID: 16775352 PMCID: PMC1488943 DOI: 10.1128/jvi.00173-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The nuclear shuttle protein (NSP) from bipartite geminiviruses facilitates the intracellular transport of viral DNA from the nucleus to the cytoplasm and acts in concert with the movement protein (MP) to promote the cell-to-cell spread of the viral DNA. A proline-rich extensin-like receptor protein kinase (PERK) was found to interact specifically with NSP of Cabbage leaf curl virus (CaLCuV) and of tomato-infecting geminiviruses through a yeast two-hybrid screening. The PERK-like protein, which we designated NsAK (for NSP-associated kinase), is structurally organized into a proline-rich N-terminal domain, followed by a transmembrane segment and a C-terminal serine/threonine kinase domain. The viral protein interacted stably with defective versions of the NsAK kinase domain, but not with the potentially active enzyme, in an in vitro binding assay. In vitro-translated NsAK enhanced the phosphorylation level of NSP, indicating that NSP functions as a substrate for NsAK. These results demonstrate that NsAK is an authentic serine/threonine kinase and suggest a functional link for NSP-NsAK complex formation. This interpretation was corroborated by in vivo infectivity assays showing that loss of NsAK function reduces the efficiency of CaLCuV infection and attenuates symptom development. Our data implicate NsAK as a positive contributor to geminivirus infection and suggest it may regulate NSP function.
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Affiliation(s)
- Lilian H Florentino
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, 36571.000 Viçosa, MG, Brazil
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94
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Steinfeldt T, Finsterbusch T, Mankertz A. Demonstration of nicking/joining activity at the origin of DNA replication associated with the rep and rep' proteins of porcine circovirus type 1. J Virol 2006; 80:6225-34. [PMID: 16775310 PMCID: PMC1488954 DOI: 10.1128/jvi.02506-05] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The replication of porcine circovirus type 1 (PCV1) is thought to occur by rolling-circle replication (RCR), whereby the introduction of a single-strand break generates a free 3'-hydroxyl group serving as a primer for subsequent DNA synthesis. The covalently closed, single-stranded genome of PCV1 replicates via a double-stranded replicative intermediate, and the two virus-encoded replication-associated proteins Rep and Rep' have been demonstrated to be necessary for virus replication. However, although postulated to be involved in RCR-based virus replication, the mechanism of action of Rep and Rep' is as yet unknown. In this study, the ability of PCV1 Rep and Rep' to "nick" and "join" strand discontinuities within synthetic oligonucleotides corresponding to the origin of replication of PCV1 was investigated in vitro. Both proteins were demonstrated to be able to cleave the viral strand between nucleotides 7 and 8 within the conserved nonanucleotide motif (5'-TAGTATTAC-3') located at the apex of a putative stem-loop structure. In addition, the Rep and Rep' proteins of PCV1 were demonstrated to be capable of joining viral single-stranded DNA fragments, suggesting that these proteins also play roles in the termination of virus DNA replication. This joining activity was demonstrated to be strictly dependent on preceding substrate cleavage and the close proximity of origin fragments accomplished by base pairing in the stem-loop structure. The dual "nicking/joining" activities associated with PCV1 Rep and Rep' are pivotal events underlying the RCR-based replication of porcine circoviruses in mammalian cells.
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Affiliation(s)
- Tobias Steinfeldt
- Division of Viral Infections (FG12), Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany
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95
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Morilla G, Castillo AG, Preiss W, Jeske H, Bejarano ER. A versatile transreplication-based system to identify cellular proteins involved in geminivirus replication. J Virol 2006; 80:3624-33. [PMID: 16537630 PMCID: PMC1440397 DOI: 10.1128/jvi.80.7.3624-3633.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Accepted: 12/17/2005] [Indexed: 01/18/2023] Open
Abstract
A versatile green fluorescent protein (GFP) expression cassette containing the replication origins of the monopartite begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV) is described. Transgenic Nicotiana benthamiana plants containing one copy of the cassette stably integrated into their genome were superinfected with TYLCSV, which mobilized and replicated the cassette as an episomal replicon. The expression of the reporter gene (the GFP gene) was thereby modified. Whereas GFP fluorescence was dimmed in the intercostal areas, an increase of green fluorescence in veins of all leaves placed above the inoculation site, as well as in transport tissues of roots and stems, was observed. The release of episomal trans replicons from the transgene and the increase in GFP expression were dependent on the cognate geminiviral replication-associated protein (Rep) and required interaction between Rep and the intergenic region of TYLCSV. This expression system is able to monitor the replication status of TYLCSV in plants, as induction of GFP expression is only produced in those tissues where Rep is present. To further confirm this notion, the expression of a host factor required for geminivirus replication, the proliferating cellular nuclear antigen (PCNA) was transiently silenced. Inhibition of PCNA prevented GFP induction in veins and reduced viral DNA. We propose that these plants could be widely used to easily identify host factors required for geminivirus replication by virus-induced gene silencing.
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Affiliation(s)
- Gabriel Morilla
- Unidad de Genética, Departamento de Biología Celular, Genética, y Fisiología, Universidad de Málaga, 29071 Málaga, Spain
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96
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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: 220] [Impact Index Per Article: 12.2] [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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97
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Cheung AK. Mutational analysis of the direct tandem repeat sequences at the origin of DNA replication of porcine circovirus type 1. Virology 2005; 339:192-9. [PMID: 15993915 DOI: 10.1016/j.virol.2005.05.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 05/13/2005] [Accepted: 05/26/2005] [Indexed: 11/28/2022]
Abstract
Mutational analysis was conducted to investigate the role of the nucleotide sequences flanking the stem-loop palindromic structure at the origin of DNA replication of porcine circovirus type 1 (PCV1) with respect to self-DNA replication and progeny virus generation. The results demonstrated that the A-rich sequence to the left of the palindrome is non-essential for virus replication. Although a set of four hexanucleotide (H) sequences to the right of the palindrome (organized in two tandem repeats: the proximal H1/H2 and the distal H3/H4) are binding sites for the viral Rep-associated proteins in vitro, only a proximal tandem (H/H or h-like/H) is essential for PCV1 DNA replication. In the presence of H1/H2, mutations engineered into H3/H4 were preserved in the progeny viruses. Mutations engineered into H1/H2 were invariably deleted so that the downstream H3/H4 was placed next to the palindrome. Viral genome with mutations engineered into both H1/H2 and H3/H4 underwent extensive nucleotide reorganization to yield progeny viruses containing either H3/H4, h-like/H4, or h-like/H3/H4 sequences.
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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, PO Box 70, Ames, IA 50010, USA.
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98
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Rothenstein D, Haible D, Dasgupta I, Dutt N, Patil BL, Jeske H. Biodiversity and recombination of cassava-infecting begomoviruses from southern India. Arch Virol 2005; 151:55-69. [PMID: 16132175 DOI: 10.1007/s00705-005-0624-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 07/04/2005] [Indexed: 10/25/2022]
Abstract
Cassava mosaic disease (CMD) is caused by various begomoviruses of the family Geminiviridae leading to considerable crop losses in Africa and Asia. Recombination between their genomic components has generated new pathotypes with enhanced virulence in Africa. Here, we report about a survey on the biodiversity of begomoviruses in cassava from southern India (Tamil Nadu and Kerala states) performed in 2001 and 2002. Viral DNA A components from stem cuttings were analysed using polymerase chain reaction and restriction fragment length polymorphism. Eight representative examples were completely sequenced. The majority of DNA sequences (7 of 8) obtained were more closely related to that of Sri Lankan cassava mosaic virus (SLCMV) than of Indian cassava mosaic virus (ICMV). Only one sequence collected in Kerala was related to ICMV. The diversity of the SLCMV-like sequences was rather low compared to the variability of African viruses associated with cassava mosaic disease. Based on DNA A sequence data, all of these isolates should be classified as variants of SLCMV or ICMV. Phylogenetic analysis revealed mosaic structures within the DNA sequences which may indicate footprints of recombination events between ancestors of SLCMV and ICMV.
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Affiliation(s)
- D Rothenstein
- Department of Molecular Biology and Plant Virology, University of Stuttgart, Stuttgart, Germany
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99
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Settlage SB, See RG, Hanley-Bowdoin L. Geminivirus C3 protein: replication enhancement and protein interactions. J Virol 2005; 79:9885-95. [PMID: 16014949 PMCID: PMC1181577 DOI: 10.1128/jvi.79.15.9885-9895.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 04/23/2005] [Indexed: 11/20/2022] Open
Abstract
Most dicot-infecting geminiviruses encode a replication enhancer protein (C3, AL3, or REn) that is required for optimal replication of their small, single-stranded DNA genomes. C3 interacts with C1, the essential viral replication protein that initiates rolling circle replication. C3 also homo-oligomerizes and interacts with at least two host-encoded proteins, proliferating cell nuclear antigen (PCNA) and the retinoblastoma-related protein (pRBR). It has been proposed that protein interactions contribute to C3 function. Using the C3 protein of Tomato yellow leaf curl virus, we examined the impact of mutations to amino acids that are conserved across the C3 protein family on replication enhancement and protein interactions. Surprisingly, many of the mutations did not affect replication enhancement activity of C3 in tobacco protoplasts. Other mutations either enhanced or were detrimental to C3 replication activity. Analysis of mutated proteins in yeast two-hybrid assays indicated that mutations that inactivate C3 replication enhancement activity also reduce or inactivate C3 oligomerization and interaction with C1 and PCNA. In contrast, mutated C3 proteins impaired for pRBR binding are fully functional in replication assays. Hydrophobic residues in the middle of the C3 protein were implicated in C3 interaction with itself, C1, and PCNA, while polar resides at both the N and C termini of the protein are important for C3-pRBR interaction. These experiments established the importance of C3-C3, C3-C1, and C3-PCNA interactions in geminivirus replication. While C3-pRBR interaction is not required for viral replication in cycling cells, it may play a role during infection of differentiated cells in intact plants.
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Affiliation(s)
- Sharon B Settlage
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, 27695-7622, USA.
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100
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Shivaprasad PV, Akbergenov R, Trinks D, Rajeswaran R, Veluthambi K, Hohn T, Pooggin MM. Promoters, transcripts, and regulatory proteins of Mungbean yellow mosaic geminivirus. J Virol 2005; 79:8149-63. [PMID: 15956560 PMCID: PMC1143740 DOI: 10.1128/jvi.79.13.8149-8163.2005] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 03/02/2005] [Indexed: 11/20/2022] Open
Abstract
Geminiviruses package circular single-stranded DNA and replicate in the nucleus via a double-stranded intermediate. This intermediate also serves as a template for bidirectional transcription by polymerase II. Here, we map promoters and transcripts and characterize regulatory proteins of Mungbean yellow mosaic virus-Vigna (MYMV), a bipartite geminivirus in the genus Begomovirus. The following new features, which might also apply to other begomoviruses, were revealed in MYMV. The leftward and rightward promoters on DNA-B share the transcription activator AC2-responsive region, which does not overlap the common region that is nearly identical in the two DNA components. The transcription unit for BC1 (movement protein) includes a conserved, leader-based intron. Besides negative-feedback regulation of its own leftward promoter on DNA-A, the replication protein AC1, in cooperation with AC2, synergistically transactivates the rightward promoter, which drives a dicistronic transcription unit for the coat protein AV1. AC2 and the replication enhancer AC3 are expressed from one dicistronic transcript driven by a strong promoter mapped within the upstream AC1 gene. Early and constitutive expression of AC2 is consistent with its essential dual function as an activator of viral transcription and a suppressor of silencing.
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Affiliation(s)
- P V Shivaprasad
- Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland
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