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Verchot J. Potato virus X: A global potato-infecting virus and type member of the Potexvirus genus. MOLECULAR PLANT PATHOLOGY 2022; 23:315-320. [PMID: 34791766 PMCID: PMC8828454 DOI: 10.1111/mpp.13163] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 05/24/2023]
Abstract
TAXONOMY Potato virus X is the type-member of the plant-infecting Potexvirus genus in the family Alphaflexiviridae. PHYSICAL PROPERTIES Potato virus X (PVX) virions are flexuous filaments 460-480 nm in length. Virions are 13 nm in diameter and have a helical pitch of 3.4 nm. The genome is approximately 6.4 kb with a 5' cap and 3' poly(A) terminus. PVX contains five open reading frames, four of which are essential for cell-to-cell and systemic movement. One protein encodes the viral replicase. Cellular inclusions, known as X-bodies, occur near the nucleus of virus-infected cells. HOSTS The primary host is potato, but it infects a wide range of dicots. Diagnostic hosts include Datura stramonium and Nicotiana tabacum. PVX is transmitted in nature by mechanical contact. USEFUL WEBSITE: https://talk.ictvonline.org/ictv-reports/ictv_online_report/positive-sense-rna-viruses/w/alphaflexiviridae/1330/genus-potexvirus.
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Affiliation(s)
- Jeanmarie Verchot
- Department of Plant Pathology & MicrobiologyTexas A&M UniversityCollege StationTXUSA
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2
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Wu X, Cheng X. Intercellular movement of plant RNA viruses: Targeting replication complexes to the plasmodesma for both accuracy and efficiency. Traffic 2020; 21:725-736. [PMID: 33090653 DOI: 10.1111/tra.12768] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/10/2020] [Accepted: 10/10/2020] [Indexed: 02/06/2023]
Abstract
Replication and movement are two critical steps in plant virus infection. Recent advances in the understanding of the architecture and subcellular localization of virus-induced inclusions and the interactions between viral replication complex (VRC) and movement proteins (MPs) allow for the dissection of the intrinsic relationship between replication and movement, which has revealed that recruitment of VRCs to the plasmodesma (PD) via direct or indirect MP-VRC interactions is a common strategy used for cell-to-cell movement by most plant RNA viruses. In this review, we summarize the recent advances in the understanding of virus-induced inclusions and their roles in virus replication and cell-to-cell movement, analyze the advantages of such coreplicational movement from a viral point of view and discuss the possible mechanical force by which MPs drive the movement of virions or viral RNAs through the PD. Finally, we highlight the missing pieces of the puzzle of viral movement that are especially worth investigating in the near future.
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Affiliation(s)
- Xiaoyun Wu
- Key Laboratory of Germplasm Enhancement, Physiology and Ecology of Food Crops in Cold Region of Chinese Education Ministry, College of Agriculture, Northeast Agricultural University, Harbin, China
| | - Xiaofei Cheng
- Key Laboratory of Germplasm Enhancement, Physiology and Ecology of Food Crops in Cold Region of Chinese Education Ministry, College of Agriculture, Northeast Agricultural University, Harbin, China
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Wu X, Liu J, Chai M, Wang J, Li D, Wang A, Cheng X. The Potato Virus X TGBp2 Protein Plays Dual Functional Roles in Viral Replication and Movement. J Virol 2019; 93:e01635-18. [PMID: 30541845 PMCID: PMC6384063 DOI: 10.1128/jvi.01635-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/03/2018] [Indexed: 01/27/2023] Open
Abstract
Plant viruses usually encode one or more movement proteins (MP) to accomplish their intercellular movement. A group of positive-strand RNA plant viruses requires three viral proteins (TGBp1, TGBp2, and TGBp3) that are encoded by an evolutionarily conserved genetic module of three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB). However, how these three viral movement proteins function cooperatively in viral intercellular movement is still elusive. Using a novel in vivo double-stranded RNA (dsRNA) labeling system, we showed that the dsRNAs generated by potato virus X (PVX) RNA-dependent RNA polymerase (RdRp) are colocalized with viral RdRp, which are further tightly covered by "chain mail"-like TGBp2 aggregates and localizes alongside TGBp3 aggregates. We also discovered that TGBp2 interacts with the C-terminal domain of PVX RdRp, and this interaction is required for the localization of TGBp3 and itself to the RdRp/dsRNA bodies. Moreover, we reveal that the central and C-terminal hydrophilic domains of TGBp2 are required to interact with viral RdRp. Finally, we demonstrate that knockout of the entire TGBp2 or the domain involved in interacting with viral RdRp attenuates both PVX replication and movement. Collectively, these findings suggest that TGBp2 plays dual functional roles in PVX replication and intercellular movement.IMPORTANCE Many plant viruses contain three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB), for intercellular movement. However, how the corresponding three proteins coordinate their functions remains obscure. In the present study, we provided multiple lines of evidence supporting the notion that PVX TGBp2 functions as the molecular adaptor bridging the interaction between the RdRp/dsRNA body and TGBp3 by forming "chain mail"-like structures in the RdRp/dsRNA body, which can also enhance viral replication. Taken together, our results provide new insights into the replication and movement of PVX and possibly also other TGB-containing plant viruses.
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Affiliation(s)
- Xiaoyun Wu
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Jiahui Liu
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Mengzhu Chai
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Jinhui Wang
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Dalong Li
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture, Northeast Agricultural University, Harbin, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Xiaofei Cheng
- College of Agriculture, Northeast Agriculture University, Harbin, China
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Donchenko E, Trifonova E, Nikitin N, Atabekov J, Karpova O. Alternanthera mosaic potexvirus: Several Features, Properties, and Application. Adv Virol 2018; 2018:1973705. [PMID: 30018641 PMCID: PMC6029478 DOI: 10.1155/2018/1973705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/23/2018] [Indexed: 11/18/2022] Open
Abstract
Alternanthera mosaic virus (AltMV) is a typical member of the Potexvirus genus in its morphology and genome structure; still it exhibits a number of unique features. They allow this virus to be considered a promising object for biotechnology. Virions and virus-like particles (VLPs) of AltMV are stable in a wide range of conditions, including sera of laboratory animals. AltMV VLPs can assemble at various pH and ionic strengths. Furthermore, AltMV virions and VLPs demonstrate high immunogenicity, enhancing the immune response to the target antigen thus offering the possibility of being used as potential adjuvants. Recently, for the first time for plant viruses, we showed the structural difference between morphologically similar viral and virus-like particles on AltMV virions and VLPs. In this review, we discuss the features of AltMV virions, AltMV VLP assembly, and their structure and properties, as well as the characteristics of AltMV isolates, host plants, infection symptoms, AltMV isolation and purification, genome structure, viral proteins, and AltMV-based vectors.
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Affiliation(s)
- Ekaterina Donchenko
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ekaterina Trifonova
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Nikolai Nikitin
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Joseph Atabekov
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Olga Karpova
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
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Hong JS, Ju HJ. The Plant Cellular Systems for Plant Virus Movement. THE PLANT PATHOLOGY JOURNAL 2017; 33:213-228. [PMID: 28592941 PMCID: PMC5461041 DOI: 10.5423/ppj.rw.09.2016.0198] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/05/2016] [Accepted: 11/13/2016] [Indexed: 05/24/2023]
Abstract
Plasmodesmata (PDs) are specialized intercellular channels that facilitate the exchange of various molecules, including sugars, ribonucleoprotein complexes, transcription factors, and mRNA. Their diameters, estimated to be 2.5 nm in the neck region, are too small to transfer viruses or viral genomes. Tobacco mosaic virus and Potexviruses are the most extensively studied viruses. In viruses, the movement protein (MP) is responsible for the PD gating that allows the intercellular movement of viral genomes. Various host factors interact with MP to regulate complicated mechanisms related to PD gating. Virus replication and assembly occur in viral replication complex (VRC) with membrane association, especially in the endoplasmic reticulum. VRC have a highly organized structure and are highly regulated by interactions among the various host factors, proteins encoded by the viral genome, and the viral genome. Virus trafficking requires host machineries, such as the cytoskeleton and the secretory systems. MP facilitates the virus replication and movement process. Despite the current level of understanding of virus movement, there are still many unknown and complex interactions between virus replication and virus movement. While numerous studies have been conducted to understand plant viruses with regards to cell-to-cell movement and replication, there are still many knowledge gaps. To study these interactions, adequate research tools must be used such as molecular, and biochemical techniques. Without such tools, virologists will not be able to gain an accurate or detailed understanding of the virus infection process.
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Affiliation(s)
- Jin-Sung Hong
- Department of Applied Biology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Ho-Jong Ju
- Department of Agricultural Biology, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
- Plant Medicinal Research Center, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
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Zhang K, Zhang Y, Yang M, Liu S, Li Z, Wang X, Han C, Yu J, Li D. The Barley stripe mosaic virus γb protein promotes chloroplast-targeted replication by enhancing unwinding of RNA duplexes. PLoS Pathog 2017; 13:e1006319. [PMID: 28388677 PMCID: PMC5397070 DOI: 10.1371/journal.ppat.1006319] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/19/2017] [Accepted: 03/27/2017] [Indexed: 11/19/2022] Open
Abstract
RNA viruses encode various RNA binding proteins that function in many steps of viral infection cycles. These proteins function as RNA helicases, methyltransferases, RNA-dependent RNA polymerases, RNA silencing suppressors, RNA chaperones, movement proteins, and so on. Although many of the proteins bind the viral RNA genome during different stages of infection, our knowledge about the coordination of their functions is limited. In this study, we describe a novel role for the Barley stripe mosaic virus (BSMV) γb as an enhancer of αa RNA helicase activity, and we show that the γb protein is recruited by the αa viral replication protein to chloroplast membrane sites of BSMV replication. Mutagenesis or deletion of γb from BSMV resulted in reduced positive strand (+) RNAα accumulation, but γb mutations abolishing viral suppressor of RNA silencing (VSR) activity did not completely eliminate genomic RNA replication. In addition, cis- or trans-expression of the Tomato bushy stunt virus p19 VSR protein failed to complement the γb replication functions, indicating that the direct involvement of γb in BSMV RNA replication is independent of VSR functions. These data support a model whereby two BSMV-encoded RNA-binding proteins act coordinately to regulate viral genome replication and provide new insights into strategies whereby double-stranded viral RNA unwinding is regulated, as well as formation of viral replication complexes.
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Affiliation(s)
- Kun Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Meng Yang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Songyu Liu
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Zhenggang Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Xianbing Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Chenggui Han
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Jialin Yu
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
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Makarov VV, Makarova SS, Kalinina NO. Data on structural transitions in domains of hordeivirus TGB1 protein forming ribonucleoprotein complex. Data Brief 2016; 8:258-61. [PMID: 27331098 PMCID: PMC4905938 DOI: 10.1016/j.dib.2016.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 05/01/2016] [Accepted: 05/08/2016] [Indexed: 11/05/2022] Open
Abstract
This data article is related to the research article entitled “in vitro properties of hordeivirus TGB1 protein forming ribonucleoprotein complexes” (Makarov et al., 2015 [1]), demonstrating that upon incubation with viral RNA the poa semilatent hordeivirus (PSLV) TGB1 protein (the movement 63 K protein encoded by the first gene of the triple gene block) in vitro forms RNP structures resembling filamentous virus-like particles and its internal domain (ID) performs a major structural role in this process. This article reports the additional results on the structural lability of ID and the structural transitions in the C-terminal NTPase/helicase domain (HELD) induced by interaction with tRNA and phosphorylation.
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Affiliation(s)
- Valentin V Makarov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
| | - Svetlana S Makarova
- Department of Virology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
| | - Natalia O Kalinina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
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8
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Lico C, Benvenuto E, Baschieri S. The Two-Faced Potato Virus X: From Plant Pathogen to Smart Nanoparticle. FRONTIERS IN PLANT SCIENCE 2015; 6:1009. [PMID: 26635836 PMCID: PMC4646960 DOI: 10.3389/fpls.2015.01009] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 10/30/2015] [Indexed: 05/24/2023]
Abstract
Potato virus X (PVX) is a single-stranded RNA plant virus, historically investigated in light of the detrimental effects on potato, the world's fourth most important food commodity. The study of the interactions with cells, and more generally with the plant, both locally and systemically, significantly contributed to unveil the mechanisms underlying gene silencing, fundamental not only in plant virology but also in the study of gene expression regulation. Unraveling the molecular events of PVX infection paved the way for the development of different viral expression vectors and consequential applications in functional genomics and in the biosynthesis of heterologous proteins in plants. Apart from that, the ease of manipulation and the knowledge of the virus structure (particle dimensions, shape and physicochemical features) are inspiring novel applications, mainly focused on nanobiotechnology. This review will lead the reader in this area, spanning from fundamental to applied research, embracing fields from plant pathology to vaccine and drug-targeted delivery, imaging and material sciences. Due to the versatile moods, PVX holds promise to become an interesting nanomaterial, in view to create the widest possible arsenal of new "bio-inspired" devices to face evolving issues in biomedicine and beyond.
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Affiliation(s)
- Chiara Lico
- Laboratory of Biotechnology , ENEA, Rome, Italy
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Makarov VV, Makarova SS, Makhotenko AV, Obraztsova EA, Kalinina NO. In vitro properties of hordeivirus TGB1 protein forming ribonucleoprotein complexes. J Gen Virol 2015; 96:3422-3431. [PMID: 26276346 DOI: 10.1099/jgv.0.000252] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hordeivirus movement protein encoded by the first gene of the triple gene block (TGB1 protein, TGBp1) interacts in vivo with viral genomic and subgenomic RNAs to form ribonucleoprotein (RNP) particles that are considered to be a form of viral genome (non-virion transport form) capable of cell-to-cell and long-distance transport in infected plants. The structures of these RNPs have not been elucidated. The poa semilatent virus (PSLV) TGBp1 contains a structured C-terminal NTPase/helicase domain and an N-terminal extension region consisting of two domains - a completely intrinsically disordered extreme N-terminal domain and an internal domain (ID) with structure resembling a partially disordered molten globule. Here, we characterized the structures assembled in vitro by the full-length PSLV TGBp1 alone or in the presence of viral RNA. The PSLV TGBp1 was capable of multimerization and self-assembly into extended high-molecular-mass complexes. These complexes disassembled to apparent monomers upon incubation with ATP. Upon incubation with viral RNA, the PSLV TGBp1 in vitro formed RNP structures that appeared as filamentous particles resembling virions of helical filamentous plant viruses in morphology and dimensions. By comparing the biophysical characteristics of PSLV TGBp1 and its domains in the presence and absence of RNA, we show that the ID plays the main structural role in the self-interactions and RNA interactions of TGBp1 leading to the assembly of virus-like RNP particles.
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Affiliation(s)
- Valentin V Makarov
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
| | - Svetlana S Makarova
- Department of Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
| | - Antonida V Makhotenko
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
| | - Ekaterina A Obraztsova
- M. M. Shemyakin and Yu. A. Ovchinnikov Bioorganic Chemistry Institute, Miklukho-Maklaya str. 16/10, Moscow 117997, Russia
| | - Natalia O Kalinina
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninsky Gory, Moscow 119992, Russia
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Xue B, Blocquel D, Habchi J, Uversky AV, Kurgan L, Uversky VN, Longhi S. Structural disorder in viral proteins. Chem Rev 2014; 114:6880-911. [PMID: 24823319 DOI: 10.1021/cr4005692] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Bin Xue
- Department of Cell Biology, Microbiology and Molecular Biology, College of Fine Arts and Sciences, and ‡Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida , Tampa, Florida 33620, United States
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Seo EY, Nam J, Kim HS, Park YH, Hong SM, Lakshman D, Bae H, Hammond J, Lim HS. Selective Interaction Between Chloroplast β-ATPase and TGB1L88 Retards Severe Symptoms Caused by Alternanthera mosaic virus Infection. THE PLANT PATHOLOGY JOURNAL 2014; 30:58-67. [PMID: 25288986 PMCID: PMC4174830 DOI: 10.5423/ppj.oa.09.2013.0097] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 10/13/2013] [Accepted: 10/13/2013] [Indexed: 05/02/2023]
Abstract
The multifunctional triple gene block protein 1 (TGB1) of the Potexvirus Alternanthera mosaic virus (AltMV) has been reported to have silencing suppressor, cell-to-cell movement, and helicase functions. Yeast two hybrid screening using an Arabidopsis thaliana cDNA library with TGB1 as bait, and co-purification with TGB1 inclusion bodies identified several host proteins which interact with AltMV TGB1. Host protein interactions with TGB1 were confirmed by biomolecular fluorescence complementation, which showed positive TGB1 interaction with mitochondrial ATP synthase delta' chain subunit (ATP synthase delta'), light harvesting chlorophyll-protein complex I subunit A4 (LHCA4), chlorophyll a/b binding protein 1 (LHB1B2), chloroplast-localized IscA-like protein (ATCPISCA), and chloroplast β-ATPase. However, chloroplast β-ATPase interacts only with TGB1L88, and not with weak silencing suppressor TGB1P88. This selective interaction indicates that chloroplast β-ATPase is not required for AltMV movement and replication; however, TRV silencing of chloroplast β-ATPase in Nicotiana benthamiana induced severe tissue necrosis when plants were infected by AltMV TGB1L88 but not AltMV TGB1P88, suggesting that β-ATPase selectively responded to TGB1L88 to induce defense responses.
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Affiliation(s)
- Eun-Young Seo
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Jiryun Nam
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
- Department of Bioscience II, Bio-Medical Science, Daejeon 305-301, Korea
| | - Hyun-Seung Kim
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Young-Hwan Park
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Korea
| | - Seok Myeong Hong
- Department of Medicine, Graduate School, Chung-Ang University, Seoul 156-756, Korea
| | - Dilip Lakshman
- USDA-ARS, US National Arboretum, Floral and Nursery Plants Research Unit, Beltsville, MD 20705, USA
| | - Hanhong Bae
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Korea
- Hanhong Bae, Phone) +82-51-455-5495, FAX) +82-51-455-5494, E-mail)
| | - John Hammond
- USDA-ARS, US National Arboretum, Floral and Nursery Plants Research Unit, Beltsville, MD 20705, USA
- John Hammond, Phone) +1-301-504-5313, FAX) +301-504-5096, E-mail)
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
- Co-corresponding authors. Hyoun-Sub Lim, Phone) +82-42-821-5766, FAX) +82-42-823-8679, E-mail)
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12
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Das PK, Merits A, Lulla A. Functional cross-talk between distant domains of chikungunya virus non-structural protein 2 is decisive for its RNA-modulating activity. J Biol Chem 2014; 289:5635-53. [PMID: 24407286 DOI: 10.1074/jbc.m113.503433] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chikungunya virus (CHIKV) non-structural protein 2 (nsP2) is a multifunctional protein that is considered a master regulator of the viral life cycle and a main viral factor responsible for cytopathic effects and subversion of antiviral defense. The C-terminal part of nsP2 possesses protease activity, whereas the N-terminal part exhibits NTPase and RNA triphosphatase activity and is proposed to have helicase activity. Bioinformatics analysis classified CHIKV nsP2 into helicase superfamily 1. However, the biochemical significance of a coexistence of two functionally unrelated modules in this single protein remains unknown. In this study, recombinant nsP2 demonstrated unwinding of double-stranded RNA in a 5'-3' directionally biased manner and RNA strand annealing activity. Comparative analysis of NTPase and helicase activities of wild type nsP2 with enzymatic capabilities of different truncated or N-terminally extended variants of nsP2 revealed that the C-terminal part of the protein is indispensable for helicase functionality and presumably provides a platform for RNA binding, whereas the N-terminal-most region is apparently involved in obtaining a conformation of nsP2 that allows for its maximal enzymatic activities. The establishment of the protocols for the production of biochemically active CHIKV nsP2 and optimization of the parameters for helicase and NTPase assays are expected to provide the starting point for a further search of possibilities for therapeutic interventions to suppress alphaviral infections.
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Affiliation(s)
- Pratyush Kumar Das
- From the Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
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Park MR, Jeong RD, Kim KH. Understanding the intracellular trafficking and intercellular transport of potexviruses in their host plants. FRONTIERS IN PLANT SCIENCE 2014; 5:60. [PMID: 24672528 PMCID: PMC3957223 DOI: 10.3389/fpls.2014.00060] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/06/2014] [Indexed: 05/22/2023]
Abstract
The movement of potexviruses through the cytoplasm to plasmodesmata (PD) and through PD to adjacent cells depends on the viral and host cellular proteins. Potexviruses encode three movement proteins [referred to as the triple gene block (TGB1-3)]. TGB1 protein moves cell-to-cell through PD and requires TGB2 and TGB3, which are endoplasmic reticulum (ER)-located proteins. TGB3 protein directs the movement of the ER-derived vesicles induced by TGB2 protein from the perinuclear ER to the cortical ER. TGB2 protein physically interacts with TGB3 protein in a membrane-associated form and also interacts with either coat protein (CP) or TGB1 protein at the ER network. Recent studies indicate that potexvirus movement involves the interaction between TGB proteins and CP with host proteins including membrane rafts. A group of host cellular membrane raft proteins, remorins, can serve as a counteracting membrane platform for viral ribonucleoprotein (RNP) docking and can thereby inhibit viral movement. The CP, which is a component of the RNP movement complex, is also critical for viral cell-to-cell movement through the PD. Interactions between TGB1 protein and/or the CP subunit with the 5'-terminus of genomic RNA [viral RNA (vRNA)] form RNP movement complexes and direct the movement of vRNAs through the PD. Recent studies show that tobacco proteins such as NbMPB2C or NbDnaJ-like proteins interact with the stem-loop 1 RNA located at the 5'-terminus of Potato virus X vRNA and regulate intracellular as well as intercellular movement. Although several host proteins that interact with vRNAs or viral proteins and that are crucial for vRNA transport have been screened and characterized, additional host proteins and details of viral movement remain to be characterized. In this review, we describe recent progress in understanding potexvirus movement within and between cells and how such movement is affected by interactions between vRNA/proteins and host proteins.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
| | - Rae-Dong Jeong
- Advanced Radiation Technology Institute, Korea Atomic Energy Research InstituteJeongeup, South Korea
| | - Kook-Hyung Kim
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
- *Correspondence: Kook-Hyung Kim, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, South Korea e-mail:
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Nam J, Nam M, Bae H, Lee C, Lee BC, Hammond J, Lim HS. AltMV TGB1 Nucleolar Localization Requires Homologous Interaction and Correlates with Cell Wall Localization Associated with Cell-to-Cell Movement. THE PLANT PATHOLOGY JOURNAL 2013; 29:454-9. [PMID: 25288976 PMCID: PMC4174812 DOI: 10.5423/ppj.nt.04.2013.0045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 05/30/2013] [Accepted: 05/30/2013] [Indexed: 05/08/2023]
Abstract
The Potexvirus Alternanthera mosaic virus (AltMV) has multifunctional triple gene block (TGB) proteins, among which our studies have focused on the properties of the TGB1 protein. The TGB1 of AltMV has functions including RNA binding, RNA silencing suppression, and cell-to-cell movement, and is known to form homologous interactions. The helicase domains of AltMV TGB1 were separately mutated to identify which regions are involved in homologous TGB1 interactions. The yeast two hybrid system and Bimolecular Fluorescence Complementation (BiFC) in planta were utilized to examine homologous interactions of the mutants. Helicase motif I of AltMV TGB1 was found to be critical to maintain homologous interactions. Mutations in the remaining helicase motifs did not inhibit TGB1 homologous interactions. In the absence of homologous interaction of TGB1, subcellular localization of helicase domain I mutants showed distinctively different patterns from that of WT TGB1. These results provide important information to study viral movement and replication of AltMV.
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Affiliation(s)
- Jiryun Nam
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
- Department of Bioscience II, Bio-Medical Science, Daejeon 305-301, Korea
| | - Moon Nam
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
| | - Hanhong Bae
- Department of Biological Science, Youngnam University, Gyeongsan 712-749, Korea
| | - Cheolho Lee
- Department of Chemical and Biological Engineering, Seokyoung University, Seoul 136-704, Korea
| | - Bong-Chun Lee
- Crop Environment Research Division, National Institute of Crop Science, RDA, Suwon 441-100, Korea
| | - John Hammond
- USDA-ARS, US National Arboretum, Floral and Nursery Plants Research Unit, Beltsville, MD 20705, USA
- Corresponding authors. Phone) +82-42-821-5766, FAX) +82-42-823-8679, E-mail) Phone) +301-504-5313, FAX) +301-504-5096, E-mail) John.
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National University, Daejeon 305-764, Korea
- Corresponding authors. Phone) +82-42-821-5766, FAX) +82-42-823-8679, E-mail) Phone) +301-504-5313, FAX) +301-504-5096, E-mail) John.
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15
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Tilsner J, Linnik O, Louveaux M, Roberts IM, Chapman SN, Oparka KJ. Replication and trafficking of a plant virus are coupled at the entrances of plasmodesmata. J Cell Biol 2013; 201:981-95. [PMID: 23798728 PMCID: PMC3691464 DOI: 10.1083/jcb.201304003] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/16/2013] [Indexed: 02/04/2023] Open
Abstract
Plant viruses use movement proteins (MPs) to modify intercellular pores called plasmodesmata (PD) to cross the plant cell wall. Many viruses encode a conserved set of three MPs, known as the triple gene block (TGB), typified by Potato virus X (PVX). In this paper, using live-cell imaging of viral RNA (vRNA) and virus-encoded proteins, we show that the TGB proteins have distinct functions during movement. TGB2 and TGB3 established endoplasmic reticulum-derived membranous caps at PD orifices. These caps harbored the PVX replicase and nonencapsidated vRNA and represented PD-anchored viral replication sites. TGB1 mediated insertion of the viral coat protein into PD, probably by its interaction with the 5' end of nascent virions, and was recruited to PD by the TGB2/3 complex. We propose a new model of plant virus movement, which we term coreplicational insertion, in which MPs function to compartmentalize replication complexes at PD for localized RNA synthesis and directional trafficking of the virus between cells.
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Affiliation(s)
- Jens Tilsner
- Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, Scotland, UK.
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16
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Schomburg D, Schomburg I. RNA helicase 3.6.4.13. CLASS 3.4–6 HYDROLASES, LYASES, ISOMERASES, LIGASES 2013. [PMCID: PMC7123474 DOI: 10.1007/978-3-642-36260-6_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
EC number 3.6.4.13 Systematic name ATP phosphohydrolase (RNA helix unwinding) Recommended name RNA helicase Synonyms 1a NTPase/helicase <16> [5] ATP/dATP-dependent RNA helicase <1,42> [32] ATPase <10,12> [1,36] ATPase/RNA helicase <1,42> [32] ATPase/helicase <10> [36,41] BMV 1a protein <16> [5] BmL3-helicase <1,42> [32] Brr2p <6> [50] DBP2 <24> [30] DDX17 <33> [12] DDX19 <43> [56] DDX25 <23,34,35> [12,21] DDX3 <25> [8] DDX3X <25> (<25> the gene is localized to the X chromosome [12]) [12] DDX3Y <29> (<29> the gene is localized to the Y chromosome [12]) [12] DDX4 <30> [12] DDX5 <32> [12] DEAD box RNA helicase <1,2,3> [32,45,52] DEAD box helicase <2> [45] DEAD-box RNA helicase <4,5,7,38,47,48> [9,14,16,25,53,55] DEAD-box protein DED1 <38> [11] DEAD-box rRNA helicase <5> [26] DEAH-box RNA helicase <24> [30] DEAH-box protein 2 <24> [30] DED1 <38> [11,14] DENV NS3H <10> [41] DEXD/H-box RNA helicase <43> [56] DEx(H/D)RNA helicase <12> [23] DHX9 <44> [58] DbpA <5> [10,25,26] Dhx9/RNA helicase A <13> [61] EhDEAD1 <7> [16] EhDEAD1 RNA helicase <7> [16] FRH <9> [54] FRQ-interacting RNA helicase <9> [54] GRTH <3> [57] GRTH/DDX25 <3,35> [21,51] HCV NS3 helicase <12> [48] KOKV helicase <27> [7] Mtr4p <31> [22] NPH-II <8> [18,28] NS3 <10,12,17,20,39,41> (<12,39> ambiguous [27,42,44]) [1,2,4,27,35,36,39, 42,44,46] NS3 ATPase/helicase <10> [41] NS3 NTPase/helicase <17> (<17> ambiguous [46]) [46] NS3 helicase <10,12,17> [15,44,46] NS3 protein <10,12,17,18> (<12> ambiguous [39]) [15,39,40,41,62] NTPase/helicase <12> (<12> ambiguous [37]) [37,39] RHA <6> [31,49] RNA helicase <2> [45] RNA helicase A <6,44> [31,49,58] RNA helicase CrhR <14> [59] RNA helicase DDX3 <25> [8] RNA helicase Ddx39 <47> [53] RNA helicase Hera <4> [9] RNA-dependent ATPase <37> [34] RNA-dependent NTPase/helicase <12> [1] RTPase <10> [36] RhlB <5> [43] SpolvlgA <48> [55] Supv3L1 <46> [64] TGBp1 NTPase/helicase domain <22,28> [24] Tk-DeaD <15> [47] VRH1 <26> [33] YxiN <2> [45] eIF4A <36> [20] eIF4A helicase <36> [20] eIF4AIII <37> [34] eukaryotic initiation factor eIF 4A <36> [20] gonadotropin-regulated testicular RNA helicase <3> [51,57] helicase <10> [41] helicase B <5> [43] helicase/nucleoside triphosphatase <10> [4] non structural protein 3 <12> (<12> ambiguous [37,38]) [37,38] non-structural 3 <10> [36] non-structural protein 3 <17> [46] non-structural protein 3 protein <18> [40] nonstructural protein 3 <12,17,20,39,40,41> (<12,17,39,40> ambiguous [6,27, 39,42,44,46]) [1,2,6,27,35,39,42,44,46] nucleoside 5’-triphosphatase <10> [4] nucleoside triphosphatase/RNA helicase and 5’-RNA triphosphatase <20> [2] nucleoside triphosphatase/helicase <16> [5] p54 RNA helicase <45> [60] p68 RNA helicase <3,6> [52,63] protein NS3 <12> (<12> ambiguous [38]) [38]
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Lee MY, Yan L, Gorter FA, Kim BYT, Cui Y, Hu Y, Yuan C, Grindheim J, Ganesan U, Liu Z, Han C, Yu J, Li D, Jackson AO. Brachypodium distachyon line Bd3-1 resistance is elicited by the barley stripe mosaic virus triple gene block 1 movement protein. J Gen Virol 2012; 93:2729-2739. [DOI: 10.1099/vir.0.045880-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Barley stripe mosaic virus North Dakota 18 (ND18), Beijing (BJ), Xinjiang (XJ), Type (TY) and CV21 strains are unable to infect the Brachypodium distachyon Bd3-1 inbred line, which harbours a resistance gene designated Bsr1, but the Norwich (NW) strain is virulent on Bd3-1. Analysis of ND18 and NW genomic RNA reassortants and RNAβ mutants demonstrates that two amino acids within the helicase motif of the triple gene block 1 (TGB1) movement protein have major effects on their Bd3-1 phenotypes. Resistance to ND18 correlates with an arginine residue at TGB1 position 390 (R390) and a threonine at position 392 (T392), whereas the virulent NW strain contains lysines (K) at both positions. ND18 TGB1 R390K (NDTGB1R390K) and NDTGB1T392K single substitutions, and an NDTGB1R390K,T392K double mutation resulted in systemic infections of Bd3-1. Reciprocal NDTGB1 substitutions into NWTGB1 (NWTGB1K390R and NWTGB1K392T) failed to affect virulence, implying that K390 and K392 compensate for each other. In contrast, an NWTGB1K390R,K392T double mutant exhibited limited vascular movement in Bd3-1, but developed prominent necrotic streaks that spread from secondary leaf veins. This phenotype, combined with the appearance of necrotic spots in certain ND18 mutants, and necrosis and rapid wilting of Bd3-1 plants after BJ strain (BJTGB1K390,T392) inoculations, show that Bd3-1 Bsr1 resistance is elicited by the TGB1 protein and suggest that it involves a hypersensitive response.
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Affiliation(s)
- Mi Yeon Lee
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Lijie Yan
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Florien A. Gorter
- Laboratory of Genetics, Department of Plant Sciences, Wageningen University, 6700 AH Wageningen, The Netherlands
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Brian Y. T. Kim
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Yu Cui
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Yue Hu
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Cheng Yuan
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Jessica Grindheim
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Uma Ganesan
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
| | - Zhiyong Liu
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Chenggui Han
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Jialin Yu
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology, China Agricultural University, Beijing 100193, PR China
| | - Andrew O. Jackson
- Department of Plant and Microbial Biology, University of California–Berkeley, Berkeley, CA 94720, USA
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18
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Semashko MA, González I, Shaw J, Leonova OG, Popenko VI, Taliansky ME, Canto T, Kalinina NO. The extreme N-terminal domain of a hordeivirus TGB1 movement protein mediates its localization to the nucleolus and interaction with fibrillarin. Biochimie 2012; 94:1180-8. [PMID: 22349738 DOI: 10.1016/j.biochi.2012.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/06/2012] [Indexed: 01/13/2023]
Abstract
The hordeiviral movement protein encoded by the first gene of the triple gene block (TGBp1) of Poa semilatent virus (PSLV), interacts with viral genomic RNAs to form RNP particles which are considered to be a form of viral genome capable of cell-to-cell and long-distance transport in infected plants. The PSLV TGBp1 contains a C-terminal NTPase/helicase domain (HELD) and an N-terminal extension region consisting of two structurally and functionally distinct domains: an extreme N-terminal domain (NTD) and an internal domain (ID). This study demonstrates that transient expression of TGBp1 fused to GFP in Nicotiana benthamiana leaves results in faint but obvious fluorescence in the nucleolus in addition to cytosolic distribution. Mutagenesis of the basic amino acids inside the NTD clusters A (116)KSKRKKKNKK(125) and B (175)KKATKKESKKQTK(187) reveals that these clusters are indispensable for nuclear and nucleolar targeting of PSLV TGBp1 and may contain nuclear and nucleolar localization signals or their elements. The PSLV TGBp1 is able to bind to fibrillarin, the major nucleolar protein (AtFib2 from Arabidopsis thaliana) in vitro. This protein-protein interaction occurs between the glycine-arginine-rich (GAR) domain of fibrillarin and the first 82 amino acid residues of TGBp1. The interaction of TGBp1 with fibrillarin is also visualized in vivo by bimolecular fluorescence complementation (BiFC) during co-expression of TGBp1 or its deletion mutants, and fibrillarin as fusions to different halves of YFP in N. benthamiana plants. The sites responsible for nuclear/nucleolar localization and fibrillarin binding, have been located within the intrinsically disordered TGBp1 NTD. These data could suggest that specific functions of hordeivirus TGBp1 may depend on its interaction with nucleolar components.
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Affiliation(s)
- Maria A Semashko
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninsky Gory, Moscow, 119992, Russia
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19
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Lu Y, Yan F, Guo W, Zheng H, Lin L, Peng J, Adams MJ, Chen J. Garlic virus X 11-kDa protein granules move within the cytoplasm and traffic a host protein normally found in the nucleolus. MOLECULAR PLANT PATHOLOGY 2011; 12:666-76. [PMID: 21726366 PMCID: PMC6640471 DOI: 10.1111/j.1364-3703.2010.00699.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The subcellular localization of the 11-kDa protein (p11) encoded by ORF3 of Garlic virus X (GarVX; genus Allexivirus, family Alphaflexiviridae) was examined by confocal microscopy. Granules with intense fluorescence were visible on the endoplasmic reticulum when p11 fused with green or red fluorescent protein (GFP or RFP) was expressed in epidermal cells of Nicotiana benthamiana. Moreover, the p11-RFP granules moved in the cytoplasm, along the cell periphery and through the cell membranes to adjacent cells. A 17-kDa protein (p17) of garlic interacting with p11 was identified by yeast two-hybridization and bimolecular fluorescence complementation assay. When p17 fused to GFP was expressed in epidermal cells of N. benthamiana, it localized to the nucleolus. However, in the presence of GarVX p11, the distribution of p17 changed to that of p11, but did not appear to affect the pattern of movement of p11.
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Affiliation(s)
- Yuwen Lu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA and Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
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20
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Schoelz JE, Harries PA, Nelson RS. Intracellular transport of plant viruses: finding the door out of the cell. MOLECULAR PLANT 2011; 4:813-31. [PMID: 21896501 PMCID: PMC3183398 DOI: 10.1093/mp/ssr070] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/18/2011] [Indexed: 05/03/2023]
Abstract
Plant viruses are a class of plant pathogens that specialize in movement from cell to cell. As part of their arsenal for infection of plants, every virus encodes a movement protein (MP), a protein dedicated to enlarging the pore size of plasmodesmata (PD) and actively transporting the viral nucleic acid into the adjacent cell. As our knowledge of intercellular transport has increased, it has become apparent that viruses must also use an active mechanism to target the virus from their site of replication within the cell to the PD. Just as viruses are too large to fit through an unmodified plasmodesma, they are also too large to be freely diffused through the cytoplasm of the cell. Evidence has accumulated now for the involvement of other categories of viral proteins in intracellular movement in addition to the MP, including viral proteins originally associated with replication or gene expression. In this review, we will discuss the strategies that viruses use for intracellular movement from the replication site to the PD, in particular focusing on the role of host membranes for intracellular transport and the coordinated interactions between virus proteins within cells that are necessary for successful virus spread.
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Affiliation(s)
- James E. Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Phillip A. Harries
- Department of Biology, Pittsburg State University, Pittsburg, KS 66762, USA
| | - Richard S. Nelson
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, OK 73401, USA
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21
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Shemyakina EA, Erokhina TN, Gorshkova EN, Schiemann J, Solovyev AG, Morozov SY. Formation of protein complexes containing plant virus movement protein TGBp3 is necessary for its intracellular trafficking. Biochimie 2011; 93:742-8. [PMID: 21251950 DOI: 10.1016/j.biochi.2011.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 01/11/2011] [Indexed: 12/11/2022]
Abstract
Cell-to-cell movement of Poa semilatent virus (genus Hordeivirus) in infected plants is mediated by three viral 'triple gene block' (TGB) proteins. One of those termed TGBp3 is an integral membrane protein essential for intracellular transport of other TGB proteins and viral genomic RNA to plasmodesmata. TGBp3 targeting to plasmodesmata-associated sites is believed to involve an unconventional mechanism which does not employ endoplasmic reticulum-derived transport vesicles. Previously TGBp3 has been shown to contain a composite transport signal consisting of the central hydrophilic protein region which includes a conserved pentapeptide YQDLN and the C-terminal transmembrane segment. This study demonstrates that these TGBp3 structural elements have distinct functions in protein transport. The YQDLN-containing region is essential for TGBp3 incorporation into high-molecular-mass protein complexes. In transient expression assay formation of such complexes is necessary for entering the TGBp3-specific pathway of intracellular transport and protein delivery to plasmodesmata-associated sites. In virus-infected plants TGBp3 is also found predominantly in the form of high-molecular-mass complexes. When the complex-formation function of YQDLN-containing region is disabled by a mutation, targeting to plasmodesmata-associated sites can be complemented by a heterologous peptide capable of formation multimeric complexes. The C-terminal transmembrane segment is found to be an essential signal of TGBp3 intracellular transport to peripheral sites.
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Affiliation(s)
- Elena A Shemyakina
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
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22
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Shemyakina EA, Solovyev AG, Leonova OG, Popenko VI, Schiemann J, Morozov SY. The Role of Microtubule Association in Plasmodesmal Targeting of Potato mop-top virus Movement Protein TGBp1. Open Virol J 2011; 5:1-11. [PMID: 21660184 PMCID: PMC3109696 DOI: 10.2174/1874357901105010001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/11/2010] [Accepted: 10/25/2010] [Indexed: 12/19/2022] Open
Abstract
Cell-to-cell movement of Potato mop-top virus (PMTV) is mediated by three virus-encoded ‘triple gene block’ (TGB) proteins termed TGBp1, TGBp2 and TGBp3. TGBp1 binds virus RNAs to form viral ribonucleoprotein complexes (vRNPs), the transport form of viral genome. TGBp2 and TGBp3 are necessary for intracellular delivery of TGBp1-containing vRNPs to plasmodesmata. To analyze subcellular localization and transport of TGBp1 we used a single binary vector for agrobacterium-mediated co-expression of PMTV TGBp1 fused to green fluorescent protein and TGBp2/TGBp3. At two days post infiltration (dpi) TGBp1 was found in the nucleus and in association with microtubules (MTs). Similar localization pattern was revealed in cells expressing GFP-TGBp1 alone after particle bombardment. At 3 dpi, in addition to the nucleus and MTs, TGBp1 was detected in numerous granular bodies located both along the MTs and at the cell wall. The latter structures co-localized with plasmodesmata-associated callose depositions. At 4 dpi, GFP-TGBp1 was detected in cell wall-associated bodies and also in residual MTs, the nucleoplasm and large perinuclear inclusions resembling aggresomes. Therefore GFP-TGBp1 association with MTs preceded to its localization to plasmodesmata. Disassembly of cell MTs by colchicine prevented GFP-TGBp1 targeting to plasmodesmata and the MT-dependent aggresome formation. Deletion analysis also revealed a correlation between TGBp1 microtubule association and plasmodesmata targeting. We propose that TGBp1 interaction with MTs may be important for the formation of vRNP bodies destined for the transport to plasmodesmata as well as degradation of the excessive TGBp1.
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Affiliation(s)
- Elena A Shemyakina
- Department of Virology, Biological Faculty, Moscow State University, Moscow, 119992, Russia
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23
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Wright KM, Cowan GH, Lukhovitskaya NI, Tilsner J, Roberts AG, Savenkov EI, Torrance L. The N-terminal domain of PMTV TGB1 movement protein is required for nucleolar localization, microtubule association, and long-distance movement. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1486-97. [PMID: 20923354 DOI: 10.1094/mpmi-05-10-0105] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The triple-gene-block (TGB)1 protein of Potato mop-top virus (PMTV) was fused to fluorescent proteins and expressed in epidermal cells of Nicotiana benthamiana under the control of the 35S promoter. TGB1 fluorescence was observed in the cytoplasm, nucleus, and nucleolus and occasionally associated with microtubules. When expressed from a modified virus (PMTV.YFP-TGB1) which formed local lesions but was not competent for systemic movement, yellow fluorescent protein (YFP)-TGB1 labeled plasmodesmata in cells at the leading edge of the lesion and plasmodesmata, microtubules, nuclei, and nucleoli in cells immediately behind the leading edge. Deletion of 84 amino acids from the N-terminus of unlabeled TGB1 within the PMTV genome abolished movement of viral RNA to noninoculated leaves. When the same deletion was introduced into PMTV.YFP-TGB1, labeling of microtubules and nucleoli was abolished. The N-terminal 84 amino acids of TGB1 were fused to green fluorescent protein (GFP) and expressed in epidermal cells where GFP localized strongly to the nucleolus (not seen with unfused GFP), indicating that these amino acids contain a nucleolar localization signal; the fusion protein did not label microtubules. This is the first report of nucleolar and microtubule association of a TGB movement protein. The results suggest that PMTV TGB1 requires interaction with nuclear components and, possibly, microtubules for long-distance movement of viral RNA.
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Affiliation(s)
- Kathryn M Wright
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
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24
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Verchot-Lubicz J, Torrance L, Solovyev AG, Morozov SY, Jackson AO, Gilmer D. Varied movement strategies employed by triple gene block-encoding viruses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1231-47. [PMID: 20831404 DOI: 10.1094/mpmi-04-10-0086] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Several RNA virus genera belonging to the Virgaviridae and Flexiviridae families encode proteins organized in a triple gene block (TGB) that facilitate cell-to-cell and long-distance movement. The TGB proteins have been traditionally classified as hordei-like or potex-like based on phylogenetic comparisons and differences in movement mechanisms of the Hordeivirus and Potexvirus spp. However, accumulating data from other model viruses suggests that a revised framework is needed to accommodate the profound differences in protein interactions occurring during infection and ancillary capsid protein requirements for movement. The goal of this article is to highlight common features of the TGB proteins and salient differences in movement properties exhibited by individual viruses encoding these proteins. We discuss common and divergent aspects of the TGB transport machinery, describe putative nucleoprotein movement complexes, highlight recent data on TGB protein interactions and topological properties, and review membrane associations occurring during subcellular targeting and cell-to-cell movement. We conclude that the existing models cannot be used to explain all TGB viruses, and we propose provisional Potexvirus, Hordeivirus, and Pomovirus models. We also suggest areas that might profit from future research on viruses harboring this intriguing arrangement of movement proteins.
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Affiliation(s)
- Jeanmarie Verchot-Lubicz
- Oklahoma State University, Department of Entomology and Plant Pathology, Stillwater, OK 74078, USA.
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25
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Makarov VV, Obraztsova EA, Solovyev AG, Morozov SY, Taliansky ME, Yaminsky IV, Kalinina NO. The internal domain of hordeivirus movement protein TGB1 forms in vitro filamentous structures. BIOCHEMISTRY (MOSCOW) 2010; 75:752-8. [DOI: 10.1134/s0006297910060106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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26
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Makarov VV, Rybakova EN, Efimov AV, Dobrov EN, Serebryakova MV, Solovyev AG, Yaminsky IV, Taliansky ME, Morozov SY, Kalinina NO. Domain organization of the N-terminal portion of hordeivirus movement protein TGBp1. J Gen Virol 2009; 90:3022-3032. [DOI: 10.1099/vir.0.013862-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Three ‘triple gene block’ proteins known as TGBp1, TGBp2 and TGBp3 are required for cell-to-cell movement of plant viruses belonging to a number of genera including Hordeivirus. Hordeiviral TGBp1 interacts with viral genomic RNAs to form ribonucleoprotein (RNP) complexes competent for translocation between cells through plasmodesmata and over long distances via the phloem. Binding of hordeivirus TGBp1 to RNA involves two protein regions, the C-terminal NTPase/helicase domain and the N-terminal extension region. This study demonstrated that the extension region of hordeivirus TGBp1 consists of two structurally and functionally distinct domains called the N-terminal domain (NTD) and the internal domain (ID). In agreement with secondary structure predictions, analysis of circular dichroism spectra of the isolated NTD and ID demonstrated that the NTD represents a natively unfolded protein domain, whereas the ID has a pronounced secondary structure. Both the NTD and ID were able to bind ssRNA non-specifically. However, whilst the NTD interacted with ssRNA non-cooperatively, the ID bound ssRNA in a cooperative manner. Additionally, both domains bound dsRNA. The NTD and ID formed low-molecular-mass oligomers, whereas the ID also gave rise to high-molecular-mass complexes. The isolated ID was able to interact with both the NTD and the C-terminal NTPase/helicase domain in solution. These data demonstrate that the hordeivirus TGBp1 has three RNA-binding domains and that interaction between these structural units can provide a basis for remodelling of viral RNP complexes at different steps of cell-to-cell and long-distance transport of virus infection.
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Affiliation(s)
- Valentin V. Makarov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Ekaterina N. Rybakova
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Alexander V. Efimov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
| | - Eugene N. Dobrov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | | | - Andrey G. Solovyev
- Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Moscow 127550, Russia
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Igor V. Yaminsky
- Physical Faculty, Moscow State University, Moscow 119992, Russia
| | | | - Sergey Yu. Morozov
- Department of Virology, Biological Faculty, Moscow State University, Moscow 119992, Russia
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Natalia O. Kalinina
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
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27
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Lukashina E, Badun G, Fedorova N, Ksenofontov A, Nemykh M, Serebryakova M, Mukhamedzhanova A, Karpova O, Rodionova N, Baratova L, Dobrov E. Tritium planigraphy study of structural alterations in the coat protein of Potato virus X induced by binding of its triple gene block 1 protein to virions. FEBS J 2009; 276:7006-15. [DOI: 10.1111/j.1742-4658.2009.07408.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Lim HS, Bragg JN, Ganesan U, Ruzin S, Schichnes D, Lee MY, Vaira AM, Ryu KH, Hammond J, Jackson AO. Subcellular localization of the barley stripe mosaic virus triple gene block proteins. J Virol 2009; 83:9432-48. [PMID: 19570874 PMCID: PMC2738231 DOI: 10.1128/jvi.00739-09] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 06/22/2009] [Indexed: 02/07/2023] Open
Abstract
Barley stripe mosaic virus (BSMV) spreads from cell to cell through the coordinated actions of three triple gene block (TGB) proteins (TGB1, TGB2, and TGB3) arranged in overlapping open reading frames (ORFs). Our previous studies (D. M. Lawrence and A. O. Jackson, J. Virol. 75:8712-8723, 2001; D. M. Lawrence and A. O. Jackson, Mol. Plant Pathol. 2:65-75, 2001) have shown that each of these proteins is required for cell-to-cell movement in monocot and dicot hosts. We recently found (H.-S. Lim, J. N. Bragg, U. Ganesan, D. M. Lawrence, J. Yu, M. Isogai, J. Hammond, and A. O. Jackson, J. Virol. 82:4991-5006, 2008) that TGB1 engages in homologous interactions leading to the formation of a ribonucleoprotein complex containing viral genomic and messenger RNAs, and we have also demonstrated that TGB3 functions in heterologous interactions with TGB1 and TGB2. We have now used Agrobacterium tumefaciens-mediated protein expression in Nicotiana benthamiana leaf cells and site-specific mutagenesis to determine how TGB protein interactions influence their subcellular localization and virus spread. Confocal microscopy revealed that the TGB3 protein localizes at the cell wall (CW) in close association with plasmodesmata and that the deletion or mutagenesis of a single amino acid at the immediate C terminus can affect CW targeting. TGB3 also directed the localization of TGB2 from the endoplasmic reticulum to the CW, and this targeting was shown to be dependent on interactions between the TGB2 and TGB3 proteins. The optimal localization of the TGB1 protein at the CW also required TGB2 and TGB3 interactions, but in this context, site-specific TGB1 helicase motif mutants varied in their localization patterns. The results suggest that the ability of TGB1 to engage in homologous binding interactions is not essential for targeting to the CW. However, the relative expression levels of TGB2 and TGB3 influenced the cytosolic and CW distributions of TGB1 and TGB2. Moreover, in both cases, localization at the CW was optimal at the 10:1 TGB2-to-TGB3 ratios occurring in virus infections, and mutations reducing CW localization had corresponding effects on BSMV movement phenotypes. These data support a model whereby TGB protein interactions function in the subcellular targeting of movement protein complexes and the ability of BSMV to move from cell to cell.
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Affiliation(s)
- Hyoun-Sub Lim
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Jennifer N. Bragg
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Uma Ganesan
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Steven Ruzin
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Denise Schichnes
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Mi Yeon Lee
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Anna Maria Vaira
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Ki Hyun Ryu
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - John Hammond
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Andrew O. Jackson
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
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29
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Lu HC, Chen CE, Tsai MH, Wang HI, Su HJ, Yeh HH. Cymbidium mosaic potexvirus isolate-dependent host movement systems reveal two movement control determinants and the coat protein is the dominant. Virology 2009; 388:147-59. [PMID: 19345971 PMCID: PMC7103407 DOI: 10.1016/j.virol.2009.02.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 01/28/2009] [Accepted: 02/28/2009] [Indexed: 11/30/2022]
Abstract
Little is known about how plant viruses of a single species exhibit different movement behavior in different host species. Two Cymbidium mosaic potexvirus (CymMV) isolates, M1 and M2, were studied. Both can infect Phalaenopsis orchids, but only M1 can systemically infect Nicotiana benthamiana plants. Protoplast inoculation and whole-mount in situ hybridization revealed that both isolates can replicate in N. benthamiana; however, M2 was restricted to the initially infected cells. Genome shuffling between M1 and M2 revealed that two control modes are involved in CymMV host dependent movement. The M1 coat protein (CP) plays a dominant role in controlling CymMV movement between cells, because all chimeric CymMV viruses containing the M1 CP systemically infected N. benthamiana plants. Without the M1 CP, one chimeric virus containing the combination of the M1 triple gene block proteins (TGBps), the M2 5' RNA (1-4333), and the M2 CP effectively moved in N. benthamiana plants. Further complementation analysis revealed that M1 TGBp1 and TGBp3 are co-required to complement the movement of the chimeric viruses in N. benthamiana. The amino acids within the CP, TGBp1 and TGBp3 which are required or important for CymMV M2 movement in N. benthamiana plants were mapped. The required amino acids within the CP map to the predicted RNA binding domain. RNA-protein binding assays revealed that M1 CP has higher RNA binding affinity than does M2 CP. Yeast two-hybrid assays to detect all possible interactions of M1 TGBps and CP, and only TGBp1 and CP self-interactions were observed.
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Affiliation(s)
- Hsiang-Chia Lu
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Cheng-En Chen
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Meng-Hsiun Tsai
- Department of Management Information Systems, National Chung Hsing University, 250, Kuo Kuang Rd., Taichung 402, Taiwan
| | - Hsiang-iu Wang
- Department of Computer Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - Hong-Ji Su
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Hsin-Hung Yeh
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
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30
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Jackson AO, Lim HS, Bragg J, Ganesan U, Lee MY. Hordeivirus replication, movement, and pathogenesis. ANNUAL REVIEW OF PHYTOPATHOLOGY 2009; 47:385-422. [PMID: 19400645 DOI: 10.1146/annurev-phyto-080508-081733] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The last Hordeivirus review appearing in this series 20 years ago focused on the comparative biology, relationships, and genome organization of members of the genus ( 68 ). Prior to the 1989 review, useful findings about the origin, disease occurrence, host ranges, and general biological properties of Barley stripe mosaic virus (BSMV) were summarized in three comprehensive reviews ( 26, 67, 107 ). Several recent reviews emphasizing contemporary molecular genetic findings also may be of interest to various readers ( 15, 37, 42, 69, 70, 88, 113 ). In the current review, we briefly reiterate the biological properties of the four members of the Hordeivirus genus and describe advances in our understanding of organization and expression of the viral genomes. We also discuss the infection processes and pathogenesis of the most extensively characterized Hordeiviruses and frame these advances in the broader context of viruses in other families that have encoded triple gene block proteins. In addition, an overview of recent advances in the use of BSMV for virus-induced gene silencing is presented.
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Affiliation(s)
- Andrew O Jackson
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
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31
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Rebelo AR, Niewiadomski S, Prosser SW, Krell P, Meng B. Subcellular localization of the triple gene block proteins encoded by a Foveavirus infecting grapevines. Virus Res 2008; 138:57-69. [PMID: 18804498 DOI: 10.1016/j.virusres.2008.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 08/13/2008] [Accepted: 08/14/2008] [Indexed: 11/25/2022]
Abstract
Grapevine rupestris stem pitting-associated virus (GRSPaV; Foveavirus; Flexiviridae) contains a positive-sense, ssRNA genome. GRSPaV occurs worldwide in grapes and is involved in the Rugose Wood disease complex. The GRSPaV genome contains the triple gene block (TGB), a genetic module present in several genera of plant RNA viruses. TGB encodes three proteins (TGBp1, TGBp2 and TGBp3) that are believed to work together to achieve intra- and inter-cellular transport of virions in infected plants. To reveal the subcellular localization of each TGB protein and to examine the impact that different fusion positions may have on the behavior of the native protein, we made a series of expression constructs and expressed the corresponding protein fusions in Nicotiana tabacum BY-2 cells and protoplasts. We demonstrated that TGBp1 had both a cytosolic and nuclear distribution. Two TGBp1 fusions (GFP fused at the N- or C-terminus) differ in subcellular distribution. Through the use of truncation mutants, we mapped TGBp1 regions responsible for the formation of two distinct types of aggregates. Sequence analyses predicted two and one transmembrane domains in TGBp2 and TGBp3, respectively. GFP fusions at either terminus of TGBp2 revealed identical localization to the ER network and ER-derived structures. In contrast, the two TGBp3 fusions to mRFP differed in localization. This is the first report on the subcellular localization of the viral proteins of a member of the Foveavirus genus.
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Affiliation(s)
- Ana Rita Rebelo
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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32
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Leshchiner AD, Minina EA, Rakitina DV, Vishnichenko VK, Solovyev AG, Morozov SY, Kalinina NO. Oligomerization of the potato virus X 25-kD movement protein. BIOCHEMISTRY (MOSCOW) 2008; 73:50-5. [PMID: 18294129 DOI: 10.1134/s0006297908010070] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A 25-kD movement protein (25K protein) encoded by the first gene of the potexvirus Potato virus X triple gene block of transport genes is essential for the viral movement in infected plants. The 25K protein belongs to superfamily 1 of NTPase/helicases and exhibits in vitro RNA helicase, Mg2+-dependent NTPase, and RNA-binding activities. In the present work, the ability of 25K protein for homologous interactions was studied using the yeast two-hybrid system, protein chemical cross-linking in the presence of glutaraldehyde, far-Western blotting, and ultracentrifugation in sucrose density gradients. The 25K protein was shown to form homodimers and homooligomers. Sites of homologous protein-protein interactions were found in both the N- and C-terminal portions of the protein.
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Affiliation(s)
- A D Leshchiner
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
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33
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Triple gene block protein interactions involved in movement of Barley stripe mosaic virus. J Virol 2008; 82:4991-5006. [PMID: 18353960 DOI: 10.1128/jvi.02586-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Barley stripe mosaic virus (BSMV) encodes three movement proteins in an overlapping triple gene block (TGB), but little is known about the physical interactions of these proteins. We have characterized a ribonucleoprotein (RNP) complex consisting of the TGB1 protein and plus-sense BSMV RNAs from infected barley plants and have identified TGB1 complexes in planta and in vitro. Homologous TGB1 binding was disrupted by site-specific mutations in each of the first two N-terminal helicase motifs but not by mutations in two C-terminal helicase motifs. The TGB2 and TGB3 proteins were not detected in the RNP, but affinity chromatography and yeast two-hybrid experiments demonstrated that TGB1 binds to TGB3 and that TGB2 and TGB3 form heterologous interactions. These interactions required the TGB2 glycine 40 and the TGB3 isoleucine 108 residues, and BSMV mutants containing these amino acid substitution were unable to move from cell to cell. Infectivity experiments indicated that TGB1 separated on a different genomic RNA from TGB2 and TGB3 could function in limited cell-to-cell movement but that the rates of movement depended on the levels of expression of the proteins and the contexts in which they are expressed. Moreover, elevated expression of the wild-type TGB3 protein interfered with cell-to-cell movement but movement was not affected by the similar expression of a TGB3 mutant that fails to interact with TGB2. These experiments suggest that BSMV movement requires physical interactions of TGB2 and TGB3 and that substantial deviation from the TGB protein ratios expressed by the wild-type virus compromises movement.
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Guenoune-Gelbart D, Elbaum M, Sagi G, Levy A, Epel BL. Tobacco mosaic virus (TMV) replicase and movement protein function synergistically in facilitating TMV spread by lateral diffusion in the plasmodesmal desmotubule of Nicotiana benthamiana. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:335-45. [PMID: 18257683 DOI: 10.1094/mpmi-21-3-0335] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Virus spread through plasmodesmata (Pd) is mediated by virus-encoded movement proteins (MPs) that modify Pd structure and function. The MP of Tobacco mosaic virus ((TMV)MP) is an endoplasmic reticulum (ER) integral membrane protein that binds viral RNA (vRNA), forming a vRNA:MP:ER complex. It has been hypothesized that (TMV)MP causes Pd to dilate, thus potentiating a cytoskeletal mediated sliding of the vRNA:MP:ER complex through Pd; in the absence of MP, by contrast, the ER cannot move through Pd. An alternate model proposes that cell-to-cell spread takes place by diffusion of the MP:vRNA complex in the ER membranes which traverse Pd. To test these models, we measured the effect of (TMV)MP and replicase expression on cell-to-cell spread of several green fluorescent protein-fused probes: a soluble cytoplasmic protein, two ER lumen proteins, and two ER membrane-bound proteins. Our data support the diffusion model in which a complex that includes ER-embedded MP, vRNA, and other components diffuses in the ER membrane within the Pd driven by the concentration gradient between an infected cell and adjacent noninfected cells. The data also suggest that the virus replicase and MP function together in altering Pd conductivity.
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Schepetilnikov MV, Solovyev AG, Gorshkova EN, Schiemann J, Prokhnevsky AI, Dolja VV, Morozov SY. Intracellular targeting of a hordeiviral membrane-spanning movement protein: sequence requirements and involvement of an unconventional mechanism. J Virol 2008; 82:1284-93. [PMID: 18032484 PMCID: PMC2224415 DOI: 10.1128/jvi.01164-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Accepted: 11/12/2007] [Indexed: 12/14/2022] Open
Abstract
The membrane-spanning protein TGBp3 is one of the three movement proteins (MPs) of Poa semilatent virus. TGBp3 is thought to direct other viral MPs and genomic RNA to peripheral bodies located in close proximity to plasmodesmata. We used the ectopic expression of green fluorescent protein-fused TGBp3 in epidermal cells of Nicotiana benthamiana leaves to study the TGBp3 intracellular trafficking pathway. Treatment with inhibitors was used to reveal that the targeting of TGBp3 to plasmodesmata does not require a functional cytoskeleton or secretory system. In addition, the suppression of endoplasmic reticulum-derived vesicle formation by a dominant negative mutant of small GTPase Sar1 had no detectable effect on TGBp3 trafficking to peripheral bodies. Collectively, these results suggested the involvement of an unconventional pathway in the intracellular transport of TGBp3. The determinants of targeting to plasmodesmata were localized to the C-terminal region of TGBp3, including the conserved hydrophilic and terminal membrane-spanning domains.
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Affiliation(s)
- Mikhail V Schepetilnikov
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall 2082, Corvallis, OR 97331, USA
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36
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Verchot-Lubicz J, Ye CM, Bamunusinghe D. Molecular biology of potexviruses: recent advances. J Gen Virol 2007; 88:1643-1655. [PMID: 17485523 DOI: 10.1099/vir.0.82667-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Recent advances in potexvirus research have produced new models describing virus replication, cell-to-cell movement, encapsidation, R gene-mediated resistance and gene silencing. Interactions between distant RNA elements are a central theme in potexvirus replication. The 5′ non-translated region (NTR) regulates genomic and subgenomic RNA synthesis and encapsidation, as well as virus plasmodesmal transport. The 3′ NTR regulates both plus- and minus-strand RNA synthesis. How the triple gene-block proteins interact for virus movement is still elusive. As the potato virus X (PVX) TGBp1 protein gates plasmodesmata, regulates virus translation and is a suppressor of RNA silencing, further research is needed to determine how these properties contribute to propelling virus through the plasmodesmata. Specifically, TGBp1 suppressor activity is required for virus movement, but how the silencing machinery relates to plasmodesmata is not known. The TGBp2 and TGBp3 proteins are endoplasmic reticulum (ER)-associated proteins required for virus movement. TGBp2 associates with ER-derived vesicles that traffic along the actin network. Future research will determine whether the virus-induced vesicles are cytopathic structures regulating events along the ER or are vehicles carrying virus to the plasmodesmata for transfer into neighbouring cells. Efforts to assemble virions in vitro identified a single-tailed particle (STP) comprising RNA, coat protein (CP) and TGBp1. It has been proposed that TGBp1 aids in transport of virions or STP between cells and ensures translation of RNA in the receiving cells. PVX is also a tool for studying Avr–R gene interactions and gene silencing in plants. The PVX CP is the elicitor for the Rx gene. Recent reports of the PVX CP reveal how CP interacts with the Rx gene product.
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Affiliation(s)
- Jeanmarie Verchot-Lubicz
- Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK 74078, USA
| | - Chang-Ming Ye
- Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK 74078, USA
| | - Devinka Bamunusinghe
- Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK 74078, USA
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