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Luan H, Song D, Huang K, Li S, Xu H, Kachroo P, Kachroo A, Zhao L. Genome-wide analysis of the soybean eEF gene family and its involvement in virus resistance. FRONTIERS IN PLANT SCIENCE 2024; 15:1421221. [PMID: 39224853 PMCID: PMC11366645 DOI: 10.3389/fpls.2024.1421221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Accepted: 07/31/2024] [Indexed: 09/04/2024]
Abstract
Eukaryotic elongation factors (eEFs) are protein factors that mediate the extension of peptide chain, among which eukaryotic elongation factor 1 alpha (eEF1A) is one of the most abundant protein synthesis factors. Previously we showed that the P3 protein of Soybean mosaic virus (SMV), one of the most destructive and successful viral pathogens of soybean, targets a component of the soybean translation elongation complex to facilitate its pathogenesis. Here, we conducted a systematic analyses of the soybean eEF (GmeEF) gene family in soybean and examinedits role in virus resistance. In this study, GmeEF family members were identified and characterized based on sequence analysis. The 42 members, which were unevenly distributed across the 15 chromosomes, were renamed according to their chromosomal locations. The GmeEF members were further divided into 12 subgroups based on conserved motif, gene structure, and phylogenetic analyses. Analysis of the promoter regions showed conspicuous presence of myelocytomatosis (MYC) and ethylene-responsive (ERE) cis-acting elements, which are typically involved in drought and phytohormone response, respectively, and thereby in plant stress response signaling. Transcriptome data showed that the expression of 15 GmeEF gene family members changed significantly in response to SMV infection. To further examine EF1A function in pathogen response, three different Arabidopsis mutants carrying T-DNA insertions in orthologous genes were analyzed for their response to Turnip crinkle virus (TCV) and Cucumber mosaic virus (CMV). Results showed that there was no difference in viral response between the mutants and the wild type plants. This study provides a systematic analysis of the GmeEF gene family through analysis of expression patterns and predicted protein features. Our results lay a foundation for understanding the role of eEF gene in soybean anti-viral response.
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Affiliation(s)
- Hexiang Luan
- Institute of Plant Genetic Engineering, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Daiqiao Song
- Institute of Plant Genetic Engineering, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Kai Huang
- Institute of Plant Genetic Engineering, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Shuxin Li
- Institute of Plant Genetic Engineering, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Hao Xu
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Pradeep Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Aardra Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington, KY, United States
| | - Longgang Zhao
- College of Grassland Science, Qingdao Agricultural University, Qingdao, China
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Kitazawa Y, Iwabuchi N, Maejima K, Sasano M, Matsumoto O, Koinuma H, Tokuda R, Suzuki M, Oshima K, Namba S, Yamaji Y. A phytoplasma effector acts as a ubiquitin-like mediator between floral MADS-box proteins and proteasome shuttle proteins. THE PLANT CELL 2022; 34:1709-1723. [PMID: 35234248 PMCID: PMC9048881 DOI: 10.1093/plcell/koac062] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/14/2022] [Indexed: 06/01/2023]
Abstract
Plant pathogenic bacteria have developed effectors to manipulate host cell functions to facilitate infection. A certain number of effectors use the conserved ubiquitin-proteasome system in eukaryotic to proteolyze targets. The proteasome utilization mechanism is mainly mediated by ubiquitin interaction with target proteins destined for degradation. Phyllogens are a family of protein effectors produced by pathogenic phytoplasmas that transform flowers into leaves in diverse plants. Here, we present a noncanonical mechanism for phyllogen action that involves the proteasome and is ubiquitin-independent. Phyllogens induce proteasomal degradation of floral MADS-box transcription factors (MTFs) in the presence of RADIATION-SENSITIVE23 (RAD23) shuttle proteins, which recruit ubiquitinated proteins to the proteasome. Intracellular localization analysis revealed that phyllogen induced colocalization of MTF with RAD23. The MTF/phyllogen/RAD23 ternary protein complex was detected not only in planta but also in vitro in the absence of ubiquitin, showing that phyllogen directly mediates interaction between MTF and RAD23. A Lys-less nonubiquitinated phyllogen mutant induced degradation of MTF or a Lys-less mutant of MTF. Furthermore, the method of sequential formation of the MTF/phyllogen/RAD23 protein complex was elucidated, first by MTF/phyllogen interaction and then RAD23 recruitment. Phyllogen recognized both the evolutionarily conserved tetramerization region of MTF and the ubiquitin-associated domain of RAD23. Our findings indicate that phyllogen functionally mimics ubiquitin as a mediator between MTF and RAD23.
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Affiliation(s)
- Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Nozomu Iwabuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | | | - Momoka Sasano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Oki Matsumoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Ryosuke Tokuda
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Masato Suzuki
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kenro Oshima
- Faculty of Bioscience and Applied Chemistry, Hosei University, Tokyo 184-8584, Japan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Chen X, He L, Xu M, Yang J, Li J, Zhang T, Liao Q, Zhang H, Yang J, Chen J. Binding between elongation factor 1A and the 3'-UTR of Chinese wheat mosaic virus is crucial for virus infection. MOLECULAR PLANT PATHOLOGY 2021; 22:1383-1398. [PMID: 34405507 PMCID: PMC8518580 DOI: 10.1111/mpp.13120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 05/06/2023]
Abstract
The Chinese wheat mosaic virus (CWMV) genome consists of two positive-strand RNAs that are required for CWMV replication and translation. The eukaryotic translation elongation factor (eEF1A) is crucial for the elongation of protein translation in eukaryotes. Here, we show that silencing eEF1A expression in Nicotiana benthamiana plants by performing virus-induced gene silencing can greatly reduce the accumulation of CWMV genomic RNAs, whereas overexpression of eEF1A in plants increases the accumulation of CWMV genomic RNAs. In vivo and in vitro assays showed that eEF1A does not interact with CWMV RNA-dependent RNA polymerase. Electrophoretic mobility shift assays revealed that eEF1A can specifically bind to the 3'-untranslated region (UTR) of CWMV genomic RNAs. By performing mutational analyses, we determined that the conserved region in the 3'-UTR of CWMV genomic RNAs is necessary for CWMV replication and translation, and that the sixth stem-loop (SL-6) in the 3'-UTR of CWMV genomic RNAs plays a key role in CWMV infection. We conclude that eEF1A is an essential host factor for CWMV infection. This finding should help us to develop new strategies for managing CWMV infections in host plants.
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Affiliation(s)
- Xuan Chen
- College of Plant ProtectionNorthwest Agriculture and Forestry UniversityYanglingChina
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
- Institute of Virology and BiotechnologyZhejiang Academy of Agricultural SciencesHangzhouChina
| | - Long He
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
| | - Miaoze Xu
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
| | - Jin Yang
- College of Plant ProtectionNorthwest Agriculture and Forestry UniversityYanglingChina
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
| | - Juan Li
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
| | - Tianye Zhang
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
| | - Qiansheng Liao
- College of Life ScienceZhejiang SCI‐Tech UniversityHangzhouChina
| | - Hengmu Zhang
- Institute of Virology and BiotechnologyZhejiang Academy of Agricultural SciencesHangzhouChina
| | - Jian Yang
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
- Institute of Virology and BiotechnologyZhejiang Academy of Agricultural SciencesHangzhouChina
| | - Jianping Chen
- College of Plant ProtectionNorthwest Agriculture and Forestry UniversityYanglingChina
- State Key Laboratory for Quality and Safety of Agro‐productsInstitute of Plant Virology of Ningbo UniversityNingboChina
- Institute of Virology and BiotechnologyZhejiang Academy of Agricultural SciencesHangzhouChina
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Langeberg CJ, Sherlock ME, MacFadden A, Kieft JS. An expanded class of histidine-accepting viral tRNA-like structures. RNA (NEW YORK, N.Y.) 2021; 27:653-664. [PMID: 33811147 PMCID: PMC8127992 DOI: 10.1261/rna.078550.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/30/2021] [Indexed: 05/12/2023]
Abstract
Structured RNA elements are common in the genomes of RNA viruses, often playing critical roles during viral infection. Some viral RNA elements use forms of tRNA mimicry, but the diverse ways this mimicry can be achieved are poorly understood. Histidine-accepting tRNA-like structures (TLSHis) are examples found at the 3' termini of some positive-sense single-stranded RNA (+ssRNA) viruses where they interact with several host proteins, induce histidylation of the RNA genome, and facilitate processes important for infection, to include genome replication. As only five TLSHis examples had been reported, we explored the possible larger phylogenetic distribution and diversity of this TLS class using bioinformatic approaches. We identified many new examples of TLSHis, yielding a rigorous consensus sequence and secondary structure model that we validated by chemical probing of representative TLSHis RNAs. We confirmed new examples as authentic TLSHis by demonstrating their ability to be histidylated in vitro, then used mutational analyses to imply a tertiary interaction that is likely analogous to the D- and T-loop interaction found in canonical tRNAs. These results expand our understanding of how diverse RNA sequences achieve tRNA-like structure and function in the context of viral RNA genomes and lay the groundwork for high-resolution structural studies of tRNA mimicry by histidine-accepting TLSs.
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Affiliation(s)
- Conner J Langeberg
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Madeline E Sherlock
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Andrea MacFadden
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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5
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Changes in Subcellular Localization of Host Proteins Induced by Plant Viruses. Viruses 2021; 13:v13040677. [PMID: 33920930 PMCID: PMC8071230 DOI: 10.3390/v13040677] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 12/24/2022] Open
Abstract
Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses.
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Iwabuchi N, Kitazawa Y, Maejima K, Koinuma H, Miyazaki A, Matsumoto O, Suzuki T, Nijo T, Oshima K, Namba S, Yamaji Y. Functional variation in phyllogen, a phyllody-inducing phytoplasma effector family, attributable to a single amino acid polymorphism. MOLECULAR PLANT PATHOLOGY 2020; 21:1322-1336. [PMID: 32813310 PMCID: PMC7488466 DOI: 10.1111/mpp.12981] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/25/2020] [Accepted: 07/05/2020] [Indexed: 05/08/2023]
Abstract
Flower malformation represented by phyllody is a common symptom of phytoplasma infection induced by a novel family of phytoplasma effectors called phyllogens. Despite the accumulation of functional and structural phyllogen information, the molecular mechanisms of phyllody have not yet been integrated with their evolutionary aspects due to the limited data on their homologs across diverse phytoplasma lineages. Here, we developed a novel universal PCR-based approach to identify 25 phytoplasma phyllogens related to nine "Candidatus Phytoplasma" species, including four species whose phyllogens have not yet been identified. Phylogenetic analyses showed that the phyllogen family consists of four groups (phyl-A, -B, -C, and -D) and that the evolutionary relationships of phyllogens were significantly distinct from those of phytoplasmas, suggesting that phyllogens were transferred horizontally among phytoplasma strains and species. Although phyllogens belonging to the phyl-A, -C, and -D groups induced phyllody, the phyl-B group lacked the ability to induce phyllody. Comparative functional analyses of phyllogens revealed that a single amino acid polymorphism in phyl-B group phyllogens prevented interactions between phyllogens and A- and E-class MADS domain transcription factors (MTFs), resulting in the inability to degrade several MTFs and induce phyllody. Our finding of natural variation in the function of phytoplasma effectors provides new insights into molecular mechanisms underlying the aetiology of phytoplasma diseases.
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Affiliation(s)
- Nozomu Iwabuchi
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yugo Kitazawa
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Kensaku Maejima
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Akio Miyazaki
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Ouki Matsumoto
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Takumi Suzuki
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Takamichi Nijo
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | | | - Shigetou Namba
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
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7
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Ibrahim A, Yang X, Liu C, Cooper KD, Bishop BA, Zhu M, Kwon S, Schoelz JE, Nelson RS. Plant SNAREs SYP22 and SYP23 interact with Tobacco mosaic virus 126 kDa protein and SYP2s are required for normal local virus accumulation and spread. Virology 2020; 547:57-71. [PMID: 32560905 DOI: 10.1016/j.virol.2020.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/18/2020] [Accepted: 04/07/2020] [Indexed: 10/24/2022]
Abstract
Viral proteins often interact with multiple host proteins during virus accumulation and spread. Identities and functions of all interacting host proteins are not known. Through a yeast two-hybrid screen an Arabidopsis thaliana Qa-SNARE protein [syntaxin of plants 23 (AtSYP23)], associated with pre-vacuolar compartment and vacuolar membrane fusion activities, interacted with Tobacco mosaic virus (TMV) 126 kDa protein, associated with virus accumulation and spread. In planta, AtSYP23 and AtSYP22 each fused with mCherry, co-localized with 126 kDa protein-GFP. Additionally, A. thaliana and Nicotiana benthamiana SYP2 proteins and 126 kDa protein interacted during bimolecular fluorescence complementation analysis. Decreased TMV accumulation in Arabidopsis plants lacking SYP23 and in N. benthamiana plants subjected to virus-induced gene silencing (VIGS) of SYP2 orthologs was observed. Diminished TMV accumulation during VIGS correlated with less intercellular virus spread. The inability to eliminate virus accumulation suggests that SYP2 proteins function redundantly for TMV accumulation, as for plant development.
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Affiliation(s)
- Amr Ibrahim
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA; Department of Nucleic Acid and Protein Structure, Agricultural Genetic Engineering Research Institute, Agricultural Research Center, Giza, Egypt.
| | - Xiaohua Yang
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - Chengke Liu
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | | | | | - Min Zhu
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - Soonil Kwon
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - James E Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA
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Sun D, Ji X, Jia Y, Huo D, Si S, Zeng L, Zhang Y, Niu L. LreEF1A4, a Translation Elongation Factor from Lilium regale, Is Pivotal for Cucumber Mosaic Virus and Tobacco Rattle Virus Infections and Tolerance to Salt and Drought. Int J Mol Sci 2020; 21:E2083. [PMID: 32197393 PMCID: PMC7139328 DOI: 10.3390/ijms21062083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic translation elongation factors are implicated in protein synthesis across different living organisms, but their biological functions in the pathogenesis of cucumber mosaic virus (CMV) and tobacco rattle virus (TRV) infections are poorly understood. Here, we isolated and characterized a cDNA clone, LreEF1A4, encoding the alpha subunit of elongation factor 1, from a CMV-elicited suppression subtractive hybridization library of Lilium regale. The infection tests using CMV remarkably increased transcript abundance of LreEF1A4; however, it also led to inconsistent expression profiles of three other LreEF1A homologs (LreEF1A1-3). Protein modelling analysis revealed that the amino acid substitutions among four LreEF1As may not affect their enzymatic functions. LreEF1A4 was ectopically overexpressed in petunia (Petunia hybrida), and transgenic plants exhibited delayed leaf and flower senescence, concomitant with increased transcription of photosynthesis-related genes and reduced expression of senescence-associated genes, respectively. A compromised resistance to CMV and TRV infections was found in transgenic petunia plants overexpressing LreEF1A4, whereas its overexpression resulted in an enhanced tolerance to salt and drought stresses. Taken together, our data demonstrate that LreEF1A4 functions as a positive regulator in viral multiplication and plant adaption to high salinity and dehydration.
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Affiliation(s)
- Daoyang Sun
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Xiaotong Ji
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Yong Jia
- State Agricultural Biotechnology Centre, School of Veterinary and Life Sciences, Murdoch University, Perth 6150, Australia
| | - Dan Huo
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Shiying Si
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Lingling Zeng
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Yanlong Zhang
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
| | - Lixin Niu
- College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China
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Adkar-Purushothama CR, Perreault JP. Current overview on viroid-host interactions. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1570. [PMID: 31642206 DOI: 10.1002/wrna.1570] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 09/12/2019] [Accepted: 09/17/2019] [Indexed: 01/03/2023]
Abstract
Viroids are one of the most enigmatic highly structured, circular, single-stranded RNA phytopathogens. Although they are not known to code for any peptide, viroids induce visible symptoms in susceptible host plants that resemble those associated with many plant viruses. It is known that viroids induce disease symptoms by direct interaction with host factors; however, the precise mechanism by which this occurs remains poorly understood. Studies on the host's responses to viroid infection, host susceptibility and nonhost resistance have been underway for several years, but much remains to be done in order to fully understand the complex nature of viroid-host interactions. Recent progress using molecular biology techniques combined with computational algorithms, in particular evidence of the role of viroid-derived small RNAs in the RNA silencing pathways of a disease network, has widened the knowledge of viroid pathogenicity. The complexity of viroid-host interactions has been revealed in the past decades to include, but not be limited to, the involvement of host factors, viroid structural complexity, and viroid-induced ribosomal stress, which is further boosted by the discovery of long noncoding RNAs (lncRNAs). In this review, the current understanding of the viroid-host interaction has been summarized with the goal of simplifying the complexity of viroid biology for future research. This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Charith Raj Adkar-Purushothama
- MYM Nutraceuticals Inc, Vancouver, British Columbia, Canada.,RNA Group/Groupe ARN, Département de Biochimie, Faculté de médecine des sciences de la santé, Pavillon de Recherche Appliquée au Cancer, Université de Sherbrooke, Québec, Canada
| | - Jean-Pierre Perreault
- RNA Group/Groupe ARN, Département de Biochimie, Faculté de médecine des sciences de la santé, Pavillon de Recherche Appliquée au Cancer, Université de Sherbrooke, Québec, Canada
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10
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Navarro JA, Sanchez-Navarro JA, Pallas V. Key checkpoints in the movement of plant viruses through the host. Adv Virus Res 2019; 104:1-64. [PMID: 31439146 DOI: 10.1016/bs.aivir.2019.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Plant viruses cannot exploit any of the membrane fusion-based routes of entry described for animal viruses. In addition, one of the distinctive structures of plant cells, the cell wall, acts as the first barrier against the invasion of pathogens. To overcome the rigidity of the cell wall, plant viruses normally take advantage of the way of life of different biological vectors. Alternatively, the physical damage caused by environmental stresses can facilitate virus entry. Once inside the cell and taking advantage of the characteristic symplastic continuity of plant cells, viruses need to remodel and/or modify the restricted pore size of the plasmodesmata (channels that connect plant cells). In a successful interaction for the virus, it can reach the vascular tissue to systematically invade the plant. The connections between the different cell types in this path are not designed to allow the passage of molecules with the complexity of viruses. During this process, viruses face different cell barriers that must be overcome to reach the distal parts of the plant. In this review, we highlight the current knowledge about how plant RNA viruses enter plant cells, move between them to reach vascular cells and overcome the different physical and cellular barriers that the phloem imposes. Finally, we update the current research on cellular organelles as key regulator checkpoints in the long-distance movement of plant viruses.
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Affiliation(s)
- Jose A Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Jesus A Sanchez-Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Vicente Pallas
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain.
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11
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Yusa A, Neriya Y, Hashimoto M, Yoshida T, Fujimoto Y, Hosoe N, Keima T, Tokumaru K, Maejima K, Netsu O, Yamaji Y, Namba S. Functional conservation of EXA1 among diverse plant species for the infection by a family of plant viruses. Sci Rep 2019; 9:5958. [PMID: 30976020 PMCID: PMC6459814 DOI: 10.1038/s41598-019-42400-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/20/2019] [Indexed: 12/20/2022] Open
Abstract
Since the propagation of plant viruses depends on various host susceptibility factors, deficiency in them can prevent viral infection in cultivated and model plants. Recently, we identified the susceptibility factor Essential for poteXvirus Accumulation 1 (EXA1) in Arabidopsis thaliana, and revealed that EXA1-mediated resistance was effective against three potexviruses. Although EXA1 homolog genes are found in tomato and rice, little is known about which viruses depend on EXA1 for their infection capability and whether the function of EXA1 homologs in viral infection is conserved across multiple plant species, including crops. To address these questions, we generated knockdown mutants using virus-induced gene silencing in two Solanaceae species, Nicotiana benthamiana and tomato. In N. benthamiana, silencing of an EXA1 homolog significantly compromised the accumulation of potexviruses and a lolavirus, a close relative of potexviruses, whereas transient expression of EXA1 homologs from tomato and rice complemented viral infection. EXA1 dependency for potexviral infection was also conserved in tomato. These results indicate that EXA1 is necessary for effective accumulation of potexviruses and a lolavirus, and that the function of EXA1 in viral infection is conserved among diverse plant species.
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Affiliation(s)
- Akira Yusa
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Yutaro Neriya
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
- Laboratory of Plant Pathology, School of Agriculture, Utsunomiya University, Mine-machi 350, Utsunomiya, Tochigi, 321-8505, Japan
| | - Masayoshi Hashimoto
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Tetsuya Yoshida
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Yuji Fujimoto
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Naoi Hosoe
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Takuya Keima
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kai Tokumaru
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kensaku Maejima
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Osamu Netsu
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Yasuyuki Yamaji
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Shigetou Namba
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan.
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12
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Park CJ, Park JM. Endoplasmic Reticulum Plays a Critical Role in Integrating Signals Generated by Both Biotic and Abiotic Stress in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:399. [PMID: 31019523 PMCID: PMC6458287 DOI: 10.3389/fpls.2019.00399] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/15/2019] [Indexed: 05/19/2023]
Abstract
Most studies of environmental adaptations in plants have focused on either biotic or abiotic stress factors in an attempt to understand the defense mechanisms of plants against individual stresses. However, in the natural ecosystem, plants are simultaneously exposed to multiple stresses. Stress-tolerant crops developed in translational studies based on a single stress often fail to exhibit the expected traits in the field. To adapt to abiotic stress, recent studies have identified the need for interactions of plants with various microorganisms. These findings highlight the need to understand the multifaceted interactions of plants with biotic and abiotic stress factors. The endoplasmic reticulum (ER) is an organelle that links various stress responses. To gain insight into the molecular integration of biotic and abiotic stress responses in the ER, we focused on the interactions of plants with RNA viruses. This interaction points toward the relevance of ER in viral pathogenicity as well as plant responses. In this mini review, we explore the molecular crosstalk between biotic and abiotic stress signaling through the ER by elaborating ER-mediated signaling in response to RNA viruses and abiotic stresses. Additionally, we summarize the results of a recent study on phytohormones that induce ER-mediated stress response. These studies will facilitate the development of multi-stress-tolerant transgenic crops in the future.
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Affiliation(s)
- Chang-Jin Park
- Department of Bioresources Engineering, Sejong University, Seoul, South Korea
- Plant Engineering Research Institute, Sejong University, Seoul, South Korea
- *Correspondence: Chang-Jin Park,
| | - Jeong Mee Park
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
- Department of Biosystems and Bioengineering, University of Science and Technology (UST), Daejeon, South Korea
- Jeong Mee Park,
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13
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Repression of Cell Differentiation by a cis-Acting lincRNA in Fission Yeast. Curr Biol 2018; 28:383-391.e3. [PMID: 29395921 DOI: 10.1016/j.cub.2017.12.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/19/2017] [Accepted: 12/20/2017] [Indexed: 11/20/2022]
Abstract
The cell fate decision leading to gametogenesis requires the convergence of multiple signals on the promoter of a master regulator. In fission yeast, starvation-induced signaling leads to the transcriptional induction of the ste11 gene, which encodes the central inducer of mating and gametogenesis, known as sporulation. We find that the long intergenic non-coding (linc) RNA rse1 is transcribed divergently upstream of the ste11 gene. During vegetative growth, rse1 directly recruits a Mug187-Lid2-Set1 complex that mediates cis repression at the ste11 promoter through SET3C-dependent histone deacetylation. The absence of rse1 bypasses the starvation-induced signaling and induces gametogenesis in the presence of nutrients. Our data reveal that the remodeling of chromatin through ncRNA scaffolding of repressive complexes that is observed in higher eukaryotes is a conserved, likely very ancient mechanism for tight control of cell differentiation.
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14
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Kachroo A, Vincelli P, Kachroo P. Signaling Mechanisms Underlying Resistance Responses: What Have We Learned, and How Is It Being Applied? PHYTOPATHOLOGY 2017; 107:1452-1461. [PMID: 28609156 DOI: 10.1094/phyto-04-17-0130-rvw] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Plants have evolved highly specific mechanisms to resist pathogens including preformed barriers and the induction of elaborate signaling pathways. Induced signaling requires recognition of the pathogen either via conserved pathogen-derived factors or specific pathogen-encoded proteins called effectors. Recognition of these factors by host encoded receptor proteins can result in the elicitation of different tiers of resistance at the site of pathogen infection. In addition, plants induce a type of systemic immunity which is effective at the whole plant level and protects against a broad spectrum of pathogens. Advances in our understanding of pathogen-recognition mechanisms, identification of the underlying molecular components, and their significant conservation across diverse plant species has enabled the development of novel strategies to combat plant diseases. This review discusses key advances in plant defense signaling that have been adapted or have the potential to be adapted for plant protection against microbial diseases.
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Affiliation(s)
- Aardra Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington 40546
| | - Paul Vincelli
- Department of Plant Pathology, University of Kentucky, Lexington 40546
| | - Pradeep Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington 40546
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15
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Kitazawa Y, Iwabuchi N, Himeno M, Sasano M, Koinuma H, Nijo T, Tomomitsu T, Yoshida T, Okano Y, Yoshikawa N, Maejima K, Oshima K, Namba S. Phytoplasma-conserved phyllogen proteins induce phyllody across the Plantae by degrading floral MADS domain proteins. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2799-2811. [PMID: 28505304 PMCID: PMC5853863 DOI: 10.1093/jxb/erx158] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/13/2017] [Indexed: 05/21/2023]
Abstract
ABCE-class MADS domain transcription factors (MTFs) are key regulators of floral organ development in angiosperms. Aberrant expression of these genes can result in abnormal floral traits such as phyllody. Phyllogen is a virulence factor conserved in phytoplasmas, plant pathogenic bacteria of the class Mollicutes. It triggers phyllody in Arabidopsis thaliana by inducing degradation of A- and E-class MTFs. However, it is still unknown whether phyllogen can induce phyllody in plants other than A. thaliana, although phytoplasma-associated phyllody symptoms are observed in a broad range of angiosperms. In this study, phyllogen was shown to cause phyllody phenotypes in several eudicot species belonging to three different families. Moreover, phyllogen can interact with MTFs of not only angiosperm species including eudicots and monocots but also gymnosperms and a fern, and induce their degradation. These results suggest that phyllogen induces phyllody in angiosperms and inhibits MTF function in diverse plant species.
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Affiliation(s)
- Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Nozomu Iwabuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Misako Himeno
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Momoka Sasano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Takamichi Nijo
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Tatsuya Tomomitsu
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Tetsuya Yoshida
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Yukari Okano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Nobuyuki Yoshikawa
- Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka-shi, Iwate, Japan
| | - Kensaku Maejima
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Kenro Oshima
- Faculty of Bioscience, Hosei University, 3-7-2 Kajino-cho, Koganei-shi, Tokyo, Japan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
- Correspondence:
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16
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Huang YP, Chen IH, Tsai CH. Host Factors in the Infection Cycle of Bamboo mosaic virus. Front Microbiol 2017; 8:437. [PMID: 28360904 PMCID: PMC5350103 DOI: 10.3389/fmicb.2017.00437] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/02/2017] [Indexed: 12/02/2022] Open
Abstract
To complete the infection cycle efficiently, the virus must hijack the host systems in order to benefit for all the steps and has to face all the defense mechanisms from the host. This review involves a discussion of how these positive and negative factors regulate the viral RNA accumulation identified for the Bamboo mosaic virus (BaMV), a single-stranded RNA virus. The genome of BaMV is approximately 6.4 kb in length, encoding five functional polypeptides. To reveal the host factors involved in the infection cycle of BaMV, a few different approaches were taken to screen the candidates. One of the approaches is isolating the viral replicase-associated proteins by co-immunoprecipitation with the transiently expressed tagged viral replicase in plants. Another approach is using the cDNA-amplified fragment length polymorphism technique to screen the differentially expressed genes derived from N. benthamiana plants after infection. The candidates are examined by knocking down the expression in plants using the Tobacco rattle virus-based virus-induced gene silencing technique following BaMV inoculation. The positive or negative regulators could be described as reducing or enhancing the accumulation of BaMV in plants when the expression levels of these proteins are knocked down. The possible roles of these host factors acting on the accumulation of BaMV will be discussed.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
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17
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Machado JPB, Calil IP, Santos AA, Fontes EPB. Translational control in plant antiviral immunity. Genet Mol Biol 2017; 40:292-304. [PMID: 28199446 PMCID: PMC5452134 DOI: 10.1590/1678-4685-gmb-2016-0092] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/27/2016] [Indexed: 01/11/2023] Open
Abstract
Due to the limited coding capacity of viral genomes, plant viruses depend extensively on the host cell machinery to support the viral life cycle and, thereby, interact with a large number of host proteins during infection. Within this context, as plant viruses do not harbor translation-required components, they have developed several strategies to subvert the host protein synthesis machinery to produce rapidly and efficiently the viral proteins. As a countermeasure against infection, plants have evolved defense mechanisms that impair viral infections. Among them, the host-mediated translational suppression has been characterized as an efficient mean to restrict infection. To specifically suppress translation of viral mRNAs, plants can deploy susceptible recessive resistance genes, which encode translation initiation factors from the eIF4E and eIF4G family and are required for viral mRNA translation and multiplication. Additionally, recent evidence has demonstrated that, alternatively to the cleavage of viral RNA targets, host cells can suppress viral protein translation to silence viral RNA. Finally, a novel strategy of plant antiviral defense based on suppression of host global translation, which is mediated by the transmembrane immune receptor NIK1 (nuclear shuttle protein (NSP)-Interacting Kinase1), is discussed in this review.
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Affiliation(s)
- João Paulo B Machado
- Department of Biochemistry and Molecular Biology, BIOAGRO, National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36571.000, Viçosa, MG, Brazil
| | - Iara P Calil
- Department of Biochemistry and Molecular Biology, BIOAGRO, National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36571.000, Viçosa, MG, Brazil
| | - Anésia A Santos
- Department of General Biology, Universidade Federal de Viçosa, 36571.000, Viçosa, MG, Brazil
| | - Elizabeth P B Fontes
- Department of Biochemistry and Molecular Biology, BIOAGRO, National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36571.000, Viçosa, MG, Brazil
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18
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Hashimoto M, Neriya Y, Yamaji Y, Namba S. Recessive Resistance to Plant Viruses: Potential Resistance Genes Beyond Translation Initiation Factors. Front Microbiol 2016; 7:1695. [PMID: 27833593 PMCID: PMC5080351 DOI: 10.3389/fmicb.2016.01695] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 10/11/2016] [Indexed: 12/13/2022] Open
Abstract
The ability of plant viruses to propagate their genomes in host cells depends on many host factors. In the absence of an agrochemical that specifically targets plant viral infection cycles, one of the most effective methods for controlling viral diseases in plants is taking advantage of the host plant’s resistance machinery. Recessive resistance is conferred by a recessive gene mutation that encodes a host factor critical for viral infection. It is a branch of the resistance machinery and, as an inherited characteristic, is very durable. Moreover, recessive resistance may be acquired by a deficiency in a negative regulator of plant defense responses, possibly due to the autoactivation of defense signaling. Eukaryotic translation initiation factor (eIF) 4E and eIF4G and their isoforms are the most widely exploited recessive resistance genes in several crop species, and they are effective against a subset of viral species. However, the establishment of efficient, recessive resistance-type antiviral control strategies against a wider range of plant viral diseases requires genetic resources other than eIF4Es. In this review, we focus on recent advances related to antiviral recessive resistance genes evaluated in model plants and several crop species. We also address the roles of next-generation sequencing and genome editing technologies in improving plant genetic resources for recessive resistance-based antiviral breeding in various crop species.
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Affiliation(s)
- Masayoshi Hashimoto
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan
| | - Yutaro Neriya
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan
| | - Yasuyuki Yamaji
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan
| | - Shigetou Namba
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan
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19
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Abstract
Tobacco mosaic virus and other tobamoviruses have served as models for studying the mechanisms of viral RNA replication. In tobamoviruses, genomic RNA replication occurs via several steps: (a) synthesis of viral replication proteins by translation of the genomic RNA; (b) translation-coupled binding of the replication proteins to a 5'-terminal region of the genomic RNA; (c) recruitment of the genomic RNA by replication proteins onto membranes and formation of a complex with host proteins TOM1 and ARL8; (d) synthesis of complementary (negative-strand) RNA in the complex; and (e) synthesis of progeny genomic RNA. This article reviews current knowledge on tobamovirus RNA replication, particularly regarding how the genomic RNA is specifically selected as a replication template and how the replication proteins are activated. We also focus on the roles of the replication proteins in evading or suppressing host defense systems.
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Affiliation(s)
- Kazuhiro Ishibashi
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
| | - Masayuki Ishikawa
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
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20
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Muratoglu H, Nalcacioglu R, Arif BM, Demirbag Z. Genome-wide analysis of differential mRNA expression of Amsacta moorei entomopoxvirus, mediated by the gene encoding a viral protein kinase (AMV197). Virus Res 2016; 215:25-36. [PMID: 26820433 DOI: 10.1016/j.virusres.2016.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 01/19/2016] [Accepted: 01/19/2016] [Indexed: 11/16/2022]
Abstract
Insect-born entomopoxviruses (Fam: Poxviridae) are potentially important bio-pesticide against insect pests and expression vectors as well as vectors for transient human gene therapies including recombinant viral vaccines. For these reasons, it is necessary to understand the regulatory genes functions to improve its biotechnological potential. Here, we focused on the characterization of serine/threonine (Ser/Thr; ORF AMV197) protein kinase gene from the Amsacta moorei entomopoxvirus (AMEV), the type species of the genus Betaentomopoxvirus. Transcription of the parental and an amv197-null recombinant AMEV was compared by whole-genome gene expression microarray analysis. Blast2GO analysis reflected a broad diversity of upregulated and downregulated genes. Results showed that expression levels of 102 genes (45%) out of 226 tested genes changed significantly in the recombinant AMEV infected cells. Of these transcripts, 72 (70.58%) were upregulated and 30 (29.41%) were downregulated throughout the infection period. Genes involved in DNA repair, replication and nucleotide metabolism, transcription and RNA modification, and protein modification were mostly upregulated at different times in cells infected with the recombinant virus. Furthermore, transcription of all studied cellular genes including metabolism of apoptosis (Nedd2-like caspase, hemolin and elongation factor-1 alpha (ef1a) gene) was downregulated in the absence of amv197. Quantitative real time reverse transcription-PCR confirmed viral transcriptional changes obtained by microarray. The results of this study indicated that the product of amv197 appears to affect the transcriptional regulation of most viral and many cellular genes. Further investigations are, however, needed to narrow down the role of AMV197 throughout the infection process.
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Affiliation(s)
- Hacer Muratoglu
- Karadeniz Technical University, Faculty of Sciences, Department of Molecular Biology and Genetic, 61080 Trabzon, Turkey
| | - Remziye Nalcacioglu
- Karadeniz Technical University, Faculty of Sciences, Department of Biology, 61080 Trabzon, Turkey
| | - Basil M Arif
- Laboratory for Molecular Virology, Great Lakes Forestry Centre, Sault Ste. Marie, Ontario, Canada
| | - Zihni Demirbag
- Karadeniz Technical University, Faculty of Sciences, Department of Biology, 61080 Trabzon, Turkey.
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21
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Ding B, Qin Y, Chen M. Nucleocapsid proteins: roles beyond viral RNA packaging. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:213-26. [PMID: 26749541 PMCID: PMC7169677 DOI: 10.1002/wrna.1326] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/15/2015] [Accepted: 11/17/2015] [Indexed: 12/22/2022]
Abstract
Viral nucleocapsid proteins (NCs) enwrap the RNA genomes of viruses to form NC–RNA complexes, which act as a template and are essential for viral replication and transcription. Beyond packaging viral RNA, NCs also play important roles in virus replication, transcription, assembly, and budding by interacting with viral and host cellular proteins. Additionally, NCs can inhibit interferon signaling response and function in cell stress response, such as inducing apoptosis. Finally, NCs can be the target of vaccines, benefiting from their conserved gene sequences. Here, we summarize important findings regarding the additional functions of NCs as much more than structural RNA‐binding proteins, with specific emphasis on (1) their association with the viral life cycle, (2) their association with host cells, and (3) as ideal candidates for vaccine development. WIREs RNA 2016, 7:213–226. doi: 10.1002/wrna.1326 This article is categorized under:
RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications Translation > Translation Regulation
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Affiliation(s)
- Binbin Ding
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Yali Qin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Mingzhou Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
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22
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Li S, Feng S, Wang JH, He WR, Qin HY, Dong H, Li LF, Yu SX, Li Y, Qiu HJ. eEF1A Interacts with the NS5A Protein and Inhibits the Growth of Classical Swine Fever Virus. Viruses 2015; 7:4563-81. [PMID: 26266418 PMCID: PMC4576194 DOI: 10.3390/v7082833] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/03/2015] [Accepted: 08/05/2015] [Indexed: 12/23/2022] Open
Abstract
The NS5A protein of classical swine fever virus (CSFV) is involved in the RNA synthesis and viral replication. However, the NS5A-interacting cellular proteins engaged in the CSFV replication are poorly defined. Using yeast two-hybrid screen, the eukaryotic elongation factor 1A (eEF1A) was identified to be an NS5A-binding partner. The NS5A-eEF1A interaction was confirmed by coimmunoprecipitation, glutathione S-transferase (GST) pulldown and laser confocal microscopy assays. The domain I of eEF1A was shown to be critical for the NS5A-eEF1A interaction. Overexpression of eEF1A suppressed the CSFV growth markedly, and conversely, knockdown of eEF1A enhanced the CSFV replication significantly. Furthermore, eEF1A, as well as NS5A, was found to reduce the translation efficiency of the internal ribosome entry site (IRES) of CSFV in a dose-dependent manner, as demonstrated by luciferase reporter assay. Streptavidin pulldown assay revealed that eEF1A could bind to the CSFV IRES. Collectively, our results suggest that eEF1A interacts with NS5A and negatively regulates the growth of CSFV.
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Affiliation(s)
- Su Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China
| | - Shuo Feng
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Jing-Han Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Wen-Rui He
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Hua-Yang Qin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Hong Dong
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Lian-Feng Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Shao-Xiong Yu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Yongfeng Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
| | - Hua-Ji Qiu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, Heilongjiang, China.
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23
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Plant Translation Factors and Virus Resistance. Viruses 2015; 7:3392-419. [PMID: 26114476 PMCID: PMC4517107 DOI: 10.3390/v7072778] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/18/2015] [Accepted: 06/19/2015] [Indexed: 02/06/2023] Open
Abstract
Plant viruses recruit cellular translation factors not only to translate their viral RNAs but also to regulate their replication and potentiate their local and systemic movement. Because of the virus dependence on cellular translation factors, it is perhaps not surprising that many natural plant recessive resistance genes have been mapped to mutations of translation initiation factors eIF4E and eIF4G or their isoforms, eIFiso4E and eIFiso4G. The partial functional redundancy of these isoforms allows specific mutation or knock-down of one isoform to provide virus resistance without hindering the general health of the plant. New possible targets for antiviral strategies have also been identified following the characterization of other plant translation factors (eIF4A-like helicases, eIF3, eEF1A and eEF1B) that specifically interact with viral RNAs and proteins and regulate various aspects of the infection cycle. Emerging evidence that translation repression operates as an alternative antiviral RNA silencing mechanism is also discussed. Understanding the mechanisms that control the development of natural viral resistance and the emergence of virulent isolates in response to these plant defense responses will provide the basis for the selection of new sources of resistance and for the intelligent design of engineered resistance that is broad-spectrum and durable.
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Hwang J, Lee S, Lee JH, Kang WH, Kang JH, Kang MY, Oh CS, Kang BC. Plant Translation Elongation Factor 1Bβ Facilitates Potato Virus X (PVX) Infection and Interacts with PVX Triple Gene Block Protein 1. PLoS One 2015; 10:e0128014. [PMID: 26020533 PMCID: PMC4447259 DOI: 10.1371/journal.pone.0128014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 04/21/2015] [Indexed: 11/19/2022] Open
Abstract
The eukaryotic translation elongation factor 1 (eEF1) has two components: the G-protein eEF1A and the nucleotide exchange factor eEF1B. In plants, eEF1B is itself composed of a structural protein (eEF1Bγ) and two nucleotide exchange subunits (eEF1Bα and eEF1Bβ). To test the effects of elongation factors on virus infection, we isolated eEF1A and eEF1B genes from pepper (Capsicum annuum) and suppressed their homologs in Nicotiana benthamiana using virus-induced gene silencing (VIGS). The accumulation of a green fluorescent protein (GFP)-tagged Potato virus X (PVX) was significantly reduced in the eEF1Bβ- or eEF1Bɣ-silenced plants as well as in eEF1A-silenced plants. Yeast two-hybrid and co-immunoprecipitation analyses revealed that eEF1Bα and eEF1Bβ interacted with eEF1A and that eEF1A and eEF1Bβ interacted with triple gene block protein 1 (TGBp1) of PVX. These results suggest that both eEF1A and eEF1Bβ play essential roles in the multiplication of PVX by physically interacting with TGBp1. Furthermore, using eEF1Bβ deletion constructs, we found that both N- (1-64 amino acids) and C-terminal (150-195 amino acids) domains of eEF1Bβ are important for the interaction with PVX TGBp1 and that the C-terminal domain of eEF1Bβ is involved in the interaction with eEF1A. These results suggest that eEF1Bβ could be a potential target for engineering virus-resistant plants.
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Affiliation(s)
- JeeNa Hwang
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
- Korea Institute of Science and Technology Information, Seoul, 130–741, Korea
| | - Seonhee Lee
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
| | - Joung-Ho Lee
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
| | - Won-Hee Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
| | - Jin-Ho Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 232–916, Korea
| | - Min-Young Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
| | - Chang-Sik Oh
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, 446–701, Korea
| | - Byoung-Cheorl Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151–921, Korea
- Crop Biotechnology Institute/GreenBio Science and Technology, Seoul National University, Pyeongchang, 232–916, Korea
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Chujo T, Ishibashi K, Miyashita S, Ishikawa M. Functions of the 5'- and 3'-untranslated regions of tobamovirus RNA. Virus Res 2015; 206:82-9. [PMID: 25683511 DOI: 10.1016/j.virusres.2015.01.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 01/23/2015] [Accepted: 01/30/2015] [Indexed: 12/17/2022]
Abstract
The tobamovirus genome is a 5'-m(7)G-capped RNA that carries a tRNA-like structure at its 3'-terminus. The genomic RNA serves as the template for both translation and negative-strand RNA synthesis. The 5'- and 3'-untranslated regions (UTRs) of the genomic RNA contain elements that enhance translation, and the 3'-UTR also contains the elements necessary for the initiation of negative-strand RNA synthesis. Recent studies using a cell-free viral RNA translation-replication system revealed that a 70-nucleotide region containing a part of the 5'-UTR is bound cotranslationally by tobacco mosaic virus (TMV) replication proteins translated from the genomic RNA and that the binding leads the genomic RNA to RNA replication pathway. This mechanism explains the cis-preferential replication of TMV by the replication proteins. The binding also inhibits further translation to avoid a fatal ribosome-RNA polymerase collision, which might arise if translation and negative-strand synthesis occur simultaneously on a single genomic RNA molecule. Therefore, the 5'- and 3'-UTRs play multiple important roles in the life cycle of tobamovirus.
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Affiliation(s)
- Tetsuya Chujo
- Plant-Microbe Interactions Research Unit, Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Kazuhiro Ishibashi
- Plant-Microbe Interactions Research Unit, Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Shuhei Miyashita
- Plant-Microbe Interactions Research Unit, Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Masayuki Ishikawa
- Plant-Microbe Interactions Research Unit, Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan.
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Ishikawa K, Miura C, Maejima K, Komatsu K, Hashimoto M, Tomomitsu T, Fukuoka M, Yusa A, Yamaji Y, Namba S. Nucleocapsid protein from fig mosaic virus forms cytoplasmic agglomerates that are hauled by endoplasmic reticulum streaming. J Virol 2015; 89:480-91. [PMID: 25320328 PMCID: PMC4301128 DOI: 10.1128/jvi.02527-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/13/2014] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED Although many studies have demonstrated intracellular movement of viral proteins or viral replication complexes, little is known about the mechanisms of their motility. In this study, we analyzed the localization and motility of the nucleocapsid protein (NP) of Fig mosaic virus (FMV), a negative-strand RNA virus belonging to the recently established genus Emaravirus. Electron microscopy of FMV-infected cells using immunogold labeling showed that NPs formed cytoplasmic agglomerates that were predominantly enveloped by the endoplasmic reticulum (ER) membrane, while nonenveloped NP agglomerates also localized along the ER. Likewise, transiently expressed NPs formed agglomerates, designated NP bodies (NBs), in close proximity to the ER, as was the case in FMV-infected cells. Subcellular fractionation and electron microscopic analyses of NP-expressing cells revealed that NBs localized in the cytoplasm. Furthermore, we found that NBs moved rapidly with the streaming of the ER in an actomyosin-dependent manner. Brefeldin A treatment at a high concentration to disturb the ER network configuration induced aberrant accumulation of NBs in the perinuclear region, indicating that the ER network configuration is related to NB localization. Dominant negative inhibition of the class XI myosins, XI-1, XI-2, and XI-K, affected both ER streaming and NB movement in a similar pattern. Taken together, these results showed that NBs localize in the cytoplasm but in close proximity to the ER membrane to form enveloped particles and that this causes passive movements of cytoplasmic NBs by ER streaming. IMPORTANCE Intracellular trafficking is a primary and essential step for the cell-to-cell movement of viruses. To date, many studies have demonstrated the rapid intracellular movement of viral factors but have failed to provide evidence for the mechanism or biological significance of this motility. Here, we observed that agglomerates of nucleocapsid protein (NP) moved rapidly throughout the cell, and we performed live imaging and ultrastructural analysis to identify the mechanism of motility. We provide evidence that cytoplasmic protein agglomerates were passively dragged by actomyosin-mediated streaming of the endoplasmic reticulum (ER) in plant cells. In virus-infected cells, NP agglomerates were surrounded by the ER membranes, indicating that NP agglomerates form the basis of enveloped virus particles in close proximity to the ER. Our work provides a sophisticated model of macromolecular trafficking in plant cells and improves our understanding of the formation of enveloped particles of negative-strand RNA viruses.
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Affiliation(s)
- Kazuya Ishikawa
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Chihiro Miura
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kensaku Maejima
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ken Komatsu
- Laboratory of Plant Pathology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
| | - Masayoshi Hashimoto
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Tatsuya Tomomitsu
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Misato Fukuoka
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Akira Yusa
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yasuyuki Yamaji
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shigetou Namba
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Wang A. Dissecting the molecular network of virus-plant interactions: the complex roles of host factors. ANNUAL REVIEW OF PHYTOPATHOLOGY 2015; 53:45-66. [PMID: 25938276 DOI: 10.1146/annurev-phyto-080614-120001] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A successful infection by a plant virus results from the complex molecular interplay between the host plant and the invading virus. Thus, dissecting the molecular network of virus-host interactions advances the understanding of the viral infection process and may assist in the development of novel antiviral strategies. In the past decade, molecular identification and functional characterization of host factors in the virus life cycle, particularly single-stranded, positive-sense RNA viruses, have been a research focus in plant virology. As a result, a number of host factors have been identified. These host factors are implicated in all the major steps of the infection process. Some host factors are diverted for the viral genome translation, some are recruited to improvise the viral replicase complexes for genome multiplication, and others are components of transport complexes for cell-to-cell spread via plasmodesmata and systemic movement through the phloem. This review summarizes current knowledge about host factors and discusses future research directions.
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Affiliation(s)
- Aiming Wang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada;
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Wei T, Li D, Marcial D, Khan M, Lin MH, Snape N, Ghildyal R, Harrich D, Spann K. The eukaryotic elongation factor 1A is critical for genome replication of the paramyxovirus respiratory syncytial virus. PLoS One 2014; 9:e114447. [PMID: 25479059 PMCID: PMC4257679 DOI: 10.1371/journal.pone.0114447] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 11/06/2014] [Indexed: 01/01/2023] Open
Abstract
The eukaryotic translation factor eEF1A assists replication of many RNA viruses by various mechanisms. Here we show that down-regulation of eEF1A restricts the expression of viral genomic RNA and the release of infectious virus, demonstrating a biological requirement for eEF1A in the respiratory syncytial virus (RSV) life cycle. The key proteins in the replicase/transcriptase complex of RSV; the nucleocapsid (N) protein, phosphoprotein (P) and matrix (M) protein, all associate with eEF1A in RSV infected cells, although N is the strongest binding partner. Using individually expressed proteins, N, but not P or M bound to eEF1A. This study demonstrates a novel interaction between eEF1A and the RSV replication complex, through binding to N protein, to facilitate genomic RNA synthesis and virus production.
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Affiliation(s)
- Ting Wei
- Queensland Institute of Medical Research Berghofer, Herston, Australia
| | - Dongsheng Li
- Queensland Institute of Medical Research Berghofer, Herston, Australia
| | - Daneth Marcial
- Queensland Institute of Medical Research Berghofer, Herston, Australia
- Clinical Medical Virology Centre, The University of Queensland, Herston, Australia
- Sir Albert Sakzewski Virus Research Centre, Childrens Health Queensland, Herston, Australia
| | - Moshin Khan
- Queensland Institute of Medical Research Berghofer, Herston, Australia
- Sir Albert Sakzewski Virus Research Centre, Childrens Health Queensland, Herston, Australia
| | - Min-Hsuan Lin
- Queensland Institute of Medical Research Berghofer, Herston, Australia
| | - Natale Snape
- Clinical Medical Virology Centre, The University of Queensland, Herston, Australia
- Sir Albert Sakzewski Virus Research Centre, Childrens Health Queensland, Herston, Australia
| | - Reena Ghildyal
- Centre for Research in Therapeutic Solutions, University of Canberra, Canberra, Australia
| | - David Harrich
- Queensland Institute of Medical Research Berghofer, Herston, Australia
- Australian Infectious Disease Research Centre, St Lucia, Australia
- * E-mail: (KS); (DH)
| | - Kirsten Spann
- Clinical Medical Virology Centre, The University of Queensland, Herston, Australia
- Sir Albert Sakzewski Virus Research Centre, Childrens Health Queensland, Herston, Australia
- Australian Infectious Disease Research Centre, St Lucia, Australia
- * E-mail: (KS); (DH)
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Okano Y, Senshu H, Hashimoto M, Neriya Y, Netsu O, Minato N, Yoshida T, Maejima K, Oshima K, Komatsu K, Yamaji Y, Namba S. In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor. THE PLANT CELL 2014; 26:2168-2183. [PMID: 24879427 PMCID: PMC4079376 DOI: 10.1105/tpc.113.120535] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 04/23/2014] [Accepted: 05/09/2014] [Indexed: 05/22/2023]
Abstract
RNA silencing plays an important antiviral role in plants and invertebrates. To counteract antiviral RNA silencing, most plant viruses have evolved viral suppressors of RNA silencing (VSRs). TRIPLE GENE BLOCK PROTEIN1 (TGBp1) of potexviruses is a well-characterized VSR, but the detailed mechanism by which it suppresses RNA silencing remains unclear. We demonstrate that transgenic expression of TGBp1 of plantago asiatica mosaic virus (PlAMV) induced developmental abnormalities in Arabidopsis thaliana similar to those observed in mutants of SUPPRESSOR OF GENE SILENCING3 (SGS3) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6) required for the trans-acting small interfering RNA synthesis pathway. PlAMV-TGBp1 inhibits SGS3/RDR6-dependent double-stranded RNA synthesis in the trans-acting small interfering RNA pathway. TGBp1 interacts with SGS3 and RDR6 and coaggregates with SGS3/RDR6 bodies, which are normally dispersed in the cytoplasm. In addition, TGBp1 forms homooligomers, whose formation coincides with TGBp1 aggregation with SGS3/RDR6 bodies. These results reveal the detailed molecular function of TGBp1 as a VSR and shed new light on the SGS3/RDR6-dependent double-stranded RNA synthesis pathway as another general target of VSRs.
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Affiliation(s)
- Yukari Okano
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hiroko Senshu
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Masayoshi Hashimoto
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yutaro Neriya
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Osamu Netsu
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Nami Minato
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tetsuya Yoshida
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kensaku Maejima
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kenro Oshima
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ken Komatsu
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yasuyuki Yamaji
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shigetou Namba
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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Maejima K, Iwai R, Himeno M, Komatsu K, Kitazawa Y, Fujita N, Ishikawa K, Fukuoka M, Minato N, Yamaji Y, Oshima K, Namba S. Recognition of floral homeotic MADS domain transcription factors by a phytoplasmal effector, phyllogen, induces phyllody. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:541-54. [PMID: 24597566 PMCID: PMC4282529 DOI: 10.1111/tpj.12495] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 02/14/2014] [Accepted: 02/19/2014] [Indexed: 05/18/2023]
Abstract
Plant pathogens alter the course of plant developmental processes, resulting in abnormal morphology in infected host plants. Phytoplasmas are unique plant-pathogenic bacteria that transform plant floral organs into leaf-like structures and cause the emergence of secondary flowers. These distinctive symptoms have attracted considerable interest for many years. Here, we revealed the molecular mechanisms of the floral symptoms by focusing on a phytoplasma-secreted protein, PHYL1, which induces morphological changes in flowers that are similar to those seen in phytoplasma-infected plants. PHYL1 is a homolog of the phytoplasmal effector SAP54 that also alters floral development. Using yeast two-hybrid and in planta transient co-expression assays, we found that PHYL1 interacts with and degrades the floral homeotic MADS domain proteins SEPALLATA3 (SEP3), APETALA1 (AP1) and CAULIFLOWER (CAL). This degradation of MADS domain proteins was dependent on the ubiquitin-proteasome pathway. The expression of floral development genes downstream of SEP3 and AP1 was disrupted in 35S::PHYL1 transgenic plants. PHYL1 was genetically and functionally conserved among other phytoplasma strains and species. We designate PHYL1, SAP54 and their homologs as members of the phyllody-inducing gene family of 'phyllogens'.
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Affiliation(s)
- Kensaku Maejima
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Ryo Iwai
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Misako Himeno
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Ken Komatsu
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Naoko Fujita
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Kazuya Ishikawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Misato Fukuoka
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Nami Minato
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Kenro Oshima
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo1–1–1 Yayoi, Bunkyo–ku, Tokyo, 113–8657, Japan
- * For correspondence (e-mail )
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Abstract
BACKGROUND Synthetic biology is a discipline that includes making life forms artificially from chemicals. Here, a DNA molecule was enzymatically synthesized in vitro from DNA templates made from oligonucleotides representing the text of the first Tobacco mosaic virus (TMV) sequence elucidated in 1982. No infectious DNA molecule of that seminal reference sequence exists, so the goal was to synthesize it and then build viral chimeras. RESULTS RNA was transcribed from synthetic DNA and encapsidated with capsid protein in vitro to make synthetic virions. Plants inoculated with the virions did not develop symptoms. When two nucleotide mutations present in the original sequence, but not present in most other TMV sequences in GenBank, were altered to reflect the consensus, the derivative synthetic virions produced classic TMV symptoms. Chimeras were then made by exchanging TMV capsid protein DNA with Tomato mosaic virus (ToMV) and Barley stripe mosaic virus (BSMV) capsid protein DNA. Virus expressing ToMV capsid protein exhibited altered, ToMV-like symptoms in Nicotiana sylvestris. A hybrid ORF6 protein unknown to nature, created by substituting the capsid protein genes in the virus, was found to be a major symptom determinant in Nicotiana benthamiana. Virus expressing BSMV capsid protein did not have an extended host range to barley, but did produce novel symptoms in N. benthamiana. CONCLUSIONS This first report of the chemical synthesis and artificial assembly of a plant virus corrects a long-standing error in the TMV reference genome sequence and reveals that unnatural hybrid virus proteins can alter symptoms unexpectedly.
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Affiliation(s)
- Bret Cooper
- Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, USA
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The unexpected roles of eukaryotic translation elongation factors in RNA virus replication and pathogenesis. Microbiol Mol Biol Rev 2014; 77:253-66. [PMID: 23699257 DOI: 10.1128/mmbr.00059-12] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The prokaryotic translation elongation factors were identified as essential cofactors for RNA-dependent RNA polymerase activity of the bacteriophage Qβ more than 40 years ago. A growing body of evidence now shows that eukaryotic translation elongation factors (eEFs), predominantly eEF1A, acting in partially characterized complexes sometimes involving additional eEFs, facilitate virus replication. The functions of eEF1A as a protein chaperone and an RNA- and actin-binding protein enable its "moonlighting" roles as a virus replication cofactor. A diverse group of viruses, from human immunodeficiency type 1 and West Nile virus to tomato bushy stunt virus, have adapted to use eEFs as cofactors for viral transcription, translation, assembly, and pathogenesis. Here we review the mechanisms used by viral pathogens to usurp these abundant cellular proteins for their replication.
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Li Z, Gonzalez PA, Sasvari Z, Kinzy TG, Nagy PD. Methylation of translation elongation factor 1A by the METTL10-like See1 methyltransferase facilitates tombusvirus replication in yeast and plants. Virology 2014; 448:43-54. [PMID: 24314635 DOI: 10.1016/j.virol.2013.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 09/10/2013] [Accepted: 09/12/2013] [Indexed: 11/17/2022]
Abstract
Replication of tombusviruses and other plus-strand RNA viruses depends on several host factors that are recruited into viral replicase complexes. Previous studies have shown that eukaryotic translation elongation factor 1A (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. In this paper, we show that methylation of eEF1A by the METTL10-like See1p methyltransferase is required for tombusvirus and unrelated nodavirus RNA replication in yeast model host. Similar to the effect of SEE1 deletion, yeast expressing only a mutant form of eEF1A lacking the 4 known lysines subjected to methylation supported reduced TBSV accumulation. We show that the half-life of several viral replication proteins is decreased in see1Δ yeast or when a mutated eEF1A was expressed as a sole source for eEF1A. Silencing of the plant ortholog of See1 methyltransferase also decreased tombusvirus RNA accumulation in Nicotiana benthamiana.
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Affiliation(s)
- Zhenghe Li
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, United States
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Songbai Z, Zhenguo D, Liang Y, Zhengjie Y, Kangcheng W, Guangpu L, Zujian W, Lianhui X. Identification and characterization of the interaction between viroplasm-associated proteins from two different plant-infecting reoviruses and eEF-1A of rice. Arch Virol 2013; 158:2031-9. [PMID: 23605590 DOI: 10.1007/s00705-013-1703-x] [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: 12/11/2012] [Accepted: 03/21/2013] [Indexed: 12/14/2022]
Abstract
A rice protein homologous to eukaryotic translation elongation factor 1A (eEF-1A) was found to interact with the Pns6 of rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus, family Reoviridae, in yeast two-hybrid screening. The interaction between the rice protein, designated OseEF-1A, and RRSV Pns6 was confirmed by bimolecular fluorescence complementation. Besides Pns6, OseEF-1A also interacted with the viroplasm matrix protein, Pns10, of RRSV. When expressed together, OseEF-1A co-localized with RRSV Pns10 in epidermal cells of Nicotiana benthamiana. Pns6 of southern rice black-streaked dwarf virus (SRBSDV), a newly reported member of the genus Fijivirus, family Reoviridae, was the only non-structural SRBSDV protein studied here that also interacted with OseEF-1A. Like Pns6 of rice black-streaked dwarf virus (RBSDV), SRBSDV Pns6 interacted with itself and co-localized with Pns9-1 in N. benthamiana. In the presence of Pns6, OseEF-1A co-localized with Pns9-1, the putative viroplasm matrix protein of SRBSDV.
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Affiliation(s)
- Zhang Songbai
- Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
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Hwang J, Oh CS, Kang BC. Translation elongation factor 1B (eEF1B) is an essential host factor for Tobacco mosaic virus infection in plants. Virology 2013; 439:105-14. [PMID: 23490052 DOI: 10.1016/j.virol.2013.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 01/30/2013] [Accepted: 02/07/2013] [Indexed: 11/16/2022]
Abstract
Identifying host factors provides an important clue to understand virus infection. We selected 10 host factor candidate genes and each gene was silenced in Nicotiana benthamiana (N. benthamiana) to investigate their roles in virus infection. The resulting plants were infected with Tobacco mosaic virus (TMV). The accumulation of viral coat protein and the spread of virus were greatly reduced in the plants that eukaryotic translation elongation factor 1A (eEF1A) or 1B (eEF1B) was silenced. These results suggest both eEF1A and eEF1B are required for TMV infection. We also tested for interactions between the eEFs and viral proteins of TMV. Both eEF1A and eEF1B proteins interacted directly with the methyltransferase (MT) domain of the TMV RNA-dependent RNA polymerase (RdRp). eEF1A and eEF1B also interacted with each other in vivo. Our data suggest that eEF1B may be a component of the TMV replication complex which interacts with MT domain of TMV RdRp and eEF1A.
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Affiliation(s)
- JeeNa Hwang
- Department of Plant Science, Plant Genomics & Breeding Institute and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Korea
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36
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A vicilin-like seed storage protein, PAP85, is involved in tobacco mosaic virus replication. J Virol 2013; 87:6888-900. [PMID: 23576511 DOI: 10.1128/jvi.00268-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
One striking feature of viruses with RNA genomes is the modification of the host membrane structure during early infection. This process requires both virus- and host-encoded proteins; however, the host factors involved and their role in this process remain largely unknown. On infection with Tobacco mosaic virus (TMV), a positive-strand RNA virus, the filamentous and tubular endoplasmic reticulum (ER) converts to aggregations at the early stage and returns to filamentous at the late infectious stage, termed the ER transition. Also, membrane- or vesicle-packaged viral replication complexes (VRCs) are induced early during infection. We used microarray assays to screen the Arabidopsis thaliana gene(s) responding to infection with TMV in the initial infection stage and identified an Arabidopsis gene, PAP85 (annotated as a vicilin-like seed storage protein), with upregulated expression during 0.5 to 6 h of TMV infection. TMV accumulation was reduced in pap85-RNA interference (RNAi) Arabidopsis and restored to wild-type levels when PAP85 was overexpressed in pap85-RNAi Arabidopsis. We did not observe the ER transition in TMV-infected PAP85-knockdown Arabidopsis protoplasts. In addition, TMV accumulation was reduced in PAP85-knockdown protoplasts. VRC accumulation was reduced, but not significantly (P = 0.06), in PAP85-knockdown protoplasts. Coexpression of PAP85 and the TMV main replicase (P126), but not their expression alone in Arabidopsis protoplasts, could induce ER aggregations.
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Gushchin VA, Andreev DE, Taliansky ME, Macfarlane SE, Solovyev AG, Morozov SY. Single amino acid substitution in the tobacco mosaic virus ORF6 protein suppresses formation of complex with eEF1A and cooperative nucleic acids binding in vitro. DOKL BIOCHEM BIOPHYS 2013; 448:1-4. [PMID: 23478975 DOI: 10.1134/s1607672913010018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Indexed: 12/16/2023]
Affiliation(s)
- V A Gushchin
- Belozerskii Institute of Physicochemical Biology, Moscow State University, Moscow, Russia
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Bhat S, Folimonova SY, Cole AB, Ballard KD, Lei Z, Watson BS, Sumner LW, Nelson RS. Influence of host chloroplast proteins on Tobacco mosaic virus accumulation and intercellular movement. PLANT PHYSIOLOGY 2013; 161:134-47. [PMID: 23096159 PMCID: PMC3532247 DOI: 10.1104/pp.112.207860] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 10/22/2012] [Indexed: 05/18/2023]
Abstract
Tobacco mosaic virus (TMV) forms dense cytoplasmic bodies containing replication-associated proteins (virus replication complexes [VRCs]) upon infection. To identify host proteins that interact with individual viral components of VRCs or VRCs in toto, we isolated viral replicase- and VRC-enriched fractions from TMV-infected Nicotiana tabacum plants. Two host proteins in enriched fractions, ATP-synthase γ-subunit (AtpC) and Rubisco activase (RCA) were identified by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry or liquid chromatography-tandem mass spectrometry. Through pull-down analysis, RCA bound predominantly to the region between the methyltransferase and helicase domains of the TMV replicase. Tobamovirus, but not Cucumber mosaic virus or Potato virus X, infection of N. tabacum plants resulted in 50% reductions in Rca and AtpC messenger RNA levels. To investigate the role of these host proteins in TMV accumulation and plant defense, we used a Tobacco rattle virus vector to silence these genes in Nicotiana benthamiana plants prior to challenge with TMV expressing green fluorescent protein. TMV-induced fluorescent lesions on Rca- or AtpC-silenced leaves were, respectively, similar or twice the size of those on leaves expressing these genes. Silencing Rca and AtpC did not influence the spread of Tomato bushy stunt virus and Potato virus X. In AtpC- and Rca-silenced leaves TMV accumulation and pathogenicity were greatly enhanced, suggesting a role of both host-encoded proteins in a defense response against TMV. In addition, silencing these host genes altered the phenotype of the TMV infection foci and VRCs, yielding foci with concentric fluorescent rings and dramatically more but smaller VRCs. The concentric rings occurred through renewed virus accumulation internal to the infection front.
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Affiliation(s)
- Sumana Bhat
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
| | | | | | - Kimberly D. Ballard
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
| | - Zhentian Lei
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
| | - Bonnie S. Watson
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
| | - Lloyd W. Sumner
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
| | - Richard S. Nelson
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, Oklahoma 73401
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39
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Unusual roles of host metabolic enzymes and housekeeping proteins in plant virus replication. Curr Opin Virol 2012; 2:676-82. [DOI: 10.1016/j.coviro.2012.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 09/20/2012] [Accepted: 10/01/2012] [Indexed: 11/20/2022]
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40
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p33-Independent activation of a truncated p92 RNA-dependent RNA polymerase of Tomato bushy stunt virus in yeast cell-free extract. J Virol 2012; 86:12025-38. [PMID: 22933278 DOI: 10.1128/jvi.01303-12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Plus-stranded RNA viruses replicate in membrane-bound structures containing the viral replicase complex (VRC). A key component of the VRC is the virally encoded RNA-dependent RNA polymerase (RdRp), which should be activated and incorporated into the VRC after its translation. To study the activation of the RdRp of Tomato bushy stunt virus (TBSV), a small tombusvirus of plants, we used N-terminal truncated recombinant RdRp, which supported RNA synthesis in a cell-free yeast extract-based assay. The truncated RdRp required a cis-acting RNA replication element and soluble host factors, while unlike the full-length TBSV RdRp, the truncated RdRp did not need the viral p33 replication cofactor or cellular membranes for RNA synthesis. Interestingly, the truncated RdRp used 3'-terminal extension for initiation and terminated prematurely at an internal cis-acting element. However, the truncated RdRp could perform de novo initiation on a TBSV plus-strand RNA template in the presence of the p33 replication cofactor, cellular membranes, and soluble host proteins. Altogether, the data obtained with the truncated RdRp indicate that this RdRp still requires activation, but with the participation of fewer components than with the full-length RdRp, making it suitable for future studies on dissection of the RdRp activation mechanism.
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41
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Eukaryotic elongation factor 1 complex subunits are critical HIV-1 reverse transcription cofactors. Proc Natl Acad Sci U S A 2012; 109:9587-92. [PMID: 22628567 DOI: 10.1073/pnas.1204673109] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cellular proteins have been implicated as important for HIV-1 reverse transcription, but whether any are reverse transcription complex (RTC) cofactors or affect reverse transcription indirectly is unclear. Here we used protein fractionation combined with an endogenous reverse transcription assay to identify cellular proteins that stimulated late steps of reverse transcription in vitro. We identified 25 cellular proteins in an active protein fraction, and here we show that the eEF1A and eEF1G subunits of eukaryotic elongation factor 1 (eEF1) are important components of the HIV-1 RTC. eEF1A and eEF1G were identified in fractionated human T-cell lysates as reverse transcription cofactors, as their removal ablated the ability of active protein fractions to stimulate late reverse transcription in vitro. We observed that the p51 subunit of reverse transcriptase and integrase, two subunits of the RTC, coimmunoprecipitated with eEF1A and eEF1G. Moreover eEF1A and eEF1G associated with purified RTCs and colocalized with reverse transcriptase following infection of cells. Reverse transcription in cells was sharply down-regulated when eEF1A or eEF1G levels were reduced by siRNA treatment as a result of reduced levels of RTCs in treated cells. The combined evidence indicates that these eEF1 subunits are critical RTC stability cofactors required for efficient completion of reverse transcription. The identification of eEF1 subunits as unique RTC components provides a basis for further investigations of reverse transcription and trafficking of the RTC to the nucleus.
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Sasikumar AN, Perez WB, Kinzy TG. The many roles of the eukaryotic elongation factor 1 complex. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:543-55. [PMID: 22555874 DOI: 10.1002/wrna.1118] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The vast majority of proteins are believed to have one specific function. Throughout the course of evolution, however, some proteins have acquired additional functions to meet the demands of a complex cellular milieu. In some cases, changes in RNA or protein processing allow the cell to make the most of what is already encoded in the genome to produce slightly different forms. The eukaryotic elongation factor 1 (eEF1) complex subunits, however, have acquired such moonlighting functions without alternative forms. In this article, we discuss the canonical functions of the components of the eEF1 complex in translation elongation as well as the secondary interactions they have with other cellular factors outside of the translational apparatus. The eEF1 complex itself changes in composition as the complexity of eukaryotic organisms increases. Members of the complex are also subject to phosphorylation, a potential modulator of both canonical and non-canonical functions. Although alternative functions of the eEF1A subunit have been widely reported, recent studies are shedding light on additional functions of the eEF1B subunits. A thorough understanding of these alternate functions of eEF1 is essential for appreciating their biological relevance.
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Affiliation(s)
- Arjun N Sasikumar
- Department of Molecular Genetics, Microbiology and Immunology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ, USA
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43
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Wang LY, Lin SS, Hung TH, Li TK, Lin NC, Shen TL. Multiple domains of the tobacco mosaic virus p126 protein can independently suppress local and systemic RNA silencing. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:648-57. [PMID: 22324815 DOI: 10.1094/mpmi-06-11-0155] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Small RNA-mediated RNA silencing is a widespread antiviral mechanism in plants and other organisms. Many viruses encode suppressors of RNA silencing for counter-defense. The p126 protein encoded by Tobacco mosaic virus (TMV) has been reported to be a suppressor of RNA silencing but the mechanism of its function remains unclear. This protein is unique among the known plant viral silencing suppressors because of its large size and multiple domains. Here, we report that the methyltransferase, helicase, and nonconserved region II (NONII) of p126 each has silencing-suppressor function. The silencing-suppression activities of methyltransferase and helicase can be uncoupled from their enzyme activities. Specific amino acids in NONII previously shown to be crucial for viral accumulation and symptom development are also crucial for silencing suppression. These results suggest that some viral proteins have evolved to possess modular structural domains that can independently interfere with host silencing, and that this may be an effective mechanism of increasing the robustness of a virus.
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Affiliation(s)
- Li-Ya Wang
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan
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44
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Nishikiori M, Mori M, Dohi K, Okamura H, Katoh E, Naito S, Meshi T, Ishikawa M. A host small GTP-binding protein ARL8 plays crucial roles in tobamovirus RNA replication. PLoS Pathog 2011; 7:e1002409. [PMID: 22174675 PMCID: PMC3234234 DOI: 10.1371/journal.ppat.1002409] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 10/14/2011] [Indexed: 12/16/2022] Open
Abstract
Tomato mosaic virus (ToMV), like other eukaryotic positive-strand RNA viruses, replicates its genomic RNA in replication complexes formed on intracellular membranes. Previous studies showed that a host seven-pass transmembrane protein TOM1 is necessary for efficient ToMV multiplication. Here, we show that a small GTP-binding protein ARL8, along with TOM1, is co-purified with a FLAG epitope-tagged ToMV 180K replication protein from solubilized membranes of ToMV-infected tobacco (Nicotiana tabacum) cells. When solubilized membranes of ToMV-infected tobacco cells that expressed FLAG-tagged ARL8 were subjected to immunopurification with anti-FLAG antibody, ToMV 130K and 180K replication proteins and TOM1 were co-purified and the purified fraction showed RNA-dependent RNA polymerase activity that transcribed ToMV RNA. From uninfected cells, TOM1 co-purified with FLAG-tagged ARL8 less efficiently, suggesting that a complex containing ToMV replication proteins, TOM1, and ARL8 are formed on membranes in infected cells. In Arabidopsis thaliana, ARL8 consists of four family members. Simultaneous mutations in two specific ARL8 genes completely inhibited tobamovirus multiplication. In an in vitro ToMV RNA translation-replication system, the lack of either TOM1 or ARL8 proteins inhibited the production of replicative-form RNA, indicating that TOM1 and ARL8 are required for efficient negative-strand RNA synthesis. When ToMV 130K protein was co-expressed with TOM1 and ARL8 in yeast, RNA 5'-capping activity was detected in the membrane fraction. This activity was undetectable or very weak when the 130K protein was expressed alone or with either TOM1 or ARL8. Taken together, these results suggest that TOM1 and ARL8 are components of ToMV RNA replication complexes and play crucial roles in a process toward activation of the replication proteins' RNA synthesizing and capping functions.
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Affiliation(s)
- Masaki Nishikiori
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Masashi Mori
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa, Japan
| | - Koji Dohi
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa, Japan
| | - Hideyasu Okamura
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Etsuko Katoh
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Satoshi Naito
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tetsuo Meshi
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Masayuki Ishikawa
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
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45
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Yue J, Shukla R, Accardi R, Zanella-Cleon I, Siouda M, Cros MP, Krutovskikh V, Hussain I, Niu Y, Hu S, Becchi M, Jurdic P, Tommasino M, Sylla BS. Cutaneous human papillomavirus type 38 E7 regulates actin cytoskeleton structure for increasing cell proliferation through CK2 and the eukaryotic elongation factor 1A. J Virol 2011; 85:8477-94. [PMID: 21697493 PMCID: PMC3165781 DOI: 10.1128/jvi.02561-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 06/06/2011] [Indexed: 01/13/2023] Open
Abstract
We previously reported that the oncoproteins E6 and E7 from cutaneous human papillomavirus type 38 (HPV38) can immortalize primary human keratinocytes in vitro and sensitize transgenic mice to develop skin cancer in vivo. Immunofluorescence staining revealed that human keratinocytes immortalized by HPV38 E6 and E7 display fewer actin stress fibers than do control primary keratinocyte cells, raising the possibility of a role of the viral oncoproteins in the remodeling of the actin cytoskeleton. In this study, we show that HPV38 E7 induces actin stress fiber disruption and that this phenomenon correlates with its ability to downregulate Rho activity. The downregulation of Rho activity by HPV38 E7 is mediated through the activation of the CK2-MEK-extracellular signal-regulated kinase (ERK) pathway. In addition, HPV38 E7 is able to induce actin fiber disruption by binding directly to eukaryotic elongation factor 1A (eEF1A) and abolishing its effects on actin fiber formation. Finally, we found that the downregulation of Rho activity by HPV38 E7 through the CK2-MEK-ERK pathway facilitates cell growth proliferation. Taken together, our data support the conclusion that HPV38 E7 promotes keratinocyte proliferation in part by negatively regulating actin cytoskeleton fiber formation through the CK2-MEK-ERK-Rho pathway and by binding to eEF1A and inhibiting its effects on actin cytoskeleton remodeling.
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Affiliation(s)
- Jiping Yue
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Ruchi Shukla
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Rosita Accardi
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Isabelle Zanella-Cleon
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, IFR 128 Biosciences, Lyon, France
| | - Maha Siouda
- International Agency for Research on Cancer (IARC), Lyon, France
| | | | | | - Ishraq Hussain
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Yamei Niu
- International Agency for Research on Cancer (IARC), Lyon, France
| | - Shiqiong Hu
- Institut de Génomique Fonctionnelle de Lyon, Université Lyon 1, CNRS, INRA, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France
| | - Michel Becchi
- Institut de Biologie et Chimie des Protéines (IBCP), CNRS UMR5086, IFR 128 Biosciences, Lyon, France
| | - Pierre Jurdic
- Institut de Génomique Fonctionnelle de Lyon, Université Lyon 1, CNRS, INRA, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France
| | | | - Bakary S. Sylla
- International Agency for Research on Cancer (IARC), Lyon, France
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46
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Abstract
Plus-strand +RNA viruses co-opt host RNA-binding proteins (RBPs) to perform many functions during viral replication. A few host RBPs have been identified that affect the recruitment of viral +RNAs for replication. Other subverted host RBPs help the assembly of the membrane-bound replicase complexes, regulate the activity of the replicase and control minus- or plus-strand RNA synthesis. The host RBPs also affect the stability of viral RNAs, which have to escape cellular RNA degradation pathways. While many host RBPs seem to have specialized functions, others participate in multiple events during infection. Several conserved RBPs, such as eEF1A, hnRNP proteins and Lsm 1-7 complex, are co-opted by evolutionarily diverse +RNA viruses, underscoring some common themes in virus-host interactions. On the other hand, viruses also hijack unique RBPs, suggesting that +RNA viruses could utilize different RBPs to perform similar functions. Moreover, different +RNA viruses have adapted unique strategies for co-opting unique RBPs. Altogether, a deeper understanding of the functions of the host RBPs subverted for viral replication will help development of novel antiviral strategies and give new insights into host RNA biology.
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Affiliation(s)
- Zhenghe Li
- Department of Plant Pathology, University of Kentucky, Lexington, KY, USA
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47
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Emerging picture of host chaperone and cyclophilin roles in RNA virus replication. Virology 2011; 411:374-82. [PMID: 21295323 DOI: 10.1016/j.virol.2010.12.061] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 12/31/2010] [Indexed: 11/23/2022]
Abstract
Many plus-strand (+)RNA viruses co-opt protein chaperones from the host cell to assist the synthesis, localization and folding of abundant viral proteins, to regulate viral replication via activation of replication proteins and to interfere with host antiviral responses. The most frequently subverted host chaperones are heat shock protein 70 (Hsp70), Hsp90 and the J-domain co-chaperones. The various roles of these host chaperones in RNA virus replication are presented to illustrate the astonishing repertoire of host chaperone functions that are subverted by RNA viruses. This review also discusses the emerging roles of cyclophilins, which are peptidyl-prolyl isomerases with chaperone functions, in replication of selected (+)RNA viruses.
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48
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Li Z, Pogany J, Tupman S, Esposito AM, Kinzy TG, Nagy PD. Translation elongation factor 1A facilitates the assembly of the tombusvirus replicase and stimulates minus-strand synthesis. PLoS Pathog 2010; 6:e1001175. [PMID: 21079685 PMCID: PMC2973826 DOI: 10.1371/journal.ppat.1001175] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 10/01/2010] [Indexed: 11/18/2022] Open
Abstract
Replication of plus-strand RNA viruses depends on host factors that are recruited into viral replicase complexes. Previous studies showed that eukaryotic translation elongation factor (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. Using a random library of eEF1A mutants, we identified one mutant that decreased and three mutants that increased Tomato bushy stunt virus (TBSV) replication in a yeast model host. Additional in vitro assays with whole cell extracts prepared from yeast strains expressing the eEF1A mutants demonstrated several functions for eEF1A in TBSV replication: facilitating the recruitment of the viral RNA template into the replicase complex; the assembly of the viral replicase complex; and enhancement of the minus-strand synthesis by promoting the initiation step. These roles for eEF1A are separate from its canonical role in host and viral protein translation, emphasizing critical functions for this abundant cellular protein during TBSV replication. Plus-stranded RNA viruses are important pathogens of plants, animals and humans. They replicate in the infected cells by assembling viral replicase complexes consisting of viral- and host-coded proteins. In this paper, we show that the eukaryotic translation elongation factor (eEF1A), which is one of the resident host proteins in the highly purified tombusvirus replicase complex, is important for Tomato bushy stunt virus (TBSV) replication in a yeast model host. Based on a random library of eEF1A mutants, we identified eEF1A mutants that either decreased or increased TBSV replication. In vitro studies revealed that eEF1A facilitated the recruitment of the viral RNA template for replication and the assembly of the viral replicase complex, as well as eEF1A enhanced viral RNA synthesis in vitro. Altogether, this study demonstrates that eEF1A has several functions during TBSV replication.
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Affiliation(s)
- Zhenghe Li
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Judit Pogany
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Steven Tupman
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Anthony M. Esposito
- Department of Molecular Genetics, Microbiology, and Immunology, UMDNJ Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Terri Goss Kinzy
- Department of Molecular Genetics, Microbiology, and Immunology, UMDNJ Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Peter D. Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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49
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Ishibashi K, Nishikiori M, Ishikawa M. Interactions between tobamovirus replication proteins and cellular factors: their impacts on virus multiplication. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1413-9. [PMID: 20636106 DOI: 10.1094/mpmi-04-10-0102] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Most viral gene products function inside cells in the presence of various host proteins, nucleic acids, and lipids. Thus, viral gene products come into direct contact with these molecules. The replication proteins of tobamovirus participate not only in viral genome replication but also in counterdefense mechanisms against RNA silencing and other plant defense systems. Accumulating evidence indicates that these functions are carried out through interactions with specific host components. Interactions with some cellular factors, however, are inhibitory to virus multiplication and contribute to host range restriction of tobamovirus. The interactions that have positive and negative impacts on virus multiplication should have been maintained and lost, respectively, during adaptation of the viruses to their respective natural hosts. This review lists the host factors that interact with the replication proteins of tobamovirus and discusses how they influence multiplication of the virus.
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Affiliation(s)
- Kazuhiro Ishibashi
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan
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50
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Yamaji Y, Hamada K, Yoshinuma T, Sakurai K, Yoshii A, Shimizu T, Hashimoto M, Suzuki M, Namba S, Hibi T. Inhibitory effect on the tobacco mosaic virus infection by a plant RING finger protein. Virus Res 2010; 153:50-7. [PMID: 20621138 DOI: 10.1016/j.virusres.2010.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 06/29/2010] [Accepted: 07/05/2010] [Indexed: 11/18/2022]
Abstract
In the yeast two-hybrid screening of plant factors interacting with tobacco mosaic virus (TMV) RNA-dependent RNA polymerase (RdRp), we found a protein containing a RING finger motif in tobacco (Nicotiana tabacum) and designated it as TARF (TMV-associated RING finger protein). TARF is a homologue of a Lotus japonicus RING finger protein (LjnsRING) involved in the symbiotic interaction between L. japonicus and Mesorhizobium loti. When TARF was silenced by virus-induced gene silencing (VIGS) method, TMV RNA accumulation as well as the number of foci formed by GFP-tagged TMV increased drastically. Transient overexpression of TARF reduced the accumulation of TMV. Moreover, TARF transcription was rapidly upregulated by the inoculation of TMV in tobacco plants. These results indicated that TARF is a RING finger protein that inhibits the accumulation of TMV via the interaction of TMV RdRp.
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Affiliation(s)
- Yasuyuki Yamaji
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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