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Li M, Li C, Jiang K, Li K, Zhang J, Sun M, Wu G, Qing L. Characterization of Pathogenicity-Associated V2 Protein of Tobacco Curly Shoot Virus. Int J Mol Sci 2021; 22:E923. [PMID: 33477652 PMCID: PMC7831499 DOI: 10.3390/ijms22020923] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 11/17/2022] Open
Abstract
V2 proteins encoded by some whitefly-transmitted geminiviruses were reported to be functionally important proteins. However, the functions of the V2 protein of tobacco curly shoot virus (TbCSV), a monopartite begomovirus that causes leaf curl disease on tomato and tobacco in China, remains to be characterized. In our report, an Agrobacterium infiltration-mediated transient expression assay indicated that TbCSV V2 can suppress local and systemic RNA silencing and the deletion analyses demonstrated that the amino acid region 1-92 of V2, including the five predicted α-helices, are required for local RNA silencing suppression. Site-directed substitutions showed that the conserved basic and ring-structured amino acids in TbCSV V2 are critical for its suppressor activity. Potato virus X-mediated heteroexpression of TbCSV V2 in Nicotiana benthamiana induced hypersensitive response-like (HR-like) cell death and systemic necrosis in a manner independent of V2's suppressor activity. Furthermore, TbCSV infectious clone mutant with untranslated V2 protein (TbCSV∆V2) could not induce visual symptoms, and coinfection with betasatellite (TbCSB) could obviously elevate the viral accumulation and symptom development. Interestingly, symptom recovery occurred at 15 days postinoculation (dpi) and onward in TbCSV∆V2/TbCSB-inoculated plants. The presented work contributes to understanding the RNA silencing suppression activity of TbCSV V2 and extends our knowledge of the multifunctional role of begomovirus-encoded V2 proteins during viral infections.
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Affiliation(s)
- Mingjun Li
- Correspondence: (M.L.); (L.Q.); Tel.: +86-023-68250517 (L.Q.)
| | | | | | | | | | | | | | - Ling Qing
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing 400716, China; (C.L.); (K.J.); (K.L.); (J.Z.); (M.S.); (G.W.)
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2
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Luna AP, Romero-Rodríguez B, Rosas-Díaz T, Cerero L, Rodríguez-Negrete EA, Castillo AG, Bejarano ER. Characterization of Curtovirus V2 Protein, a Functional Homolog of Begomovirus V2. FRONTIERS IN PLANT SCIENCE 2020; 11:835. [PMID: 32636860 PMCID: PMC7318802 DOI: 10.3389/fpls.2020.00835] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/25/2020] [Indexed: 05/30/2023]
Abstract
Geminiviruses are single-stranded DNA plant viruses with circular genomes packaged within geminate particles. Among the Geminiviridae family, Begomovirus and Curtovirus comprise the two best characterized genera. Curtovirus and Old World begomovirus possess similar genome structures with six to seven open-reading frames (ORF). Among them, begomovirus and curtovirus V2 ORFs share the same location in the viral genome, encode proteins of similar size, but show extremely poor sequence homology between the genera. V2 from Beet curly top virus (BCTV), the model species for the Curtovirus genus, as it begomoviral counterpart, suppresses post-transcriptional gene silencing (PTGS) by impairing the RDR6/SGS3 pathway and localizes in the nucleus spanning from the perinuclear region to the cell periphery. By aminoacid sequence comparison we have identified that curtoviral and begomoviral V2 proteins shared two hydrophobic domains and a putative phosphorylation motif. These three domains are essential for BCTV V2 silencing suppression activity, for the proper nuclear localization of the protein and for systemic infection. The lack of suppression activity in the mutated versions of V2 is complemented by the impaired function of RDR6 in Nicotiana benthamiana but the ability of the viral mutants to produce a systemic infection is not recovered in gene silencing mutant backgrounds. We have also demonstrated that, as its begomoviral homolog, V2 from BCTV is able to induce systemic symptoms and necrosis associated with a hypersensitive response-like (HR-like) when expressed from Potato virus X vector in N. benthamiana, and that this pathogenicity activity does not dependent of its ability to supress PTGS.
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Affiliation(s)
- Ana P Luna
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Beatriz Romero-Rodríguez
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Tábata Rosas-Díaz
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Laura Cerero
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Edgar A Rodríguez-Negrete
- CONACyT, Departamento de Biotecnología Agrícola, Instituto Politécnico Nacional, CIIDIR-Unidad Sinaloa, Guasave, Mexico
| | - Araceli G Castillo
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Eduardo R Bejarano
- Departamento de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
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3
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Mubin M, Briddon RW, Mansoor S. The V2 protein encoded by a monopartite begomovirus is a suppressor of both post-transcriptional and transcriptional gene silencing activity. Gene 2019; 686:43-48. [PMID: 30399424 DOI: 10.1016/j.gene.2018.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/08/2018] [Accepted: 11/01/2018] [Indexed: 11/23/2022]
Abstract
Papaya leaf curl virus (PaLCuV) is a begomovirus (genus Begomovirus; family Geminiviridae) with a monopartite genome that is usually associated with beta- and alphasatellites in plants. Geminiviruses are DNA viruses with small circular genomes that occur as minichromosomes in the nucleus and are susceptible to post-transcriptional gene silencing (PTGS) and transcriptional gene silencing (TGS). Transient expression of the PaLCuV V2 (PV2) protein together with the green fluorescent protein (GFP) in Nicotiana benthamiana resulted in enhanced levels of GFP fluorescence and GFP mRNA, indicative of suppression of PTGS. Expression of PV2 from a Potato virus X vector restored GFP expression in N. benthamiana plants harbouring a transcriptionally silenced GFP transgene, indicative of suppression of TGS. The results show that the PV2 protein encoded by PaLCuV has both suppressor of PTGS and TGS activity and is an important factor in overcoming host RNA-silencing based defenses.
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Affiliation(s)
- Muhammad Mubin
- Virology Lab, Centre of Agricultural Biochemistry and Biotechnology, University of Agriculture, Faisalabad 38000, Pakistan; Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan.
| | - Rob W Briddon
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - Shahid Mansoor
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
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Abbas Q, Amin I, Mansoor S, Shafiq M, Wassenegger M, Briddon RW. The Rep proteins encoded by alphasatellites restore expression of a transcriptionally silenced green fluorescent protein transgene in Nicotiana benthamiana. Virusdisease 2017; 30:101-105. [PMID: 31143837 DOI: 10.1007/s13337-017-0413-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 11/15/2017] [Indexed: 10/18/2022] Open
Abstract
Alphasatellites are non-essential satellite-like components associated with geminiviruses. The precise selective advantage to a geminivirus infection of an alphasatellite remains unclear. The ability of the cotton leaf curl Multan alphasatellite (CLCuMuA)-encoded replication-associated protein (Rep) to suppress TGS was investigated by using Nicotiana benthamiana line 16-TGS (16-TGS) harbouring a transcriptionally silenced green fluorescent protein (GFP) transgene. Inoculation of 16-TGS plants with a recombinant Potato virus X (PVX) vector carrying CLCuMuA Rep resulted in restoration of GFP expression. Northern blot analysis confirmed that the observed GFP fluorescence was associated with GFP mRNA accumulation. Inoculation with PVX vectors harbouring a further six Rep proteins, encoded by genetically distinct alphasatellites, were similarly shown to result in 16-TGS plants with restored GFP expression. These results indicate that the alphasatellite-encoded Rep can restore the expression of a transcriptionally silenced GFP transgene in N. benthamiana, indicating that alphasatellites are involved in overcoming host defence.
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Affiliation(s)
- Qamar Abbas
- 1National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan.,RLP-Agroscience, AlPlanta - Institute for Plant Research, Neustadt, Germany
| | - Imran Amin
- 1National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - Shahid Mansoor
- 1National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - Muhammad Shafiq
- 1National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan.,RLP-Agroscience, AlPlanta - Institute for Plant Research, Neustadt, Germany.,3Present Address: Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | | | - Rob W Briddon
- 1National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
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5
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Kushwaha NK, Bhardwaj M, Chakraborty S. The replication initiator protein of a geminivirus interacts with host monoubiquitination machinery and stimulates transcription of the viral genome. PLoS Pathog 2017; 13:e1006587. [PMID: 28859169 PMCID: PMC5597257 DOI: 10.1371/journal.ppat.1006587] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 09/13/2017] [Accepted: 08/16/2017] [Indexed: 12/13/2022] Open
Abstract
Geminiviruses constitute a group of plant viruses, with a ssDNA genome, whose replication in the nucleus of an infected cell requires the function of geminivirus-encoded replication initiator protein (Rep). Our results suggest that monoubiquitinated histone 2B (H2B-ub) promotes tri-methylation of histone 3 at lysine 4 (H3-K4me3) on the promoter of Chilli leaf curl virus (ChiLCV). We isolated homologues of two major components of the monoubiquitination machinery: UBIQUITIN-CONJUGATING ENZYME2 (NbUBC2) and HISTONE MONOUBIQUITINATION1 (NbHUB1) from N. benthamiana. ChiLCV failed to cause disease in NbUBC2-, and NbHUB1-silenced plants, at the same time, H2B-ub and H3-K4me3 modifications were decreased, and the occupancy of RNA polymerase II on the viral promoter was reduced as well. In further investigations, Rep protein of ChiLCV was found to re-localize NbUBC2 from the cytoplasm to the nucleoplasm, like NbHUB1, the cognate partner of NbUBC2. Rep was observed to interact and co-localize with NbHUB1 and NbUBC2 in the nuclei of the infected cells. In summary, the current study reveals that the ChiLCV Rep protein binds the viral genome and interacts with NbUBC2 and NbHUB1 for the monoubiquitination of histone 2B that subsequently promotes trimethylation of histone 3 at lysine 4 on ChiLCV mini-chromosomes and enhances transcription of the viral genes.
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Affiliation(s)
- Nirbhay Kumar Kushwaha
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mansi Bhardwaj
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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6
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Ju Z, Wang L, Cao D, Zuo J, Zhu H, Fu D, Luo Y, Zhu B. A viral satellite DNA vector-induced transcriptional gene silencing via DNA methylation of gene promoter in Nicotiana benthamiana. Virus Res 2016; 223:99-107. [PMID: 27422476 DOI: 10.1016/j.virusres.2016.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/05/2016] [Accepted: 07/08/2016] [Indexed: 11/19/2022]
Abstract
Virus-induced gene silencing (VIGS) has been widely used for plant functional genomics study at the post-transcriptional level using various DNA or RNA viral vectors. However, while virus-induced transcriptional gene silencing (VITGS) via DNA methylation of gene promoter was achieved using several plant RNA viral vectors, it has not yet been done using a satellite DNA viral vector. In this study, a viral satellite DNA associated with tomato yellow leaf curl China virus (TYLCCNV), which has been modified as a VIGS vector in previous research, was developed as a VITGS vector. Firstly, the viral satellite DNA VIGS vector was further optimized to a more convenient p1.7A+2mβ vector with high silencing efficiency of the phytoene desaturase (PDS) gene in Nicotiana benthamiana plants. Secondly, the constructed VITGS vector (TYLCCNV:35S), which carried a portion of the cauliflower mosaic virus 35S promoter, could successfully induce heritable transcriptional gene silencing (TGS) of the green fluorescent protein (GFP) gene in the 35S-GFP transgenic N. benthamiana line 16c plants. Moreover, bisulfite sequencing results revealed higher methylated cytosine residues at CG, CHG and CHH sites of the 35S promoter sequence in TYLCCNV:35S-inoculated plants than in TYLCCNV-inoculated line 16c plants (control). Overall, these results demonstrated that the viral satellite DNA vector could be used as an effective VITGS vector to study DNA methylation in plant genomes.
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Affiliation(s)
- Zheng Ju
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Lei Wang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Dongyan Cao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Jinhua Zuo
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
| | - Hongliang Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Daqi Fu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Yunbo Luo
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Benzhong Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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7
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Akbar F, Iqbal Z, Briddon RW, Vazquez F, Saeed M. The 35-amino acid C2 protein of Cotton leaf curl Kokhran virus, Burewala, implicated in resistance breaking in cotton, retains some activities of the full-length protein. Virus Genes 2016; 52:688-97. [PMID: 27209537 DOI: 10.1007/s11262-016-1357-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/12/2016] [Indexed: 11/26/2022]
Abstract
With one exception, all the begomoviruses characterized so far encode an ~134-amino acid (aa) (A)C2 protein. The exception is the "Burewala" strain of Cotton leaf curl Kokhran virus (CLCuKoV-Bu), associated with resistance breaking in cotton across Pakistan and northwestern India, that encodes a truncated 35-aa C2. The C2 protein encoded by begomoviruses performs multiple functions including suppression of post-transcriptional gene silencing (PTGS), modulating microRNA (miRNA) expression and may be a pathogenicity determinant. The study described here was designed to investigate whether the CLCuKoV-Bu 35-aa C2 retains the activities of the full-length C2 protein. The results showed the 35-aa C2 of CLCuKoV-Bu acts as a pathogenicity determinant, suppresses PTGS and upregulates miRNA expression when expressed from a Potato virus X vector in Nicotiana benthamiana. The symptoms induced by expression of full-length C2 were more severe than those induced by the 35-aa C2. The accumulation of most developmental miRNAs decreases with the full-length C2 protein and increases with the 35-aa peptide of CLCuKoV-Bu. The study also revealed that 35-aa peptide of CLCuKoV-Bu maintains suppressor of silencing activity at a level equal to that of full-length C2. The significance of the results with respect to virus fitness and resistance breaking is discussed.
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Affiliation(s)
- Fazal Akbar
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
- Botanical Institute of the University of Basel, Zürich-Basel Plant Science Center, Part of the Swiss Plant Science Web, Schnbeinstrasse 6, 4056, Basel, Switzerland
- Centre for Biotechnology and Microbiology, University of Swat, Swat, Pakistan
| | - Zafar Iqbal
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
- Institute of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan
| | - Rob W Briddon
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - Franck Vazquez
- Botanical Institute of the University of Basel, Zürich-Basel Plant Science Center, Part of the Swiss Plant Science Web, Schnbeinstrasse 6, 4056, Basel, Switzerland
- MDPI AG, Klybeckstrasse 64, 4057, Basel, Switzerland
| | - Muhammad Saeed
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan.
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Saeed M, Briddon RW, Dalakouras A, Krczal G, Wassenegger M. Functional Analysis of Cotton Leaf Curl Kokhran Virus/Cotton Leaf Curl Multan Betasatellite RNA Silencing Suppressors. BIOLOGY 2015; 4:697-714. [PMID: 26512705 PMCID: PMC4690014 DOI: 10.3390/biology4040697] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 12/13/2022]
Abstract
In South Asia, Cotton leaf curl disease (CLCuD) is caused by a complex of phylogenetically-related begomovirus species and a specific betasatellite, Cotton leaf curl Multan betasatellite (CLCuMuB). The post-transcriptional gene silencing (PTGS) suppression activities of the transcriptional activator protein (TrAP), C4, V2 and βC1 proteins encoded by Cotton leaf curl Kokhran virus (CLCuKoV)/CLCuMuB were assessed in Nicotiana benthamiana. A variable degree of local silencing suppression was observed for each viral protein tested, with V2 protein exhibiting the strongest suppression activity and only the C4 protein preventing the spread of systemic silencing. The CLCuKoV-encoded TrAP, C4, V2 and CLCuMuB-encoded βC1 proteins were expressed in Escherichia coli and purified. TrAP was shown to bind various small and long nucleic acids including single-stranded (ss) and double-stranded (ds) RNA and DNA molecules. C4, V2, and βC1 bound ssDNA and dsDNA with varying affinities. Transgenic expression of C4 under the constitutive 35S Cauliflower mosaic virus promoter and βC1 under a dexamethasone inducible promoter induced severe developmental abnormalities in N. benthamiana. The results indicate that homologous proteins from even quite closely related begomoviruses may differ in their suppressor activity and mechanism of action. The significance of these findings is discussed.
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Affiliation(s)
- Muhammad Saeed
- RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany.
- National Institute for Biotechnology and Genetic Engineering, Jhang Road, PO Box 577, Faisalabad 38000, Pakistan.
| | - Rob W Briddon
- National Institute for Biotechnology and Genetic Engineering, Jhang Road, PO Box 577, Faisalabad 38000, Pakistan.
| | - Athanasios Dalakouras
- RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany.
| | - Gabi Krczal
- RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany.
| | - Michael Wassenegger
- RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany.
- Centre for Organismal Studies (COS) Heidelberg, University of Heidelberg, Im Neuenheimer Feld 360, Heidelberg D-69120, Germany.
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