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Filipe IC, Guedes MS, Zdobnov EM, Tapparel C. Enterovirus D: A Small but Versatile Species. Microorganisms 2021; 9:1758. [PMID: 34442837 PMCID: PMC8400195 DOI: 10.3390/microorganisms9081758] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 12/13/2022] Open
Abstract
Enteroviruses (EVs) from the D species are the causative agents of a diverse range of infectious diseases in spite of comprising only five known members. This small clade has a diverse host range and tissue tropism. It contains types infecting non-human primates and/or humans, and for the latter, they preferentially infect the eye, respiratory tract, gastrointestinal tract, and nervous system. Although several Enterovirus D members, in particular EV-D68, have been associated with neurological complications, including acute myelitis, there is currently no effective treatment or vaccine against any of them. This review highlights the peculiarities of this viral species, focusing on genome organization, functional elements, receptor usage, and pathogenesis.
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Affiliation(s)
- Ines Cordeiro Filipe
- Department of Microbiology and Molecular Medicine, University of Geneva, 1206 Geneva, Switzerland;
| | - Mariana Soares Guedes
- Department of Microbiology and Molecular Medicine, University of Geneva, 1206 Geneva, Switzerland;
| | - Evgeny M. Zdobnov
- Department of Genetic Medicine and Development, Switzerland and Swiss Institute of Bioinformatics, University of Geneva, 1206 Geneva, Switzerland;
| | - Caroline Tapparel
- Department of Microbiology and Molecular Medicine, University of Geneva, 1206 Geneva, Switzerland;
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2
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Eruera AR, McSweeney AM, McKenzie-Goldsmith GM, Ward VK. Protein Nucleotidylylation in +ssRNA Viruses. Viruses 2021; 13:1549. [PMID: 34452414 PMCID: PMC8402628 DOI: 10.3390/v13081549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 12/22/2022] Open
Abstract
Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the Caliciviridae, Coronaviridae, Picornaviridae and Potyviridae virus families. This modification occurs when the RNA-dependent RNA polymerase (RdRp) attaches one or more nucleotides to a target protein through a nucleotidyl-transferase reaction. The most characterized nucleotidylylation target is VPg (viral protein genome-linked), a protein linked to the 5' end of the genome in Caliciviridae, Picornaviridae and Potyviridae. The nucleotidylylation of VPg by RdRp is a critical step for the VPg protein to act as a primer for genome replication and, in Caliciviridae and Potyviridae, for the initiation of translation. In contrast, Coronaviridae do not express a VPg protein, but the nucleotidylylation of proteins involved in replication initiation is critical for genome replication. Furthermore, the RdRp proteins of the viruses that perform nucleotidylylation are themselves nucleotidylylated, and in the case of coronavirus, this has been shown to be essential for viral replication. This review focuses on nucleotidylylation within the picornavirus supergroup of viruses, including the proteins that are modified, what is known about the nucleotidylylation process and the roles that these modifications have in the viral life cycle.
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Affiliation(s)
| | | | | | - Vernon K. Ward
- Department of Microbiology & Immunology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand; (A.-R.E.); (A.M.M.); (G.M.M.-G.)
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Jackson T, Belsham GJ. Picornaviruses: A View from 3A. Viruses 2021; 13:v13030456. [PMID: 33799649 PMCID: PMC7999760 DOI: 10.3390/v13030456] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Picornaviruses are comprised of a positive-sense RNA genome surrounded by a protein shell (or capsid). They are ubiquitous in vertebrates and cause a wide range of important human and animal diseases. The genome encodes a single large polyprotein that is processed to structural (capsid) and non-structural proteins. The non-structural proteins have key functions within the viral replication complex. Some, such as 3Dpol (the RNA dependent RNA polymerase) have conserved functions and participate directly in replicating the viral genome, whereas others, such as 3A, have accessory roles. The 3A proteins are highly divergent across the Picornaviridae and have specific roles both within and outside of the replication complex, which differ between the different genera. These roles include subverting host proteins to generate replication organelles and inhibition of cellular functions (such as protein secretion) to influence virus replication efficiency and the host response to infection. In addition, 3A proteins are associated with the determination of host range. However, recent observations have challenged some of the roles assigned to 3A and suggest that other viral proteins may carry them out. In this review, we revisit the roles of 3A in the picornavirus life cycle. The 3AB precursor and mature 3A have distinct functions during viral replication and, therefore, we have also included discussion of some of the roles assigned to 3AB.
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Affiliation(s)
- Terry Jackson
- The Pirbright Institute, Pirbright, Woking, Surrey GU24 0NF, UK;
| | - Graham J. Belsham
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark
- Correspondence:
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Han KR, Lee JH, Kotiguda GG, Jung KH, Chung MS, Kang S, Hwang S, Kim KH. Nucleotide triphosphatase and RNA chaperone activities of murine norovirus NS3. J Gen Virol 2018; 99:1482-1493. [PMID: 30265237 DOI: 10.1099/jgv.0.001151] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Modulation of RNA structure is essential in the life cycle of RNA viruses. Immediate replication upon infection requires RNA unwinding to ensure that RNA templates are not in intra- or intermolecular duplex forms. The calicivirus NS3, one of the highly conserved nonstructural (NS) proteins, has conserved motifs common to helicase superfamily 3 among six genogroups. However, its biological functions are not fully understood. In this study we report the oligomeric state and the nucleotide triphosphatase (NTPase) and RNA chaperone activities of the recombinant full-length NS3 derived from murine norovirus (MNV). The MNV NS3 has an Mg2+-dependent NTPase activity, and site-directed mutagenesis of the conserved NTPase motifs blocked enzyme activity and viral replication in cells. Further, the NS3 was found via fluorescence resonance energy transfer (FRET)-based assays to destabilize double-stranded RNA in the presence of Mg2+ or Mn2+ in an NTP-independent manner. However, the RNA destabilization activity was not affected by mutagenesis of the conserved motifs of NTPase. These results reveal that the MNV NS3 has an NTPase-independent RNA chaperone-like activity, and that a FRET-based RNA destabilization assay has the potential to identify new antiviral drugs targeting NS3.
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Affiliation(s)
- Kang Rok Han
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea.,†Present address: Konkuk University, Seoul, Republic of Korea
| | - Ji-Hye Lee
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
| | - Giri Gowda Kotiguda
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea.,‡Present address: Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Kyoung Ho Jung
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
| | - Mi Sook Chung
- 2Department of Food and Nutrition, Duksung Women's University, Seoul 132-714, Republic of Korea
| | - Soowon Kang
- 3Department of Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Seungmin Hwang
- 3Department of Pathology, The University of Chicago, Chicago, IL 60637, USA
| | - Kyung Hyun Kim
- 1Department of Biotechnology and Bioinformatics, Korea University, Sejong 339-700, Republic of Korea
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Bentley K, Evans DJ. Mechanisms and consequences of positive-strand RNA virus recombination. J Gen Virol 2018; 99:1345-1356. [PMID: 30156526 DOI: 10.1099/jgv.0.001142] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Genetic recombination in positive-strand RNA viruses is a significant evolutionary mechanism that drives the creation of viral diversity by the formation of novel chimaeric genomes. The process and its consequences, for example the generation of viruses with novel phenotypes, has historically been studied by analysis of the end products. More recently, with an appreciation that there are both replicative and non-replicative mechanisms at work, and with new approaches and techniques to analyse intermediate products, the viral and cellular factors that influence the process are becoming understood. The major influence on replicative recombination is the fidelity of viral polymerase, although RNA structures and sequences may also have an impact. In replicative recombination the viral polymerase is necessary and sufficient, although roles for other viral or cellular proteins may exist. In contrast, non-replicative recombination appears to be mediated solely by cellular components. Despite these insights, the relative importance of replicative and non-replicative mechanisms is not clear. Using single-stranded positive-sense RNA viruses as exemplars, we review the current state of understanding of the processes and consequences of recombination.
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Affiliation(s)
- Kirsten Bentley
- Biomedical Sciences Research Complex and School of Biology, University of St Andrews, St Andrews, UK
| | - David J Evans
- Biomedical Sciences Research Complex and School of Biology, University of St Andrews, St Andrews, UK
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Reovirus Nonstructural Protein σNS Acts as an RNA Stability Factor Promoting Viral Genome Replication. J Virol 2018; 92:JVI.00563-18. [PMID: 29769334 DOI: 10.1128/jvi.00563-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/07/2018] [Indexed: 12/23/2022] Open
Abstract
Viral nonstructural proteins, which are not packaged into virions, are essential for the replication of most viruses. Reovirus, a nonenveloped, double-stranded RNA (dsRNA) virus, encodes three nonstructural proteins that are required for viral replication and dissemination in the host. The reovirus nonstructural protein σNS is a single-stranded RNA (ssRNA)-binding protein that must be expressed in infected cells for production of viral progeny. However, the activities of σNS during individual steps of the reovirus replication cycle are poorly understood. We explored the function of σNS by disrupting its expression during infection using cells expressing a small interfering RNA (siRNA) targeting the σNS-encoding S3 gene and found that σNS is required for viral genome replication. Using complementary biochemical assays, we determined that σNS forms complexes with viral and nonviral RNAs. We also discovered, using in vitro and cell-based RNA degradation experiments, that σNS increases the RNA half-life. Cryo-electron microscopy revealed that σNS and ssRNAs organize into long, filamentous structures. Collectively, our findings indicate that σNS functions as an RNA-binding protein that increases the viral RNA half-life. These results suggest that σNS forms RNA-protein complexes in preparation for genome replication.IMPORTANCE Following infection, viruses synthesize nonstructural proteins that mediate viral replication and promote dissemination. Viruses from the family Reoviridae encode nonstructural proteins that are required for the formation of progeny viruses. Although nonstructural proteins of different viruses in the family Reoviridae diverge in primary sequence, they are functionally homologous and appear to facilitate conserved mechanisms of dsRNA virus replication. Using in vitro and cell culture approaches, we found that the mammalian reovirus nonstructural protein σNS binds and stabilizes viral RNA and is required for genome synthesis. This work contributes new knowledge about basic mechanisms of dsRNA virus replication and provides a foundation for future studies to determine how viruses in the family Reoviridae assort and replicate their genomes.
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Human Norovirus NS3 Has RNA Helicase and Chaperoning Activities. J Virol 2018; 92:JVI.01606-17. [PMID: 29237842 DOI: 10.1128/jvi.01606-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/07/2017] [Indexed: 12/22/2022] Open
Abstract
RNA-remodeling proteins, including RNA helicases and chaperones, act to remodel RNA structures and/or protein-RNA interactions and are required for all processes involving RNAs. Although many viruses encode RNA helicases and chaperones, their in vitro activities and their roles in infected cells largely remain elusive. Noroviruses are a diverse group of positive-strand RNA viruses in the family Caliciviridae and constitute a significant and potentially fatal threat to human health. Here, we report that the protein NS3 encoded by human norovirus has both ATP-dependent RNA helicase activity that unwinds RNA helices and ATP-independent RNA-chaperoning activity that can remodel structured RNAs and facilitate strand annealing. Moreover, NS3 can facilitate viral RNA synthesis in vitro by norovirus polymerase. NS3 may therefore play an important role in norovirus RNA replication. Lastly, we demonstrate that the RNA-remodeling activity of NS3 is inhibited by guanidine hydrochloride, an FDA-approved compound, and, more importantly, that it reduces the replication of the norovirus replicon in cultured human cells. Altogether, these findings are the first to demonstrate the presence of RNA-remodeling activities encoded by Caliciviridae and highlight the functional significance of NS3 in the noroviral life cycle.IMPORTANCE Noroviruses are a diverse group of positive-strand RNA viruses, which annually cause hundreds of millions of human infections and over 200,000 deaths worldwide. For RNA viruses, cellular or virus-encoded RNA helicases and/or chaperones have long been considered to play pivotal roles in viral life cycles. However, neither RNA helicase nor chaperoning activity has been demonstrated to be associated with any norovirus-encoded proteins, and it is also unknown whether norovirus replication requires the participation of any viral or cellular RNA helicases/chaperones. We found that a norovirus protein, NS3, not only has ATP-dependent helicase activity, but also acts as an ATP-independent RNA chaperone. Also, NS3 can facilitate in vitro viral RNA synthesis, suggesting the important role of NS3 in norovirus replication. Moreover, NS3 activities can be inhibited by an FDA-approved compound, which also suppresses norovirus replicon replication in human cells, raising the possibility that NS3 could be a target for antinoroviral drug development.
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Abstract
RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging and slow. Therefore, cells and viruses encode a variety of RNA remodeling proteins, including helicases and RNA chaperones. In RNA viruses, these proteins are believed to play pivotal roles in all the processes involving viral RNAs during the life cycle. RNA helicases have been studied extensively for decades, whereas RNA chaperones, particularly virus-encoded RNA chaperones, are often overlooked. This review describes the activities of RNA chaperones encoded by RNA viruses, particularly the ones identified and characterized in recent years, and the functions of these proteins in different steps of viral life cycles, and presents an overview of this unique group of proteins.
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Affiliation(s)
- Jie Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Hongjie Xia
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Qi Qian
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xi Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
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Xia H, Wang P, Wang GC, Yang J, Sun X, Wu W, Qiu Y, Shu T, Zhao X, Yin L, Qin CF, Hu Y, Zhou X. Human Enterovirus Nonstructural Protein 2CATPase Functions as Both an RNA Helicase and ATP-Independent RNA Chaperone. PLoS Pathog 2015. [PMID: 26218680 PMCID: PMC4517893 DOI: 10.1371/journal.ppat.1005067] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
RNA helicases and chaperones are the two major classes of RNA remodeling proteins, which function to remodel RNA structures and/or RNA-protein interactions, and are required for all aspects of RNA metabolism. Although some virus-encoded RNA helicases/chaperones have been predicted or identified, their RNA remodeling activities in vitro and functions in the viral life cycle remain largely elusive. Enteroviruses are a large group of positive-stranded RNA viruses in the Picornaviridae family, which includes numerous important human pathogens. Herein, we report that the nonstructural protein 2CATPase of enterovirus 71 (EV71), which is the major causative pathogen of hand-foot-and-mouth disease and has been regarded as the most important neurotropic enterovirus after poliovirus eradication, functions not only as an RNA helicase that 3′-to-5′ unwinds RNA helices in an adenosine triphosphate (ATP)-dependent manner, but also as an RNA chaperone that destabilizes helices bidirectionally and facilitates strand annealing and complex RNA structure formation independently of ATP. We also determined that the helicase activity is based on the EV71 2CATPase middle domain, whereas the C-terminus is indispensable for its RNA chaperoning activity. By promoting RNA template recycling, 2CATPase facilitated EV71 RNA synthesis in vitro; when 2CATPase helicase activity was impaired, EV71 RNA replication and virion production were mostly abolished in cells, indicating that 2CATPase-mediated RNA remodeling plays a critical role in the enteroviral life cycle. Furthermore, the RNA helicase and chaperoning activities of 2CATPase are also conserved in coxsackie A virus 16 (CAV16), another important enterovirus. Altogether, our findings are the first to demonstrate the RNA helicase and chaperoning activities associated with enterovirus 2CATPase, and our study provides both in vitro and cellular evidence for their potential roles during viral RNA replication. These findings increase our understanding of enteroviruses and the two types of RNA remodeling activities. Enteroviruses contain a large number of closely related human pathogens, including poliovirus, EV71, and coxsackie viruses, and cause ~3 billion infections annually. Among the nonstructural proteins of enteroviruses or picornaviruses, protein 2CATPase is the most conserved and complex but the least understood. On the basis of sequence analyses, this protein has been predicted as a putative superfamily 3 (SF3) helicase that supposedly plays a pivotal role in enteroviral RNA replication. However, attempts to determine the helicase activity associated with 2CATPase have been unsuccessful. We found that eukaryotically expressed EV71 or CAV16 2CATPase does possess an ATP-dependent RNA helicase activity that 3′→5′ unwinds RNA helices like other SF3 helicases; surprisingly, it also functions as an RNA chaperone that remodels RNA structures in an ATP-independent manner. Moreover, we determined the domain requirements for these two RNA remodeling activities associated with 2CATPase and provide both in vitro and cellular evidence of their potential roles during viral RNA replication. Additionally, our study provides the first evidence that RNA helicase and chaperoning activities can be integrated within one protein, thereby introducing an extended view of RNA remodeling proteins.
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Affiliation(s)
- Hongjie Xia
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Peipei Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Guang-Chuan Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jie Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xianlin Sun
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Wenzhe Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Yang Qiu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ting Shu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xiaolu Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Lei Yin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Cheng-Feng Qin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yuanyang Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xi Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
- * E-mail:
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Paul AV, Wimmer E. Initiation of protein-primed picornavirus RNA synthesis. Virus Res 2015; 206:12-26. [PMID: 25592245 DOI: 10.1016/j.virusres.2014.12.028] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/16/2014] [Accepted: 12/24/2014] [Indexed: 12/14/2022]
Abstract
Plus strand RNA viruses use different mechanisms to initiate the synthesis of their RNA chains. The Picornaviridae family constitutes a large group of plus strand RNA viruses that possess a small terminal protein (VPg) covalently linked to the 5'-end of their genomes. The RNA polymerases of these viruses use VPg as primer for both minus and plus strand RNA synthesis. In the first step of the initiation reaction the RNA polymerase links a UMP to the hydroxyl group of a tyrosine in VPg using as template a cis-replicating element (cre) positioned in different regions of the viral genome. In this review we will summarize what is known about the initiation reaction of protein-primed RNA synthesis by the RNA polymerases of the Picornaviridae. As an example we will use the RNA polymerase of poliovirus, the prototype of Picornaviridae. We will also discuss models of how these nucleotidylylated protein primers might be used, together with viral and cellular replication proteins and other cis-replicating RNA elements, during minus and plus strand RNA synthesis.
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Affiliation(s)
- Aniko V Paul
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States.
| | - Eckard Wimmer
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States
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Sun Y, Guo Y, Lou Z. Formation and working mechanism of the picornavirus VPg uridylylation complex. Curr Opin Virol 2014; 9:24-30. [PMID: 25240314 DOI: 10.1016/j.coviro.2014.09.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 02/05/2023]
Abstract
The initiation of picornavirus replication is featured by the uridylylation of viral protein genome-linked (VPg). In this process, viral RNA-dependent RNA polymerase (RdRp) catalyzes two uridine monophosphate (UMP) molecules to the hydroxyl group of the third tyrosine residue of VPg. Subsequently, the uridylylated VPg (VPg-pUpU) functions as the protein primer to initiate the replication of the viral genome. Although a large body of functional and structural works has been performed to define individual snapshots for particular stages of the VPg uridylylation process, the formation, dynamics and mechanism of the whole VPg uridylylation complex still requires further elucidation. We would like to provide an overview of the current knowledge of the picornaviral VPg uridylylation complex in this paper.
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Affiliation(s)
- Yuna Sun
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China; School of Medicine and MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing 100084, China
| | - Yu Guo
- College of Pharmacy and State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
| | - Zhiyong Lou
- School of Medicine and MOE Key Laboratory of Protein Sciences, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center for Biotherapy, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center for Biotherapy, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, China.
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12
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Tang F, Xia H, Wang P, Yang J, Zhao T, Zhang Q, Hu Y, Zhou X. The identification and characterization of nucleic acid chaperone activity of human enterovirus 71 nonstructural protein 3AB. Virology 2014; 464-465:353-364. [PMID: 25113906 PMCID: PMC7112070 DOI: 10.1016/j.virol.2014.07.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 06/17/2014] [Accepted: 07/22/2014] [Indexed: 11/17/2022]
Abstract
Human enterovirus 71 (EV71) belongs to the genus Enterovirus in the family Picornaviridae and has been recognized as one of the most important pathogens that cause emerging infectious disease. Despite of the importance of EV71, the nonstructural protein 3AB from this virus is little understood for its function during EV71 replication. Here we expressed EV71 3AB protein as recombinant protein in a eukaryotic expression system and uncovered that this protein possesses a nucleic acid helix-destabilizing and strand annealing acceleration activity in a dose-dependent manner, indicating that EV71 3AB is a nucleic acid chaperone protein. Moreover, we characterized the RNA chaperone activity of EV71 3AB, and revealed that divalent metal ions, such as Mg2+ and Zn2+, were able to inhibit the RNA helix-destabilizing activity of 3AB to different extents. Moreover, we determined that 3B plus the last 7 amino acids at the C-terminal of 3A (termed 3B+7) possess the RNA chaperone activity, and five amino acids, i.e. Lys-80, Phe-82, Phe-85, Tyr-89, and Arg-103, are critical and probably the active sites of 3AB for its RNA chaperone activity. This report reveals that EV71 3AB displays an RNA chaperone activity, adds a new member to the growing list of virus-encoded RNA chaperones, and provides novel knowledge about the virology of EV71.
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Affiliation(s)
- Fenfen Tang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Hongjie Xia
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Peipei Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Jie Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Tianyong Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Qi Zhang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China
| | - Yuanyang Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China.
| | - Xi Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072 China.
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13
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Yang J, Cheng Z, Zhang S, Xiong W, Xia H, Qiu Y, Wang Z, Wu F, Qin CF, Yin L, Hu Y, Zhou X. A cypovirus VP5 displays the RNA chaperone-like activity that destabilizes RNA helices and accelerates strand annealing. Nucleic Acids Res 2013; 42:2538-54. [PMID: 24319147 PMCID: PMC3936753 DOI: 10.1093/nar/gkt1256] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
For double-stranded RNA (dsRNA) viruses in the family Reoviridae, their inner capsids function as the machinery for viral RNA (vRNA) replication. Unlike other multishelled reoviruses, cypovirus has a single-layered capsid, thereby representing a simplified model for studying vRNA replication of reoviruses. VP5 is one of the three major cypovirus capsid proteins and functions as a clamp protein to stabilize cypovirus capsid. Here, we expressed VP5 from type 5 Helicoverpa armigera cypovirus (HaCPV-5) in a eukaryotic system and determined that this VP5 possesses RNA chaperone-like activity, which destabilizes RNA helices and accelerates strand annealing independent of ATP. Our further characterization of VP5 revealed that its helix-destabilizing activity is RNA specific, lacks directionality and could be inhibited by divalent ions, such as Mg(2+), Mn(2+), Ca(2+) or Zn(2+), to varying degrees. Furthermore, we found that HaCPV-5 VP5 facilitates the replication initiation of an alternative polymerase (i.e. reverse transcriptase) through a panhandle-structured RNA template, which mimics the 5'-3' cyclization of cypoviral positive-stranded RNA. Given that the replication of negative-stranded vRNA on the positive-stranded vRNA template necessitates the dissociation of the 5'-3' panhandle, the RNA chaperone activity of VP5 may play a direct role in the initiation of reoviral dsRNA synthesis.
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Affiliation(s)
- Jie Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China and Department of Biochemistry, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China
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14
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McDonald SM. RNA synthetic mechanisms employed by diverse families of RNA viruses. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:351-67. [PMID: 23606593 PMCID: PMC7169773 DOI: 10.1002/wrna.1164] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RNA viruses are ubiquitous in nature, infecting every known organism on the planet. These viruses can also be notorious human pathogens with significant medical and economic burdens. Central to the lifecycle of an RNA virus is the synthesis of new RNA molecules, a process that is mediated by specialized virally encoded enzymes called RNA‐dependent RNA polymerases (RdRps). RdRps directly catalyze phosphodiester bond formation between nucleoside triphosphates in an RNA‐templated manner. These enzymes are strikingly conserved in their structural and functional features, even among diverse RNA viruses belonging to different families. During host cell infection, the activities of viral RdRps are often regulated by viral cofactor proteins. Cofactors can modulate the type and timing of RNA synthesis by directly engaging the RdRp and/or by indirectly affecting its capacity to recognize template RNA. High‐resolution structures of RdRps as apoenzymes, bound to RNA templates, in the midst of catalysis, and/or interacting with regulatory cofactor proteins, have dramatically increased our understanding of viral RNA synthetic mechanisms. Combined with elegant biochemical studies, such structures are providing a scientific platform for the rational design of antiviral agents aimed at preventing and treating RNA virus‐induced diseases. WIREs RNA 2013, 4:351–367. doi: 10.1002/wrna.1164 This article is categorized under:
RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes RNA in Disease and Development > RNA in Disease
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Affiliation(s)
- Sarah M McDonald
- Virginia Tech Carilion Research Institute and School of Medicine, Roanoke, VA, USA.
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15
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The nonstructural protein 2C of a Picorna-like virus displays nucleic acid helix destabilizing activity that can be functionally separated from its ATPase activity. J Virol 2013; 87:5205-18. [PMID: 23449794 DOI: 10.1128/jvi.00245-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Picorna-like viruses in the Picornavirales order are a large group of positive-strand RNA viruses that include numerous important pathogens for plants, insects, and humans. In these viruses, nonstructural protein 2C is one of the most conserved proteins and contains ATPase activity and putative RNA helicase activity. Here we expressed 2C protein of Ectropis obliqua picorna-like virus (EoV; genus Iflavirus, family Iflaviridae, order Picornavirales) in a eukaryotic expression system and determined that EoV 2C displays ATP-independent nucleic acid helix destabilizing and strand annealing acceleration activity in a concentration-dependent manner, indicating that this picornaviral 2C is more like an RNA chaperone than like the previously predicted RNA helicase. Our further characterization of EoV 2C revealed that divalent metal ions, such as Mg(2+) and Zn(2+), inhibit 2C-mediated helix destabilization to different extents. Moreover, we determined that EoV 2C also contains ATPase activity like that of other picornaviral 2C proteins and further assessed the functional relevance between its RNA chaperone-like and ATPase activities using mutational analysis as well as their responses to Mg(2+). Our data show that, when one of the two 2C activities was dramatically inhibited or almost abolished, the other activity could remain intact, showing that the RNA chaperone-like and ATPase activities of EoV 2C can be functionally separated. This report reveals that a picorna-like virus 2C protein displays RNA helix destabilizing and strand annealing acceleration activity, which may be critical for picornaviral replication and pathogenesis, and should foster our understanding of picorna-like viruses and viral RNA chaperones.
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16
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Godet J, Boudier C, Humbert N, Ivanyi-Nagy R, Darlix JL, Mély Y. Comparative nucleic acid chaperone properties of the nucleocapsid protein NCp7 and Tat protein of HIV-1. Virus Res 2012; 169:349-60. [PMID: 22743066 PMCID: PMC7114403 DOI: 10.1016/j.virusres.2012.06.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/18/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
Abstract
RNA chaperones are proteins able to rearrange nucleic acid structures towards their most stable conformations. In retroviruses, the reverse transcription of the viral RNA requires multiple and complex nucleic acid rearrangements that need to be chaperoned. HIV-1 has evolved different viral-encoded proteins with chaperone activity, notably Tat and the well described nucleocapsid protein NCp7. We propose here an overview of the recent reports that examine and compare the nucleic acid chaperone properties of Tat and NCp7 during reverse transcription to illustrate the variety of mechanisms of action of the nucleic acid chaperone proteins.
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Affiliation(s)
- Julien Godet
- Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg, 67401 Illkirch, France
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17
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Hull C, Szewcyk C, St John PM. Effects of locked nucleic acid substitutions on the stability of oligonucleotide hairpins. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 31:28-41. [PMID: 22257208 DOI: 10.1080/15257770.2011.639826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
An understanding of the stability of nucleic acid folding is critical for applications involving RNA viruses, small molecule-RNA binding, and therapeutics, for example. To explore factors that affect this stability, hairpins made from oligonucleotides containing both a GAAA tetraloop and three to five complements in the stem have been used as models where locked nucleic acids (LNAs) have been substituted into the sequence. UV spectroscopy was used to obtain melting curves in 20% by volume formamide, and the enthalpies and entropies of melting were determined. Although LNA substitutions typically increase the stability of a hybrid, we have found a decrease in stability for DNA and RNA GAAA hairpins when LNA is substituted into the loop. Tetraloops synthesized from natural bases show higher enthalpies and entropies of melting compared to the LNA substituted sequences indicating that LNA substitutions can destabilize a hairpin but stabilize the corresponding double stranded structure.
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Affiliation(s)
- Chelsea Hull
- Chemistry Department, State University of New York at New Paltz, New Paltz, New York 12561, USA
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18
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Stork J, Kovalev N, Sasvari Z, Nagy PD. RNA chaperone activity of the tombusviral p33 replication protein facilitates initiation of RNA synthesis by the viral RdRp in vitro. Virology 2010; 409:338-47. [PMID: 21071052 PMCID: PMC7173327 DOI: 10.1016/j.virol.2010.10.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 09/19/2010] [Accepted: 10/12/2010] [Indexed: 12/18/2022]
Abstract
Small plus-stranded RNA viruses do not code for RNA helicases that would facilitate the proper folding of viral RNAs during replication. Instead, these viruses might use RNA chaperones as shown here for the essential p33 replication protein of Tomato bushy stunt virus (TBSV). In vitro experiments demonstrate that the purified recombinant p33 promotes strand separation of a DNA/RNA duplex. In addition, p33 renders dsRNA templates sensitive to single-strand specific S1 nuclease, suggesting that p33 can destabilize highly structured RNAs. We also demonstrate that the RNA chaperone activity of p33 facilitates self-cleavage by a ribozyme in vitro. In addition, purified p33 facilitates in vitro RNA synthesis on double-stranded (ds)RNA templates up to 5-fold by a viral RNA-dependent RNA polymerase. We propose that the RNA chaperone activity of p33 facilitates the initiation of plus-strand synthesis as well as affects RNA recombination. Altogether, the TBSV RNA chaperone might perform similar biological functions to the helicases of other RNA viruses with much larger coding capacity.
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Affiliation(s)
- Jozsef Stork
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA
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19
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Gangaramani DR, Eden EL, Shah M, Destefano JJ. The twenty-nine amino acid C-terminal cytoplasmic domain of poliovirus 3AB is critical for nucleic acid chaperone activity. RNA Biol 2010; 7:820-9. [PMID: 21045553 DOI: 10.4161/rna.7.6.13781] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Poliovirus 3AB protein is the first picornavirus protein demonstrated to have nucleic acid chaperone activity. Further characterization of 3AB demonstrates that the C-terminal 22 amino acids (3B region (also referred to as VPg), amino acid 88-109) of the protein is required for chaperone activity, as mutations in this region abrogate nucleic acid binding and chaperone function. Protein 3B alone has no chaperone activity as determined by established assays that include the ability to stimulate nucleic acid hybridization in a primer-template annealing assay, helix-destabilization in a nucleic acid unwinding assay, or aggregation of nucleic acids. In contrast, the putative 3AB C-terminal cytoplasmic domain (C terminal amino acids 81-109, 3B + the last 7 C-terminal amino acids of 3A, termed 3B+7 in this report) possesses strong activity in these assays, albeit at much higher concentrations than 3AB. The characteristics of several mutations in 3B+7 are described here, as well as a model proposing that 3B+7 is the site of the "intrinsic" chaperone activity of 3AB while the 3A N-terminal region (amino acids 1-58) and/or membrane anchor domain (amino acids 59-80) serve to increase the effective concentration of the 3B+7 region leading to the potent chaperone activity of 3AB.
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Affiliation(s)
- Divya R Gangaramani
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
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20
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Dedepsidis E, Kyriakopoulou Z, Pliaka V, Markoulatos P. Correlation between recombination junctions and RNA secondary structure elements in poliovirus Sabin strains. Virus Genes 2010; 41:181-91. [PMID: 20640496 PMCID: PMC7089419 DOI: 10.1007/s11262-010-0512-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 06/28/2010] [Indexed: 11/25/2022]
Abstract
In order to test the hypothesis that RNA structural elements promote the distribution of certain types of recombination junctions in each one of the 2C and 3D poliovirus genomic regions (Sabin 3/Sabin 2 or Sabin 1 in 2C and Sabin 2/Sabin 1 or Sabin 3 in 3D), we searched in 2C and 3D regions of reference Sabin strains for high probability RNA structural elements that could promote recombination. Recombination junctions that were identified in clinical strains of this study, as well as in clinical strains of previous studies, were superimposed on RNA secondary structure models of 2C and 3D genomic regions. Furthermore, we created an in vitro model, based on double infection of cell-culture with two poliovirus strains, for the production and identification of recombinant Sabin strains in 2C and 3D regions. Our intention was to compare the results that refer to the correlation of recombination junctions and RNA secondary structures in 2C and 3D regions of clinical strains, with the respective results of the in vitro model. Most of the recombination junctions of the clinical strains were correlated with RNA secondary structure elements, which were identical between recombining Sabin strains, and also presented high predictive value. In consensus were, the respective results originated from the in vitro model. We propose that the distribution of specific types of recombination junctions in certain regions of Sabin strains is not fortuitous and is correlated with RNA secondary structure elements identical to both recombination partners. Furthermore, results of this study highlight an important role for the stem region of the RNA structure elements in promoting recombination.
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Affiliation(s)
- Evaggelos Dedepsidis
- Department of Biochemistry and Biotechnology, Microbiology–Virology Laboratory, University of Thessaly, 26 Ploutonos and Aiolou Str., Larisa, 41221 Greece
| | - Zaharoula Kyriakopoulou
- Department of Biochemistry and Biotechnology, Microbiology–Virology Laboratory, University of Thessaly, 26 Ploutonos and Aiolou Str., Larisa, 41221 Greece
| | - Vaia Pliaka
- Department of Biochemistry and Biotechnology, Microbiology–Virology Laboratory, University of Thessaly, 26 Ploutonos and Aiolou Str., Larisa, 41221 Greece
| | - Panayotis Markoulatos
- Department of Biochemistry and Biotechnology, Microbiology–Virology Laboratory, University of Thessaly, 26 Ploutonos and Aiolou Str., Larisa, 41221 Greece
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21
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Cameron CE, Oh HS, Moustafa IM. Expanding knowledge of P3 proteins in the poliovirus lifecycle. Future Microbiol 2010; 5:867-81. [PMID: 20521933 PMCID: PMC2904470 DOI: 10.2217/fmb.10.40] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Poliovirus is the most extensively studied member of the order Picornavirales, which contains numerous medical, veterinary and agricultural pathogens. The picornavirus genome encodes a single polyprotein that is divided into three regions: P1, P2 and P3. P3 proteins are known to participate more directly in genome replication, for example by containing the viral RNA-dependent RNA polymerase (RdRp or 3Dpol), among several other proteins and enzymes. We will review recent data that provide new insight into the structure, function and mechanism of P3 proteins and their complexes, which are required for initiation of genome replication. Replication of poliovirus genomes occurs within macromolecular complexes, containing viral RNA, viral proteins and host-cell membranes, collectively referred to as replication complexes. P2 proteins clearly contribute to interactions with the host cell that are required for virus multiplication, including formation of replication complexes. We will discuss recent data that suggest a role for P3 proteins in formation of replication complexes. Among the least understood steps of the poliovirus lifecycle is encapsidation of genomic RNA. We will also describe data that suggest a role for P3 proteins in this step.
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Affiliation(s)
- Craig E Cameron
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA.
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22
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Lin JY, Chen TC, Weng KF, Chang SC, Chen LL, Shih SR. Viral and host proteins involved in picornavirus life cycle. J Biomed Sci 2009; 16:103. [PMID: 19925687 PMCID: PMC2785775 DOI: 10.1186/1423-0127-16-103] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2009] [Accepted: 11/20/2009] [Indexed: 01/11/2023] Open
Abstract
Picornaviruses cause several diseases, not only in humans but also in various animal hosts. For instance, human enteroviruses can cause hand-foot-and-mouth disease, herpangina, myocarditis, acute flaccid paralysis, acute hemorrhagic conjunctivitis, severe neurological complications, including brainstem encephalitis, meningitis and poliomyelitis, and even death. The interaction between the virus and the host is important for viral replication, virulence and pathogenicity. This article reviews studies of the functions of viral and host factors that are involved in the life cycle of picornavirus. The interactions of viral capsid proteins with host cell receptors is discussed first, and the mechanisms by which the viral and host cell factors are involved in viral replication, viral translation and the switch from translation to RNA replication are then addressed. Understanding how cellular proteins interact with viral RNA or viral proteins, as well as the roles of each in viral infection, will provide insights for the design of novel antiviral agents based on these interactions.
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Affiliation(s)
- Jing-Yi Lin
- Research Center for Emerging Viral Infections, Chang Gung University, Tao-Yuan, Taiwan.
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23
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Effect of reaction conditions and 3AB on the mutation rate of poliovirus RNA-dependent RNA polymerase in a alpha-complementation assay. Virus Res 2009; 147:53-9. [PMID: 19850090 DOI: 10.1016/j.virusres.2009.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 10/01/2009] [Accepted: 10/09/2009] [Indexed: 12/11/2022]
Abstract
The fidelity of poliovirus RNA-dependent RNA polymerase (3Dpol) was determined using a modified alpha-complementation assay. Several polymerases have been analyzed by this approach allowing comparisons to be drawn. Various conditions including high and low MgCl(2), replacing MgCl(2) with MnCl(2), skewed nucleotide pools, and the presence of poliovirus protein 3AB were analyzed. The assay included RNA synthesis by 3Dpol on an RNA template that coded for a region of the alpha peptide of beta-galactosidase (lacZ-alpha). The product of this reaction was used as a template for a second round of 3Dpol synthesis and the resulting RNA was reverse transcribed to DNA by reverse transcriptase. The DNA was amplified by PCR and inserted into a vector used to transform Escherichia coli. The bacteria were screened for beta-galactosidase activity by blue-white phenotype analysis with white or faint blue colonies scored as errors made during synthesis on lacZ-alpha. Although 3AB strongly stimulated 3Dpol synthesis as expected, no change in fidelity was detected. Changes in MgCl(2) also showed little effect. Mutation rates of approximately 9 x 10(-5) (approximately 1 error per 11,000 incorporations) were estimated for these conditions. In contrast, MnCl(2) or skewed nucleotide pools were highly mutagenic resulting in lowered fidelity.
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Zúñiga S, Sola I, Cruz JLG, Enjuanes L. Role of RNA chaperones in virus replication. Virus Res 2008; 139:253-66. [PMID: 18675859 PMCID: PMC7114511 DOI: 10.1016/j.virusres.2008.06.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 06/18/2008] [Accepted: 06/23/2008] [Indexed: 01/06/2023]
Abstract
RNA molecules are functionally diverse in part due to their extreme structural flexibility that allows rapid regulation by refolding. RNA folding could be a difficult process as often molecules adopt a spatial conformation that is very stable but not biologically functional, named a kinetic trap. RNA chaperones are non-specific RNA binding proteins that help RNA folding by resolving misfolded structures or preventing their formation. There is a large number of viruses whose genome is RNA that allows some evolutionary advantages, such as rapid genome mutation. On the other hand, regions of the viral RNA genomes can adopt different structural conformations, some of them lacking functional relevance and acting as misfolded intermediates. In fact, for an efficient replication, they often require RNA chaperone activities. There is a growing list of RNA chaperones encoded by viruses involved in different steps of the viral cycle. Also, cellular RNA chaperones have been involved in replication of RNA viruses. This review briefly describes RNA chaperone activities and is focused in the roles that viral or cellular nucleic acid chaperones have in RNA virus replication, particularly in those viruses that require discontinuous RNA synthesis.
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Affiliation(s)
- Sonia Zúñiga
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universitario de Cantoblanco, Darwin 3, 28049 Madrid, Spain
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Live cell imaging of protein interactions in poliovirus RNA replication complex using fluorescence resonance energy transfer (FRET). Biochem Biophys Res Commun 2008; 368:489-94. [PMID: 18252199 DOI: 10.1016/j.bbrc.2008.01.094] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 01/17/2008] [Indexed: 11/23/2022]
Abstract
Poliovirus RNA replication is directed by a replication complex on the rosette-like arrangement of membranous vesicles. Proteins derived from the p3 region of the polioviral genome, such as 3D, 3AB, and 3B (VPg), play key roles in the formation and function of the replication complex. In the present study, by using an acceptor photobleaching protocol for fluorescence resonance energy transfer (FRET) imaging, we visualized the interactions of 3D, 3AB, and VPg in living cells. The interaction of 3AB-VPg was determined by live cell FRET analysis. Quantitative analyses showed that the FRET efficiencies of 3AB-3D, VPg-3D, and 3AB-VPg were 3.9+/-0.4% (n=36), 4.5+/-0.4% (n=39), and 8.3+/-0.6% (n=44), respectively, in the cell cytoplasm where viral replication complexes are formed and function. Poliovirus infection enhanced the protein interactions of VPg-3D and 3AB-3D, with FRET efficiencies in the virus-infected cells of 10.7+/-1.1% (n=39) and 9.0+/-0.9% (n=37), respectively. This method of live cell analysis of protein interactions in the poliovirus RNA replication complex lays the foundation for further understanding of the real-time process of poliovirus RNA replication.
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Zúñiga S, Sola I, Moreno JL, Sabella P, Plana-Durán J, Enjuanes L. Coronavirus nucleocapsid protein is an RNA chaperone. Virology 2006; 357:215-27. [PMID: 16979208 PMCID: PMC7111943 DOI: 10.1016/j.virol.2006.07.046] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 07/11/2006] [Accepted: 07/29/2006] [Indexed: 01/19/2023]
Abstract
RNA chaperones are nonspecific nucleic acid binding proteins with long disordered regions that help RNA molecules to adopt its functional conformation. Coronavirus nucleoproteins (N) are nonspecific RNA-binding proteins with long disordered regions. Therefore, we investigated whether transmissible gastroenteritis coronavirus (TGEV) N protein was an RNA chaperone. Purified N protein enhanced hammerhead ribozyme self-cleavage and nucleic acids annealing, which are properties that define RNA chaperones. In contrast, another RNA-binding protein, PTB, did not show these activities. N protein chaperone activity was blocked by specific monoclonal antibodies. Therefore, it was concluded that TGEV N protein is an RNA chaperone. In addition, we have shown that purified severe acute respiratory syndrome (SARS)-CoV N protein also has RNA chaperone activity. In silico predictions of disordered domains showed a similar pattern for all coronavirus N proteins evaluated. Altogether, these data led us to suggest that all coronavirus N proteins might be RNA chaperones.
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Affiliation(s)
- Sonia Zúñiga
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Darwin 3, Cantoblanco, 28049 Madrid, Spain
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