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Qi F, Li J, Ai Y, Shangguan K, Li P, Lin F, Liang Y. DGK5β-derived phosphatidic acid regulates ROS production in plant immunity by stabilizing NADPH oxidase. Cell Host Microbe 2024; 32:425-440.e7. [PMID: 38309260 DOI: 10.1016/j.chom.2024.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/20/2023] [Accepted: 01/23/2024] [Indexed: 02/05/2024]
Abstract
In plant immunity, phosphatidic acid (PA) regulates reactive oxygen species (ROS) by binding to respiratory burst oxidase homolog D (RBOHD), an NADPH oxidase responsible for ROS production. Here, we analyze the influence of PA binding on RBOHD activity and the mechanism of RBOHD-bound PA generation. PA binding enhances RBOHD protein stability by inhibiting vacuolar degradation, thereby increasing chitin-induced ROS production. Mutations in diacylglycerol kinase 5 (DGK5), which phosphorylates diacylglycerol to produce PA, impair chitin-induced PA and ROS production. The DGK5 transcript DGK5β (but not DGK5α) complements reduced PA and ROS production in dgk5-1 mutants, as well as resistance to Botrytis cinerea. Phosphorylation of S506 residue in the C-terminal calmodulin-binding domain of DGK5β contributes to the activation of DGK5β to produce PA. These findings suggest that DGK5β-derived PA regulates ROS production by inhibiting RBOHD protein degradation, elucidating the role of PA-ROS interplay in immune response regulation.
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Affiliation(s)
- Fan Qi
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China
| | - Jianwei Li
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China
| | - Yingfei Ai
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China
| | - Keke Shangguan
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China
| | - Ping Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Hangzhou 311200, China
| | - Fucheng Lin
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Hangzhou 311200, China.
| | - Yan Liang
- Zhejiang Xianghu Laboratory, Department of Plant Protection, Zhejiang University, Hangzhou 310058, China.
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2
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Lin J, Zhao J, Du L, Wang P, Sun B, Zhang C, Shi Y, Li H, Sun H. Activation of MAPK-mediated immunity by phosphatidic acid in response to positive-strand RNA viruses. PLANT COMMUNICATIONS 2024; 5:100659. [PMID: 37434356 PMCID: PMC10811337 DOI: 10.1016/j.xplc.2023.100659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/31/2023] [Accepted: 07/07/2023] [Indexed: 07/13/2023]
Abstract
Increasing evidence suggests that mitogen-activated protein kinase (MAPK) cascades play a crucial role in plant defense against viruses. However, the mechanisms that underlie the activation of MAPK cascades in response to viral infection remain unclear. In this study, we discovered that phosphatidic acid (PA) represents a major class of lipids that respond to Potato virus Y (PVY) at an early stage of infection. We identified NbPLDα1 (Nicotiana benthamiana phospholipase Dα1) as the key enzyme responsible for increased PA levels during PVY infection and found that it plays an antiviral role. 6K2 of PVY interacts with NbPLDα1, leading to elevated PA levels. In addition, NbPLDα1 and PA are recruited by 6K2 to membrane-bound viral replication complexes. On the other hand, 6K2 also induces activation of the MAPK pathway, dependent on its interaction with NbPLDα1 and the derived PA. PA binds to WIPK/SIPK/NTF4, prompting their phosphorylation of WRKY8. Notably, spraying with exogenous PA is sufficient to activate the MAPK pathway. Knockdown of the MEK2-WIPK/SIPK-WRKY8 cascade resulted in enhanced accumulation of PVY genomic RNA. 6K2 of Turnip mosaic virus and p33 of Tomato bushy stunt virus also interacted with NbPLDα1 and induced the activation of MAPK-mediated immunity. Loss of function of NbPLDα1 inhibited virus-induced activation of MAPK cascades and promoted viral RNA accumulation. Thus, activation of MAPK-mediated immunity by NbPLDα1-derived PA is a common strategy employed by hosts to counteract positive-strand RNA virus infection.
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Affiliation(s)
- Jiayu Lin
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Jinpeng Zhao
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Linlin Du
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Pengkun Wang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Bingjian Sun
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Chao Zhang
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Yan Shi
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Honglian Li
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China
| | - Hangjun Sun
- The Engineering Research Center for Plant Health Protection Technology in Henan Province, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450046, China.
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3
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Jovanović I, Frantová N, Zouhar J. A sword or a buffet: plant endomembrane system in viral infections. FRONTIERS IN PLANT SCIENCE 2023; 14:1226498. [PMID: 37636115 PMCID: PMC10453817 DOI: 10.3389/fpls.2023.1226498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023]
Abstract
The plant endomembrane system is an elaborate collection of membrane-bound compartments that perform distinct tasks in plant growth and development, and in responses to abiotic and biotic stresses. Most plant viruses are positive-strand RNA viruses that remodel the host endomembrane system to establish intricate replication compartments. Their fundamental role is to create optimal conditions for viral replication, and to protect replication complexes and the cell-to-cell movement machinery from host defenses. In addition to the intracellular antiviral defense, represented mainly by RNA interference and effector-triggered immunity, recent findings indicate that plant antiviral immunity also includes membrane-localized receptor-like kinases that detect viral molecular patterns and trigger immune responses, which are similar to those observed for bacterial and fungal pathogens. Another recently identified part of plant antiviral defenses is executed by selective autophagy that mediates a specific degradation of viral proteins, resulting in an infection arrest. In a perpetual tug-of-war, certain host autophagy components may be exploited by viral proteins to support or protect an effective viral replication. In this review, we present recent advances in the understanding of the molecular interplay between viral components and plant endomembrane-associated pathways.
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Affiliation(s)
- Ivana Jovanović
- Department of Crop Science, Breeding and Plant Medicine, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Nicole Frantová
- Department of Crop Science, Breeding and Plant Medicine, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Jan Zouhar
- Central European Institute of Technology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
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4
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He R, Li Y, Bernards MA, Wang A. Manipulation of the Cellular Membrane-Cytoskeleton Network for RNA Virus Replication and Movement in Plants. Viruses 2023; 15:744. [PMID: 36992453 PMCID: PMC10056259 DOI: 10.3390/v15030744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/15/2023] Open
Abstract
Viruses infect all cellular life forms and cause various diseases and significant economic losses worldwide. The majority of viruses are positive-sense RNA viruses. A common feature of infection by diverse RNA viruses is to induce the formation of altered membrane structures in infected host cells. Indeed, upon entry into host cells, plant-infecting RNA viruses target preferred organelles of the cellular endomembrane system and remodel organellar membranes to form organelle-like structures for virus genome replication, termed as the viral replication organelle (VRO) or the viral replication complex (VRC). Different viruses may recruit different host factors for membrane modifications. These membrane-enclosed virus-induced replication factories provide an optimum, protective microenvironment to concentrate viral and host components for robust viral replication. Although different viruses prefer specific organelles to build VROs, at least some of them have the ability to exploit alternative organellar membranes for replication. Besides being responsible for viral replication, VROs of some viruses can be mobile to reach plasmodesmata (PD) via the endomembrane system, as well as the cytoskeleton machinery. Viral movement protein (MP) and/or MP-associated viral movement complexes also exploit the endomembrane-cytoskeleton network for trafficking to PD where progeny viruses pass through the cell-wall barrier to enter neighboring cells.
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Affiliation(s)
- Rongrong He
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
| | - Mark A. Bernards
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON N6A 5B7, Canada
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5
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Nagy PD. Co-opted membranes, lipids, and host proteins: what have we learned from tombusviruses? Curr Opin Virol 2022; 56:101258. [PMID: 36166851 DOI: 10.1016/j.coviro.2022.101258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/01/2022] [Accepted: 08/21/2022] [Indexed: 11/28/2022]
Abstract
Positive-strand RNA viruses replicate in intracellular membranous structures formed after virus-driven intensive manipulation of subcellular organelles and membranes. These unique structures are called viral-replication organelles (VROs). To build VROs, the replication proteins coded by (+)RNA viruses co-opt host proteins, including membrane-shaping, lipid synthesis, and lipid-modification enzymes to create an optimal microenvironment that (i) concentrates the viral replicase and associated host proteins and the viral RNAs; (ii) regulates enzymatic activities and spatiotemporally the replication process; and (iii) protects the viral RNAs from recognition and degradation by the host innate immune defense. Tomato bushy stunt virus (TBSV), a plant (+)RNA virus, serves as an advanced model to study the interplay among viral components, co-opted host proteins, lipids, and membranes. This review presents our current understanding of the complex interaction between TBSV and host with panviral implications.
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Affiliation(s)
- Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
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6
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Zhou Y, Zhou DM, Yu WW, Shi LL, Zhang Y, Lai YX, Huang LP, Qi H, Chen QF, Yao N, Li JF, Xie LJ, Xiao S. Phosphatidic acid modulates MPK3- and MPK6-mediated hypoxia signaling in Arabidopsis. THE PLANT CELL 2022; 34:889-909. [PMID: 34850198 PMCID: PMC8824597 DOI: 10.1093/plcell/koab289] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/19/2021] [Indexed: 05/07/2023]
Abstract
Phosphatidic acid (PA) is an important lipid essential for several aspects of plant development and biotic and abiotic stress responses. We previously suggested that submergence induces PA accumulation in Arabidopsis thaliana; however, the molecular mechanism underlying PA-mediated regulation of submergence-induced hypoxia signaling remains unknown. Here, we showed that in Arabidopsis, loss of the phospholipase D (PLD) proteins PLDα1 and PLDδ leads to hypersensitivity to hypoxia, but increased tolerance to submergence. This enhanced tolerance is likely due to improvement of PA-mediated membrane integrity. PA bound to the mitogen-activated protein kinase 3 (MPK3) and MPK6 in vitro and contributed to hypoxia-induced phosphorylation of MPK3 and MPK6 in vivo. Moreover, mpk3 and mpk6 mutants were more sensitive to hypoxia and submergence stress compared with wild type, and fully suppressed the submergence-tolerant phenotypes of pldα1 and pldδ mutants. MPK3 and MPK6 interacted with and phosphorylated RELATED TO AP2.12, a master transcription factor in the hypoxia signaling pathway, and modulated its activity. In addition, MPK3 and MPK6 formed a regulatory feedback loop with PLDα1 and/or PLDδ to regulate PLD stability and submergence-induced PA production. Thus, our findings demonstrate that PA modulates plant tolerance to submergence via both membrane integrity and MPK3/6-mediated hypoxia signaling in Arabidopsis.
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Affiliation(s)
- Ying Zhou
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - De-Mian Zhou
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei-Wei Yu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Li-Li Shi
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yi Zhang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yong-Xia Lai
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Li-Ping Huang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Hua Qi
- Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Qin-Fang Chen
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Nan Yao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Jian-Feng Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | | | - Shi Xiao
- Authors for correspondence: (S.X.) and (L.J.X.)
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7
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Takata S, Mise K, Takano Y, Kaido M. Subcellular dynamics of red clover necrotic mosaic virus double-stranded RNAs in infected plant cells. Virology 2022; 568:126-139. [DOI: 10.1016/j.virol.2022.01.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/23/2022] [Accepted: 01/29/2022] [Indexed: 11/29/2022]
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8
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Effects of the noncoding subgenomic RNA of red clover necrotic mosaic virus in virus infection. J Virol 2021; 96:e0181521. [PMID: 34851690 PMCID: PMC8826918 DOI: 10.1128/jvi.01815-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In recent years, a new class of viral noncoding subgenomic RNA (ncsgRNA) has been identified. This RNA is generated as a stable degradation product via an exoribonuclease-resistant RNA (xrRNA) structure, which blocks the progression of 5′→3′ exoribonuclease on viral RNAs in infected cells. Here, we assess the effects of the ncsgRNA of red clover necrotic mosaic virus (RCNMV), called SR1f, in infected plants. We demonstrate the following: (i) the absence of SR1f reduces symptoms and decreases viral RNA accumulation in Nicotiana benthamiana and Arabidopsis thaliana plants; (ii) SR1f has an essential function other than suppression of RNA silencing; and (iii) the cytoplasmic exoribonuclease involved in mRNA turnover, XRN4, is not required for SR1f production or virus infection. A comparative transcriptomic analysis in N. benthamiana infected with wild-type RCNMV or an SR1f-deficient mutant RCNMV revealed that wild-type RCNMV infection, which produces SR1f and much higher levels of virus, has a greater and more significant impact on cellular gene expression than the SR1f-deficient mutant. Upregulated pathways include plant hormone signaling, plant-pathogen interaction, MAPK signaling, and several metabolic pathways, while photosynthesis-related genes were downregulated. We compare this to host genes known to participate in infection by other tombusvirids. Viral reads revealed a 10- to 100-fold ratio of positive to negative strand, and the abundance of reads of both strands mapping to the 3′ region of RCNMV RNA1 support the premature transcription termination mechanism of synthesis for the coding sgRNA. These results provide a framework for future studies of the interactions and functions of noncoding RNAs of plant viruses. IMPORTANCE Knowledge of how RNA viruses manipulate host and viral gene expression is crucial to our understanding of infection and disease. Unlike viral protein-host interactions, little is known about the control of gene expression by viral RNA. Here, we begin to address this question by investigating the noncoding subgenomic RNA (ncsgRNA) of red clover necrotic mosaic virus (RCNMV), called SR1f. Similar exoribonuclease-resistant RNAs of flaviviruses are well studied, but the roles of plant viral ncsgRNAs, and how they arise, are poorly understood. Surprisingly, we find the likely exonuclease candidate, XRN4, is not required to generate SR1f, and we assess the effects of SR1f on virus accumulation and symptom development. Finally, we compare the effects of infection by wild-type RCNMV versus an SR1f-deficient mutant on host gene expression in Nicotiana benthamiana, which reveals that ncsgRNAs such as SR1f are key players in virus-host interactions to facilitate productive infection.
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9
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Phospholipases C and D and Their Role in Biotic and Abiotic Stresses. PLANTS 2021; 10:plants10050921. [PMID: 34064485 PMCID: PMC8148002 DOI: 10.3390/plants10050921] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 02/03/2023]
Abstract
Plants, as sessile organisms, have adapted a fine sensing system to monitor environmental changes, therefore allowing the regulation of their responses. As the interaction between plants and environmental changes begins at the surface, these changes are detected by components in the plasma membrane, where a molecule receptor generates a lipid signaling cascade via enzymes, such as phospholipases (PLs). Phospholipids are the key structural components of plasma membranes and signaling cascades. They exist in a wide range of species and in different proportions, with conversion processes that involve hydrophilic enzymes, such as phospholipase-C (PLC), phospholipase-D (PLD), and phospholipase-A (PLA). Hence, it is suggested that PLC and PLD are highly conserved, compared to their homologous genes, and have formed clusters during their adaptive history. Additionally, they generate responses to different functions in accordance with their protein structure, which should be reflected in specific signal transduction responses to environmental stress conditions, including innate immune responses. This review summarizes the phospholipid systems associated with signaling pathways and the innate immune response.
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10
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Abstract
Viruses manipulate cellular lipids and membranes at each stage of their life cycle. This includes lipid-receptor interactions, the fusion of viral envelopes with cellular membranes during endocytosis, the reorganization of cellular membranes to form replication compartments, and the envelopment and egress of virions. In addition to the physical interactions with cellular membranes, viruses have evolved to manipulate lipid signaling and metabolism to benefit their replication. This review summarizes the strategies that viruses use to manipulate lipids and membranes at each stage in the viral life cycle.
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Affiliation(s)
- Ellen Ketter
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, USA;
| | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, USA;
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11
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He G, Zhang Z, Sathanantham P, Zhang X, Wu Z, Xie L, Wang X. An engineered mutant of a host phospholipid synthesis gene inhibits viral replication without compromising host fitness. J Biol Chem 2019; 294:13973-13982. [PMID: 31362985 DOI: 10.1074/jbc.ra118.007051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 07/16/2019] [Indexed: 12/24/2022] Open
Abstract
Viral infections universally rely on numerous hijacked host factors to be successful. It is therefore possible to control viral infections by manipulating host factors that are critical for viral replication. Given that host genes may play essential roles in certain cellular processes, any successful manipulations for virus control should cause no or mild effects on host fitness. We previously showed that a group of positive-strand RNA viruses enrich phosphatidylcholine (PC) at the sites of viral replication. Specifically, brome mosaic virus (BMV) replication protein 1a interacts with and recruits a PC synthesis enzyme, phosphatidylethanolamine methyltransferase, Cho2p, to the viral replication sites that are assembled on the perinuclear endoplasmic reticulum (ER) membrane. Deletion of the CHO2 gene inhibited BMV replication by 5-fold; however, it slowed down host cell growth as well. Here, we show that an engineered Cho2p mutant supports general PC synthesis and normal cell growth but blocks BMV replication. This mutant interacts and colocalizes with BMV 1a but prevents BMV 1a from localizing to the perinuclear ER membrane. The mislocalized BMV 1a fails to induce the formation of viral replication complexes. Our study demonstrates an effective antiviral strategy in which a host lipid synthesis gene is engineered to control viral replication without comprising host growth.
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Affiliation(s)
- Guijuan He
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.,School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Zhenlu Zhang
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.,School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061.,National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China
| | - Preethi Sathanantham
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Xin Zhang
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061
| | - Zujian Wu
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Lianhui Xie
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xiaofeng Wang
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061
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12
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Zhang Z, He G, Filipowicz NA, Randall G, Belov GA, Kopek BG, Wang X. Host Lipids in Positive-Strand RNA Virus Genome Replication. Front Microbiol 2019; 10:286. [PMID: 30863375 PMCID: PMC6399474 DOI: 10.3389/fmicb.2019.00286] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 02/04/2019] [Indexed: 12/19/2022] Open
Abstract
Membrane association is a hallmark of the genome replication of positive-strand RNA viruses [(+)RNA viruses]. All well-studied (+)RNA viruses remodel host membranes and lipid metabolism through orchestrated virus-host interactions to create a suitable microenvironment to survive and thrive in host cells. Recent research has shown that host lipids, as major components of cellular membranes, play key roles in the replication of multiple (+)RNA viruses. This review focuses on how (+)RNA viruses manipulate host lipid synthesis and metabolism to facilitate their genomic RNA replication, and how interference with the cellular lipid metabolism affects viral replication.
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Affiliation(s)
- Zhenlu Zhang
- National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Guijuan He
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | | | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, IL, United States
| | - George A. Belov
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | | | - Xiaofeng Wang
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
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13
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Meijer HJG, Schoina C, Wang S, Bouwmeester K, Hua C, Govers F. Phytophthora infestans small phospholipase D-like proteins elicit plant cell death and promote virulence. MOLECULAR PLANT PATHOLOGY 2019; 20:180-193. [PMID: 30171659 PMCID: PMC6637911 DOI: 10.1111/mpp.12746] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The successful invasion of host tissue by (hemi-)biotrophic plant pathogens is dependent on modifications of the host plasma membrane to facilitate the two-way transfer of proteins and other compounds. Haustorium formation and the establishment of extrahaustorial membranes are probably dependent on a variety of enzymes that modify membranes in a coordinated fashion. Phospholipases, enzymes that hydrolyse phospholipids, have been implicated as virulence factors in several pathogens. The oomycete Phytophthora infestans is a hemibiotrophic pathogen that causes potato late blight. It possesses different classes of phospholipase D (PLD) proteins, including small PLD-like proteins with and without signal peptide (sPLD-likes and PLD-likes, respectively). Here, we studied the role of sPLD-like-1, sPLD-like-12 and PLD-like-1 in the infection process. They are expressed in expanding lesions on potato leaves and during in vitro growth, with the highest transcript levels in germinating cysts. When expressed in planta in the presence of the silencing suppressor P19, all three elicited a local cell death response that was visible at the microscopic level as autofluorescence and strongly boosted in the presence of calcium. Moreover, inoculation of leaves expressing the small PLD-like genes resulted in increased lesion growth and greater numbers of sporangia, but this was abolished when mutated PLD-like genes were expressed with non-functional PLD catalytic motifs. These results show that the three small PLD-likes are catalytically active and suggest that their enzymatic activity is required for the promotion of virulence, possibly by executing membrane modifications to support the growth of P. infestans in the host.
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Affiliation(s)
- Harold J. G. Meijer
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
- Wageningen Plant ResearchWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
| | - Charikleia Schoina
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
| | - Shutong Wang
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
- College of Plant ProtectionAgricultural University of HebeiBaoding071001China
| | - Klaas Bouwmeester
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
| | - Chenlei Hua
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
- Present address:
Center of Plant Molecular Biology (ZMBP)Eberhard‐Karls‐University TübingenTübingenD‐72076Germany
| | - Francine Govers
- Laboratory of PhytopathologyWageningen University and ResearchPO Box 16Wageningen6700AAthe Netherlands
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Li J, Wang X. Phospholipase D and phosphatidic acid in plant immunity. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 279:45-50. [PMID: 30709492 DOI: 10.1016/j.plantsci.2018.05.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/21/2018] [Accepted: 05/23/2018] [Indexed: 05/20/2023]
Abstract
Phospholipase D (PLD) hydrolyzes membrane phospholipids to generate phosphatidic acid (PA). Both PLD and its lipid product PA are involved in various physiological processes, including plant response to pathogens. The PLD family is comprised of multiple members in higher plants, and PLDs have been reported to play positive and/or negative roles in plant immunity, depending on the types of pathogens and specific PLDs involved. Individual PLDs have distinguishable biochemical properties, such as Ca2+ and phosphatidylinositide requirements. In addition, PLDs and PA are found to interact with various proteins in hormone and stress signaling. The different biochemical and regulatory properties of PLDs and PA shed light on the mechanisms for the functional diversity of PLDs in plant defense signaling and response.
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Affiliation(s)
- Jianwu Li
- Henan Agricultural University, Henan, 450002, China; Department of Biology, University of Missouri, St. Louis, MO 63121, United States; Donald Danforth Plant Science Center, St. Louis, MO 63132, United States.
| | - Xuemin Wang
- Department of Biology, University of Missouri, St. Louis, MO 63121, United States; Donald Danforth Plant Science Center, St. Louis, MO 63132, United States.
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15
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Hyodo K, Suzuki N, Okuno T. Hijacking a host scaffold protein, RACK1, for replication of a plant RNA virus. THE NEW PHYTOLOGIST 2019; 221:935-945. [PMID: 30169907 DOI: 10.1111/nph.15412] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 07/25/2018] [Indexed: 05/23/2023]
Abstract
Receptor for activated C kinase 1 (RACK1) is strictly conserved across eukaryotes and acts as a versatile scaffold protein involved in various signaling pathways. Plant RACK1 is known to exert important functions in innate immunity against fungal and bacterial pathogens. However, the role of the RACK1 in plant-virus interactions remains unknown. Here, we addressed the role of RACK1 of Nicotiana benthamiana during infection by red clover necrotic mosaic virus (RCNMV), a plant positive-stranded RNA virus. NbRACK1 was shown to be recruited by the p27 viral replication protein into endoplasmic reticulum-derived aggregated structures (possible replication sites). Downregulation of NbRACK1 by virus-induced gene silencing inhibited viral cap-independent translation and p27-mediated reactive oxygen species (ROS) accumulation, which are prerequisite for RCNMV replication. We also found that NbRACK1 interacted with a host calcium-dependent protein kinase (NbCDPKiso2) that activated a ROS-generating enzyme. Interestingly, NbRACK1 was required for the interaction of p27 with NbCDPKiso2, suggesting that NbRACK1 acts as a bridge between the p27 viral replication protein and NbCDPKiso2. Collectively, our findings provide an example of a viral strategy in which a host multifaceted scaffold protein RACK1 is highjacked for promoting viral protein-triggered ROS production necessary for robust viral replication.
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Grants
- 15H04456 JSPS KAKENHI
- 17K15229 JSPS KAKENHI
- 16H06429 Ministry of Education, Culture, Science, Sports and Technology (MEXT)
- 16K21723 Ministry of Education, Culture, Science, Sports and Technology (MEXT)
- 16H06436 Ministry of Education, Culture, Science, Sports and Technology (MEXT)
- 17H05818 Ministry of Education, Culture, Science, Sports and Technology (MEXT)
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Affiliation(s)
- Kiwamu Hyodo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Tetsuro Okuno
- Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga, 520-2194, Japan
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16
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Mamode Cassim A, Gouguet P, Gronnier J, Laurent N, Germain V, Grison M, Boutté Y, Gerbeau-Pissot P, Simon-Plas F, Mongrand S. Plant lipids: Key players of plasma membrane organization and function. Prog Lipid Res 2018; 73:1-27. [PMID: 30465788 DOI: 10.1016/j.plipres.2018.11.002] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 11/07/2018] [Accepted: 11/09/2018] [Indexed: 12/29/2022]
Abstract
The plasma membrane (PM) is the biological membrane that separates the interior of all cells from the outside. The PM is constituted of a huge diversity of proteins and lipids. In this review, we will update the diversity of molecular species of lipids found in plant PM. We will further discuss how lipids govern global properties of the plant PM, explaining that plant lipids are unevenly distributed and are able to organize PM in domains. From that observation, it emerges a complex picture showing a spatial and multiscale segregation of PM components. Finally, we will discuss how lipids are key players in the function of PM in plants, with a particular focus on plant-microbe interaction, transport and hormone signaling, abiotic stress responses, plasmodesmata function. The last chapter is dedicated to the methods that the plant membrane biology community needs to develop to get a comprehensive understanding of membrane organization in plants.
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Affiliation(s)
- Adiilah Mamode Cassim
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Paul Gouguet
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Julien Gronnier
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Nelson Laurent
- Agroécologie, AgroSup Dijon, INRA, University of Bourgogne Franche-Comté, F-21000 Dijon, ERL 6003 CNRS, Dijon, France
| | - Véronique Germain
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Magali Grison
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Yohann Boutté
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France
| | - Patricia Gerbeau-Pissot
- Agroécologie, AgroSup Dijon, INRA, University of Bourgogne Franche-Comté, F-21000 Dijon, ERL 6003 CNRS, Dijon, France
| | - Françoise Simon-Plas
- Agroécologie, AgroSup Dijon, INRA, University of Bourgogne Franche-Comté, F-21000 Dijon, ERL 6003 CNRS, Dijon, France.
| | - Sébastien Mongrand
- Laboratoire de Biogenèse Membranaire (LBM), CNRS, University of Bordeaux, UMR 5200, F-33882 Villenave d'Ornon, France.
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17
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Ku YS, Sintaha M, Cheung MY, Lam HM. Plant Hormone Signaling Crosstalks between Biotic and Abiotic Stress Responses. Int J Mol Sci 2018; 19:ijms19103206. [PMID: 30336563 PMCID: PMC6214094 DOI: 10.3390/ijms19103206] [Citation(s) in RCA: 257] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 10/13/2018] [Accepted: 10/14/2018] [Indexed: 01/01/2023] Open
Abstract
In the natural environment, plants are often bombarded by a combination of abiotic (such as drought, salt, heat or cold) and biotic (necrotrophic and biotrophic pathogens) stresses simultaneously. It is critical to understand how the various response pathways to these stresses interact with one another within the plants, and where the points of crosstalk occur which switch the responses from one pathway to another. Calcium sensors are often regarded as the first line of response to external stimuli to trigger downstream signaling. Abscisic acid (ABA) is a major phytohormone regulating stress responses, and it interacts with the jasmonic acid (JA) and salicylic acid (SA) signaling pathways to channel resources into mitigating the effects of abiotic stresses versus defending against pathogens. The signal transduction in these pathways are often carried out via GTP-binding proteins (G-proteins) which comprise of a large group of proteins that are varied in structures and functions. Deciphering the combined actions of these different signaling pathways in plants would greatly enhance the ability of breeders to develop food crops that can thrive in deteriorating environmental conditions under climate change, and that can maintain or even increase crop yield.
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Affiliation(s)
- Yee-Shan Ku
- Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.
| | - Mariz Sintaha
- Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.
| | - Ming-Yan Cheung
- Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.
| | - Hon-Ming Lam
- Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.
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18
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Zhang Z, He G, Han GS, Zhang J, Catanzaro N, Diaz A, Wu Z, Carman GM, Xie L, Wang X. Host Pah1p phosphatidate phosphatase limits viral replication by regulating phospholipid synthesis. PLoS Pathog 2018; 14:e1006988. [PMID: 29649282 PMCID: PMC5916857 DOI: 10.1371/journal.ppat.1006988] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/24/2018] [Accepted: 03/24/2018] [Indexed: 11/20/2022] Open
Abstract
Replication of positive-strand RNA viruses [(+)RNA viruses] takes place in membrane-bound viral replication complexes (VRCs). Formation of VRCs requires virus-mediated manipulation of cellular lipid synthesis. Here, we report significantly enhanced brome mosaic virus (BMV) replication and much improved cell growth in yeast cells lacking PAH1 (pah1Δ), the sole yeast ortholog of human LIPIN genes. PAH1 encodes Pah1p (phosphatidic acid phosphohydrolase), which converts phosphatidate (PA) to diacylglycerol that is subsequently used for the synthesis of the storage lipid triacylglycerol. Inactivation of Pah1p leads to altered lipid composition, including high levels of PA, total phospholipids, ergosterol ester, and free fatty acids, as well as expansion of the nuclear membrane. In pah1Δ cells, BMV replication protein 1a and double-stranded RNA localized to the extended nuclear membrane, there was a significant increase in the number of VRCs formed, and BMV genomic replication increased by 2-fold compared to wild-type cells. In another yeast mutant that lacks both PAH1 and DGK1 (encodes diacylglycerol kinase converting diacylglycerol to PA), which has a normal nuclear membrane but maintains similar lipid compositional changes as in pah1Δ cells, BMV replicated as efficiently as in pah1Δ cells, suggesting that the altered lipid composition was responsible for the enhanced BMV replication. We further showed that increased levels of total phospholipids play an important role because the enhanced BMV replication required active synthesis of phosphatidylcholine, the major membrane phospholipid. Moreover, overexpression of a phosphatidylcholine synthesis gene (CHO2) promoted BMV replication. Conversely, overexpression of PAH1 or plant PAH1 orthologs inhibited BMV replication in yeast or Nicotiana benthamiana plants. Competing with its host for limited resources, BMV inhibited host growth, which was markedly alleviated in pah1Δ cells. Our work suggests that Pah1p promotes storage lipid synthesis and thus represses phospholipid synthesis, which in turn restricts both viral replication and cell growth during viral infection.
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Affiliation(s)
- Zhenlu Zhang
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, United States of America
| | - Guijuan He
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, United States of America
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, United States of America
| | - Jiantao Zhang
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, United States of America
| | - Nicholas Catanzaro
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States of America
| | - Arturo Diaz
- Department of Biology, La Sierra University, Riverside, VA, United States of America
| | - Zujian Wu
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - George M. Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, United States of America
| | - Lianhui Xie
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Xiaofeng Wang
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, United States of America
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19
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Jin X, Cao X, Wang X, Jiang J, Wan J, Laliberté JF, Zhang Y. Three-Dimensional Architecture and Biogenesis of Membrane Structures Associated with Plant Virus Replication. FRONTIERS IN PLANT SCIENCE 2018; 9:57. [PMID: 29441085 PMCID: PMC5797596 DOI: 10.3389/fpls.2018.00057] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/11/2018] [Indexed: 05/20/2023]
Abstract
Positive-sense (+) RNA viruses represent the most abundant group of viruses and are dependent on the host cell machinery to replicate. One remarkable feature that occurs after (+) RNA virus entry into cells is the remodeling of host endomembranes, leading to the formation of viral replication factories. Recently, rapid progress in three-dimensional (3D) imaging technologies, such as electron tomography (ET) and focused ion beam-scanning electron microscopy (FIB-SEM), has enabled researchers to visualize the novel membrane structures induced by viruses at high resolution. These 3D imaging technologies provide new mechanistic insights into the viral infection cycle. In this review, we summarize the latest reports on the cellular remodeling that occurs during plant virus infection; in particular, we focus on studies that provide 3D architectural information on viral replication factories. We also outline the mechanisms underlying the formation of these membranous structures and discuss possible future research directions.
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Affiliation(s)
- Xuejiao Jin
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiuling Cao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jun Jiang
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Juan Wan
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
- *Correspondence: Jean-François Laliberté
| | - 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, China
- Yongliang Zhang
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20
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Hyodo K, Nagai H, Okuno T. Dual function of a cis-acting RNA element that acts as a replication enhancer and a translation repressor in a plant positive-stranded RNA virus. Virology 2017; 512:74-82. [PMID: 28941403 DOI: 10.1016/j.virol.2017.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 09/05/2017] [Accepted: 09/10/2017] [Indexed: 02/07/2023]
Abstract
The genome of red clover necrotic mosaic virus is divided into two positive-stranded RNA molecules of RNA1 and RNA2, which have no 5' cap structure and no 3' poly(A) tail. Previously, we showed that any mutations in the cis-acting RNA replication elements of RNA2 abolished its cap-independent translational activity, suggesting a strong link between RNA replication and translation. Here, we investigated the functions of the 5' untranslated region (UTR) of RNA2 and revealed that the basal stem-structure (5'BS) predicted in the 5' UTR is essential for robust RNA replication. Interestingly, RNA2 mutants with substitution or deletion in the right side of the 5'BS showed strong translational activity, despite their impaired replication competency. Furthermore, nucleotide sequences other than the 5'BS of the 5' UTR were essential to facilitate the replication-associated translation. Overall, these cis-acting RNA elements seem to coordinately regulate the balance between RNA replication and replication-associated translation.
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Affiliation(s)
- Kiwamu Hyodo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
| | - Hikari Nagai
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Tetsuro Okuno
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga 520-2194, Japan.
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21
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Tajima Y, Iwakawa HO, Hyodo K, Kaido M, Mise K, Okuno T. Requirement for eukaryotic translation initiation factors in cap-independent translation differs between bipartite genomic RNAs of red clover necrotic mosaic virus. Virology 2017. [DOI: 10.1016/j.virol.2017.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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22
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Hyodo K, Suzuki N, Mise K, Okuno T. Roles of superoxide anion and hydrogen peroxide during replication of two unrelated plant RNA viruses in Nicotiana benthamiana. PLANT SIGNALING & BEHAVIOR 2017; 12:e1338223. [PMID: 28594275 PMCID: PMC5566351 DOI: 10.1080/15592324.2017.1338223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 05/09/2023]
Abstract
Reactive oxygen species (ROS), including superoxide anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical, act as signaling molecules to transduce biotic and abiotic stimuli into stress adaptations in plants. A respiratory burst oxidase homolog B of Nicotiana benthamiana (NbRBOHB) is responsible for O2- production to inhibit pathogen infection during plant innate immunity. RBOH-derived O2- can be immediately converted into H2O2 by the action of superoxide dismutase. Interestingly, we recently showed that red clover necrotic mosaic virus (RCNMV), a plant positive-strand RNA [(+)RNA] virus, hijacks the host's ROS-generating machinery during infection. An RCNMV replication protein associates with NbRBOHB and triggers intracellular ROS bursts. These bursts are required for robust viral RNA replication. However, what types of ROS are required for viral replication is currently unknown. Here, we found that RCNMV replication was sensitive to an O2- scavenger but insensitive to an H2O2 scavenger. Interestingly, replication of another plant (+)RNA virus, brome mosaic virus, was sensitive to both types of scavengers. These results indicate a virus-specific pattern requirement of O2- and H2O2 for (+)RNA virus replication and suggest a conserved nature of the roles of ROS in (+)RNA virus replication.
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Affiliation(s)
- Kiwamu Hyodo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan
| | - Kazuyuki Mise
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Tetsuro Okuno
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
- Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga, Japan
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23
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Abstract
Phospholipase D (PLD) enzymes are one source of receptor-generated phosphatidic acid (PtdOH),which may subsequently be metabolized to diacylglycerol (DAG) and lysophosphatidic acid. There are other pathways that lead to PtdOH generation, but differences in pathways and in the acyl composition of the products seem to provide some specificity. Both direct and indirect inhibitors of PLD activity have been identified despite a long-held suspicion that this pathway was undruggable. The identification of raloxifene and halopemide as direct inhibitors was followed by the systematic development of isoenzyme-preferring compounds that have been used to further differentiate the functions of PLD1 and PLD2. PLD2 in host cells has been associated with viral entry processes and innate immune response pathways such that inhibition blocks efficient infection. This PLD2 pathway has been linked to autophagy via AKT kinases. As a potential target in antiretroviral therapy, PLD1 works through the CAD enzyme (which contains carbamoyl aspartate synthase, aspartate transcarbamylase and dihydro-orotase domains) to modulate pyrimidine biosynthesis. PLD activity and expression have been shown to be upregulated in several types of human cancers, in which PLD enzymes function downstream of a variety of known oncogenes. Inhibition of PtdOH production has a marked effect on tumorigenesis and malignant invasion. PLD1, PLD2 and PLD3 have each been suggested to have a role in Alzheimer disease and other neurodegenerative conditions, but a mechanism has not yet emerged to explain the roles of these proteins in central nervous system pathophysiology.
Lipid second messengers such as phosphatidic acid (PtdOH) have a role in a wide range of pathological processes, and phospholipase D (PLD) enzymes are one of the major sources of signal-activated PtdOH generation. In this Review, Brown, Thomas and Lindsley discuss the development of PLD inhibitors, with a focus on isoform-specific inhibitors, and their potential applications in the treatment of cancer, neurodegeneration and infection. Lipid second messengers have essential roles in cellular function and contribute to the molecular mechanisms that underlie inflammation, malignant transformation, invasiveness, neurodegenerative disorders, and infectious and other pathophysiological processes. The phospholipase D (PLD) isoenzymes PLD1 and PLD2 are one of the major sources of signal-activated phosphatidic acid (PtdOH) generation downstream of a variety of cell-surface receptors, including G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and integrins. Recent advances in the development of isoenzyme-selective PLD inhibitors and in molecular genetics have suggested that PLD isoenzymes in mammalian cells and pathogenic organisms may be valuable targets for the treatment of several human diseases. Isoenzyme-selective inhibitors have revealed complex inter-relationships between PtdOH biosynthetic pathways and the role of PtdOH in pathophysiology. PLD enzymes were once thought to be undruggable owing to the ubiquitous nature of PtdOH in cell signalling and concerns that inhibitors would be too toxic for use in humans. However, recent promising discoveries suggest that small-molecule isoenzyme-selective inhibitors may provide novel compounds for a unique approach to the treatment of cancers, neurodegenerative disorders and other afflictions of the central nervous system, and potentially serve as broad-spectrum antiviral and antimicrobial therapeutics.
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Hyodo K, Hashimoto K, Kuchitsu K, Suzuki N, Okuno T. Harnessing host ROS-generating machinery for the robust genome replication of a plant RNA virus. Proc Natl Acad Sci U S A 2017; 114:E1282-E1290. [PMID: 28154139 PMCID: PMC5320965 DOI: 10.1073/pnas.1610212114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
As sessile organisms, plants have to accommodate to rapid changes in their surrounding environment. Reactive oxygen species (ROS) act as signaling molecules to transduce biotic and abiotic stimuli into plant stress adaptations. It is established that a respiratory burst oxidase homolog B of Nicotiana benthamiana (NbRBOHB) produces ROS in response to microbe-associated molecular patterns to inhibit pathogen infection. Plant viruses are also known as causative agents of ROS induction in infected plants; however, the function of ROS in plant-virus interactions remains obscure. Here, we show that the replication of red clover necrotic mosaic virus (RCNMV), a plant positive-strand RNA [(+)RNA] virus, requires NbRBOHB-mediated ROS production. The RCNMV replication protein p27 plays a pivotal role in this process, redirecting the subcellular localization of NbRBOHB and a subgroup II calcium-dependent protein kinase of N. benthamiana (NbCDPKiso2) from the plasma membrane to the p27-containing intracellular aggregate structures. p27 also induces an intracellular ROS burst in an RBOH-dependent manner. NbCDPKiso2 was shown to be an activator of the p27-triggered ROS accumulations and to be required for RCNMV replication. Importantly, this RBOH-derived ROS is essential for robust viral RNA replication. The need for RBOH-derived ROS was demonstrated for the replication of another (+)RNA virus, brome mosaic virus, suggesting that this characteristic is true for plant (+)RNA viruses. Collectively, our findings revealed a hitherto unknown viral strategy whereby the host ROS-generating machinery is diverted for robust viral RNA replication.
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Affiliation(s)
- Kiwamu Hyodo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan;
| | - Kenji Hashimoto
- Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan
| | - Kazuyuki Kuchitsu
- Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan
- Imaging Frontier Center, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - Tetsuro Okuno
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;
- Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Seta, Otsu 520-2194, Japan
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Escobar-Sepúlveda HF, Trejo-Téllez LI, Pérez-Rodríguez P, Hidalgo-Contreras JV, Gómez-Merino FC. Diacylglycerol Kinases Are Widespread in Higher Plants and Display Inducible Gene Expression in Response to Beneficial Elements, Metal, and Metalloid Ions. FRONTIERS IN PLANT SCIENCE 2017; 8:129. [PMID: 28223993 PMCID: PMC5293798 DOI: 10.3389/fpls.2017.00129] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 01/21/2017] [Indexed: 05/20/2023]
Abstract
Diacylglycerol kinases (DGKs) are pivotal signaling enzymes that phosphorylate diacylglycerol (DAG) to yield phosphatidic acid (PA). The biosynthesis of PA from phospholipase D (PLD) and the coupled phospholipase C (PLC)/DGK route is a crucial signaling process in eukaryotic cells. Next to PLD, the PLC/DGK pathway is the second most important generator of PA in response to biotic and abiotic stresses. In eukaryotic cells, DGK, DAG, and PA are implicated in vital processes such as growth, development, and responses to environmental cues. A plethora of DGK isoforms have been identified so far, making this a rather large family of enzymes in plants. Herein we performed a comprehensive phylogenetic analysis of DGK isoforms in model and crop plants in order to gain insight into the evolution of higher plant DGKs. Furthermore, we explored the expression profiling data available in public data bases concerning the regulation of plant DGK genes in response to beneficial elements and other metal and metalloid ions, including silver (Ag), aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and sodium (Na). In all plant genomes explored, we were able to find DGK representatives, though in different numbers. The phylogenetic analysis revealed that these enzymes fall into three major clusters, whose distribution depends on the composition of structural domains. The catalytic domain conserves the consensus sequence GXGXXG/A where ATP binds. The expression profiling data demonstrated that DGK genes are rapidly but transiently regulated in response to certain concentrations and time exposures of beneficial elements and other ions in different plant tissues analyzed, suggesting that DGKs may mediate signals triggered by these elements. Though this evidence is conclusive, further signaling cascades that such elements may stimulate during hormesis, involving the phosphoinositide signaling pathway and DGK genes and enzymes, remain to be elucidated.
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Affiliation(s)
| | | | | | | | - Fernando C. Gómez-Merino
- Colegio de Postgraduados Campus Córdoba, Amatlán de los ReyesVeracruz, Mexico
- *Correspondence: Fernando C. Gómez-Merino,
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Nagy PD. Tombusvirus-Host Interactions: Co-Opted Evolutionarily Conserved Host Factors Take Center Court. Annu Rev Virol 2016; 3:491-515. [PMID: 27578441 DOI: 10.1146/annurev-virology-110615-042312] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plant positive-strand (+)RNA viruses are intracellular infectious agents that reorganize subcellular membranes and rewire the cellular metabolism of host cells to achieve viral replication in elaborate replication compartments. This review describes the viral replication process based on tombusviruses, highlighting common strategies with other plant and animal viruses. Overall, the works on Tomato bushy stunt virus (TBSV) have revealed intriguing and complex functions of co-opted cellular translation factors, heat shock proteins, DEAD-box helicases, lipid transfer proteins, and membrane-deforming proteins in virus replication. The emerging picture is that many of the co-opted host factors are from highly expressed and conserved protein families. By hijacking host proteins, phospholipids, sterols, and the actin network, TBSV exerts supremacy over the host cell to support viral replication in large replication compartments. Altogether, these advances in our understanding of tombusvirus-host interactions are broadly applicable to many other viruses, which also usurp conserved host factors for various viral processes.
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Affiliation(s)
- Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky 40546;
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Abstract
Tobacco mosaic virus and other tobamoviruses have served as models for studying the mechanisms of viral RNA replication. In tobamoviruses, genomic RNA replication occurs via several steps: (a) synthesis of viral replication proteins by translation of the genomic RNA; (b) translation-coupled binding of the replication proteins to a 5'-terminal region of the genomic RNA; (c) recruitment of the genomic RNA by replication proteins onto membranes and formation of a complex with host proteins TOM1 and ARL8; (d) synthesis of complementary (negative-strand) RNA in the complex; and (e) synthesis of progeny genomic RNA. This article reviews current knowledge on tobamovirus RNA replication, particularly regarding how the genomic RNA is specifically selected as a replication template and how the replication proteins are activated. We also focus on the roles of the replication proteins in evading or suppressing host defense systems.
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Affiliation(s)
- Kazuhiro Ishibashi
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
| | - Masayuki Ishikawa
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
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28
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Dynamic lipid landscape of picornavirus replication organelles. Curr Opin Virol 2016; 19:1-6. [PMID: 27240115 DOI: 10.1016/j.coviro.2016.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/06/2016] [Accepted: 05/13/2016] [Indexed: 01/03/2023]
Abstract
Picornavirus infection induces rapid reorganization of the cellular membrane architecture and appearance of novel membranous structures associated with the viral RNA replication and virion assembly-replication organelles. Recent studies significantly advanced our understanding of their lipid composition and cellular mechanisms involved in their development. Picornaviruses activate synthesis of both structural and signaling lipids and reroute cellular cholesterol trafficking pathways to create unique membranous domains favoring viral replication. Rapidly replicating picornaviruses rely on posttranslational activation and/or specific recruitment of cellular proteins rather than on modulation of expression of cellular genes to create favorable membrane microenvironment. At the same time picornaviruses demonstrate remarkable adaptability to changes in the lipid landscape which should be taken into account when developing novel antiviral strategies.
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Wang XY, Yu HZ, Geng L, Xu JP, Yu D, Zhang SZ, Ma Y, Fei DQ. Comparative Transcriptome Analysis of Bombyx mori (Lepidoptera) Larval Midgut Response to BmNPV in Susceptible and Near-Isogenic Resistant Strains. PLoS One 2016; 11:e0155341. [PMID: 27168061 PMCID: PMC4864234 DOI: 10.1371/journal.pone.0155341] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/27/2016] [Indexed: 01/04/2023] Open
Abstract
Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the primary pathogens causing severe economic losses in sericulture. However, the molecular mechanism of silkworm resistance to BmNPV remains largely unknown. Here, the recurrent parent P50 (susceptible strain) and the near-isogenic line BC9 (resistance strain) were used in a comparative transcriptome study examining the response to infection with BmNPV. A total of 14,300 unigenes were obtained from two different resistant strains; of these, 869 differentially expressed genes (DEGs) were identified after comparing the four transcriptomes. Many DEGs associated with protein metabolism, cytoskeleton, and apoptosis may be involved in the host response to BmNPV infection. Moreover, some immunity related genes were also altered following BmNPV infection. Specifically, after removing genetic background and individual immune stress response genes, 22 genes were found to be potentially involved in repressing BmNPV infection. These genes were related to transport, virus replication, intracellular innate immune, and apoptosis. Our study provided an overview of the molecular mechanism of silkworm resistance to BmNPV infection and laid a foundation for controlling BmNPV in the future.
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Affiliation(s)
- Xue-Yang Wang
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Hai-Zhong Yu
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Lei Geng
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Jia-Ping Xu
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
- * E-mail:
| | - Dong Yu
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Shang-Zhi Zhang
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Yan Ma
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
| | - Dong-Qiong Fei
- School of Life Sciences, Anhui Agricultural University, Hefei, People’s Republic of China
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30
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Hong Y, Zhao J, Guo L, Kim SC, Deng X, Wang G, Zhang G, Li M, Wang X. Plant phospholipases D and C and their diverse functions in stress responses. Prog Lipid Res 2016; 62:55-74. [DOI: 10.1016/j.plipres.2016.01.002] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 12/23/2015] [Accepted: 01/01/2016] [Indexed: 12/25/2022]
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31
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Hyodo K, Okuno T. Pathogenesis mediated by proviral host factors involved in translation and replication of plant positive-strand RNA viruses. Curr Opin Virol 2016; 17:11-18. [DOI: 10.1016/j.coviro.2015.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/05/2015] [Accepted: 11/11/2015] [Indexed: 01/04/2023]
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32
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Nagy PD, Pogany J, Xu K. Cell-Free and Cell-Based Approaches to Explore the Roles of Host Membranes and Lipids in the Formation of Viral Replication Compartment Induced by Tombusviruses. Viruses 2016; 8:68. [PMID: 26950140 PMCID: PMC4810258 DOI: 10.3390/v8030068] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/18/2016] [Accepted: 02/22/2016] [Indexed: 01/14/2023] Open
Abstract
Plant positive strand RNA viruses are intracellular infectious agents that take advantage of cellular lipids and membranes to support replication and protect viral RNA from degradation by host antiviral responses. In this review, we discuss how Tomato bushy stunt virus (TBSV) co-opts lipid transfer proteins and modulates lipid metabolism and transport to facilitate the assembly of the membrane-bound viral replicase complexes within intricate replication compartments. Identification and characterization of the proviral roles of specific lipids and proteins involved in lipid metabolism based on results from yeast (Saccharomyces cerevisiae) model host and cell-free approaches are discussed. The review also highlights the advantage of using liposomes with chemically defined composition to identify specific lipids required for TBSV replication. Remarkably, all the known steps in TBSV replication are dependent on cellular lipids and co-opted membranes.
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Affiliation(s)
- Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
| | - Judit Pogany
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
| | - Kai Xu
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
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33
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Positive-strand RNA viruses stimulate host phosphatidylcholine synthesis at viral replication sites. Proc Natl Acad Sci U S A 2016; 113:E1064-73. [PMID: 26858414 DOI: 10.1073/pnas.1519730113] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
All positive-strand RNA viruses reorganize host intracellular membranes to assemble their viral replication complexes (VRCs); however, how these viruses modulate host lipid metabolism to accommodate such membrane proliferation and rearrangements is not well defined. We show that a significantly increased phosphatidylcholine (PC) content is associated with brome mosaic virus (BMV) replication in both natural host barley and alternate host yeast based on a lipidomic analysis. Enhanced PC levels are primarily associated with the perinuclear ER membrane, where BMV replication takes place. More specifically, BMV replication protein 1a interacts with and recruits Cho2p (choline requiring 2), a host enzyme involved in PC synthesis, to the site of viral replication. These results suggest that PC synthesized at the site of VRC assembly, not the transport of existing PC, is responsible for the enhanced accumulation. Blocking PC synthesis by deleting the CHO2 gene resulted in VRCs with wider diameters than those in wild-type cells; however, BMV replication was significantly inhibited, highlighting the critical role of PC in VRC formation and viral replication. We further show that enhanced PC levels also accumulate at the replication sites of hepatitis C virus and poliovirus, revealing a conserved feature among a group of positive-strand RNA viruses. Our work also highlights a potential broad-spectrum antiviral strategy that would disrupt PC synthesis at the sites of viral replication but would not alter cellular processes.
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