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Zong T, Yin J, Jin T, Wang L, Luo M, Li K, Zhi H. A DnaJ protein that interacts with soybean mosaic virus coat protein serves as a key susceptibility factor for viral infection. Virus Res 2020; 281:197870. [PMID: 31962064 DOI: 10.1016/j.virusres.2020.197870] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/15/2020] [Accepted: 01/18/2020] [Indexed: 12/11/2022]
Abstract
Soybean mosaic virus (SMV)-disease is one of the most serious and widespread diseases in soybean (Glycine max). In the present study, a DnaJ protein in soybean designated GmCPIP (SMV coat protein-interacting protein) was screened by the QIS-Seq (quantitative interactor screening with next-generation sequencing) method, and the interaction between SMV CP and GmCPIP was confirmed by the yeast two-hybrid (Y2H) system and bimolecular fluorescence complementation (BiFC) assay. Subcellular localization analysis indicated that both proteins are localized in the cytoplasm, cytomembrane and nucleus. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that infection with SMV-SC4 temporarily increased the transcription of GmCPIP. Virus-induced gene silencing (VIGS) down-regulated the GmCPIP gene by 82%, and the accumulation of SMV was decreased by 88.6% in GmCPIP-silenced plants inoculated with SMV-SC4. The interaction of GmCPIP with SMV CP seems to contribute to SMV infection in soybean.
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Affiliation(s)
- Tingxuan Zong
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China
| | - Jinlong Yin
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China
| | - Tongtong Jin
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China
| | - Liqun Wang
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China
| | - Minxuan Luo
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China
| | - Kai Li
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China.
| | - Haijian Zhi
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, China.
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2
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Metabolic Reprogramming of Host Cells in Response to Enteroviral Infection. Cells 2020; 9:cells9020473. [PMID: 32085644 PMCID: PMC7072837 DOI: 10.3390/cells9020473] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/13/2020] [Accepted: 02/17/2020] [Indexed: 12/15/2022] Open
Abstract
Enterovirus 71 (EV71) infection is an endemic disease in Southeast Asia and China. We have previously shown that EV71 virus causes functional changes in mitochondria. It is speculative whether EV71 virus alters the host cell metabolism to its own benefit. Using a metabolomics approach, we demonstrate that EV71-infected Vero cells had significant changes in metabolism. Glutathione and its related metabolites, and several amino acids, such as glutamate and aspartate, changed significantly with the infectious dose of virus. Other pathways, including glycolysis and tricarboxylic acid cycle, were also altered. A change in glutamine/glutamate metabolism is critical to the viral infection. The presence of glutamine in culture medium was associated with an increase in viral replication. Dimethyl α-ketoglutarate treatment partially mimicked the effect of glutamine supplementation. In addition, the immunoblot analysis revealed that the expression of glutamate dehydrogenase (GDH) and trifunctional carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase (CAD) increased during infection. Knockdown of expression of glutaminase (GLS), GDH and CAD drastically reduced the cytopathic effect (CPE) and viral replication. Furthermore, we found that CAD bound VP1 to promote the de novo pyrimidine synthesis. Our findings suggest that virus may induce metabolic reprogramming of host cells to promote its replication through interactions between viral and host cell proteins.
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de Wispelaere M, Sivanandam V, Rao ALN. Regulation of Positive-Strand Accumulation by Capsid Protein During Brome mosaic virus Infection In Planta. PHYTOPATHOLOGY 2020; 110:228-236. [PMID: 31411546 DOI: 10.1094/phyto-07-19-0236-fi] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A hallmark feature of (+)-strand RNA viruses of eukaryotic cells is that progeny (+)-strands are accumulated 100-fold over (-)-strands. Previous experimental evidence suggests that, in Brome mosaic virus (BMV), a plant-infecting member of the alphavirus-like superfamily, the addition of RNA3 and, specifically, translation of the wild-type (WT) coat protein (CP) gene contributes to increased accumulation of (+)-strands. It is unclear whether this stimulation of (+)-strand accumulation by CP is due to direct regulation of viral RNA replication or RNA stabilization via encapsidation. Analysis of BMV progeny RNA in Nicotiana benthamiana plants revealed that expression of RNA3 variants that did not express WT CP led to a severe defect in BMV (+)-strand accumulation. The (+)-strand accumulation could be rescued when CP was complemented in trans. To verify whether stimulation of (+)-strand accumulation is coupled with encapsidation, two independent mutations were engineered into CP open reading frames. An N-terminal deletion that prevented CP binding to the viral RNAs resulted in a severe reduction of BMV (+)-strand accumulation but stimulated (-)-strand accumulation over the WT. On the other hand, a C-terminal mutation affecting CP dimerization caused a significant decrease in (+)-strand accumulation but had no detectable effect on (-)-strand accumulation. Nucleotide sequences in the movement protein-coding region were also found to contribute to (+)-strand accumulation, in part by providing packaging signals for efficient RNA3 encapsidation. Overall, these results show that RNA encapsidation is a significant determinant of BMV RNA intracellular accumulation.
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Affiliation(s)
- Mélissanne de Wispelaere
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521-0122
| | - Venkatesh Sivanandam
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521-0122
| | - A L N Rao
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521-0122
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4
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Kumar S, Karmakar R, Garg DK, Gupta I, Patel AK. Elucidating the functional aspects of different domains of bean common mosaic virus coat protein. Virus Res 2019; 273:197755. [PMID: 31525400 DOI: 10.1016/j.virusres.2019.197755] [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: 06/10/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 10/26/2022]
Abstract
The coat protein (CP) is the only structural protein present in the polyprotein of bean common mosaic virus. The well known characteristics of the CP are self-oligomerization and nucleic acid binding activity. The studies of the coat protein mutants revealed that the oligomeric property of CP solely depends on the amino-terminal residues and the nucleic acid binding domain present at the 194-202 residue position. The 3'UTR RNA of the virus showed high binding affinity with the RNA binding domain as compared to the 5'UTR RNA. Further, the intrinsic fluorescence study of the CP also suggested that the N- and C-terminal of CP contains a highly disordered region. The present study also illustrates that the coat protein contains a conserved RNA binding pocket among the potyviruses, but displays divergent oligomerization propensities due to the difference in residue at the N- and C-terminal.
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Affiliation(s)
- Sunil Kumar
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Ruma Karmakar
- Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Dushyant Kumar Garg
- School of Biotechnology, Jawaharlal Nehru University, New Mehrauli Road, New Delhi, 110067, India
| | - Ishu Gupta
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Ashok Kumar Patel
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India.
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5
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Bakshi A, Savithri HS. Functional insights into the role of C-terminal disordered domain of Sesbania mosaic virus RNA-dependent RNA polymerase and the coat protein in viral replication in vivo. Virus Res 2019; 267:26-35. [PMID: 31054934 DOI: 10.1016/j.virusres.2019.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/24/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
Abstract
The C-terminal disordered domain of sesbania mosaic virus (SeMV) RNA-dependent RNA polymerase (RdRp) interacts with the viral protein P10. The functional significance of this interaction in viral replication was examined by a comparative analysis of genomic and sub-genomic RNA levels (obtained by quantitative real time PCR) in the total RNA extracted from Cyamopsis plants agro-infiltrated with wild-type or mutant forms of SeMV infectious cDNA (icDNA). The sgRNA copy numbers were found to be significantly higher than those of gRNA in the wild-type icDNA transfected plants. Transfection of a mutant icDNA expressing an RdRp lacking the C-terminal disordered domain led to a drastic reduction in the copy numbers of both forms of viral RNA. This could be due to the loss of interaction between the disordered domain of RdRp and P10 and possibly other viral/host proteins that might be required for the assembly of viral replicase. The C-terminal disordered domain also harbours the motif E which is essential for the catalytic function of RdRp. Mutation of the conserved tyrosine within this motif in the full length icDNA resulted in complete inhibition of progeny RNA synthesis in the transfected plants confirming the importance of motif E in the polymerase function in vivo. The role of coat protein (CP) in viral infection was also investigated by agro-infiltration of a CP start codon mutant icDNA which suggested that CP is essential for the encapsidation of viral progeny RNAs at later stages of infection.
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Affiliation(s)
- Arindam Bakshi
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
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Wang X, Cao X, Liu M, Zhang R, Zhang X, Gao Z, Zhao X, Xu K, Li D, Zhang Y. Hsc70-2 is required for Beet black scorch virus infection through interaction with replication and capsid proteins. Sci Rep 2018; 8:4526. [PMID: 29540800 PMCID: PMC5852052 DOI: 10.1038/s41598-018-22778-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 02/27/2018] [Indexed: 11/09/2022] Open
Abstract
Dissecting the complex molecular interplay between the host plant and invading virus improves our understanding of the mechanisms underlying viral pathogenesis. In this study, immunoprecipitation together with the mass spectrometry analysis revealed that the heat shock protein 70 (Hsp70) family homolog, Hsc70-2, was co-purified with beet black scorch virus (BBSV) replication protein p23 and coat protein (CP), respectively. Further experiments demonstrated that Hsc70-2 interacts directly with both p23 and CP, whereas there is no interaction between p23 and CP. Hsc70-2 expression is induced slightly during BBSV infection of Nicotiana benthamiana, and overexpression of Hsc70-2 promotes BBSV accumulation, while knockdown of Hsc70-2 in N. benthamiana leads to drastic reduction of BBSV accumulation. Infection experiments revealed that CP negatively regulates BBSV replication, which can be mitigated by overexpression of Hsc70-2. Further experiments indicate that CP impairs the interaction between Hsc70-2 and p23 in a dose-dependent manner. Altogether, we provide evidence that besides specific functions of Hsp70 family proteins in certain aspects of viral infection, they can serve as a mediator for the orchestration of virus infection by interacting with different viral components. Our results provide new insight into the role of Hsp70 family proteins in virus infection.
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Affiliation(s)
- Xiaoling Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. 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, 100193, P. R. China
| | - Min Liu
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Ruiqi Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Xin Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Zongyu Gao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Xiaofei Zhao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, 210046, P. R. China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, P. R. China.
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7
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Jacobs A, Hoover H, Smith E, Clemmer DE, Kim CH, Kao CC. The intrinsically disordered N-terminal arm of the brome mosaic virus coat protein specifically recognizes the RNA motif that directs the initiation of viral RNA replication. Nucleic Acids Res 2018; 46:324-335. [PMID: 29140480 PMCID: PMC5758871 DOI: 10.1093/nar/gkx1087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/28/2017] [Accepted: 10/20/2017] [Indexed: 12/18/2022] Open
Abstract
In the brome mosaic virus (BMV) virion, the coat protein (CP) selectively contacts the RNA motifs that regulate translation and RNA replication (Hoover et al., 2016. J. Virol. 90, 7748). We hypothesize that the unstructured N-terminal arm (NTA) of the BMV CP can specifically recognize RNA motifs. Using ion mobility spectrometry-mass spectrometry, we demonstrate that peptides containing the NTA of the CP were found to preferentially bind to an RNA hairpin motif that directs the initiation of BMV RNA synthesis. RNA binding causes the peptide to change from heterogeneous structures to a single family of structures. Fluorescence anisotropy, fluorescence quenching and size exclusion chromatography experiments all confirm that the NTA can specific recognize the RNA motif. The peptide introduced into plants along with BMV virion increased accumulation of the BMV CP and accelerated the rate of minus-strand RNA synthesis. The intrinsically disordered BMV NTA could thus specifically recognize BMV RNAs to affect viral infection.
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Affiliation(s)
- Alexander Jacobs
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Haley Hoover
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Edward Smith
- Department of Chemistry and Biochemistry, California State University East Bay, Hayward, CA 94542, USA
| | - David E Clemmer
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Chul-Hyun Kim
- Department of Chemistry and Biochemistry, California State University East Bay, Hayward, CA 94542, USA
| | - C Cheng Kao
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
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8
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Biophysical analysis of BMV virions purified using a novel method. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1068-1069:157-163. [PMID: 29069631 DOI: 10.1016/j.jchromb.2017.10.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/03/2017] [Accepted: 10/09/2017] [Indexed: 01/12/2023]
Abstract
Brome mosaic virus (BMV) has been successfully loaded with different types of nanoparticles. However, studies concerning its application as a nanoparticle carrier demand high-purity virions in large amounts. Existing BMV purification protocols rely on multiple differential ultracentrifugation runs of the initially purified viral preparation. Herein, we describe an alternative method for BMV purification based on ion-exchange chromatography and size-exclusion chromatography (SEC) yielding 0.2mg of virus from 1g of plant tissue. Our method is of similar efficiency to previously described protocols and can easily be scaled up. The method results in high-quality BMV preparations as confirmed by biophysical analyses, including cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), static light scattering (SLS), and circular dichroism (CD) measurements and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy. Our results revealed that purified BMV capsids are stable and monodisperse and can be used for further downstream applications. In this work, we also characterize secondary structure and size fluctuations of the BMV virion at different pH values.
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9
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Wu B, Zwart MP, Sánchez-Navarro JA, Elena SF. Within-host Evolution of Segments Ratio for the Tripartite Genome of Alfalfa Mosaic Virus. Sci Rep 2017; 7:5004. [PMID: 28694514 PMCID: PMC5504059 DOI: 10.1038/s41598-017-05335-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/25/2017] [Indexed: 12/19/2022] Open
Abstract
The existence of multipartite viruses is an intriguing mystery in evolutionary virology. Several hypotheses suggest benefits that should outweigh the costs of a reduced transmission efficiency and of segregation of coadapted genes associated with encapsidating each segment into a different particle. Advantages range from increasing genome size despite high mutation rates, faster replication, more efficient selection resulting from reassortment during mixed infections, better regulation of gene expression, or enhanced virion stability and cell-to-cell movement. However, support for these hypotheses is scarce. Here we report experiments testing whether an evolutionary stable equilibrium exists for the three genomic RNAs of Alfalfa mosaic virus (AMV). Starting infections with different segment combinations, we found that the relative abundance of each segment evolves towards a constant ratio. Population genetic analyses show that the segment ratio at this equilibrium is determined by frequency-dependent selection. Replication of RNAs 1 and 2 was coupled and collaborative, whereas the replication of RNA 3 interfered with the replication of the other two. We found that the equilibrium solution is slightly different for the total amounts of RNA produced and encapsidated, suggesting that competition exists between all RNAs during encapsidation. Finally, we found that the observed equilibrium appears to be host-species dependent.
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Affiliation(s)
- Beilei Wu
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Mark P Zwart
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain
- Institute of Theoretical Physics, University of Cologne, Cologne, Germany
| | - Jesús A Sánchez-Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain
| | - Santiago F Elena
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain.
- Instituto de Biología Integrativa de Sistemas (I2SysBio), Consejo Superior de Investigaciones Científicas-Universitat de València, Valencia, Spain.
- The Santa Fe Institute, New Mexico, USA.
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10
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Zhang XP, Liu DS, Yan T, Fang XD, Dong K, Xu J, Wang Y, Yu JL, Wang XB. Cucumber mosaic virus coat protein modulates the accumulation of 2b protein and antiviral silencing that causes symptom recovery in planta. PLoS Pathog 2017; 13:e1006522. [PMID: 28727810 PMCID: PMC5538744 DOI: 10.1371/journal.ppat.1006522] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/01/2017] [Accepted: 07/11/2017] [Indexed: 11/30/2022] Open
Abstract
Shoot apical meristems (SAM) are resistant to most plant viruses due to RNA silencing, which is restrained by viral suppressors of RNA silencing (VSRs) to facilitate transient viral invasion of the SAM. In many cases chronic symptoms and long-term virus recovery occur, but the underlying mechanisms are poorly understood. Here, we found that wild-type Cucumber mosaic virus (CMVWT) invaded the SAM transiently, but was subsequently eliminated from the meristems. Unexpectedly, a CMV mutant, designated CMVRA that harbors an alanine substitution in the N-terminal arginine-rich region of the coat protein (CP) persistently invaded the SAM and resulted in visible reductions in apical dominance. Notably, the CMVWT virus elicited more potent antiviral silencing than CMVRA in newly emerging leaves of infected plants. However, both viruses caused severe symptoms with minimal antiviral silencing effects in the Arabidopsis mutants lacking host RNA-DEPENDENT RNA POLYMERASE 6 (RDR6) or SUPPRESSOR OF GENE SILENCING 3 (SGS3), indicating that CMVWT induced host RDR6/SGS3-dependent antiviral silencing. We also showed that reduced accumulation of the 2b protein is elicited in the CMVWT infection and consequently rescues potent antiviral RNA silencing. Indeed, co-infiltration assays showed that the suppression of posttranscriptional gene silencing mediated by 2b is more severely compromised by co-expression of CPWT than by CPRA. We further demonstrated that CPWT had high RNA binding activity leading to translation inhibition in wheat germ systems, and CPWT was associated with SGS3 into punctate granules in vivo. Thus, we propose that the RNAs bound and protected by CPWT possibly serve as templates of RDR6/SGS3 complexes for siRNA amplification. Together, these findings suggest that the CMV CP acts as a central hub that modulates antiviral silencing and VSRs activity, and mediates viral self-attenuation and long-term symptom recovery.
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Affiliation(s)
- Xiao-Peng Zhang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - De-Shui Liu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Teng Yan
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiao-Dong Fang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Kai Dong
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jin Xu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Ying Wang
- College of Plant Protection, China Agricultural University, Beijing, China
| | - Jia-Lin Yu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xian-Bing Wang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
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11
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Sokoloski KJ, Nease LM, May NA, Gebhart NN, Jones CE, Morrison TE, Hardy RW. Identification of Interactions between Sindbis Virus Capsid Protein and Cytoplasmic vRNA as Novel Virulence Determinants. PLoS Pathog 2017; 13:e1006473. [PMID: 28662211 PMCID: PMC5507600 DOI: 10.1371/journal.ppat.1006473] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 07/12/2017] [Accepted: 06/15/2017] [Indexed: 12/17/2022] Open
Abstract
Alphaviruses are arthropod-borne viruses that represent a significant threat to public health at a global level. While the formation of alphaviral nucleocapsid cores, consisting of cargo nucleic acid and the viral capsid protein, is an essential molecular process of infection, the precise interactions between the two partners are ill-defined. A CLIP-seq approach was used to screen for candidate sites of interaction between the viral Capsid protein and genomic RNA of Sindbis virus (SINV), a model alphavirus. The data presented in this report indicates that the SINV capsid protein binds to specific viral RNA sequences in the cytoplasm of infected cells, but its interaction with genomic RNA in mature extracellular viral particles is largely non-specific in terms of nucleotide sequence. Mutational analyses of the cytoplasmic viral RNA-capsid interaction sites revealed a functional role for capsid binding early in infection. Interaction site mutants exhibited decreased viral growth kinetics; however, this defect was not a function of decreased particle production. Rather mutation of the cytoplasmic capsid-RNA interaction sites negatively affected the functional capacity of the incoming viral genomic RNAs leading to decreased infectivity. Furthermore, cytoplasmic capsid interaction site mutants are attenuated in a murine model of neurotropic alphavirus infection. Collectively, the findings of this study indicate that the identified cytoplasmic interactions of the viral capsid protein and genomic RNA, while not essential for particle formation, are necessary for genomic RNA function early during infection. This previously unappreciated role of capsid protein during the alphaviral replication cycle also constitutes a novel virulence determinant. Alphaviruses can cause significant disease in infected individuals; however, our understanding of the molecular interactions that enable infection and contribute to the development of disease is limited. The work detailed in this manuscript characterizes the interaction of a viral RNA-binding protein, Capsid, with the viral genomic RNA. Importantly, these interactions were found to be at specific sites on the genome but not essential for virus assembly. Mutation of the capsid / RNA interaction sites decreased the replication of the virus and the severity of disease in a mouse model of infection. Taken together, these findings identify a previously undiscovered determinant of disease severity, and provide a potential basis for the development of new vaccines.
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Affiliation(s)
- Kevin J. Sokoloski
- Department of Microbiology and Immunology, and the Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville School of Medicine, Louisville KY, United States of America
| | - Lauren M. Nease
- Department of Biology, College of Arts and Sciences, Indiana University, Bloomington IN, United States of America
| | - Nicholas A. May
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Natasha N. Gebhart
- Department of Biology, College of Arts and Sciences, Indiana University, Bloomington IN, United States of America
| | - Claire E. Jones
- Department of Microbiology and Immunology, and the Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville School of Medicine, Louisville KY, United States of America
| | - Thomas E. Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Richard W. Hardy
- Department of Biology, College of Arts and Sciences, Indiana University, Bloomington IN, United States of America
- * E-mail:
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12
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Coat Protein Regulation by CK2, CPIP, HSP70, and CHIP Is Required for Potato Virus A Replication and Coat Protein Accumulation. J Virol 2017; 91:JVI.01316-16. [PMID: 27852853 DOI: 10.1128/jvi.01316-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 11/10/2016] [Indexed: 01/15/2023] Open
Abstract
We demonstrate here that both coat protein (CP) phosphorylation by protein kinase CK2 and a chaperone system formed by two heat shock proteins, CP-interacting protein (CPIP) and heat shock protein 70 (HSP70), are essential for potato virus A (PVA; genus Potyvirus) replication and that all these host proteins have the capacity to contribute to the level of PVA CP accumulation. An E3 ubiquitin ligase called carboxyl terminus Hsc70-interacting protein (CHIP), which may participate in the CPIP-HSP70-mediated CP degradation, is also needed for robust PVA gene expression. Residue Thr243 within the CK2 consensus sequence of PVA CP was found to be essential for viral replication and to regulate CP protein stability. Substitution of Thr243 either with a phosphorylation-mimicking Asp (CPADA) or with a phosphorylation-deficient Ala (CPAAA) residue in CP expressed from viral RNA limited PVA gene expression to the level of nonreplicating PVA. We found that both the CPAAA mutant and CK2 silencing inhibited, whereas CPADA mutant and overexpression of CK2 increased, PVA translation. From our previous studies, we know that phosphorylation reduces the RNA binding capacity of PVA CP and an excess of CP fully blocks viral RNA translation. Together, these findings suggest that binding by nonphosphorylated PVA CP represses viral RNA translation, involving further CP phosphorylation and CPIP-HSP70 chaperone activities as prerequisites for PVA replication. We propose that this mechanism contributes to shifting potyvirus RNA from translation to replication. IMPORTANCE Host protein kinase CK2, two host chaperones, CPIP and HSP70, and viral coat protein (CP) phosphorylation at Thr243 are needed for potato virus A (PVA) replication. Our results show that nonphosphorylated CP blocks viral translation, likely via binding to viral RNA. We propose that this translational block is needed to allow time and space for the formation of potyviral replication complex around the 3' end of viral RNA. Progression into replication involves CP regulation by both CK2 phosphorylation and chaperones CPIP and HSP70.
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Chu W, Weerasekera A, Kim CH. On the conformational stability of the smallest RNA kissing complexes maintained through two G·C base pairs. Biochem Biophys Res Commun 2017; 483:39-44. [PMID: 28063925 DOI: 10.1016/j.bbrc.2017.01.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/03/2017] [Indexed: 11/19/2022]
Abstract
Two identical 5'GACG3' tetra-loop motifs with different stem sequences (called H2 and H3) are found in the 5' end region of Moloney Murine Leukemia Virus (MMLV) genomic RNA. They play important roles in RNA dimerization and encapsidation through two identical tetra-loops (5'GACG3') forming a loop-to-loop kissing complex, the smallest RNA kissing complex ever found in nature. We examined the effects of a loop-closing base pair as well as a stem sequence on the conformational stability of the kissing complex. UV melting analysis and gel electrophoresis were performed on eight RNA sequences mimicking the H2 and H3 hairpin tetra-loops with variation in loop-closing base pairs. Our results show that changing the loop-closing base pair from the wildtype (5'A·U3' for H3, 5'U·A3' for H2) to 5'G·C3'/5'C·G3' has significant effect on the stability of the kissing complexes: the substitution to 5'C·G3' significantly decreases both thermal and mechanical stability, while switching to the 5'G·C3' significantly increases the mechanical stability only. The kissing complexes with the wildtype loop-closing base pairs (5'A·U3' for H3 and 5'U·A3' for H2) show different stability when attached to a different stem sequence (H2 stem vs. H3 stem). This suggests that not only the loop-closing base pair itself, but also the stem sequence, affects the conformational stability of the RNA kissing complex.
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Affiliation(s)
- Wally Chu
- Department of Chemistry and Biochemistry, California State University East Bay, Hayward, CA 94542, United States
| | - Akila Weerasekera
- Department of Chemistry and Biochemistry, California State University East Bay, Hayward, CA 94542, United States
| | - Chul-Hyun Kim
- Department of Chemistry and Biochemistry, California State University East Bay, Hayward, CA 94542, United States.
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Doumayrou J, Sheber M, Bonning BC, Miller WA. Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector. Viruses 2016; 8:E312. [PMID: 27869713 PMCID: PMC5127026 DOI: 10.3390/v8110312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/14/2016] [Accepted: 11/02/2016] [Indexed: 11/16/2022] Open
Abstract
Understanding the molecular mechanisms involved in plant virus-vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP) are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus, Luteoviridae) and Pea enation mosaic virus 2 (PEMV2, Umbravirus, Tombusviridae) are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum, and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum. Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.
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Affiliation(s)
- Juliette Doumayrou
- Department of Plant Pathology & Microbiology, 351 Bessey Hall, Iowa State University, Ames, IA 50011, USA.
| | - Melissa Sheber
- Department of Plant Pathology & Microbiology, 351 Bessey Hall, Iowa State University, Ames, IA 50011, USA.
| | - Bryony C Bonning
- Department of Entomology, 339 Science II, Iowa State University, Ames, IA 50011, USA.
| | - W Allen Miller
- Department of Plant Pathology & Microbiology, 351 Bessey Hall, Iowa State University, Ames, IA 50011, USA.
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Fan B, Ni P, Kao CC. Mapping RNA interactions to proteins in virions using CLIP-Seq. Methods Mol Biol 2016; 1297:213-24. [PMID: 25896006 DOI: 10.1007/978-1-4939-2562-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
RNA nanotechnology often involves protein-RNA complexes that require significant understanding of how the proteins and RNAs contact each other. The CLIP-Seq (cross-linking immunoprecipitation, and DNA sequencing) protocol can be used to probe the RNA molecules that interact with proteins. We have optimized the procedures for RNA fragmentation, immunoprecipitation, and library construction in CLIP-Seq to map the interactions between the RNA and the capsid of a simple positive-strand RNA virus. The results show that distinct portions of the viral RNA contact the capsid. The protocol should be applicable to other RNA virions and also RNA-protein nanoparticles.
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Affiliation(s)
- Baochang Fan
- Department of Molecular and Cellular Biochemistry, Indiana University, 212 S. Hawthorne St., 201A Simon Hall, Bloomington, IN, 47405, USA
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Stockley PG, White SJ, Dykeman E, Manfield I, Rolfsson O, Patel N, Bingham R, Barker A, Wroblewski E, Chandler-Bostock R, Weiß EU, Ranson NA, Tuma R, Twarock R. Bacteriophage MS2 genomic RNA encodes an assembly instruction manual for its capsid. BACTERIOPHAGE 2016; 6:e1157666. [PMID: 27144089 PMCID: PMC4836477 DOI: 10.1080/21597081.2016.1157666] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/15/2016] [Accepted: 02/17/2016] [Indexed: 12/11/2022]
Abstract
Using RNA-coat protein crosslinking we have shown that the principal RNA recognition surface on the interior of infectious MS2 virions overlaps with the known peptides that bind the high affinity translational operator, TR, within the phage genome. The data also reveal the sequences of genomic fragments in contact with the coat protein shell. These show remarkable overlap with previous predictions based on the hypothesis that virion assembly is mediated by multiple sequences-specific contacts at RNA sites termed Packaging Signals (PSs). These PSs are variations on the TR stem-loop sequence and secondary structure. They act co-operatively to regulate the dominant assembly pathway and ensure cognate RNA encapsidation. In MS2, they also trigger conformational change in the dimeric capsomere creating the A/B quasi-conformer, 60 of which are needed to complete the T=3 capsid. This is the most compelling demonstration to date that this ssRNA virus, and by implications potentially very many of them, assemble via a PS-mediated assembly mechanism.
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Affiliation(s)
- Peter G. Stockley
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Simon J. White
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Eric Dykeman
- Department of Biology and Mathematics & York Center for Complex Systems Analysis, University of York, York, UK
| | - Iain Manfield
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Ottar Rolfsson
- Center for Systems Biology, University of Iceland, University of Iceland Biomedical Center, Reykjavik, Iceland
| | - Nikesh Patel
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Richard Bingham
- Department of Biology and Mathematics & York Center for Complex Systems Analysis, University of York, York, UK
| | - Amy Barker
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Emma Wroblewski
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | | | - Eva U. Weiß
- Department of Biology and Mathematics & York Center for Complex Systems Analysis, University of York, York, UK
| | - Neil A. Ranson
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Roman Tuma
- Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Reidun Twarock
- Department of Biology and Mathematics & York Center for Complex Systems Analysis, University of York, York, UK
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Besong-Ndika J, Ivanov KI, Hafrèn A, Michon T, Mäkinen K. Cotranslational coat protein-mediated inhibition of potyviral RNA translation. J Virol 2015; 89:4237-48. [PMID: 25631087 PMCID: PMC4442359 DOI: 10.1128/jvi.02915-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 01/22/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Potato virus A (PVA) is a single-stranded positive-sense RNA virus and a member of the family Potyviridae. The PVA coat protein (CP) has an intrinsic capacity to self-assemble into filamentous virus-like particles, but the mechanism responsible for the initiation of viral RNA encapsidation in vivo remains unclear. Apart from virion assembly, PVA CP is also involved in the inhibition of viral RNA translation. In this study, we show that CP inhibits PVA RNA translation in a dose-dependent manner, through a mechanism involving the CP-encoding region. Analysis of this region, however, failed to identify any RNA secondary structure(s) preferentially recognized by CP, suggesting that the inhibition depends on CP-CP rather than CP-RNA interactions. In agreement with this possibility, insertion of an in-frame stop codon upstream of the CP sequence led to a marked decrease in the inhibition of viral RNA translation. Based on these results, we propose a model in which the cotranslational interactions between excess CP accumulating in trans and CP translated from viral RNA in cis are required to initiate the translational repression. This model suggests a mechanism for how viral RNA can be sequestered from translation and specifically selected for encapsidation at the late stages of viral infection. IMPORTANCE The main functions of the CP during potyvirus infection are to protect viral RNA from degradation and to transport it locally, systemically, and from host to host. Although virion assembly is a key step in the potyviral infectious cycle, little is known about how it is initiated and how viral RNA is selected for encapsidation. The results presented here suggest that CP-CP rather than CP-RNA interactions are predominantly involved in the sequestration of viral RNA away from translation. We propose that the cotranslational nature of these interactions may represent a mechanism for the selection of viral RNA for encapsidation. A better understanding of the mechanism of virion assembly may lead to development of crops resistant to potyviruses at the level of viral RNA encapsidation, thereby reducing the detrimental effects of potyvirus infections on food production.
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Affiliation(s)
- Jane Besong-Ndika
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland UMR 1332 Biologie du Fruit et Pathologie, INRA-Université Bordeaux 2, Villenave d'Ornon Cedex, France
| | - Konstantin I Ivanov
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Anders Hafrèn
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Thierry Michon
- UMR 1332 Biologie du Fruit et Pathologie, INRA-Université Bordeaux 2, Villenave d'Ornon Cedex, France
| | - Kristiina Mäkinen
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
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Rao ALN, Cheng Kao C. The brome mosaic virus 3' untranslated sequence regulates RNA replication, recombination, and virion assembly. Virus Res 2015; 206:46-52. [PMID: 25687214 DOI: 10.1016/j.virusres.2015.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/04/2015] [Accepted: 02/05/2015] [Indexed: 11/18/2022]
Abstract
The 3' untranslated region in each of the three genomic RNAs of Brome mosaic virus (BMV) is highly homologous and contains a sequence that folds into a tRNA-like structure (TLS). Experiments performed over the past four decades revealed that the BMV 3' TLS regulates many important steps in BMV infection. This review summarizes in vitro and in vivo studies of the roles of the BMV 3' TLS functioning as a minus-strand promoter, in RNA recombination, and to nucleate virion assembly.
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Affiliation(s)
- A L N Rao
- Department of Plant Pathology, University of California, Riverside, CA 925210-0122, USA.
| | - C Cheng Kao
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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19
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Lin X, Thorne L, Jin Z, Hammad LA, Li S, Deval J, Goodfellow IG, Kao CC. Subgenomic promoter recognition by the norovirus RNA-dependent RNA polymerases. Nucleic Acids Res 2014; 43:446-60. [PMID: 25520198 PMCID: PMC4288183 DOI: 10.1093/nar/gku1292] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The replication enzyme of RNA viruses must preferentially recognize their RNAs in an environment that contains an abundance of cellular RNAs. The factors responsible for specific RNA recognition are not well understood, in part because viral RNA synthesis takes place within enzyme complexes associated with modified cellular membrane compartments. Recombinant RNA-dependent RNA polymerases (RdRps) from the human norovirus and the murine norovirus (MNV) were found to preferentially recognize RNA segments that contain the promoter and a short template sequence for subgenomic RNA synthesis. Both the promoter and template sequence contribute to stable RdRp binding, accurate initiation of the subgenomic RNAs and efficient RNA synthesis. Using a method that combines RNA crosslinking and mass spectrometry, residues near the template channel of the MNV RdRp were found to contact the hairpin RNA motif. Mutations in the hairpin contact site in the MNV RdRp reduced MNV replication and virus production in cells. This work demonstrates that the specific recognition of the norovirus subgenomic promoter is through binding by the viral RdRp.
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Affiliation(s)
- Xiaoyan Lin
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Lucy Thorne
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road CB2 2QQ, UK
| | - Zhinan Jin
- Alios BioPharma, Inc., 260 East Grand Avenue South, San Francisco, CA 94080, USA
| | - Loubna A Hammad
- Laboratory for Biological Mass Spectrometry, Indiana University, Bloomington, IN 47405, USA
| | - Serena Li
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Jerome Deval
- Alios BioPharma, Inc., 260 East Grand Avenue South, San Francisco, CA 94080, USA
| | - Ian G Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road CB2 2QQ, UK
| | - C Cheng Kao
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
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20
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Rao ALN, Chaturvedi S, Garmann RF. Integration of replication and assembly of infectious virions in plant RNA viruses. Curr Opin Virol 2014; 9:61-6. [DOI: 10.1016/j.coviro.2014.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/04/2014] [Accepted: 09/18/2014] [Indexed: 02/08/2023]
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21
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Rybicki EP. A Top Ten list for economically important plant viruses. Arch Virol 2014; 160:17-20. [PMID: 25430908 DOI: 10.1007/s00705-014-2295-9] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/20/2014] [Indexed: 12/31/2022]
Abstract
The concept of "Top Ten" lists of plant pathogens is in vogue in recent years, and plant viruses are no exception. However, the only list available has more to do with historical and scientific worth than it has to do with economic impact on humans and their animals. This review will discuss the most important plant viruses that cause serious harm to food plants that sustain the bulk of humankind.
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Affiliation(s)
- Edward P Rybicki
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, PB Rondebosch, Cape Town, 7701, South Africa,
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22
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Chaturvedi S, Rao ALN. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: implications for replication and genome packaging. Virology 2014; 464-465:67-75. [PMID: 25046269 DOI: 10.1016/j.virol.2014.06.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/22/2014] [Accepted: 06/22/2014] [Indexed: 10/25/2022]
Abstract
In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein-protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed.
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Affiliation(s)
- Sonali Chaturvedi
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521-0122, USA
| | - A L N Rao
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521-0122, USA.
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23
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Wen Y, Cheng Kao C. The hepatitis C virus core protein can modulate RNA-dependent RNA synthesis by the 2a polymerase. Virus Res 2014; 189:165-76. [PMID: 24874198 DOI: 10.1016/j.virusres.2014.05.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/01/2014] [Accepted: 05/07/2014] [Indexed: 01/06/2023]
Abstract
RNA replication enzymes are multi-subunit protein complexes whose activity can be modulated by other viral and cellular factors. For genotype 1b Hepatitis C virus (HCV), the RNA-dependent RNA polymerase (RdRp) subunit of the replicase, NS5B, has been reported to interact with the HCV Core protein to decrease RNA synthesis (Kang et al., 2009). Here we used a cell-based assay for RNA synthesis to examine the Core-NS5B interaction of genotype 2a HCV. Unlike the 1b NS5B, the activity of the 2a NS5B was stimulated by the Core protein. Using the bimolecular fluorescence complementation assay, the 2a Core co-localized with 2a NS5B when they were transiently expressed in cells. The two proteins can form a co-immunoprecipitable complex. Deletion analysis showed that the N-terminal 75 residues of 2a Core were required to contact 2a NS5B to modulate its activity. The C-terminal transmembrane helix of 2a NS5B also contributes to the interaction with the 2a Core. To determine the basis for the differential effects of the Core-RdRp interaction, we found that the 2a RdRp activity was enhanced by both the 1b Core and 2a Core. However, the 1b NS5B activity was slightly inhibited by either Core protein. The replication of the 2a JFH-1 replicon was increased by co-expressed 2a Core while the genotype 1b Con1 replicon was not significantly affected by the corresponding Core. Mutations in 2a NS5B that affected the closed RdRp structure were found to be less responsive to 2a Core. Finally, we determined that RNA synthesis by the RdRps from genotypes 2a, 3a and 4a HCV were increased by the Core proteins from HCV of genotypes 1-4. These results reveal another difference between RNA syntheses by the different genotype RdRps and add additional examples of a viral structural protein regulating viral RNA synthesis.
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Affiliation(s)
- Y Wen
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - C Cheng Kao
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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Li W, Zhang Y, Kao CC. The classic swine fever virus (CSFV) core protein can enhance de novo-initiated RNA synthesis by the CSFV polymerase NS5B. Virus Genes 2014; 49:106-15. [DOI: 10.1007/s11262-014-1080-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 04/23/2014] [Indexed: 12/28/2022]
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25
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Ni P, Vaughan RC, Tragesser B, Hoover H, Kao CC. The plant host can affect the encapsidation of brome mosaic virus (BMV) RNA: BMV virions are surprisingly heterogeneous. J Mol Biol 2014; 426:1061-76. [PMID: 24036424 PMCID: PMC3944473 DOI: 10.1016/j.jmb.2013.09.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/02/2013] [Accepted: 09/08/2013] [Indexed: 01/05/2023]
Abstract
Brome mosaic virus (BMV) packages its genomic and subgenomic RNAs into three separate viral particles. BMV purified from barley, wheat, and tobacco have distinct relative abundances of the encapsidated RNAs. We seek to identify the basis for the host-dependent differences in viral RNA encapsidation. Sequencing of the viral RNAs revealed recombination events in the 3' untranslated region of RNA1 of BMV purified from barley and wheat, but not from tobacco. However, the relative amounts of the BMV RNAs that accumulated in barley and wheat are similar and RNA accumulation is not sufficient to account for the difference in RNA encapsidation. Virions purified from barley and wheat were found to differ in their isoelectric points, resistance to proteolysis, and contacts between the capsid residues and the RNA. Mass spectrometric analyses revealed that virions from the three hosts had different post-translational modifications that should impact the physiochemical properties of the virions. Another major source of variation in RNA encapsidation was due to the purification of BMV particles to homogeneity. Highly enriched BMV present in lysates had a surprising range of sizes, buoyant densities, and distinct relative amounts of encapsidated RNAs. These results show that the encapsidated BMV RNAs reflect a combination of host effects on the physiochemical properties of the viral capsids and the enrichment of a subset of virions. The previously unexpected heterogeneity in BMV should influence the timing of the infection and also the host innate immune responses.
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Affiliation(s)
- Peng Ni
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Robert C Vaughan
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Brady Tragesser
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Haley Hoover
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - C Cheng Kao
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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26
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Kwon SJ, Chaturvedi S, Rao ALN. Repair of the 3' proximal and internal deletions of a satellite RNA associated with Cucumber mosaic virus is directed toward restoring structural integrity. Virology 2014; 450-451:222-32. [PMID: 24503085 DOI: 10.1016/j.virol.2013.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 11/29/2013] [Accepted: 12/08/2013] [Indexed: 11/27/2022]
Abstract
The phenomenon of rapid turnover of 3' proximal nucleotides (nt) lost by the action of nuclease in RNA viruses is integral to replication. Here, a set of six deletions encompassing the 3' 23 nt region of a satellite RNA (satRNA) of Cucumber mosaic virus (CMV) strain Q (Q-sat), were engineered. Repair of the 3' end was not observed in the absence of CMV. However, co-expression with CMV in planta revealed that Q-sat mutants lacking the 3' 18 nt but not the 3' 23 nt are repaired and the progeny accumulation was inversely proportional to the extent of the deletion. Progeny of the 3'Δ3 mutant were repaired to wild type (wt) while those from the remaining four mutants were heterogeneous, exhibiting a wt secondary structure. Analysis of additional 3' internal deletions mutants revealed that progeny with a repaired sequence reminiscent of wt secondary structure were competent for replication and systemic spread.
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Affiliation(s)
- Sun-Jung Kwon
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521-0122, United States
| | - Sonali Chaturvedi
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521-0122, United States
| | - A L N Rao
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521-0122, United States.
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Non-encapsidation activities of the capsid proteins of positive-strand RNA viruses. Virology 2013; 446:123-32. [PMID: 24074574 PMCID: PMC3818703 DOI: 10.1016/j.virol.2013.07.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 07/11/2013] [Accepted: 07/20/2013] [Indexed: 02/08/2023]
Abstract
Viral capsid proteins (CPs) are characterized by their role in forming protective shells around viral genomes. However, CPs have additional and important roles in the virus infection cycles and in the cellular responses to infection. These activities involve CP binding to RNAs in both sequence-specific and nonspecific manners as well as association with other proteins. This review focuses on CPs of both plant and animal-infecting viruses with positive-strand RNA genomes. We summarize the structural features of CPs and describe their modulatory roles in viral translation, RNA-dependent RNA synthesis, and host defense responses. We review regulatory activities of the capsid proteins of (+)-strand RNA viruses. Activities of capsid proteins due to RNA binding and protein binding. Effects of capsid proteins on viral processes. Effects of capsid proteins on cellular processes. Regulatory activities of the capsid proteins are affected by capsid concentrations.
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Coat proteins, host factors and plant viral replication. Curr Opin Virol 2012; 2:712-8. [DOI: 10.1016/j.coviro.2012.10.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/28/2012] [Accepted: 10/01/2012] [Indexed: 11/24/2022]
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Sztuba-Solińska J, Fanning SW, Horn JR, Bujarski JJ. Mutations in the coat protein-binding cis-acting RNA motifs debilitate RNA recombination of Brome mosaic virus. Virus Res 2012; 170:138-49. [PMID: 23079110 PMCID: PMC7114393 DOI: 10.1016/j.virusres.2012.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 12/14/2022]
Abstract
We have previously described the efficient homologous recombination system between 5' subgenomic RNA3a (sgRNA3a) and genomic RNA3 of Brome mosaic virus (BMV) in barley protoplasts (Sztuba-Solińska et al., 2011a). Here, we demonstrated that sequence alterations in the coat protein (CP)-binding cis-acting RNA motifs, the Bbox region (in the intercistronic RNA3 sequence) and the RNA3 packaging element (PE, in the movement protein ORF), reduced crossover frequencies in protoplasts. Additionally, the modification of Bbox-like element in the 5' UTR region strongly debilitated crossovers. Along the lines of these observations, RNA3 mutants not expressing CP or expressing mutated CPs also reduced recombination. A series of reciprocal transfections demonstrated a functional crosstalk between the Bbox and PE elements. Altogether, our data imply the role of CP in sgRNA3a-directed recombination by either facilitating the interaction of the RNA substrates and/or by creating roadblocks for the viral replicase.
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Affiliation(s)
- Joanna Sztuba-Solińska
- Plant Molecular Biology Center and the Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
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Vaughan R, Li Y, Fan B, Ranjith-Kumar CT, Kao CC. RNA binding by the NS3 protease of the hepatitis C virus. Virus Res 2012; 169:80-90. [PMID: 22814430 DOI: 10.1016/j.virusres.2012.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/08/2012] [Accepted: 07/09/2012] [Indexed: 12/22/2022]
Abstract
The hepatitis C virus (HCV) nonstructural protein 3 (NS3) is essential for the processing of the HCV polyprotein, the replication of HCV RNA, and to short circuit innate immunity signaling. NS3 contains an N-terminal domain with protease activity and a C-terminal domain with helicase activity. The two domains communicate with each other along with other HCV and cellular proteins. Herein we show that RNAs can bind directly to the active site cleft of the NS3 protease domain (NS3P) and inhibit proteolysis of peptide substrates. RNAs that are less apt to form intramolecular structures have a stronger inhibitory activity than RNAs with more stable base paired regions. Two mutations in the protease domain that resulted in decreased affinity to ssRNA were also defective in RNA-induced ATPase activity from the helicase domain of NS3. The coordinated effects on inhibition of protease activity and stimulation of ATPase activity raise the possibility that RNA serves as a regulatory switch for the two processes.
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Affiliation(s)
- Robert Vaughan
- The Biochemistry Interdisciplinary Program, Indiana University, Bloomington, IN 47405, USA
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Norovirus RNA synthesis is modulated by an interaction between the viral RNA-dependent RNA polymerase and the major capsid protein, VP1. J Virol 2012; 86:10138-49. [PMID: 22787222 DOI: 10.1128/jvi.01208-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using a cell-based assay for RNA synthesis by the RNA-dependent RNA polymerase (RdRp) of noroviruses, we previously observed that VP1, the major structural protein of the human GII.4 norovirus, enhanced the GII.4 RdRp activity but not that of the related murine norovirus (MNV) or other unrelated RNA viruses (C. V. Subba-Reddy, I. Goodfellow, and C. C. Kao, J. Virol. 85:13027-13037, 2011). Here, we examine the mechanism of VP1 enhancement of RdRp activity and the mechanism of mouse norovirus replication. We determined that the GII.4 and MNV VP1 proteins can enhance cognate RdRp activities in a concentration-dependent manner. The VP1 proteins coimmunoprecipitated with their cognate RdRps. Coexpression of individual domains of VP1 with the viral RdRps showed that the VP1 shell domain (SD) was sufficient to enhance polymerase activity. Using SD chimeras from GII.4 and MNV, three loops connecting the central β-barrel structure were found to be responsible for the species-specific enhancement of RdRp activity. A differential scanning fluorimetry assay showed that recombinant SDs can bind to the purified RdRps in vitro. An MNV replicon with a frameshift mutation in open reading frame 2 (ORF2) that disrupts VP1 expression was defective for RNA replication, as quantified by luciferase reporter assay and real-time quantitative reverse transcription-PCR (qRT-PCR). Trans-complementation of VP1 or its SD significantly recovered the VP1 knockout MNV replicon replication, and the presence or absence of VP1 affected the kinetics of viral RNA synthesis. The results document a regulatory role for VP1 in the norovirus replication cycle, further highlighting the paradigm of viral structural proteins playing additional functional roles in the virus life cycle.
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Running WE, Ni P, Kao CC, Reilly JP. Chemical reactivity of brome mosaic virus capsid protein. J Mol Biol 2012; 423:79-95. [PMID: 22750573 DOI: 10.1016/j.jmb.2012.06.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 06/01/2012] [Accepted: 06/20/2012] [Indexed: 12/12/2022]
Abstract
Viral particles are biological machines that have evolved to package, protect, and deliver the viral genome into the host via regulated conformational changes of virions. We have developed a procedure to modify lysine residues with S-methylthioacetimidate across the pH range from 5.5 to 8.5. Lysine residues that are not completely modified are involved in tertiary or quaternary structural interactions, and their extent of modification can be quantified as a function of pH. This procedure was applied to the pH-dependent structural transitions of brome mosaic virus (BMV). As the reaction pH increases from 5.5 to 8.5, the average number of modified lysine residues in the BMV capsid protein increases from 6 to 12, correlating well with the known pH-dependent swelling behavior of BMV virions. The extent of reaction of each of the capsid protein's lysine residues has been quantified at eight pH values using coupled liquid chromatography-tandem mass spectrometry. Each lysine can be assigned to one of three structural classes identified by inspection of the BMV virion crystal structure. Several lysine residues display reactivity that indicates their involvement in dynamic interactions that are not obvious in the crystal structure. The influence of several capsid protein mutants on the pH-dependent structural transition of BMV has also been investigated. Mutant H75Q exhibits an altered swelling transition accompanying solution pH increases. The H75Q capsids show increased reactivity at lysine residues 64 and 130, residues distal from the dimer interface occupied by H75, across the entire pH range.
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Affiliation(s)
- W E Running
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
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Skov J, Gaudin M, Podbevšek P, Olsthoorn RC, Petersen M. The subgenomic promoter of brome mosaic virus folds into a stem-loop structure capped by a pseudo-triloop that is structurally similar to the triloop of the genomic promoter. RNA (NEW YORK, N.Y.) 2012; 18:992-1000. [PMID: 22393035 PMCID: PMC3334706 DOI: 10.1261/rna.029918.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In brome mosaic virus, both the replication of the genomic (+)-RNA strands and the transcription of the subgenomic RNA are carried out by the viral replicase. The production of (-)-RNA strands is dependent on the formation of an AUA triloop in the stem-loop C (SLC) hairpin in the 3'-untranslated region of the (+)-RNA strands. Two alternate hypotheses have been put forward for the mechanism of subgenomic RNA transcription. One posits that transcription commences by recognition of at least four key nucleotides in the subgenomic promoter by the replicase. The other posits that subgenomic transcription starts by binding of the replicase to a hairpin formed by the subgenomic promoter that resembles the minus strand promoter hairpin SLC. In this study, we have determined the three-dimensional structure of the subgenomic promoter hairpin using NMR spectroscopy. The data show that the hairpin is stable at 30°C and that it forms a pseudo-triloop structure with a transloop base pair and a nucleotide completely excluded from the helix. The transloop base pair is capped by an AUA triloop that possesses an extremely well packed structure very similar to that of the AUA triloop of SLC, including the formation of a so-called clamped-adenine motif. The similarities of the NMR structures of the hairpins required for genomic RNA and subgenomic RNA synthesis show that the replicase recognizes structure rather than sequence-specific motifs in both promoters.
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Affiliation(s)
- Joan Skov
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - Mathieu Gaudin
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - Peter Podbevšek
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - René C.L. Olsthoorn
- Department of Molecular Genetics, Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | - Michael Petersen
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
- Corresponding author.E-mail .
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VPg-primed RNA synthesis of norovirus RNA-dependent RNA polymerases by using a novel cell-based assay. J Virol 2011; 85:13027-37. [PMID: 21994457 DOI: 10.1128/jvi.06191-11] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Molecular studies of human noroviruses (NoV) have been hampered by the lack of a permissive cell culture system. We have developed a sensitive and reliable mammalian cell-based assay for the human NoV GII.4 strain RNA-dependent RNA polymerase (RdRp). The assay is based on the finding that RNAs synthesized by transiently expressed RdRp can stimulate retinoic acid-inducible gene I (RIG-I)-dependent reporter luciferase production via the beta interferon promoter. Comparable activities were observed for the murine norovirus (MNV) RdRp. RdRps with mutations at divalent metal ion binding residues did not activate RIG-I signaling. Furthermore, both NoV and MNV RdRp activities were stimulated by the coexpression of their respective VPg proteins, while mutations in the putative site of nucleotide linkage on VPg abolished most of their stimulatory effects. Sequencing of the RNAs linked to VPg revealed that the cellular trans-Golgi network protein 2 (TGOLN2) mRNA was the template for VPg-primed RNA synthesis. Small interfering RNA knockdown of RNase L abolished the enhancement of signaling that occurred in the presence of VPg. Finally, the coexpression of each of the other NoV proteins revealed that p48 (also known as NS1-2) and VP1 enhanced and that VP2 reduced the RdRp activity. The assay should be useful for the dissection of the requirements for NoV RNA synthesis as well as the identification of inhibitors of the NoV RdRp.
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Kao CC, Ni P, Hema M, Huang X, Dragnea B. The coat protein leads the way: an update on basic and applied studies with the Brome mosaic virus coat protein. MOLECULAR PLANT PATHOLOGY 2011; 12:403-12. [PMID: 21453435 PMCID: PMC6640235 DOI: 10.1111/j.1364-3703.2010.00678.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The Brome mosaic virus (BMV) coat protein (CP) accompanies the three BMV genomic RNAs and the subgenomic RNA into and out of cells in an infection cycle. In addition to serving as a protective shell for all of the BMV RNAs, CP plays regulatory roles during the infection process that are mediated through specific binding of RNA elements in the BMV genome. One regulatory RNA element is the B box present in the 5' untranslated region (UTR) of BMV RNA1 and RNA2 that play important roles in the formation of the BMV replication factory, as well as the regulation of translation. A second element is within the tRNA-like 3' UTR of all BMV RNAs that is required for efficient RNA replication. The BMV CP can also encapsidate ligand-coated metal nanoparticles to form virus-like particles (VLPs). This update summarizes the interaction between the BMV CP and RNAs that can regulate RNA synthesis, translation and RNA encapsidation, as well as the formation of VLPs.
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Affiliation(s)
- C Cheng Kao
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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Recombination of 5' subgenomic RNA3a with genomic RNA3 of Brome mosaic bromovirus in vitro and in vivo. Virology 2010; 410:129-41. [PMID: 21111438 PMCID: PMC7111948 DOI: 10.1016/j.virol.2010.10.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 08/28/2010] [Accepted: 10/29/2010] [Indexed: 01/03/2023]
Abstract
RNA-RNA recombination salvages viral RNAs and contributes to their genomic variability. A recombinationally-active subgenomic promoter (sgp) has been mapped in Brome mosaic bromovirus (BMV) RNA3 (Wierzchoslawski et al., 2004. J. Virol.78, 8552-8864) and mRNA-like 5' sgRNA3a was characterized (Wierzchoslawski et al., 2006. J. Virol. 80, 12357-12366). In this paper we describe sgRNA3a-mediated recombination in both in vitro and in vivo experiments. BMV replicase-directed co-copying of (-) RNA3 with wt sgRNA3a generated RNA3 recombinants in vitro, but it failed to when 3'-truncated sgRNA3a was substituted, demonstrating a role for the 3' polyA tail. Barley protoplast co-transfections revealed that (i) wt sgRNA3a recombines at the 3' and the internal sites; (ii) 3'-truncated sgRNA3as recombine more upstream; and (iii) 5'-truncated sgRNA3 recombine at a low rate. In planta co-inoculations confirmed the RNA3-sgRNA3a crossovers. In summary, the non-replicating sgRNA3a recombines with replicating RNA3, most likely via primer extension and/or internal template switching.
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Hema M, Murali A, Ni P, Vaughan RC, Fujisaki K, Tsvetkova I, Dragnea B, Kao CC. Effects of amino-acid substitutions in the Brome mosaic virus capsid protein on RNA encapsidation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1433-1447. [PMID: 20923351 DOI: 10.1094/mpmi-05-10-0118] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Brome mosaic virus (BMV) packages its genomic RNAs (RNA1, RNA2, and RNA3) and subgenomic RNA4 into three different particles. However, since the RNAs in the virions have distinct lengths and electrostatic charges, we hypothesize that subsets of the virions should have distinct properties. A glutamine to cysteine substitution at position 120 of the capsid protein (CP) was found to result in a mutant virus named QC that exhibited a dramatically altered ratio of the RNAs in virions. RNA2 was far more abundant than the other RNAs, although the ratios could be affected by the host plant species. RNAs with the QC mutation were competent for replication early in the infection, suggesting that they were either selectively packaged or degraded after packaging. In support of the latter idea, low concentrations of truncated RNA1 that co-migrated with RNA2 were found in the QC virions. Spectroscopic analysis and peptide fingerprinting experiments showed that the QC virus capsid interacted with the encapsidated RNAs differently than did the wild type. Furthermore, wild-type BMV RNA1 was found to be more susceptible to nuclease digestion relative to RNA2 as a function of the buffer pH. Other BMV capsid mutants also had altered ratios of packaged RNAs.
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Affiliation(s)
- Masarapu Hema
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA
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Hepatitis C virus nonstructural protein 5A: biochemical characterization of a novel structural class of RNA-binding proteins. J Virol 2010; 84:12480-91. [PMID: 20926572 DOI: 10.1128/jvi.01319-10] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) exhibits a preference for G/U-rich RNA in vitro. Biological analysis of the NS5A RNA-binding activity and its target sites in the genome will be facilitated by a description of the NS5A-RNA complex. We demonstrate that the C-4 carbonyl of the uracil base and, by inference, the C-6 carbonyl of the guanine base interact with NS5A. U-rich RNA of 5 to 6 nucleotides (nt) is sufficient for high-affinity binding to NS5A. The minimal RNA-binding domain of NS5A consists of residues 2005 to 2221 (referred to as domain I-plus). This region of the protein includes the amino-terminal domain I as well as the subsequent linker that separates domains I and II. This linker region is the site of adaptive mutations. U-rich RNA-binding activity is not observed for an NS5A derivative containing only residues 2194 to 2419 (domains II and III). Mass spectrometric analysis of an NS5A-poly(rU) complex identified domains I and II as sites for interaction with RNA. Dimerization of NS5A was demonstrated by glutaraldehyde cross-linking. This dimerization is likely mediated by domain I-plus, as dimers of this protein are trapped by cross-linking. Dimers of the domain II-III protein are not observed. The monomer-dimer equilibrium of NS5A shifts in favor of dimer when U-rich RNA is present but not when A-rich RNA is present, consistent with an NS5A dimer being the RNA-binding-competent form of the protein. These data provide a molecular perspective of the NS5A-RNA complex and suggest possible mechanisms for regulation of HCV and cellular gene expression.
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Regulation of de novo-initiated RNA synthesis in hepatitis C virus RNA-dependent RNA polymerase by intermolecular interactions. J Virol 2010; 84:5923-35. [PMID: 20375156 DOI: 10.1128/jvi.02446-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) has been proposed to change conformations in association with RNA synthesis and to interact with cellular proteins. In vitro, the RdRp can initiate de novo from the ends of single-stranded RNA or extend a primed RNA template. The interactions between the Delta1 loop and thumb domain in NS5B are required for de novo initiation, although it is unclear whether these interactions are within an NS5B monomer or are part of a higher-order NS5B oligomeric complex. This work seeks to address how polymerase conformation and/or oligomerization affects de novo initiation. We have shown that an increasing enzyme concentration increases de novo initiation by the genotype 1b and 2a RdRps while primer extension reactions are not affected or inhibited under similar conditions. Initiation-defective mutants of the HCV polymerase can increase de novo initiation by the wild-type (WT) polymerase. GTP was also found to stimulate de novo initiation. Our results support a model in which the de novo initiation-competent conformation of the RdRp is stimulated by oligomeric contacts between individual subunits. Using electron microscopy and single-molecule reconstruction, we attempted to visualize the low-resolution conformations of a dimer of a de novo initiation-competent HCV RdRp.
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Hafrén A, Hofius D, Rönnholm G, Sonnewald U, Mäkinen K. HSP70 and its cochaperone CPIP promote potyvirus infection in Nicotiana benthamiana by regulating viral coat protein functions. THE PLANT CELL 2010; 22:523-35. [PMID: 20154150 PMCID: PMC2845415 DOI: 10.1105/tpc.109.072413] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 01/05/2010] [Accepted: 01/27/2010] [Indexed: 05/07/2023]
Abstract
This study demonstrates that heat shock protein 70 (HSP70) together with its cochaperone CPIP regulates the function of a potyviral coat protein (CP), which in turn can interfere with viral gene expression. HSP70 was copurified as a component of a membrane-associated viral ribonucleoprotein complex from Potato virus A-infected plants. Downregulation of HSP70 caused a CP-mediated defect associated with replication. When PVA CP was expressed in trans, it interfered with viral gene expression and replication-associated translation (RAT). However, CP produced in cis interfered specifically with RAT. CPIP binds to potyviral CP, and overexpression of CPIP was sufficient to restore RAT inhibited by expression of CP in trans. Restoration of RAT was dependent on the ability of CPIP to interact with HSP70 since expression of a J-domain mutant, CPIP(Delta66), had only a minor effect on RAT. CPIP-mediated delivery of CP to HSP70 promoted CP degradation by increasing its ubiquitination when assayed in the absence of virus infection. In conclusion, CPIP and HSP70 are crucial components of a distinct translation activity that is associated with potyvirus replication.
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Affiliation(s)
- Anders Hafrén
- Department of Applied Chemistry and Microbiology, University of Helsinki, 00014 Helsinki, Finland
| | - Daniel Hofius
- Department of Biology, Copenhagen Biocenter, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Gunilla Rönnholm
- Protein Chemistry Research Group and Core Facility, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Uwe Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Kristiina Mäkinen
- Department of Applied Chemistry and Microbiology, University of Helsinki, 00014 Helsinki, Finland
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Yi G, Vaughan RC, Yarbrough I, Dharmaiah S, Kao CC. RNA binding by the brome mosaic virus capsid protein and the regulation of viral RNA accumulation. J Mol Biol 2009; 391:314-26. [PMID: 19481091 PMCID: PMC2774812 DOI: 10.1016/j.jmb.2009.05.065] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2009] [Revised: 05/12/2009] [Accepted: 05/20/2009] [Indexed: 12/20/2022]
Abstract
Viral capsid proteins (CPs) can regulate gene expression and encapsulate viral RNAs. Low-level expression of the brome mosaic virus (BMV) CP was found to stimulate viral RNA accumulation, while higher levels inhibited translation and BMV RNA replication. Regulation of translation acts through an RNA element named the B box, which is also critical for the replicase assembly. The BMV CP has also been shown to preferentially bind to an RNA element named SLC that contains the core promoter for genomic minus-strand RNA synthesis. To further elucidate CP interaction with RNA, we used a reversible cross-linking-peptide fingerprinting assay to identify peptides in the capsid that contact the SLC, the B-box RNA, and the encapsidated RNA. Transient expression of three mutations made in residues within or close by the cross-linked peptides partially released the normal inhibition of viral RNA accumulation in agroinfiltrated Nicotiana benthamiana. Interestingly, two of the mutants, R142A and D148A, were found to retain the ability to down-regulate reporter RNA translation. These two mutants formed viral particles in inoculated leaves, but only R142A was able to move systemically in the inoculated plant. The R142A CP was found to have higher affinities for SLC and the B box compared with those of wild-type CP and to alter contacts to the RNA in the virion. These results better define how the BMV CP can interact with RNA and regulate different viral processes.
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Affiliation(s)
- Guanghui Yi
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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