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Qing Z, Ahmad S, Chen Y, Liang Q, Zhang L, Chen B, Wen R. P3/P3N-PIPO of PVY interacting with BI-1 inhibits the degradation of NIb by ATG6 to facilitate virus replication in N. benthamiana. FRONTIERS IN PLANT SCIENCE 2023; 14:1183144. [PMID: 37139112 PMCID: PMC10149851 DOI: 10.3389/fpls.2023.1183144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 03/31/2023] [Indexed: 05/05/2023]
Abstract
Introduction Autophagy not only plays an antiviral role but also can be utilized by viruses to facilitate virus infection. However, the underlying mechanism of potato virus Y (PVY) infection against plant autophagy remains unclear. BI-1, localizing to the endoplasmic reticulum (ER), is a multifunctional protein and may affect the virus infection. Methods In this study, Y2H, BiFC, qRT-PCR, RNA-Seq, WB and so on were used for research. Results P3 and P3N-PIPO of PVY can interact with the Bax inhibitor 1 (BI-1) of N. benthamiana. However, BI-1 knockout mutant showed better growth and development ability. In addition, when the BI-1 gene was knocked out or knocked down in N. benthamiana, the PVY-infected mutant showed milder symptoms and lower virus accumulation. Analysis of transcriptome data showed that the deletion of NbBI-1 weakened the gene expression regulation induced by PVY infection and NbBI-1 may reduce the mRNA level of NbATG6 by regulated IRE1-dependent decay (RIDD) in PVY-infected N. benthamiana. The expression level of the ATG6 gene of PVY-infected WT was significantly down-regulated, relative to the PVY-infected mutant. Further results showed that ATG6 of N. benthamiana can degrade NIb, the RNA-dependent RNA polymerase (RdRp) of PVY. NbATG6 has a higher mRNA level in PVY-infected BI-1 knockout mutants than in PVY-infected WT. Conclussion The interaction of P3 and/or P3N-PIPO of PVY with BI-1 decrease the expression of the ATG6 gene might be mediated by RIDD, which inhibits the degradation of viral NIb and enhances viral replication.
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Affiliation(s)
- Zhen Qing
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Shakeel Ahmad
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Yuemeng Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Qingmin Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Lijuan Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Baoshan Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
- College of Agriculture, Guangxi University, Nanning, China
| | - Ronghui Wen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
- *Correspondence: Ronghui Wen,
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Choudhary N, Lodha ML, Baranwal VK. The role of enzymatic activities of antiviral proteins from plants for action against plant pathogens. 3 Biotech 2020; 10:505. [PMID: 33184592 PMCID: PMC7642053 DOI: 10.1007/s13205-020-02495-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/19/2020] [Indexed: 11/25/2022] Open
Abstract
Antiviral proteins (AVPs) from plants possess multiple activities, such as N-glycosidase, RNase, DNase enzymatic activity, and induce pathogenesis-related proteins, salicylic acid, superoxide dismutase, peroxidase, and catalase. The N-glycosidase activity releases the adenine residues from sarcin/ricin (S/R) loop of large subunit of ribosomes and interfere the host protein synthesis process and this activity has been attributed for antiviral activity in plant. It has been shown that AVP binds directly to viral genome-linked protein of plant viruses and interfere with protein synthesis of virus. AVPs also possess the RNase and DNase like activity and may be targeting nucleic acid of viruses directly. Recently, the antifungal, antibacterial, and antiinsect properties of AVPs have also been demonstrated. Gene encoding for AVPs has been used for the development of transgenic resistant crops to a broad range of plant pathogens and insect pests. However, the cytotoxicity has been observed in transgenic crops using AVP gene in some cases which can be a limiting factor for its application in agriculture. In this review, we have reviewed various aspects of AVPs particularly their characteristics, possible mode of action and application.
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Affiliation(s)
- Nandlal Choudhary
- Amity Institute of Virology & Immunology, Amity University Uttar Pradesh, Noida, 201313 India
| | - M. L. Lodha
- Division of Biochemistry, Indian Agricultural Research Institute, Pusa, New Delhi, 110012 India
| | - V. K. Baranwal
- Division of Plant Pathology, Indian Agricultural Research Institute, Pusa, New Delhi, 110012 India
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Rasoulpour R, Izadpanah K, Afsharifar A. Opuntin B, the antiviral protein isolated from prickly pear (Opuntia ficus-indica (L.) Miller) cladode exhibits ribonuclease activity. Microb Pathog 2019; 140:103929. [PMID: 31846744 DOI: 10.1016/j.micpath.2019.103929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/04/2019] [Accepted: 12/13/2019] [Indexed: 10/25/2022]
Abstract
An antiviral protein, designated Opuntin B, was purified from Prickly Pear (Opuntia ficus-indica (L.) Miller) Cladode by heat treatment of the extract, protein precipitation by ammonium sulfate treatment followed by ion-exchange chromatography. Assessment of enzymatic activity of the purified protein showed that it degrades total plant genomic RNA, while causing electrophoretic mobility shifting of Cucumber mosaic virus (CMV) RNAs. However, heat-denatured viral RNA became sensitive to degradation upon treatment with antiviral protein. Opuntin B had no DNase activity on native and heat-denatured apricot genomic DNA, and on PCR-amplified coat protein gene of CMV. Using CMV as prey protein and Opuntin B as bait protein, no interaction was found between the antiviral protein and viral coat protein in far western dot blot analysis.
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Affiliation(s)
- Rasoul Rasoulpour
- Plant Virology Research Center, College of Agriculture, Shiraz University, Shiraz, Iran.
| | - Keramat Izadpanah
- Plant Virology Research Center, College of Agriculture, Shiraz University, Shiraz, Iran.
| | - Alireza Afsharifar
- Plant Virology Research Center, College of Agriculture, Shiraz University, Shiraz, Iran.
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Domashevskiy AV, Williams S, Kluge C, Cheng SY. Plant Translation Initiation Complex eIFiso4F Directs Pokeweed Antiviral Protein to Selectively Depurinate Uncapped Tobacco Etch Virus RNA. Biochemistry 2017; 56:5980-5990. [PMID: 29064680 DOI: 10.1021/acs.biochem.7b00598] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pokeweed antiviral protein (PAP) is a ribosome inactivating protein (RIP) that depurinates the sarcin/ricin loop (SRL) of rRNA, inhibiting protein synthesis. PAP depurinates viral RNA, and in doing so, lowers the infectivity of many plant viruses. The mechanism by which PAP accesses uncapped viral RNA is not known, impeding scientists from developing effective antiviral agents for the prevention of the diseases caused by uncapped RNA viruses. Kinetic rates of PAP interacting with tobacco etch virus (TEV) RNA, in the presence and absence of eIFiso4F, were examined, addressing how the eIF affects selective PAP targeting and depurination of the uncapped viral RNA. PAP-eIFs copurification assay and fluorescence resonance energy transfer demonstrate that PAP forms a ternary complex with the eIFiso4G and eIFiso4E, directing the depurination of uncapped viral RNA. eIFiso4F selectively targets PAP to depurinate TEV RNA by increasing PAP's specificity constant for uncapped viral RNA 12-fold, when compared to the depurination of an oligonucleotide RNA that mimics the SRL of large rRNA, and cellular capped luciferase mRNA. This explains how PAP is able to lower infectivity of pokeweed viruses, while preserving its own ribosomes and cellular RNA from depurination: PAP utilizes cellular eIFiso4F in a novel strategy to target uncapped viral RNA. It may be possible to modulate and utilize these PAP-eIFs interactions for their public health benefit; by repurposing them to selectively target PAP to depurinate uncapped viral RNA, many plant and animal diseases caused by these viruses could be alleviated.
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Affiliation(s)
- Artem V Domashevskiy
- Department of Sciences, John Jay College of Criminal Justice, the City University of New York , New York, New York 10019, United States
| | - Shawn Williams
- Department of Sciences, John Jay College of Criminal Justice, the City University of New York , New York, New York 10019, United States
| | - Christopher Kluge
- Department of Sciences, John Jay College of Criminal Justice, the City University of New York , New York, New York 10019, United States
| | - Shu-Yuan Cheng
- Department of Sciences, John Jay College of Criminal Justice, the City University of New York , New York, New York 10019, United States
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5
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Effect of Depurination on Cellular and Viral RNA. MODIFIED NUCLEIC ACIDS IN BIOLOGY AND MEDICINE 2016. [DOI: 10.1007/978-3-319-34175-0_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Di R, Tumer NE. Pokeweed antiviral protein: its cytotoxicity mechanism and applications in plant disease resistance. Toxins (Basel) 2015; 7:755-72. [PMID: 25756953 PMCID: PMC4379523 DOI: 10.3390/toxins7030755] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 02/11/2015] [Accepted: 03/02/2015] [Indexed: 11/16/2022] Open
Abstract
Pokeweed antiviral protein (PAP) is a 29 kDa type I ribosome inactivating protein (RIP) found in pokeweed plants. Pokeweed produces different forms of PAP. This review focuses on the spring form of PAP isolated from Phytolacca americana leaves. PAP exerts its cytotoxicity by removing a specific adenine from the α-sarcin/ricin loop of the large ribosomal RNA. Besides depurination of the rRNA, PAP has additional activities that contribute to its cytotoxicity. The mechanism of PAP cytotoxicity is summarized based on evidence from the analysis of transgenic plants and the yeast model system. PAP was initially found to be anti-viral when it was co-inoculated with plant viruses onto plants. Transgenic plants expressing PAP and non-toxic PAP mutants have displayed broad-spectrum resistance to both viral and fungal infection. The mechanism of PAP-induced disease resistance in transgenic plants is summarized.
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Affiliation(s)
- Rong Di
- Department of Plant Biology and Pathology, Rutgers, the State University of New Jersey, 59 Dudley Road, New Brunswick, NJ 08901, USA.
| | - Nilgun E Tumer
- Department of Plant Biology and Pathology, Rutgers, the State University of New Jersey, 59 Dudley Road, New Brunswick, NJ 08901, USA.
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7
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Domashevskiy AV, Goss DJ. Pokeweed antiviral protein, a ribosome inactivating protein: activity, inhibition and prospects. Toxins (Basel) 2015; 7:274-98. [PMID: 25635465 PMCID: PMC4344624 DOI: 10.3390/toxins7020274] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/07/2015] [Accepted: 01/23/2015] [Indexed: 01/30/2023] Open
Abstract
Viruses employ an array of elaborate strategies to overcome plant defense mechanisms and must adapt to the requirements of the host translational systems. Pokeweed antiviral protein (PAP) from Phytolacca americana is a ribosome inactivating protein (RIP) and is an RNA N-glycosidase that removes specific purine residues from the sarcin/ricin (S/R) loop of large rRNA, arresting protein synthesis at the translocation step. PAP is thought to play an important role in the plant's defense mechanism against foreign pathogens. This review focuses on the structure, function, and the relationship of PAP to other RIPs, discusses molecular aspects of PAP antiviral activity, the novel inhibition of this plant toxin by a virus counteraction-a peptide linked to the viral genome (VPg), and possible applications of RIP-conjugated immunotoxins in cancer therapeutics.
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MESH Headings
- Animals
- Binding Sites
- Endoribonucleases/chemistry
- Fungal Proteins/chemistry
- Genome, Viral
- Humans
- Protein Isoforms
- RNA Caps/chemistry
- RNA Caps/genetics
- RNA Caps/metabolism
- RNA, Plant/chemistry
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Ribosome Inactivating Proteins, Type 1/chemistry
- Ribosome Inactivating Proteins, Type 1/genetics
- Ribosome Inactivating Proteins, Type 1/metabolism
- Ribosome Inactivating Proteins, Type 1/pharmacology
- Ribosomes/chemistry
- Ribosomes/metabolism
- Ricin/chemistry
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Affiliation(s)
- Artem V Domashevskiy
- John Jay College of Criminal Justice, Department of Sciences, City University of New York, 524 West 59th Street, New York, NY 10019, USA.
| | - Dixie J Goss
- Department of Chemistry, Hunter College, City University of New York and the Graduate Center, 695 Park Avenue, New York, NY 10065, USA.
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Walsh D, Mathews MB, Mohr I. Tinkering with translation: protein synthesis in virus-infected cells. Cold Spring Harb Perspect Biol 2013; 5:a012351. [PMID: 23209131 DOI: 10.1101/cshperspect.a012351] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Viruses are obligate intracellular parasites, and their replication requires host cell functions. Although the size, composition, complexity, and functions encoded by their genomes are remarkably diverse, all viruses rely absolutely on the protein synthesis machinery of their host cells. Lacking their own translational apparatus, they must recruit cellular ribosomes in order to translate viral mRNAs and produce the protein products required for their replication. In addition, there are other constraints on viral protein production. Crucially, host innate defenses and stress responses capable of inactivating the translation machinery must be effectively neutralized. Furthermore, the limited coding capacity of the viral genome needs to be used optimally. These demands have resulted in complex interactions between virus and host that exploit ostensibly virus-specific mechanisms and, at the same time, illuminate the functioning of the cellular protein synthesis apparatus.
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Affiliation(s)
- Derek Walsh
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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9
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Ishag HZ, Li C, Huang L, Sun MX, Ni B, Guo CX, Mao X. Inhibition of Japanese encephalitis virus infection in vitro and in vivo by pokeweed antiviral protein. Virus Res 2013; 171:89-96. [DOI: 10.1016/j.virusres.2012.10.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 10/31/2012] [Accepted: 10/31/2012] [Indexed: 11/29/2022]
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10
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Domashevskiy AV, Miyoshi H, Goss DJ. Inhibition of pokeweed antiviral protein (PAP) by turnip mosaic virus genome-linked protein (VPg). J Biol Chem 2012; 287:29729-38. [PMID: 22773840 DOI: 10.1074/jbc.m112.367581] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pokeweed antiviral protein (PAP) from Phytolacca americana is a ribosome-inactivating protein (RIP) and an RNA N-glycosidase that removes specific purine residues from the sarcin/ricin loop of large rRNA, arresting protein synthesis at the translocation step. PAP is also a cap-binding protein and is a potent antiviral agent against many plant, animal, and human viruses. To elucidate the mechanism of RNA depurination, and to understand how PAP recognizes and targets various RNAs, the interactions between PAP and turnip mosaic virus genome-linked protein (VPg) were investigated. VPg can function as a cap analog in cap-independent translation and potentially target PAP to uncapped IRES-containing RNA. In this work, fluorescence spectroscopy and HPLC techniques were used to quantitatively describe PAP depurination activity and PAP-VPg interactions. PAP binds to VPg with high affinity (29.5 nm); the reaction is enthalpically driven and entropically favored. Further, VPg is a potent inhibitor of PAP depurination of RNA in wheat germ lysate and competes with structured RNA derived from tobacco etch virus for PAP binding. VPg may confer an evolutionary advantage by suppressing one of the plant defense mechanisms and also suggests the possible use of this protein against the cytotoxic activity of ribosome-inactivating proteins.
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Affiliation(s)
- Artem V Domashevskiy
- Department of Chemistry, Hunter College and the Graduate Center of the City University of New York, New York, NY 10065, USA
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11
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Abstract
Although viruses encode many of the functions that are required for viral replication, they are completely reliant on the protein synthesis machinery that is present in their host cells. Recruiting cellular ribosomes to translate viral mRNAs represents a crucial step in the replication of all viruses. To ensure translation of their mRNAs, viruses use a diverse collection of strategies (probably pirated from their cellular hosts) to commandeer key translation factors that are required for the initiation, elongation and termination steps of translation. Viruses also neutralize host defences that seek to incapacitate the translation machinery in infected cells.
Viruses rely on the translation machinery of the host cell to produce the proteins that are essential for their replication. Here, Walsh and Mohr discuss the diverse strategies by which viruses subvert the host protein synthesis machinery and regulate the translation of viral mRNAs. Viruses are fully reliant on the translation machinery of their host cells to produce the polypeptides that are essential for viral replication. Consequently, viruses recruit host ribosomes to translate viral mRNAs, typically using virally encoded functions to seize control of cellular translation factors and the host signalling pathways that regulate their activity. This not only ensures that viral proteins will be produced, but also stifles innate host defences that are aimed at inhibiting the capacity of infected cells for protein synthesis. Remarkably, nearly every step of the translation process can be targeted by virally encoded functions. This Review discusses the diverse strategies that viruses use to subvert host protein synthesis functions and regulate mRNA translation in infected cells.
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Characterization of pokeweed antiviral protein binding to mRNA cap analogs: competition with nucleotides and enhancement by translation initiation factor iso4G. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1789:109-16. [PMID: 18935985 DOI: 10.1016/j.bbagrm.2008.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 09/09/2008] [Accepted: 09/10/2008] [Indexed: 11/23/2022]
Abstract
Pokeweed antiviral protein (PAP) is a type I ribosomal inactivating protein (RIP). PAP binds to and depurinates the sarcin/ricin loop (SRL) of ribosomal RNA resulting in the cessation of protein synthesis. PAP has also been shown to bind to mRNA cap analogs and depurinate mRNA downstream of the cap structure. The biological role of cap binding and its possible role in PAP activity are not known. Here we show the first direct quantitative evidence for PAP binding to the cap analog m(7)GTP. We report a binding affinity of 43.3+/-0.1 nM at 25 degrees C as determined by fluorescence quenching experiments. This is similar to the values reported for wheat cap-binding proteins eIFiso4E and eIFiso4F. van't Hoff analysis of m(7)GTP-PAP equilibrium reveals a binding reaction that is enthalpy driven and entropy favored with TDeltaS degrees contributing 15% to the overall value of DeltaG degrees . This is in contrast to the wheat cap-binding proteins which are enthalpically driven in the DeltaG degrees for binding. Competition experiments indicate that ATP and GTP compete for the cap-binding site on PAP with slightly different affinities. Fluorescence studies of PAP-eIFiso4G binding reveal a protein-protein interaction with a K(d) of 108.4+/-0.3 nM. eIFiso4G was shown to enhance the interaction of PAP with m(7)GTP cap analog by 2.4-fold. These results suggest the involvement of PAP-translation initiation factor complexes in RNA selection and depurination.
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He YW, Guo CX, Pan YF, Peng C, Weng ZH. Inhibition of hepatitis B virus replication by pokeweed antiviral protein in vitro. World J Gastroenterol 2008; 14:1592-7. [PMID: 18330954 PMCID: PMC2693758 DOI: 10.3748/wjg.14.1592] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To explore the inhibitory effects of pokeweed antiviral protein seed (PAP-S) and PAP encoded by a eukaryotic expression plasmid on hepatitis B virus (HBV) replication in vitro.
METHODS: HepG2 2.2.15 cells in cultured medium were treated with different concentrations of PAP-S. HBsAg, HBeAg and HBV DNA in supernatants were determined by ELISA and fluorescent quantitative PCR respectively. MTT method was used to assay for cytotoxicity. HepG2 were cotransfected with various amounts of PAP encoded by a eukaryotic expression plasmid and replication competent wild-type HBV 1.3 fold over-length plasmid. On d 3 after transfection, HBsAg and HBeAg were determined by using ELISA. Levels of HBV core-associated DNA and RNA were detected by using Southern and Northern blot, respectively.
RESULTS: The inhibitory effects of PAP-S on HBsAg, HBeAg and HBV DNA were gradually enhanced with the increase of PAP concentration. When the concentration of PAP-S was 10 &mgr;g/mL, the inhibition rates of HBsAg, HBeAg and HBV DNA were 20.9%, 30.2% and 50%, respectively. After transfection of 1.0 &mgr;g and 2.0 &mgr;g plasmid pXF3H-PAP, the levels of HBV nucleocapside-associated DNA were reduced by 38.0% and 74.0% respectively, the levels of HBsAg in the media by 76.8% and 99.7% respectively, and the levels of HBeAg by 72.7% and 99.3% respectively as compared with controls. Transfection with 2 &mgr;g plasmid pXF3H-PAP reduced the levels of HBV nucleocapside-associated RNA by 69.0%.
CONCLUSION: Both PAP-S and PAP encoded by a eukaryotic expression plasmid could effectively inhibit HBV replication and antigen expression in vitro, and the inhibitory effects were dose-dependent.
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Treder K, Kneller ELP, Allen EM, Wang Z, Browning KS, Miller WA. The 3' cap-independent translation element of Barley yellow dwarf virus binds eIF4F via the eIF4G subunit to initiate translation. RNA (NEW YORK, N.Y.) 2008; 14:134-47. [PMID: 18025255 PMCID: PMC2151041 DOI: 10.1261/rna.777308] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 09/28/2007] [Indexed: 05/08/2023]
Abstract
The 3' cap-independent translation element (BTE) of Barley yellow dwarf virus RNA confers efficient translation initiation at the 5' end via long-distance base pairing with the 5'-untranslated region (UTR). Here we provide evidence that the BTE functions by recruiting translation initiation factor eIF4F. We show that the BTE interacts specifically with the cap-binding initiation factor complexes eIF4F and eIFiso4F in a wheat germ extract (wge). In wge depleted of cap-interacting factors, addition of eIF4F (and to a lesser extent, eIFiso4F) allowed efficient translation of an uncapped reporter construct (BLucB) containing the BTE in its 3' UTR. Translation of BLucB required much lower levels of eIF4F or eIFiso4F than did a capped, nonviral mRNA. Both full-length eIF4G and the carboxy-terminal half of eIF4G lacking the eIF4E binding site stimulated translation to 70% of the level obtained with eIF4F, indicating a minor role for the cap-binding protein, eIF4E. In wge inhibited by either BTE in trans or cap analog, eIF4G alone restored translation nearly as much as eIF4F, while addition of eIF4E alone had no effect. The BTE bound eIF4G (Kd = 177 nm) and eIF4F (Kd = 37 nm) with high affinity, but very weakly to eIF4E. These interactions correlate with the ability of the factors to facilitate BTE-mediated translation. These results and previous observations are consistent with a model in which eIF4F is delivered to the 5' UTR by the BTE, and they show that eIF4G, but not eIF4E, plays a major role in this novel mechanism of cap-independent translation.
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Affiliation(s)
- Krzysztof Treder
- Plant Pathology Department, Iowa State University, Ames, Iowa 50011, USA
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Kyrychenko AM, Telegeyeva TA, Kovalenko OG. Molecular and genetic mechanisms of resistance of plants to viruses. CYTOL GENET+ 2007. [DOI: 10.3103/s0095452707020107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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