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van Solinge TS, Mahjoum S, Ughetto S, Sammarco A, Broekman ML, Breakefield XO, O’Brien KP. Illuminating cellular and extracellular vesicle-mediated communication via a split-Nanoluc reporter in vitro and in vivo. CELL REPORTS METHODS 2023; 3:100412. [PMID: 36936071 PMCID: PMC10014296 DOI: 10.1016/j.crmeth.2023.100412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 09/01/2022] [Accepted: 01/30/2023] [Indexed: 02/25/2023]
Abstract
Tools to effectively demonstrate and quantify functional delivery in cellular communication have been lacking. This study reports the use of a fluorescently labeled split Nanoluc reporter system to demonstrate and quantify functional transfer between cells in vitro and in a subcutaneous tumor mouse model. Our construct allows monitoring of direct, indirect, and specifically extracellular vesicle-mediated functional communication.
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Affiliation(s)
- Thomas S. van Solinge
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurosurgery, Leiden University Medical Center, Leiden, the Netherlands
| | - Shadi Mahjoum
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Stefano Ughetto
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Oncology, University of Turin, Candiolo, Italy
| | - Alessandro Sammarco
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Italy
| | - Marike L.D. Broekman
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurosurgery, Leiden University Medical Center, Leiden, the Netherlands
- Department of Neurosurgery, Haaglanden Medical Center, The Hague, the Netherlands
| | - Xandra O. Breakefield
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Killian P. O’Brien
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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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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3
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Sasaki N, Takashima E, Nyunoya H. Altered Subcellular Localization of a Tobacco Membrane Raft-Associated Remorin Protein by Tobamovirus Infection and Transient Expression of Viral Replication and Movement Proteins. FRONTIERS IN PLANT SCIENCE 2018; 9:619. [PMID: 29868075 PMCID: PMC5962775 DOI: 10.3389/fpls.2018.00619] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 04/18/2018] [Indexed: 05/20/2023]
Abstract
Remorins are plant specific proteins found in plasma membrane microdomains (termed lipid or membrane rafts) and plasmodesmata. A potato remorin is reported to be involved in negatively regulating potexvirus movement and plasmodesmal permeability. In this study, we isolated cDNAs of tobacco remorins (NtREMs) and examined roles of an NtREM in infection by tomato mosaic virus (ToMV). Subcellular localization analysis using fluorescently tagged NtREM, ToMV, and viral replication and movement proteins (MPs) indicated that virus infection and transient expression of the viral proteins promoted the formation of NtREM aggregates by altering the subcellular distribution of NtREM, which was localized uniformly on the plasma membrane under normal conditions. NtREM aggregates were often observed associated closely with endoplasmic reticulum networks and bodies of the 126K replication and MPs. The bimolecular fluorescence complementation assay indicated that NtREM might interact directly with the MP on the plasma membrane and around plasmodesmata. In addition, transient overexpression of NtREM facilitated ToMV cell-to-cell movement. Based on these results, we discuss possible roles of the tobacco remorin in tobamovirus movement.
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Affiliation(s)
- Nobumitsu Sasaki
- Gene Research Center, Tokyo University of Agriculture and Technology, Fuchu, Japan
- *Correspondence: Nobumitsu Sasaki,
| | - Eita Takashima
- Gene Research Center, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Hiroshi Nyunoya
- Gene Research Center, Tokyo University of Agriculture and Technology, Fuchu, Japan
- Faculty of Science and Engineering, Waseda University, Tokyo, Japan
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4
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Han SH, Park JS, Han JY, Gong JS, Park CH, Kim JK, Seo EY, Domier LL, Hammond J, Lim HS. New Korean isolates of Pepper mild mottle virus (PMMoV) differ in symptom severity and subcellular localization of the 126 kDa protein. Virus Genes 2017; 53:434-445. [PMID: 28176159 DOI: 10.1007/s11262-017-1432-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 02/01/2017] [Indexed: 12/14/2022]
Abstract
Two isolates of Pepper mild mottle virus (PMMoV) were selected from a nationwide survey of pepper fields in South Korea in 2014 and 2015, in which Cucumber mosaic virus was also detected; the two PMMoV isolates, Sangcheong 47 (S-47, KX399390) and Jeongsong 76 (J-76, KX399389), share ~99% nucleotide and amino acid identity and are closely related to Japanese and Chinese isolates at the nucleotide level. Amino acid sequence comparisons revealed 99.73, 99.81, 98.44, and 100% identity in the ORF1, ORF2, MP, and CP, respectively, between S-47 and J-76. In addition, we generated infectious clones of S-47 and J-76, and T7 promoter driven transcripts of each inoculated to Nicotiana benthamiana produced very severe symptoms, whereas only mild symptoms developed in Capsicum annuum. Gene silencing suppressor function of 126 kDa and cytoskeleton-connected plasmodesmata localization of movement protein of S-47 and J-76 showed no difference between isolates, whereas 126 kDa of J-76 clearly formed intracellular aggregates not observed with S-47 126 kDa protein. Differences between these isolates in 126/183 kDa-related functions including subcellular localization suggest that differential interactions with host proteins may affect symptom development in C. annuum.
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Affiliation(s)
- Sang-Hyuk Han
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Jong-Seo Park
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Jae-Yeong Han
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Jun-Su Gong
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Chan-Hwan Park
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Jung-Kyu Kim
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Eun-Young Seo
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea
| | - Leslie L Domier
- United States Department of Agriculture - Agricultural Research Service, University of Illinois at Urbana-Champaign, Department of Crop Sciences, Champaign, IL, 61801, USA
| | - John Hammond
- United States Department of Agriculture - Agricultural Research Service, United States National Arboretum, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue B-010A, Beltsville, MD, 20705, USA.
| | - Hyoun-Sub Lim
- Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea.
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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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6
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Hashimoto M, Komatsu K, Iwai R, Keima T, Maejima K, Shiraishi T, Ishikawa K, Yoshida T, Kitazawa Y, Okano Y, Yamaji Y, Namba S. Cell Death Triggered by a Putative Amphipathic Helix of Radish mosaic virus Helicase Protein Is Tightly Correlated With Host Membrane Modification. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:675-88. [PMID: 25650831 DOI: 10.1094/mpmi-01-15-0004-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Systemic necrosis is one of the most severe symptoms caused by plant RNA viruses. Recently, systemic necrosis has been suggested to have similar features to a defense response referred to as the hypersensitive response (HR), a form of programmed cell death. In virus-infected plant cells, host intracellular membrane structures are changed dramatically for more efficient viral replication. However, little is known about whether this replication-associated membrane modification is the cause of the symptoms. In this study, we identified an amino-terminal amphipathic helix of the helicase encoded by Radish mosaic virus (RaMV) (genus Comovirus) as an elicitor of cell death in RaMV-infected plants. Cell death caused by the amphipathic helix had features similar to HR, such as SGT1-dependence. Mutational analyses and inhibitor assays using cerulenin demonstrated that the amphipathic helix-induced cell death was tightly correlated with dramatic alterations in endoplasmic reticulum (ER) membrane structures. Furthermore, the cell death-inducing activity of the amphipathic helix was conserved in Cowpea mosaic virus (genus Comovirus) and Tobacco ringspot virus (genus Nepovirus), both of which are classified in the family Secoviridae. Together, these results indicate that ER membrane modification associated with viral intracellular replication may be recognized to prime defense responses against plant viruses.
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Affiliation(s)
- Masayoshi Hashimoto
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ken Komatsu
- 2 Laboratory of Plant Pathology, Tokyo University of Agriculture and Technology (TUAT), 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan
| | - Ryo Iwai
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takuya Keima
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kensaku Maejima
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takuya Shiraishi
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kazuya Ishikawa
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tetsuya Yoshida
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yugo Kitazawa
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yukari Okano
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yasuyuki Yamaji
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shigetou Namba
- 1 Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, 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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7
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Csorba T, Kontra L, Burgyán J. viral silencing suppressors: Tools forged to fine-tune host-pathogen coexistence. Virology 2015; 479-480:85-103. [DOI: 10.1016/j.virol.2015.02.028] [Citation(s) in RCA: 368] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/31/2015] [Accepted: 02/16/2015] [Indexed: 12/27/2022]
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8
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Prosser SW, Xiao H, Li C, Nelson RS, Meng B. Subcellular localization and membrane association of the replicase protein of grapevine rupestris stem pitting-associated virus, family Betaflexiviridae. J Gen Virol 2015; 96:921-932. [PMID: 25502653 DOI: 10.1099/jgv.0.000019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As a member of the newly established Betaflexiviridae family, grapevine rupestris stem pitting-associated virus (GRSPaV) has an RNA genome containing five ORFs. ORF1 encodes a putative replicase polyprotein typical of the alphavirus superfamily of positive-strand ssRNA viruses. Several viruses of this superfamily have been demonstrated to replicate in structures designated viral replication complexes associated with intracellular membranes. However, structure and cellular localization of the replicase complex have not been studied for members of Betaflexiviridae, a family of mostly woody plant viruses. As a first step towards the elucidation of the replication complex of GRSPaV, we investigated the subcellular localization of full-length and truncated versions of its replicase polyprotein via fluorescent tagging, followed by fluorescence microscopy. We found that the replicase polyprotein formed distinctive punctate bodies in both Nicotiana benthamiana leaf cells and tobacco protoplasts. We further mapped a region of 76 amino acids in the methyl-transferase domain responsible for the formation of these punctate structures. The punctate structures are distributed in close proximity to the endoplasmic reticulum network. Membrane flotation and biochemical analyses demonstrate that the N-terminal region responsible for punctate structure formation associated with cellular membrane is likely through an amphipathic α helix serving as an in-plane anchor. The identity of this membrane is yet to be determined. This is, to our knowledge, the first report on the localization and membrane association of the replicase proteins of a member of the family Betaflexiviridae.
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Affiliation(s)
- Sean W Prosser
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada N1G2W1
| | - Huogen Xiao
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada N1G2W1
| | - Caihong Li
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada N1G2W1
| | - Richard S Nelson
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73410, USA
| | - Baozhong Meng
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada N1G2W1
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9
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Ghoshal K, Theilmann J, Reade R, Sanfacon H, Rochon D. The Cucumber leaf spot virus p25 auxiliary replicase protein binds and modifies the endoplasmic reticulum via N-terminal transmembrane domains. Virology 2014; 468-470:36-46. [PMID: 25129437 PMCID: PMC7112066 DOI: 10.1016/j.virol.2014.07.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 06/28/2014] [Accepted: 07/13/2014] [Indexed: 11/23/2022]
Abstract
Cucumber leaf spot virus (CLSV) is a member of the Aureusvirus genus, family Tombusviridae. The auxiliary replicase of Tombusvirids has been found to localize to endoplasmic reticulum (ER), peroxisomes or mitochondria; however, localization of the auxiliary replicase of aureusviruses has not been determined. We have found that the auxiliary replicase of CLSV (p25) fused to GFP colocalizes with ER and that three predicted transmembrane domains (TMDs) at the N-terminus of p25 are sufficient for targeting, although the second and third TMDs play the most prominent roles. Confocal analysis of CLSV infected 16C plants shows that the ER becomes modified including the formation of punctae at connections between ER tubules and in association with the nucleus. Ultrastructural analysis shows that the cytoplasm contains numerous vesicles which are also found between the perinuclear ER and nuclear membrane. It is proposed that these vesicles correspond to modified ER used as sites for CLSV replication.
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Affiliation(s)
- Kankana Ghoshal
- University of British Columbia, Faculty of Land and Food Systems, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jane Theilmann
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - Ron Reade
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - Helene Sanfacon
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - D'Ann Rochon
- University of British Columbia, Faculty of Land and Food Systems, Vancouver, British Columbia, Canada V6T 1Z4; Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0.
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10
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Amari K, Di Donato M, Dolja VV, Heinlein M. Myosins VIII and XI play distinct roles in reproduction and transport of tobacco mosaic virus. PLoS Pathog 2014; 10:e1004448. [PMID: 25329993 PMCID: PMC4199776 DOI: 10.1371/journal.ppat.1004448] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 09/04/2014] [Indexed: 12/02/2022] Open
Abstract
Viruses are obligatory parasites that depend on host cellular factors for their replication as well as for their local and systemic movement to establish infection. Although myosin motors are thought to contribute to plant virus infection, their exact roles in the specific infection steps have not been addressed. Here we investigated the replication, cell-to-cell and systemic spread of Tobacco mosaic virus (TMV) using dominant negative inhibition of myosin activity. We found that interference with the functions of three class VIII myosins and two class XI myosins significantly reduced the local and long-distance transport of the virus. We further determined that the inactivation of myosins XI-2 and XI-K affected the structure and dynamic behavior of the ER leading to aggregation of the viral movement protein (MP) and to a delay in the MP accumulation in plasmodesmata (PD). The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation. The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane. These results suggest that class XI myosins contribute to the viral propagation and intracellular trafficking, whereas myosins VIII are specifically required for the MP targeting to and virus movement through the PD. Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.
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Affiliation(s)
- Khalid Amari
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Martin Di Donato
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Valerian V. Dolja
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Manfred Heinlein
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
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11
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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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12
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Kusumanegara K, Mine A, Hyodo K, Kaido M, Mise K, Okuno T. Identification of domains in p27 auxiliary replicase protein essential for its association with the endoplasmic reticulum membranes in Red clover necrotic mosaic virus. Virology 2012; 433:131-41. [PMID: 22898643 DOI: 10.1016/j.virol.2012.07.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 06/22/2012] [Accepted: 07/19/2012] [Indexed: 11/18/2022]
Abstract
Positive-strand RNA viruses require host intracellular membranes for replicating their genomic RNAs. In this study, we determined the domains and critical amino acids in p27 of Red clover necrotic mosaic virus (RCNMV) required for its association with and targeting of ER membranes in Nicotiana benthamiana plants using a C-terminally GFP-fused and biologically functional p27. Confocal microscopy and membrane-flotation assays using an Agrobacterium-mediated expression system showed that a stretch of 20 amino acids in the N-terminal region of p27 is essential for the association of p27 with membranes. We identified the amino acids in this domain required for the association of p27 with membranes using alanine-scanning mutagenesis. We also found that this domain contains amino acids not critical for the membrane association but required for the formation of viral RNA replication complexes and negative-strand RNA synthesis. Our results extend our understanding of the multifunctional role of p27 in RCNMV replication.
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Affiliation(s)
- Kusumawaty Kusumanegara
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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13
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Tilsner J, Oparka KJ. Missing links? - The connection between replication and movement of plant RNA viruses. Curr Opin Virol 2012; 2:705-11. [PMID: 23036608 DOI: 10.1016/j.coviro.2012.09.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 09/11/2012] [Accepted: 09/11/2012] [Indexed: 12/18/2022]
Abstract
Plant virus infection spreads from cell-to-cell within the host with the aid of viral movement proteins (MPs) that transport infectious genomes through intercellular pores called plasmodesmata (PD). MPs are able to accomplish RNA trafficking independent of virus infection. However, although dispensable for replication, they often associate with or assist in the formation of viral replication complexes. Quantitative analyses of genetic bottlenecks during infection, as well as considerations of transport specificity, suggest that intricate links between replication and movement may facilitate efficient delivery of plant viruses through PD during early infection, at a stage when viral genomes are still rare.
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Affiliation(s)
- Jens Tilsner
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
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14
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Ibrahim A, Hutchens HM, Berg RH, Loesch-Fries LS. Alfalfa mosaic virus replicase proteins, P1 and P2, localize to the tonoplast in the presence of virus RNA. Virology 2012; 433:449-61. [PMID: 22999257 DOI: 10.1016/j.virol.2012.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 08/01/2012] [Accepted: 08/07/2012] [Indexed: 12/25/2022]
Abstract
To identify the virus components important for assembly of the Alfalfa mosaic virus replicase complex, we used live cell imaging of Arabidopsis thaliana protoplasts that expressed various virus cDNAs encoding native and GFP-fusion proteins of P1 and P2 replicase proteins and full-length virus RNAs. Expression of P1-GFP alone resulted in fluorescent vesicle-like bodies in the cytoplasm that colocalized with FM4-64, an endocytic marker, and RFP-AtVSR2, RabF2a/Rha1-mCherry, and RabF2b/Ara7-mCherry, all of which localize to multivesicular bodies (MVBs), which are also called prevacuolar compartments, that mediate traffic to the lytic vacuole. GFP-P2 was driven from the cytosol to MVBs when expressed with P1 indicating that P1 recruited GFP-P2. P1-GFP localized on the tonoplast, which surrounds the vacuole, in the presence of infectious virus RNA, replication competent RNA2, or P2 and replication competent RNA1 or RNA3. This suggests that a functional replication complex containing P1, P2, and a full-length AMV RNA assembles on MVBs to traffic to the tonoplast.
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Affiliation(s)
- Amr Ibrahim
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
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15
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Sardo L, Wege C, Kober S, Kocher C, Accotto GP, Noris E. RNA viruses and their silencing suppressors boost Abutilon mosaic virus, but not the Old World Tomato yellow leaf curl Sardinia virus. Virus Res 2011; 161:170-80. [PMID: 21843560 DOI: 10.1016/j.virusres.2011.07.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/26/2011] [Accepted: 07/27/2011] [Indexed: 11/19/2022]
Abstract
Mixed viral infections can induce different changes in symptom development, genome accumulation and tissue tropism. These issues were investigated for two phloem-limited begomoviruses, Abutilon mosaic virus (AbMV) and Tomato yellow leaf curl Sardinia virus (TYLCSV) in Nicotiana benthamiana plants doubly infected by either the potyvirus Cowpea aphid-borne mosaic virus (CABMV) or the tombusvirus Artichoke mottled crinkle virus (AMCV). Both RNA viruses induced an increase of the amount of AbMV, led to its occasional egress from the phloem and induced symptom aggravation, while the amount and tissue tropism of TYLCSV were almost unaffected. In transgenic plants expressing the silencing suppressors of CABMV (HC-Pro) or AMCV (P19), AbMV was supported to a much lesser extent than in the mixed infections, with the effect of CABMV HC-Pro being superior to that of AMCV P19. Neither of the silencing suppressors influenced TYLCSV accumulation. These results demonstrate that begomoviruses differentially respond to the invasion of other viruses and to silencing suppression.
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Affiliation(s)
- Luca Sardo
- Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, I-10135 Torino, Italy
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16
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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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Kramer SR, Goregaoker SP, Culver JN. Association of the Tobacco mosaic virus 126kDa replication protein with a GDI protein affects host susceptibility. Virology 2011; 414:110-8. [PMID: 21492894 DOI: 10.1016/j.virol.2010.12.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 11/14/2010] [Accepted: 12/16/2010] [Indexed: 11/23/2022]
Abstract
An interaction between the Tobacco mosaic virus (TMV) 126kDa replication protein and a host-encoded Rab GDP dissociation inhibitor (GDI2) was identified and investigated for its role in infection. GDI proteins are essential components of vesicle trafficking pathways. TMV infection alters the localization of GDI2 from the cytoplasm to ER-associated complexes. Partial silencing of GDI2 results in significant increases in the number of TMV infection foci observed in inoculated tissues. However, GDI2 silencing does not affect TMV accumulation at the infection site, cell-to-cell movement, or susceptibility of the host to mechanical inoculation. Furthermore, increases in the number of successful infection foci were specific to TMV and correlated with the appearance of vesicle-like rearrangements in the vacuolar membrane. Tissue infiltrations with brefeldin A, an inhibitor of vesicle trafficking, also enhanced host susceptibility to TMV. Combined these findings suggest that the 126kDa-GDI2 interaction alters vesicle trafficking to enhance the establishment of an infection.
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Affiliation(s)
- Sabrina R Kramer
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Harries PA, Schoelz JE, Nelson RS. Intracellular transport of viruses and their components: utilizing the cytoskeleton and membrane highways. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1381-93. [PMID: 20653412 DOI: 10.1094/mpmi-05-10-0121] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plant viruses are obligate organisms that require host components for movement within and between cells. A mechanistic understanding of virus movement will allow the identification of new methods to control virus systemic spread and serve as a model system for understanding host macromolecule intra- and intercellular transport. Recent studies have moved beyond the identification of virus proteins involved in virus movement and their effect on plasmodesmal size exclusion limits to the analysis of their interactions with host components to allow movement within and between cells. It is clear that individual virus proteins and replication complexes associate with and, in some cases, traffic along the host cytoskeleton and membranes. Here, we review these recent findings, highlighting the diverse associations observed between these components and their trafficking capacity. Plant viruses operate individually, sometimes within virus species, to utilize unique interactions between their proteins or complexes and individual host cytoskeletal or membrane elements over time or space for their movement. However, there is not sufficient information for any plant virus to create a complete model of its intracellular movement; thus, more research is needed to achieve that goal.
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Affiliation(s)
- Phillip A Harries
- Department of Biology, Pittsburg State University, Pittsburg, KS 66762, USA
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Wang X, Kelman Z, Culver JN. Helicase ATPase activity of the Tobacco mosaic virus 126-kDa protein modulates replicase complex assembly. Virology 2010; 402:292-302. [PMID: 20413140 DOI: 10.1016/j.virol.2010.03.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 02/21/2010] [Accepted: 03/11/2010] [Indexed: 11/23/2022]
Abstract
Mutations disrupting helicase domain motifs of the Tobacco mosaic virus 126/183-kDa proteins were investigated for their effect on replicase function and assembly. These mutations inhibited virus replication but did not affect 126-kDa induced N gene resistance or RNAi suppression. However, in vivo expressed 126-kDa motif mutants yielded two distinct cytoplasmic phenotypes that correlated with ATPase activity. Specifically, ATPase active 126-kDa proteins produced small cytoplasmic bodies that resembled the ovoid granular-like bodies found early in virus infection while 126-kDa proteins defective in ATPase activity produced large tubule containing cytoplasmic bodies similar to those observed late in infection. Additional studies indicate that the helicase ATPase activity resides predominantly within monomer and dimer helicase forms and that motifs affecting ATPase activity induce alterations in helicase assembly. Combined these findings indicate that helicase ATPase activity modulates the progression of replicase complex assembly and maturation.
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Affiliation(s)
- Xiao Wang
- Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Differing requirements for actin and myosin by plant viruses for sustained intercellular movement. Proc Natl Acad Sci U S A 2009; 106:17594-9. [PMID: 19805075 DOI: 10.1073/pnas.0909239106] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The actin cytoskeleton has been implicated in the intra- and intercellular movement of a growing number of plant and animal viruses. However, the range of viruses influenced by actin for movement and the mechanism of this transport are poorly understood. Here we determine the importance of microfilaments and myosins for the sustained intercellular movement of a group of RNA-based plant viruses. We demonstrate that the intercellular movement of viruses from different genera [tobacco mosaic virus (TMV), potato virus X (PVX), tomato bushy stunt virus (TBSV)], is inhibited by disruption of microfilaments. Surprisingly, turnip vein-clearing virus (TVCV), a virus from the same genus as TMV, did not require intact microfilaments for normal spread. To investigate the molecular basis for this difference we compared the subcellular location of GFP fusions to the 126-kDa protein and the homologous 125-kDa protein from TMV and TVCV, respectively. The 126-kDa protein formed numerous large cytoplasmic inclusions associated with microfilaments, whereas the 125-kDa protein formed few small possible inclusions, none associated with microfilaments. The dependence of TMV, PVX, and TBSV on intact microfilaments for intercellular movement led us to investigate the role of myosin motors in this process. Virus-induced gene silencing of the Nicotiana benthamiana myosin XI-2 gene, but not three other myosins, inhibited only TMV movement. These results indicate that RNA viruses have evolved differently in their requirements for microfilaments and the associated myosin motors, in a manner not correlated with predicted phylogeny.
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Interaction of the Tobacco mosaic virus replicase protein with a NAC domain transcription factor is associated with the suppression of systemic host defenses. J Virol 2009; 83:9720-30. [PMID: 19625399 DOI: 10.1128/jvi.00941-09] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An interaction between the helicase domain of the Tobacco mosaic virus (TMV) 126-/183-kDa replicase protein(s) and the Arabidopsis thaliana NAC domain transcription factor ATAF2 was identified via yeast two-hybrid and in planta immunoprecipitation assays. ATAF2 is transcriptionally induced in response to TMV infection, and its overexpression significantly reduces virus accumulation. Proteasome inhibition studies suggest that ATAF2 is targeted for degradation during virus infection. The transcriptional activity of known defense-associated marker genes PR1, PR2, and PDF1.2 significantly increase within transgenic plants overexpressing ATAF2. In contrast, these marker genes have reduced transcript levels in ATAF2 knockout or repressor plant lines. Thus, ATAF2 appears to function in the regulation of host basal defense responses. In response to TMV infections, ATAF2 and PR1 display increased transcript accumulations in inoculated tissues but not in systemically infected tissues. ATAF2 and PR1 transcript levels also increase in response to salicylic acid treatment. However, the salicylic acid treatment of systemically infected tissues did not produce a similar increase in either ATAF2 or PR1 transcripts, suggesting that host defense responses are attenuated during systemic virus invasion. Similarly, noninfected ATAF2 knockout or ATAF2 repressor lines display reduced levels of PR1 transcripts when treated with salicylic acid. Taken together, these findings suggest that the replicase-ATAF2 interaction suppresses basal host defenses as a means to promote systemic virus accumulation.
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Christensen N, Tilsner J, Bell K, Hammann P, Parton R, Lacomme C, Oparka K. The 5' cap of tobacco mosaic virus (TMV) is required for virion attachment to the actin/endoplasmic reticulum network during early infection. Traffic 2009; 10:536-51. [PMID: 19220815 DOI: 10.1111/j.1600-0854.2009.00889.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Almost nothing is known of the earliest stages of plant virus infections. To address this, we microinjected Cy3 (UTP)-labelled tobacco mosaic virus (TMV) into living tobacco trichome cells. The Cy3-virions were infectious, and the viral genome trafficked from cell to cell. However, neither the fluorescent vRNA pool nor the co-injected green fluorescent protein (GFP) left the injected trichome, indicating that the synthesis of (unlabelled) progeny viral (v)RNA is required to initiate cell-to-cell movement, and that virus movement is not accompanied by passive plasmodesmatal gating. Cy3-vRNA formed granules that became anchored to the motile cortical actin/endoplasmic reticulum (ER) network within minutes of injection. Granule movement on actin/ER was arrested by actin inhibitors indicating actin-dependent RNA movement. The 5' methylguanosine cap was shown to be required for vRNA anchoring to the actin/ER. TMV vRNA lacking the 5' cap failed to form granules and was degraded in the cytoplasm. Removal of the 3' untranslated region or replicase both inhibited replication but did not prevent granule formation and movement. Dual-labelled TMV virions in which the vRNA and the coat protein were highlighted with different fluorophores showed that both fluorescent signals were initially located on the same ER-bound granules, indicating that TMV virions may become attached to the ER prior to uncoating of the viral genome.
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Affiliation(s)
- Nynne Christensen
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
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Abstract
Identification of the roles of replication factors represents one of the major frontiers in current virus research. Among plant viruses, the positive-stranded (+) RNA viruses are the largest group and the most widespread. The central step in the infection cycles of (+) RNA viruses is RNA replication, which leads to rapid production of huge number of viral (+) RNA progeny in the infected plant cells. The RNA replication process is carried out by the virus-specific replicase complex consisting of viral RNA-dependent RNA polymerase, one or more auxiliary viral replication proteins, and host factors, which assemble in specialized membranous compartments in infected cells. Replication is followed by cell-to-cell and long-distance movement to invade the entire plant and/or encapsidation to facilitate transmission to new plants. This chapter provides an overview of our current understanding of the role of viral replication proteins during genome replication. The recent significant progress in this research area is based on development of powerful in vivo and in vitro approaches, including replicase assays, reverse genetic approaches, intracelular localization studies and the use of plant or yeast model hosts.
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Tobacco mosaic virus replicase-auxin/indole acetic acid protein interactions: reprogramming the auxin response pathway to enhance virus infection. J Virol 2007; 82:2477-85. [PMID: 18094187 DOI: 10.1128/jvi.01865-07] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The replicase protein of Tobacco mosaic virus (TMV) disrupts the localization and stability of interacting auxin/indole acetic acid (Aux/IAA) proteins in Arabidopsis, altering auxin-mediated gene regulation and promoting disease development (M. S. Padmanabhan, S. P. Goregaoker, S. Golem, H. Shiferaw, and J. N. Culver, J. Virol. 79:2549-2558, 2005). In this study, a similar replicase-Aux/IAA interaction affecting disease development was identified in tomato. The ability of the TMV replicase to interact with Aux/IAA proteins from diverse hosts suggests that these interactions contribute to the infection process. To examine the role of this interaction in virus pathogenicity, the replication and spread of a TMV mutant with a reduced ability to interact with specific Aux/IAA proteins were examined. Within young (4- to 6-week-old) leaf tissue, there were no significant differences in the abilities of Aux/IAA-interacting or -noninteracting viruses to replicate and spread. In contrast, in mature (10- to 12-week-old) leaf tissue, the inability to interact with specific Aux/IAA proteins correlated with a significant reduction in virus accumulation. Correspondingly, interacting Aux/IAA levels are significantly higher in older tissue and the overaccumulation of a degradation-resistant Aux/IAA protein reduced virus accumulation in young leaf tissue. Combined, these findings suggest that TMV replicase-Aux/IAA interactions selectively enhance virus pathogenicity in tissues where Aux/IAA proteins accumulate. We speculate that the virus disrupts Aux/IAA functions as a means to reprogram the cellular environment of older cells to one that is more compatible for virus replication and spread.
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Knapp E, Achor D, Lewandowski DJ. Tobacco mosaic virus defective RNAs expressing C-terminal methyltransferase domain sequences are severely impaired in long-distance movement in Nicotiana benthamiana. Virology 2007; 367:82-91. [PMID: 17602721 DOI: 10.1016/j.virol.2007.05.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 03/12/2007] [Accepted: 05/17/2007] [Indexed: 10/23/2022]
Abstract
Tobamovirus replicase proteins, which function in replication and gene expression, are also implicated in viral cell-to-cell and long-distance movement. The role(s) of Tobacco mosaic virus (TMV) 126-/183-kDa replicase protein in the complex movement process are not understood due to lack of systems that can separate the multiple steps involved. We previously developed a bipartite TMV-defective RNA (dRNA) system to dissect the role of the N-terminal methyltransferase (MT) domain in accumulation and cell-to-cell movement of dRNAs [Knapp, E., Danyluk, G.M., Achor, D., Lewandowski, D.J., 2005. A bipartite Tobacco mosaic virus-defective RNA (dRNA) system to study the role of the N-terminal methyltransferase domain in cell-to-cell movement of dRNAs. Virology 341, 47-58]. In the current study we analyzed long-distance movement of dRNAs in the presence of helper virus in Nicotiana benthamiana. dRNAs expressing approximately 50% of the MT domain (DeltaHinc151) moved long-distances in more than half of the plants. dRNAs expressing approximately 90% of the MT domain sequences (DeltaCla151) predominantly failed to accumulate in upper leaves. The helper virus moved systemically when inoculated alone or with a dRNA. In inoculated leaves, more DeltaHinc151-induced infection foci spread adjacent to class V veins compared to those of DeltaCla151. Consequently, DeltaHinc151 infected more class V veins than DeltaCla151. DeltaCla151 was only detected in bundle sheath cells, whereas DeltaHinc151 could accumulate in bundle sheath and phloem parenchyma cells of class V veins. However, the latter accumulation pattern did not always result in systemic accumulation of DeltaHinc151, suggesting that factors in addition to those affecting cell-to-cell movement played a role in long-distance movement.
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Affiliation(s)
- Elisabeth Knapp
- Department of Plant Pathology, University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
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26
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Rubino L, Navarro B, Russo M. Cymbidium ringspot virus defective interfering RNA replication in yeast cells occurs on endoplasmic reticulum-derived membranes in the absence of peroxisomes. J Gen Virol 2007; 88:1634-1642. [PMID: 17412997 DOI: 10.1099/vir.0.82729-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The replication of Cymbidium ringspot virus (CymRSV) defective interfering (DI) RNA in cells of the yeast Saccharomyces cerevisiae normally takes place in association with the peroxisomal membrane, thus paralleling the replication events in infected plant cells. However, previous results with a peroxisome-deficient mutant strain of yeast had suggested that the presence of peroxisomes is not a strict requirement for CymRSV DI RNA replication. Thus, a novel approach was used to study the putative alternative sites of replication by using S. cerevisiae strain YPH499 which does not contain normal peroxisomes. In this strain, CymRSV p33 and p92 accumulated over portions of the nuclear membrane and on membranous overgrowths which were identified as endoplasmic reticulum (ER) strands, following immunofluorescence and immunoelectron microscope observations. The proteins were not released by high-pH treatment, but were susceptible to proteolytic digestion, thus indicating peripheral and not integrated association. ER-associated p33 and p92 proteins supported in trans the replication of DI RNA. The capacity of plus-strand RNA viruses to replicate in association with different types of cell membranes was thus confirmed.
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Affiliation(s)
- Luisa Rubino
- Istituto di Virologia Vegetale del CNR, Sezione di Bari, c/o Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi, Bari, Italy
| | - Beatriz Navarro
- Istituto di Virologia Vegetale del CNR, Sezione di Bari, c/o Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi, Bari, Italy
| | - Marcello Russo
- Istituto di Virologia Vegetale del CNR, Sezione di Bari, c/o Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi, Bari, Italy
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Jonczyk M, Pathak KB, Sharma M, Nagy PD. Exploiting alternative subcellular location for replication: Tombusvirus replication switches to the endoplasmic reticulum in the absence of peroxisomes. Virology 2007; 362:320-30. [PMID: 17292435 DOI: 10.1016/j.virol.2007.01.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 11/02/2006] [Accepted: 01/03/2007] [Indexed: 11/16/2022]
Abstract
Plus-strand RNA virus replication takes place on distinct membranous surfaces in infected cells via the assembly of viral replicase complexes involving multiple viral and host proteins. One group of tombusviruses, such as Tomato bushy stunt virus (TBSV), replicate on the surfaces of peroxisomal membranes in plant and yeast cells. Surprisingly, previous genome-wide screen performed in yeast demonstrated that a TBSV replicon RNA replicated as efficiently in yeast defective in peroxisome biogenesis as in the wt yeast (Panavas et al., Proc Natl Acad Sci U S A, 2005). To further test how the lack of peroxisomes could affect tombusvirus replication, we used yeast cells missing either PEX3 or PEX19 genes, which are absolutely essential for peroxisome biogenesis. Confocal microscopy-based approach revealed that the wild-type tombusvirus p33 replication protein accumulated in the endoplasmic reticulum (ER) in pex3Delta or pex19Delta yeast, suggesting that tombusvirus replication could take place on the surface of ER membrane. The activities of the isolated tombusvirus replicase preparations from wt, pex3Delta or pex19Delta yeasts were comparable, demonstrating that the assembly of the replicase was as efficient in the ER as in the authentic subcellular environments. The generation/accumulation of tombusvirus recombinants was similar in wt, pex3Delta and pex19Delta yeasts, suggesting that the rate of mistakes occurring during tombusvirus replication is comparable in the presence or absence of peroxisomes. Overall, this work demonstrates that a tombusvirus, relying on the wt replication proteins, can efficiently replicate on an alternative intracellular membrane. This suggests that RNA viruses might have remarkable flexibility for using various host membranes for their replication.
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Affiliation(s)
- Magdalena Jonczyk
- Department of Plant Pathology, University of Kentucky, 201F Plant Science Building, Lexington, KY 40546-0312, USA
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Padmanabhan MS, Shiferaw H, Culver JN. The Tobacco mosaic virus replicase protein disrupts the localization and function of interacting Aux/IAA proteins. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2006; 19:864-73. [PMID: 16903352 DOI: 10.1094/mpmi-19-0864] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Previously, we identified a correlation between the interaction of the Tobacco mosaic virus (TMV) 126/183-kDa replicase with the auxin response regulator indole acetic acid (IAA)26/PAP1 and the development of disease symptoms. In this study, the TMV replicase protein is shown to colocalize with IAA26 in the cytoplasm and prevent its accumulation within the nucleus. Furthermore, two additional auxin (Aux)/IAA family members, IAA27 and IAA18, were found to interact with the TMV replicase and displayed alterations in their cellular localization or accumulation that corresponded with their ability to interact with the TMV replicase. In contrast, the localization and accumulation of noninteracting Aux/IAA proteins were unaffected by the presence of the viral replicase. To investigate the effects of the replicase interaction on Aux/IAA function, transgenic plants expressing a proteolysis-resistant IAA26-P108L-green fluorescent protein (GFP) protein were created. Transgenic plants accumulating IAA26-P108L-GFP displayed an abnormal developmental phenotype that included severe stunting and leaf epinasty. However, TMV infection blocked the nuclear localization of IAA26-P108L-GFP and attenuated the developmental phenotype displayed by the transgenic plants. Combined, these findings suggest that TMV-induced disease symptoms can be attributed, in part, to the ability of the viral replicase protein to disrupt the localization and subsequent function of interacting Aux/IAA proteins.
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Affiliation(s)
- Meenu S Padmanabhan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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29
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Yamaji Y, Kobayashi T, Hamada K, Sakurai K, Yoshii A, Suzuki M, Namba S, Hibi T. In vivo interaction between Tobacco mosaic virus RNA-dependent RNA polymerase and host translation elongation factor 1A. Virology 2006; 347:100-8. [PMID: 16386773 DOI: 10.1016/j.virol.2005.11.031] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 08/21/2005] [Accepted: 11/21/2005] [Indexed: 11/25/2022]
Abstract
Several host translation elongation factors have been suggested to play essential roles in the replication and translation of viral RNAs in plants, animals and bacteria. Here, we show the interaction between eukaryotic translation elongation factor 1A (eEF1A) and Tobacco mosaic virus (TMV) RNA-dependent RNA polymerase (RdRp) in vivo by immunoprecipitation. The tobacco eEF1A interacted not only with 3'-untranslated region (3'-UTR) of TMV RNA but also directly with RdRp without mediation by the 3'-UTR. The methyltransferase domain of TMV RdRp was indicated to be responsible for the interaction with eEF1A in vitro and in yeast. These results suggest that eEF1A is a component of the virus replication complex of TMV.
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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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Villanueva RA, Rouillé Y, Dubuisson J. Interactions between virus proteins and host cell membranes during the viral life cycle. ACTA ACUST UNITED AC 2006; 245:171-244. [PMID: 16125548 PMCID: PMC7112339 DOI: 10.1016/s0074-7696(05)45006-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The structure and function of cells are critically dependent on membranes, which not only separate the interior of the cell from its environment but also define the internal compartments. It is therefore not surprising that the major steps of the life cycle of viruses of animals and plants also depend on cellular membranes. Indeed, interactions of viral proteins with host cell membranes are important for viruses to enter into host cells, replicate their genome, and produce progeny particles. To replicate its genome, a virus first needs to cross the plasma membrane. Some viruses can also modify intracellular membranes of host cells to create a compartment in which genome replication will take place. Finally, some viruses acquire an envelope, which is derived either from the plasma membrane or an internal membrane of the host cell. This paper reviews recent findings on the interactions of viral proteins with host cell membranes during the viral life cycle.
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Affiliation(s)
- Rodrigo A Villanueva
- CNRS-UPR2511, Institut de Biologie de Lille, Institut Pasteur de Lille, 59021 Lille Cedex, France
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Sanfaçon H. Replication of positive-strand RNA viruses in plants: contact points between plant and virus components. ACTA ACUST UNITED AC 2005. [DOI: 10.1139/b05-121] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Positive-strand RNA viruses constitute the largest group of plant viruses and have an important impact on world agriculture. These viruses have small genomes that encode a limited number of proteins and depend on their hosts to complete the various steps of their replication cycle. In this review, the contact points between positive-strand RNA plant viruses and their hosts, which are necessary for the translation and replication of the viral genomes, are discussed. Special emphasis is placed on the description of viral replication complexes that are associated with specific membranous compartments derived from plant intracellular membranes and contain viral RNAs and proteins as well as a variety of host proteins. These complexes are assembled via an intricate network of protein–protein, protein–membrane, and protein–RNA interactions. The role of host factors in regulating the assembly, stability, and activity of viral replication complexes are also discussed.
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Affiliation(s)
- Hélène Sanfaçon
- Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97, Summerland, BC V0H 1Z0, Canada (e-mail: )
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Knapp E, Danyluk GM, Achor D, Lewandowski DJ. A bipartite Tobacco mosaic virus-defective RNA (dRNA) system to study the role of the N-terminal methyl transferase domain in cell-to-cell movement of dRNAs. Virology 2005; 341:47-58. [PMID: 16081123 DOI: 10.1016/j.virol.2005.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 04/14/2005] [Accepted: 06/15/2005] [Indexed: 11/15/2022]
Abstract
Plant viruses, in particular Tobacco mosaic virus (TMV), are model systems to study RNA and protein trafficking in plants. Although TMV cell-to-cell transport controlled by the 30-kDa movement protein (MP) has been intensively studied, it was only recently demonstrated that the 126/183-kDa replicase proteins are also involved in cell-to-cell movement. Elucidating the role(s) of 126/183-kDa proteins in movement is complicated because these proteins have multiple functions associated with replication and gene expression. To overcome these difficulties we developed a TMV helper virus-defective RNA (dRNA) system to study the role of replicase protein sequences in dRNA cell-to-cell movement. Artificially constructed dRNAs lacking sequences encoding the helicase and polymerase domains of the replicase proteins and portions of the MP were viable in protoplasts and plants in the presence of helper virus. Expression of at least approximately 50% of the methyl transferase (MT) domain was required for efficient dRNA movement in Nicotiana benthamiana. dRNAs that encoded the N-terminal 64 replicase amino acids or lacked a translatable MT domain failed to move or moved poorly. TMV dRNAs expressing 258 amino acids of the replicase protein moved into all specialized non-vascular tissues, whereas dRNAs expressing replicase sequences beyond amino acid 258 were restricted to the epidermis and palisade mesophyll tissues. Furthermore, second-site mutations within the dRNA-encoded truncated replicase protein altered efficiency in dRNA cell-to-cell movement.
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Affiliation(s)
- Elisabeth Knapp
- Department of Plant Pathology, University of Florida/IFAS, Citrus Research and Education Center, FL 33850, USA
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Zhang SC, Zhang G, Yang L, Chisholm J, Sanfaçon H. Evidence that insertion of Tomato ringspot nepovirus NTB-VPg protein in endoplasmic reticulum membranes is directed by two domains: a C-terminal transmembrane helix and an N-terminal amphipathic helix. J Virol 2005; 79:11752-65. [PMID: 16140753 PMCID: PMC1212610 DOI: 10.1128/jvi.79.18.11752-11765.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Accepted: 06/28/2005] [Indexed: 12/18/2022] Open
Abstract
The NTB-VPg protein of Tomato ringspot nepovirus is an integral membrane protein found in association with endoplasmic reticulum (ER)-derived membranes active in virus replication. A transmembrane helix present in a hydrophobic region at the C terminus of the NTB domain was previously shown to traverse the membranes, resulting in the translocation of the VPg domain in the lumen. We have now conducted an in planta analysis of membrane-targeting domains within NTB-VPg using in-frame fusions to the green fluorescent protein (GFP). As expected, the entire NTB-VPg protein directed the GFP fluorescence to ER membranes. GFP fusion proteins containing the C-terminal 86 amino acids of NTB-VPg also associated with ER membranes, resulting in ER-specific glycosylation at a naturally occurring glycosylation site in the VPg domain. Deletion of the hydrophobic region prevented the membrane association. The N-terminal 80 amino acids of NTB were also sufficient to direct the GFP fluorescence to intracellular membranes. A putative amphipathic helix in this region was necessary and sufficient to promote membrane association of the fusion proteins. Using in vitro membrane association assays and glycosylation site mapping, we show that the N terminus of NTB can be translocated in the lumen at least in vitro. This translocation was dependent on the presence of the putative amphipathic helix, suggesting that oligomeric forms of this helix traverse the membrane. Taken together, our results suggest that at least two distinct elements play a key role in the insertion of NTB-VPg in the membranes: a C-terminal transmembrane helix and an N-terminal amphipathic helix. An updated model of the topology of the protein in the membrane is presented.
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Affiliation(s)
- Shuo Cheng Zhang
- Pacific Agri-Food Research Centre, 4200 Highway 97, Summerland, BC, Canada V0H 1Z0
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Liu JZ, Blancaflor EB, Nelson RS. The tobacco mosaic virus 126-kilodalton protein, a constituent of the virus replication complex, alone or within the complex aligns with and traffics along microfilaments. PLANT PHYSIOLOGY 2005; 138:1853-65. [PMID: 16040646 PMCID: PMC1183377 DOI: 10.1104/pp.105.065722] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 05/13/2005] [Accepted: 05/16/2005] [Indexed: 05/03/2023]
Abstract
Virus-induced cytoplasmic inclusion bodies (referred to as virus replication complexes [VRCs]) consisting of virus and host components are observed in plant cells infected with tobacco mosaic virus, but the components that modulate their form and function are not fully understood. Here, we show that the tobacco mosaic virus 126-kD protein fused with green fluorescent protein formed cytoplasmic bodies (126-bodies) in the absence of other viral components. Using mutant 126-kD:green fluorescent fusion proteins and viral constructs expressing the corresponding mutant 126-kD proteins, it was determined that the size of the 126-bodies and the corresponding VRCs changed in synchrony for each 126-kD protein mutation tested. Through colabeling experiments, we observed the coalignment and intracellular trafficking of 126-bodies and, regardless of size, VRCs, along microfilaments (MFs). Disruption of MFs with MF-depolymerizing agents or through virus-induced gene silencing compromised the intracellular trafficking of the 126-bodies and VRCs and virus cell-to-cell movement, but did not decrease virus accumulation to levels that would affect virus movement or prevent VRC formation. Our results indicate that (1) the 126-kD protein modulates VRC size and traffics along MFs in cells; (2) VRCs traffic along MFs in cells, possibly through an interaction with the 126-kD protein, and the negative effect of MF antagonists on 126-body and VRC intracellular movement and virus cell-to-cell movement correlates with the disruption of this association; and (3) virus movement was not correlated with VRC size.
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Affiliation(s)
- Jian-Zhong Liu
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA
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Padmanabhan MS, Goregaoker SP, Golem S, Shiferaw H, Culver JN. Interaction of the tobacco mosaic virus replicase protein with the Aux/IAA protein PAP1/IAA26 is associated with disease development. J Virol 2005; 79:2549-58. [PMID: 15681455 PMCID: PMC546588 DOI: 10.1128/jvi.79.4.2549-2558.2005] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Accepted: 10/05/2004] [Indexed: 01/17/2023] Open
Abstract
Virus-infected plants often display developmental abnormalities that include stunting, leaf curling, and the loss of apical dominance. In this study, the helicase domain of the Tobacco mosaic virus (TMV) 126- and/or 183-kDa replicase protein(s) was found to interact with the Arabidopsis Aux/IAA protein PAP1 (also named IAA26), a putative regulator of auxin response genes involved in plant development. To investigate the role of this interaction in the display of symptoms, a TMV mutant defective in the PAP1 interaction was identified. This mutant replicated and moved normally in Arabidopsis but induced attenuated developmental symptoms. Additionally, transgenic plants in which the accumulation of PAP1 mRNA was silenced exhibit symptoms like those of virus-infected plants. In uninfected tissues, ectopically expressed PAP1 accumulated and localized to the nucleus. However, in TMV-infected tissues, PAP1 failed to accumulate to significant levels and did not localize to the nucleus, suggesting that interaction with the TMV replicase protein disrupts PAP1 localization. The consequences of this interaction would affect PAP1's putative function as a transcriptional regulator of auxin response genes. This is supported by gene expression data indicating that approximately 30% of the Arabidopsis genes displaying transcriptional alterations in response to TMV contain multiple auxin response promoter elements. Combined, these data indicate that the TMV replicase protein interferes with the plant's auxin response system to induce specific disease symptoms.
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Affiliation(s)
- Meenu S Padmanabhan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Snegireva PB, Istomina EA, Shiyan AN. A single reverse mutation in the 126/183-kDa replicase gene of the attenuated tomato strain V-69 of tobacco mosaic virus increases the virus pathogenicity. RUSS J GENET+ 2005. [DOI: 10.1007/s11177-005-0059-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Turner KA, Sit TL, Callaway AS, Allen NS, Lommel SA. Red clover necrotic mosaic virus replication proteins accumulate at the endoplasmic reticulum. Virology 2004; 320:276-90. [PMID: 15016550 DOI: 10.1016/j.virol.2003.12.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Revised: 12/09/2003] [Accepted: 12/11/2003] [Indexed: 11/18/2022]
Abstract
Red clover necrotic mosaic virus (RCNMV) encodes N-terminally overlapping proteins of 27 and 88 kDa (p27 and p88) known to be required for replication. Green fluorescent protein (GFP) fusions were used to visualize the location of p27 and p88 within Nicotiana benthamiana cells. GFP:p27 fusions localized to the endoplasmic reticulum (ER), co-localized with ER-targeted yellow fluorescent protein and caused membrane restructuring and proliferation. Cellular fractionation of virus-inoculated N. benthamiana leaves confirmed the association of p27 with ER membranes. GFP:p88 fusions also localized to the ER and co-localized with GFP:p27. Both fusion proteins co-localize to the cortical and cytoplasmic ER and were associated with invaginations of the nuclear envelope. Independent accumulation in, and perturbation of, the ER suggests that p27 and p88 function together in the replication complex. This is the first report of a member of the Tombusviridae replicating in association with the ER.
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Affiliation(s)
- Katherine A Turner
- Department of Genetics, North Carolina State University, Raleigh, NC 27695-7614, USA
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Asurmendi S, Berg RH, Koo JC, Beachy RN. Coat protein regulates formation of replication complexes during tobacco mosaic virus infection. Proc Natl Acad Sci U S A 2004; 101:1415-20. [PMID: 14745003 PMCID: PMC337067 DOI: 10.1073/pnas.0307778101] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The genome of tobacco mosaic virus (TMV) encodes replicase protein(s), movement protein (MP), and capsid protein (CP). On infection, one or more viral proteins direct the assembly of virus replication complexes (VRCs), in association with host-derived membranes. The impact of CP-mediated resistance on the structures of the replication complexes was examined in nontransgenic and transgenic BY-2 cell lines that produce wild-type CP, mutant CP(T42W), and Ds-Red, which was targeted to endoplasmic reticulum by using immunofluorescence and 3D microscopy. We developed a model of VRCs that shows a clear association of MP with and surrounding the endoplasmic reticulum. Replicase is located within the MP bodies, as well as isolated sites throughout the cell. CP surrounds the VRCs. CP enhances the production of MP and increases the size of the VRC; however, the mutant CP(T42W) reduces the amount of MP and interferes with the formation of VRCs. We propose a regulatory role of the CP in the establishment of the VRC. We suggest that the lack of formation of VRCs restricts the efficiency of virus replication and the formation of virus movement complexes, resulting in restriction of cell-cell spread of infection. This results in higher levels of plant CP-mediated protection provided by CP(T42W).
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Affiliation(s)
- S Asurmendi
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
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