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Carter T, Iqbal M. The Influenza A Virus Replication Cycle: A Comprehensive Review. Viruses 2024; 16:316. [PMID: 38400091 PMCID: PMC10892522 DOI: 10.3390/v16020316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/15/2024] [Accepted: 02/17/2024] [Indexed: 02/25/2024] Open
Abstract
Influenza A virus (IAV) is the primary causative agent of influenza, colloquially called the flu. Each year, it infects up to a billion people, resulting in hundreds of thousands of human deaths, and causes devastating avian outbreaks with worldwide losses worth billions of dollars. Always present is the possibility that a highly pathogenic novel subtype capable of direct human-to-human transmission will spill over into humans, causing a pandemic as devastating if not more so than the 1918 influenza pandemic. While antiviral drugs for influenza do exist, they target very few aspects of IAV replication and risk becoming obsolete due to antiviral resistance. Antivirals targeting other areas of IAV replication are needed to overcome this resistance and combat the yearly epidemics, which exact a serious toll worldwide. This review aims to summarise the key steps in the IAV replication cycle, along with highlighting areas of research that need more focus.
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Affiliation(s)
- Toby Carter
- The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK;
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2
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Xie E, Ahmad S, Smyth RP, Sieben C. Advanced fluorescence microscopy in respiratory virus cell biology. Adv Virus Res 2023; 116:123-172. [PMID: 37524480 DOI: 10.1016/bs.aivir.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Respiratory viruses are a major public health burden across all age groups around the globe, and are associated with high morbidity and mortality rates. They can be transmitted by multiple routes, including physical contact or droplets and aerosols, resulting in efficient spreading within the human population. Investigations of the cell biology of virus replication are thus of utmost importance to gain a better understanding of virus-induced pathogenicity and the development of antiviral countermeasures. Light and fluorescence microscopy techniques have revolutionized investigations of the cell biology of virus infection by allowing the study of the localization and dynamics of viral or cellular components directly in infected cells. Advanced microscopy including high- and super-resolution microscopy techniques available today can visualize biological processes at the single-virus and even single-molecule level, thus opening a unique view on virus infection. We will highlight how fluorescence microscopy has supported investigations on virus cell biology by focusing on three major respiratory viruses: respiratory syncytial virus (RSV), Influenza A virus (IAV) and SARS-CoV-2. We will review our current knowledge of virus replication and highlight how fluorescence microscopy has helped to improve our state of understanding. We will start by introducing major imaging and labeling modalities and conclude the chapter with a perspective discussion on remaining challenges and potential opportunities.
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Affiliation(s)
- Enyu Xie
- Nanoscale Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Shazeb Ahmad
- Helmholtz Institute for RNA-based Infection Research, Helmholtz Centre for Infection Research, Würzburg, Germany
| | - Redmond P Smyth
- Helmholtz Institute for RNA-based Infection Research, Helmholtz Centre for Infection Research, Würzburg, Germany; Faculty of Medicine, University of Würzburg, Würzburg, Germany
| | - Christian Sieben
- Nanoscale Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany; Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany.
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3
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Gaucherand L, Iyer A, Gilabert I, Rycroft CH, Gaglia MM. Cut site preference allows influenza A virus PA-X to discriminate between host and viral mRNAs. Nat Microbiol 2023; 8:1304-1317. [PMID: 37349586 PMCID: PMC10690756 DOI: 10.1038/s41564-023-01409-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 05/10/2023] [Indexed: 06/24/2023]
Abstract
Many viruses block host gene expression to take over the infected cell. This process, termed host shutoff, is thought to promote viral replication by preventing antiviral responses and redirecting cellular resources to viral processes. Several viruses from divergent families accomplish host shutoff through RNA degradation by endoribonucleases. However, viruses also need to ensure expression of their own genes. The influenza A virus endoribonuclease PA-X solves this problem by sparing viral mRNAs and some host RNAs necessary for viral replication. To understand how PA-X distinguishes between RNAs, we characterized PA-X cut sites transcriptome-wide using 5' rapid amplification of complementary DNA ends coupled to high-throughput sequencing. This analysis, along with RNA structure predictions and validation experiments using reporters, shows that PA-Xs from multiple influenza strains preferentially cleave RNAs at GCUG tetramers in hairpin loops. Importantly, GCUG tetramers are enriched in the human but not the influenza transcriptome. Moreover, optimal PA-X cut sites inserted in the influenza A virus genome are quickly selected against during viral replication in cells. This finding suggests that PA-X evolved these cleavage characteristics to preferentially target host over viral mRNAs in a manner reminiscent of cellular self versus non-self discrimination.
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Affiliation(s)
- Lea Gaucherand
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Architecture et Réactivité de l'ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Université de Strasbourg, Strasbourg, France
| | - Amrita Iyer
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Isabel Gilabert
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, Spain
| | - Chris H Rycroft
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Mathematics, University of Wisconsin-Madison, Madison, WI, USA
| | - Marta M Gaglia
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
- Institute for Molecular Virology and Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
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4
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Chakraborty S, Chauhan A. Fighting the flu: a brief review on anti-influenza agents. Biotechnol Genet Eng Rev 2023:1-52. [PMID: 36946567 DOI: 10.1080/02648725.2023.2191081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.
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Affiliation(s)
| | - Ashwini Chauhan
- Department of Microbiology, Tripura University, Agartala, India
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5
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Slavish PJ, Cuypers MG, Rimmer MA, Abdolvahabi A, Jeevan T, Kumar G, Jarusiewicz JA, Vaithiyalingam S, Jones JC, Bowling JJ, Price JE, DuBois RM, Min J, Webby RJ, Rankovic Z, White SW. Chemical scaffold recycling: Structure-guided conversion of an HIV integrase inhibitor into a potent influenza virus RNA-dependent RNA polymerase inhibitor designed to minimize resistance potential. Eur J Med Chem 2023; 247:115035. [PMID: 36603507 DOI: 10.1016/j.ejmech.2022.115035] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/14/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
Influenza is one of the leading causes of disease-related mortalities worldwide. Several strategies have been implemented during the past decades to hinder the replication cycle of influenza viruses, all of which have resulted in the emergence of resistant virus strains. The most recent example is baloxavir marboxil, where a single mutation in the active site of the target endonuclease domain of the RNA-dependent-RNA polymerase renders the recent FDA approved compound ∼1000-fold less effective. Raltegravir is a first-in-class HIV inhibitor that shows modest activity to the endonuclease. Here, we have used structure-guided approaches to create rationally designed derivative molecules that efficiently engage the endonuclease active site. The design strategy was driven by our previously published structures of endonuclease-substrate complexes, which allowed us to target functionally conserved residues and reduce the likelihood of resistance mutations. We succeeded in developing low nanomolar equipotent inhibitors of both wild-type and baloxavir-resistant endonuclease. We also developed macrocyclic versions of these inhibitors that engage the active site in the same manner as their 'open' counterparts but with reduced affinity. Structural analyses provide clear avenues for how to increase the affinity of these cyclic compounds.
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Affiliation(s)
- Peter J Slavish
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Maxime G Cuypers
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Mary Ashley Rimmer
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Alireza Abdolvahabi
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Trushar Jeevan
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Gyanendra Kumar
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jamie A Jarusiewicz
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | | | - Jeremy C Jones
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - John J Bowling
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jeanine E Price
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Rebecca M DuBois
- Baskin School of Engineering, University of California at Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Jaeki Min
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Richard J Webby
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Zoran Rankovic
- Departments of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
| | - Stephen W White
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
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6
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Strategies of Influenza A Virus to Ensure the Translation of Viral mRNAs. Pathogens 2022; 11:pathogens11121521. [PMID: 36558855 PMCID: PMC9783940 DOI: 10.3390/pathogens11121521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022] Open
Abstract
Viruses are obligatorily intracellular pathogens. To generate progeny virus particles, influenza A viruses (IAVs) have to divert the cellular machinery to ensure sufficient translation of viral mRNAs. To this end, several strategies have been exploited by IAVs, such as host gene shutoff, suppression of host innate immune responses, and selective translation of viral mRNAs. Various IAV proteins are responsible for host gene shutoff, e.g., NS1, PA-X, and RdRp, through inhibition of cellular gene transcription, suppression of cellular RNA processing, degradation of cellular RNAs, and blockage of cellular mRNA export from the nucleus. Host shutoff should suppress the innate immune responses and also increase the translation of viral mRNAs indirectly due to the reduced competition from cellular mRNAs for cellular translational machinery. However, many other mechanisms are also responsible for the suppression of innate immune responses by IAV, such as prevention of the detection of the viral RNAs by the RLRs, inhibition of the activities of proteins involved in signaling events of interferon production, and inhibition of the activities of interferon-stimulated genes, mainly through viral NS1, PB1-F2, and PA-X proteins. IAV mRNAs may be selectively translated in favor of cellular mRNAs through interacting with viral and/or cellular proteins, such as NS1, PABPI, and/or IFIT2, in the 5'-UTR of viral mRNAs. This review briefly summarizes the strategies utilized by IAVs to ensure sufficient translation of viral mRNAs focusing on recent developments.
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7
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Pyle JD, Whelan SPJ, Bloyet LM. Structure and function of negative-strand RNA virus polymerase complexes. Enzymes 2021; 50:21-78. [PMID: 34861938 DOI: 10.1016/bs.enz.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Viruses with negative-strand RNA genomes (NSVs) include many highly pathogenic and economically devastating disease-causing agents of humans, livestock, and plants-highlighted by recent Ebola and measles virus epidemics, and continuously circulating influenza virus. Because of their protein-coding orientation, NSVs face unique challenges for efficient gene expression and genome replication. To overcome these barriers, NSVs deliver a large and multifunctional RNA-dependent RNA polymerase into infected host cells. NSV-encoded polymerases contain all the enzymatic activities required for transcription and replication of their genome-including RNA synthesis and mRNA capping. Here, we review the structures and functions of NSV polymerases with a focus on key domains responsible for viral replication and gene expression. We highlight shared and unique features among polymerases of NSVs from the Mononegavirales, Bunyavirales, and Articulavirales orders.
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Affiliation(s)
- Jesse D Pyle
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States; Ph.D. Program in Virology, Harvard Medical School, Boston, MA, United States
| | - Sean P J Whelan
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
| | - Louis-Marie Bloyet
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
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8
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Abstract
Influenza polymerase (FluPol) plays a key role in the viral infection cycle by transcribing and replicating the viral genome. FluPol is a multifunctional, heterotrimeric enzyme with cap-binding, endonuclease, RNA-dependent RNA polymerase and polyadenylation activities. It performs its functions in the context of the viral ribonucleoprotein particle (RNP), wherein the template viral RNA is coated by multiple copies of viral nucleoprotein. Moreover, it interacts with a number of host proteins that are essential cofactors and, consequently, adaptive mutations in the polymerase are required for crossing the avian-human species barrier. In this review, we show how mechanistic understanding of how FluPol performs its multiple functions has greatly advanced over the last decade through determination of high-resolution structures by X-ray crystallography and cryo-electron microscopy. These have revealed not only the detailed architecture of FluPol but highlighted the remarkably conformational flexibility that is inherent to its functioning as a dynamic RNA synthesis machine. Structural studies are also underpinning current attempts to develop next-generation anti-influenza drugs that directly target FluPol.
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Affiliation(s)
- Joanna M Wandzik
- European Molecular Biology Laboratory, Grenoble 38042-Cedex 9, France
| | - Tomas Kouba
- European Molecular Biology Laboratory, Grenoble 38042-Cedex 9, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble 38042-Cedex 9, France
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9
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Kumar G, Cuypers M, Webby RR, Webb TR, White SW. Structural insights into the substrate specificity of the endonuclease activity of the influenza virus cap-snatching mechanism. Nucleic Acids Res 2021; 49:1609-1618. [PMID: 33469660 PMCID: PMC7897473 DOI: 10.1093/nar/gkaa1294] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 01/01/2023] Open
Abstract
The endonuclease activity within the influenza virus cap-snatching process is a proven therapeutic target. The anti-influenza drug baloxavir is highly effective, but is associated with resistance mutations that threaten its clinical efficacy. The endonuclease resides within the N-terminal domain of the PA subunit (PAN) of the influenza RNA dependent RNA polymerase, and we report here complexes of PAN with RNA and DNA oligonucleotides to understand its specificity and the structural basis of baloxavir resistance mutations. The RNA and DNA oligonucleotides bind within the substrate binding groove of PAN in a similar fashion, explaining the ability of the enzyme to cleave both substrates. The individual nucleotides occupy adjacent conserved pockets that flank the two-metal active site. However, the 2′ OH of the RNA ribose moieties engage in additional interactions that appear to optimize the binding and cleavage efficiency for the natural substrate. The major baloxavir resistance mutation at position 38 is at the core of the substrate binding site, but structural studies and modeling suggest that it maintains the necessary virus fitness via compensating interactions with RNA. These studies will facilitate the development of new influenza therapeutics that spatially match the substrate and are less likely to elicit resistance mutations.
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Affiliation(s)
| | - Maxime Cuypers
- Department of Structural Biology, Memphis, TN 38105, USA
| | - Richard R Webby
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Thomas R Webb
- Wildflower Biopharma, Inc., 8650 Genesee Ave. STE 214, San Diego, CA 92122, USA.,Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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10
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Dai H, Gu W. Small RNA Plays Important Roles in Virus-Host Interactions. Viruses 2020; 12:E1271. [PMID: 33171824 PMCID: PMC7695165 DOI: 10.3390/v12111271] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 10/30/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022] Open
Abstract
Non-coding small RNAs play important roles in virus-host interactions. For hosts, small RNAs can serve as sensors in antiviral pathways including RNAi and CRISPR; for viruses, small RNAs can be involved in viral transcription and replication. This paper covers several recent discoveries on small RNA mediated virus-host interactions, and focuses on influenza virus cap-snatching and a few important virus sensors including PIR-1, RIG-I like protein DRH-1 and piRNAs. The paper also discusses recent advances in mammalian antiviral RNAi.
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Affiliation(s)
| | - Weifeng Gu
- Department of Molecular, Cell and Systems Biology, University of California, Riverside 900 University Avenue, Riverside, CA 92521, USA;
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11
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Li L, Dai H, Nguyen AP, Hai R, Gu W. Influenza A virus utilizes noncanonical cap-snatching to diversify its mRNA/ncRNA. RNA (NEW YORK, N.Y.) 2020; 26:1170-1183. [PMID: 32444459 PMCID: PMC7430677 DOI: 10.1261/rna.073866.119] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/12/2020] [Indexed: 06/11/2023]
Abstract
Influenza A virus (IAV) utilizes cap-snatching to obtain host capped small RNAs for priming viral mRNA synthesis, generating capped hybrid mRNAs for translation. Previous studies have been focusing on canonical cap-snatching, which occurs at the very 5' end of viral mRNAs. Here we discovered noncanonical cap-snatching, which generates capped hybrid mRNAs/noncoding RNAs mapped to the region ∼300 nucleotides (nt) upstream of each mRNA 3' end, and to the 5' region, primarily starting at the second nt, of each virion RNAs (vRNA). Like canonical cap-snatching, noncanonical cap-snatching utilizes a base-pairing between the last nt G of host capped RNAs and a nt C of template RNAs to prime RNA synthesis. However, the nt upstream of this template C is usually A/U rather than just U; prime-realignment occurs less frequently. We also demonstrate that IAV can snatch capped IAV RNAs in addition to host RNAs. Noncanonical cap-snatching likely generates novel mRNAs with start AUG encoded in viral or host RNAs. These findings expand our understanding of cap-snatching mechanisms and suggest that IAV may utilize noncanonical cap-snatching to diversify its mRNAs/ncRNAs.
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Affiliation(s)
- Lichao Li
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, California 92521, USA
| | - Hui Dai
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, California 92521, USA
| | - An-Phong Nguyen
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, California 92521, USA
| | - Rong Hai
- Department of Microbiology and Plant Pathology, University of California, Riverside, California 92521, USA
| | - Weifeng Gu
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, California 92521, USA
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12
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Lin W, Wu R, Qiu P, Jing Jin, Yang Y, Wang J, Lin Z, Zhang J, Wu Z, Du Z. A convenient in vivo cap donor delivery system to investigate the cap snatching of plant bunyaviruses. Virology 2020; 539:114-120. [PMID: 31710910 DOI: 10.1016/j.virol.2019.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 01/19/2023]
Abstract
Like their animal-infecting counterparts, plant bunyaviruses use capped RNA leaders cleaved from host cellular mRNAs to prime viral genome transcription in a process called cap-snatching, but in vivo systems to investigate the details of this process are lacking for them. Here, we report that Rice stripe tenuivirus (RSV) and Tomato spotted wilt tospovirus (TSWV) cleave capped RNA leaders from mRNAs transiently expressed by agroinfiltration, which makes it possible to artificially deliver defined cap donors to the two plant bunyaviruses with unprecedented convenience. With this system, some ideas regarding how plant bunyaviruses select and use capped RNA leaders can be tested easily. We were also able to obtain clear evidence that the capped RNA leaders selected by TSWV are generally longer than those by RSV. TSWV frequently uses the prime-and-realign mechanism in transcription primed by capped RNA leaders shorter than a certain length, like that has been demonstrated recently for RSV.
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Affiliation(s)
- Wenzhong Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, 350002, China; Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Ran Wu
- Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Ping Qiu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, 350002, China; Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Jing Jin
- Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Yunyue Yang
- Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Jinglin Wang
- Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Zhonglong Lin
- China Tobacco Corporation Yunnan Company, Kunming, 650001, China
| | - Jie Zhang
- Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China
| | - Zujian Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, 350002, China; Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China.
| | - Zhenguo Du
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, 350002, China; Plant virus research institute, Fujian Agricultural and Forestry University, Fuzhou, 350002, China.
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13
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Pham T, Nguyen HL, Phan-Toai T, Nguyen H. Investigation of Binding Affinity between Potential Antiviral Agents and PB2 Protein of Influenza A: Non-equilibrium Molecular Dynamics Simulation Approach. Int J Med Sci 2020; 17:2031-2039. [PMID: 32788882 PMCID: PMC7415388 DOI: 10.7150/ijms.46231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 07/09/2020] [Indexed: 11/30/2022] Open
Abstract
The PB2 protein of the influenza virus RNA polymerase is a major virulence determinant of influenza viruses. It binds to the cap structure at the 5' end of host mRNA to generate short capped RNA fragments that are used as primers for viral transcription named cap-snatching. A large number of the compounds were shown to bind the minimal cap-binding domain of PB2 to inhibit the cap-snatching machinery. However, their binding in the context of an extended form of the PB2 protein has remained elusive. A previous study reported some promising compounds including azaindole and hydroxymethyl azaindole, which were analyzed here to predict binding affinity to PB2 protein using the steered molecular dynamics (SMD) and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) methods. The results show that the rupture force (Fmax) value of three complexes is in agreement with the binding free energy value (ΔGbind) estimated by the MM-PBSA method, whereas for the non-equilibrium pulling work (Wpull) value a small difference between A_PB2-4 and A_PB2-12 was observed. The binding affinity results indicate the A_PB2-12 complex is more favorable than the A_PB2-4 and A_PB2-16 complexes, which means the inhibitor (12) has the potential to be further developed as anti-influenza agents in the treatment of influenza A.
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Affiliation(s)
- Tri Pham
- Institute for Computational Science and Technology, Ho Chi Minh City, Vietnam.,VNUHCM-University of Technology, Ho Chi Minh City, Vietnam
| | - Hoang Linh Nguyen
- Institute for Computational Science and Technology, Ho Chi Minh City, Vietnam.,VNUHCM-University of Technology, Ho Chi Minh City, Vietnam
| | - Tuyn Phan-Toai
- Institute for Computational Science and Technology, Ho Chi Minh City, Vietnam
| | - Hung Nguyen
- Institute for Computational Science and Technology, Ho Chi Minh City, Vietnam
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14
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De Vlugt C, Sikora D, Rocheleau L, Pelchat M. Priming and realignment by the influenza a virus RdRp is dependent on the length of the host primers and the extent of base pairing to viral RNA. Virology 2019; 536:91-100. [PMID: 31404845 DOI: 10.1016/j.virol.2019.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/01/2019] [Accepted: 08/01/2019] [Indexed: 11/25/2022]
Abstract
Initiation of influenza A virus (IAV) transcription depends on RNA primers derived from host RNAs. During this process, some primers are elongated by a few nucleotides, realigned on the viral RNA templates (vRNA), and then used to initiate another round of transcription. Here, we used information on the host primers used by four IAV strains and four mini-replicons to investigate the characteristics of primer undergoing priming and realignment. We report that primers are biased towards this mechanism on the basis of length and RNA duplex stability with the vRNA templates. Priming and realignment results in primers three nucleotides longer, ending in a nucleotide sequence able to base pair with the 3' end of the vRNA template. By acting on primers based on length and sequence compatibility with the 3' end of the vRNA, priming and realignment rescues suboptimal primers, converting them into ones that can efficiently initiate transcription.
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Affiliation(s)
- Corey De Vlugt
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada
| | - Dorota Sikora
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada
| | - Lynda Rocheleau
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada
| | - Martin Pelchat
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada.
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15
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Yang J, Huang Y, Liu S. Investigational antiviral therapies for the treatment of influenza. Expert Opin Investig Drugs 2019; 28:481-488. [PMID: 31018720 DOI: 10.1080/13543784.2019.1606210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Influenza viral ribonucleoprotein complexes (vRNPs) play a key role in viral transcription and replication; hence, the recent development of novel anti-influenza drugs targeting vRNPs has garnered widespread interest. AREAS COVERED We discuss the function of the constituents of vRNPs and summarize those vRNPs-targeted synthetic drugs that are in preclinical and early clinical development. EXPERT OPINION vRNPs contain high-value drug targets; such targets include the subunits PA, PB1, PB2, and NP. Developing a new generation of antiviral therapies with strategies that utilize existing drugs, natural compounds originated from new resources and novel drug combinations may open up new therapeutic approaches to influenza.
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Affiliation(s)
- Jie Yang
- a Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou , China
| | - Yingna Huang
- a Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou , China
| | - Shuwen Liu
- a Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou , China.,b State Key Laboratory of Organ Failure Research, Guangdong Provincial Institute of Nephrology , Southern Medical University , Guangzhou , China
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16
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Flupyranochromene, a novel inhibitor of influenza virus cap-dependent endonuclease, from Penicillium sp. f28743. J Antibiot (Tokyo) 2019; 72:125-133. [DOI: 10.1038/s41429-018-0134-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/12/2018] [Accepted: 11/30/2018] [Indexed: 11/08/2022]
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17
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HDAC6 Restricts Influenza A Virus by Deacetylation of the RNA Polymerase PA Subunit. J Virol 2019; 93:JVI.01896-18. [PMID: 30518648 PMCID: PMC6364008 DOI: 10.1128/jvi.01896-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 11/22/2018] [Indexed: 12/23/2022] Open
Abstract
Influenza A virus (IAV) continues to threaten global public health due to drug resistance and the emergence of frequently mutated strains. Thus, it is critical to find new strategies to control IAV infection. Here, we discover one host protein, HDAC6, that can inhibit viral RNA polymerase activity by deacetylating PA and thus suppresses virus RNA replication and transcription. Previously, it was reported that IAV can utilize the HDAC6-dependent aggresome formation mechanism to promote virus uncoating, but HDAC6-mediated deacetylation of α-tubulin inhibits viral protein trafficking at late stages of the virus life cycle. These findings together will contribute to a better understanding of the role of HDAC6 in regulating IAV infection. Understanding the molecular mechanisms of HDAC6 at various periods of viral infection may illuminate novel strategies for developing antiviral drugs. The life cycle of influenza A virus (IAV) is modulated by various cellular host factors. Although previous studies indicated that IAV infection is controlled by HDAC6, the deacetylase involved in the regulation of PA remained unknown. Here, we demonstrate that HDAC6 acts as a negative regulator of IAV infection by destabilizing PA. HDAC6 binds to and deacetylates PA, thereby promoting the proteasomal degradation of PA. Based on mass spectrometric analysis, Lys(664) of PA can be deacetylated by HDAC6, and the residue is crucial for PA protein stability. The deacetylase activity of HDAC6 is required for anti-IAV activity, because IAV infection was enhanced due to elevated IAV RNA polymerase activity upon HDAC6 depletion and an HDAC6 deacetylase dead mutant (HDAC6-DM; H216A, H611A). Finally, we also demonstrate that overexpression of HDAC6 suppresses IAV RNA polymerase activity, but HDAC6-DM does not. Taken together, our findings provide initial evidence that HDAC6 plays a negative role in IAV RNA polymerase activity by deacetylating PA and thus restricts IAV RNA transcription and replication. IMPORTANCE Influenza A virus (IAV) continues to threaten global public health due to drug resistance and the emergence of frequently mutated strains. Thus, it is critical to find new strategies to control IAV infection. Here, we discover one host protein, HDAC6, that can inhibit viral RNA polymerase activity by deacetylating PA and thus suppresses virus RNA replication and transcription. Previously, it was reported that IAV can utilize the HDAC6-dependent aggresome formation mechanism to promote virus uncoating, but HDAC6-mediated deacetylation of α-tubulin inhibits viral protein trafficking at late stages of the virus life cycle. These findings together will contribute to a better understanding of the role of HDAC6 in regulating IAV infection. Understanding the molecular mechanisms of HDAC6 at various periods of viral infection may illuminate novel strategies for developing antiviral drugs.
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18
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Wang J, Chen F, Liu Y, Liu Y, Li K, Yang X, Liu S, Zhou X, Yang J. Spirostaphylotrichin X from a Marine-Derived Fungus as an Anti-influenza Agent Targeting RNA Polymerase PB2. JOURNAL OF NATURAL PRODUCTS 2018; 81:2722-2730. [PMID: 30516983 DOI: 10.1021/acs.jnatprod.8b00656] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A new spirocyclic γ-lactam, named spirostaphylotrichin X (1), and three related known spirostaphylotrichins (2-4) were isolated from the marine-derived fungus Cochliobolus lunatus SCSIO41401. Their structures were determined by spectroscopic analyses. Spirostaphylotrichin X (1) displayed obvious inhibitory activities against multiple influenza virus strains, with IC50 values from 1.2 to 5.5 μM. Investigation of the mechanism showed that 1 inhibited viral polymerase activity and interfered with the production of progeny viral RNA. Homogeneous time-resolved fluorescence, surface plasmon resonance assays, and a molecular docking study revealed that 1 could inhibit polymerase PB2 protein activity by binding to the highly conserved region of the cap-binding domain of PB2. These results suggest that 1 inhibits the replication of influenza A virus by interfering with the activity of PB2 protein and that 1 represents a new type of potential lead compound for the development of anti-influenza therapeutics.
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Affiliation(s)
- Jianjiao Wang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology, Chinese Academy of Sciences , Guangzhou 510301 , People's Republic of China
- University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Feimin Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou 510515 , People's Republic of China
| | - Yunhao Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology, Chinese Academy of Sciences , Guangzhou 510301 , People's Republic of China
| | - Yuxuan Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology, Chinese Academy of Sciences , Guangzhou 510301 , People's Republic of China
| | - Kunlong Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology, Chinese Academy of Sciences , Guangzhou 510301 , People's Republic of China
| | - Xiliang Yang
- Department of Pharmacy, Medical College , Wuhan University of Science and Technology , Wuhan 430065 , People's Republic of China
| | - Shuwen Liu
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou 510515 , People's Republic of China
- State Key Laboratory of Organ Failure Research , Southern Medical University , Guangzhou 510515 , People's Republic of China
| | - Xuefeng Zhou
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology, Chinese Academy of Sciences , Guangzhou 510301 , People's Republic of China
- State Key Laboratory of Organ Failure Research , Southern Medical University , Guangzhou 510515 , People's Republic of China
| | - Jie Yang
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences , Southern Medical University , Guangzhou 510515 , People's Republic of China
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19
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De Vlugt C, Sikora D, Pelchat M. Insight into Influenza: A Virus Cap-Snatching. Viruses 2018; 10:v10110641. [PMID: 30453478 PMCID: PMC6266781 DOI: 10.3390/v10110641] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 11/12/2018] [Accepted: 11/15/2018] [Indexed: 12/27/2022] Open
Abstract
The influenza A virus (IAV) genome consists of eight single-stranded RNA segments. Each segment is associated with a protein complex, with the 3′ and 5′ ends bound to the RNA-dependent RNA polymerase (RdRp) and the remainder associated with the viral nucleoprotein. During transcription of viral mRNA, this ribonucleoprotein complex steals short, 5′-capped transcripts produced by the cellular DNA dependent RNA polymerase II (RNAPII) and uses them to prime transcription of viral mRNA. Here, we review the current knowledge on the process of IAV cap-snatching and suggest a requirement for RNAPII promoter-proximal pausing for efficient IAV mRNA transcription.
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Affiliation(s)
- Corey De Vlugt
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
| | - Dorota Sikora
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
| | - Martin Pelchat
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
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20
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Levene RE, Gaglia MM. Host Shutoff in Influenza A Virus: Many Means to an End. Viruses 2018; 10:E475. [PMID: 30189604 PMCID: PMC6165434 DOI: 10.3390/v10090475] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 08/31/2018] [Accepted: 09/01/2018] [Indexed: 12/21/2022] Open
Abstract
Influenza A virus carries few of its own proteins, but uses them effectively to take control of the infected cells and avoid immune responses. Over the years, host shutoff, the widespread down-regulation of host gene expression, has emerged as a key process that contributes to cellular takeover in infected cells. Interestingly, multiple mechanisms of host shutoff have been described in influenza A virus, involving changes in translation, RNA synthesis and stability. Several viral proteins, notably the non-structural protein NS1, the RNA-dependent RNA polymerase and the endoribonuclease PA-X have been implicated in host shutoff. This multitude of host shutoff mechanisms indicates that host shutoff is an important component of the influenza A virus replication cycle. Here we review the various mechanisms of host shutoff in influenza A virus and the evidence that they contribute to immune evasion and/or viral replication. We also discuss what the purpose of having multiple mechanisms may be.
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Affiliation(s)
- Rachel Emily Levene
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA 02111, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA.
| | - Marta Maria Gaglia
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA 02111, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA.
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21
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Liu T, Liu M, Chen F, Chen F, Tian Y, Huang Q, Liu S, Yang J. A Small-Molecule Compound Has Anti-influenza A Virus Activity by Acting as a ‘‘PB2 Inhibitor”. Mol Pharm 2018; 15:4110-4120. [DOI: 10.1021/acs.molpharmaceut.8b00531] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Teng Liu
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Miaomiao Liu
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Feimin Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Fangzhao Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yuanxin Tian
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Qi Huang
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Shuwen Liu
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jie Yang
- Guangdong Provincial Key Laboratory of New Drug Screening, Guangzhou Key Laboratory of Drug Research for Emerging Virus Prevention and Treatment, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
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22
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Initiation, Elongation, and Realignment during Influenza Virus mRNA Synthesis. J Virol 2018; 92:JVI.01775-17. [PMID: 29142123 PMCID: PMC5774887 DOI: 10.1128/jvi.01775-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 11/03/2017] [Indexed: 01/15/2023] Open
Abstract
The RNA-dependent RNA polymerase (RdRp) of the influenza A virus replicates and transcribes the viral genome segments in the nucleus of the host cell. To transcribe these viral genome segments, the RdRp “snatches” capped RNA oligonucleotides from nascent host cell mRNAs and aligns these primers to the ultimate or penultimate nucleotide of the segments for the initiation of viral mRNA synthesis. It has been proposed that this initiation process is not processive and that the RdRp uses a prime-realign mechanism during transcription. Here we provide in vitro evidence for the existence of this transcriptional prime-realign mechanism but show that it functions efficiently only for primers that are short or cannot stably base pair with the template. In addition, we demonstrate that transcriptional elongation is dependent on the priming loop of the PB1 subunit of the RdRp. We propose that the prime-realign mechanism may be used to rescue abortive transcription initiation events or cope with sequence variation among primers. Overall, these observations advance our mechanistic understanding of how influenza A virus initiates transcription correctly and efficiently. IMPORTANCE Influenza A virus causes severe disease in humans and is considered a major global health threat. The virus replicates and transcribes its genome by using an enzyme called the RNA polymerase. To ensure that the genome is amplified faithfully and abundant viral mRNAs are made for viral protein synthesis, the viral RNA polymerase must transcribe the viral genome efficiently. In this report, we characterize a structure inside the polymerase that contributes to the efficiency of viral mRNA synthesis.
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23
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Abstract
Influenza is a negative-sense single-stranded RNA virus with segmented genome. Each segment is encapsidated by a ribonucleoprotein (RNP) complex composed of RNA-dependent RNA polymerase (RdRP) and multiple copies of nucleoprotein (NP). The RNP complex plays a crucial role in viral life cycle, supporting and regulating transcription and replication of viral genome in infected cells. The structural characterization of RdRP and RNP in recent years has shed light on its functions and mechanism of action. In this review, we summarize current understanding on the structure of RNP complex, as well as the structure of each subunit. Crucial functions of RNP are also discussed.
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Affiliation(s)
- Chun-Yeung Lo
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T, Hong Kong, China
| | - Yun-Sang Tang
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T, Hong Kong, China
| | - Pang-Chui Shaw
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T, Hong Kong, China.
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24
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Binding affinity of the L-742,001 inhibitor to the endonuclease domain of A/H1N1/PA influenza virus variants: Molecular simulation approaches. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2017.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Yi C, Zhao Z, Wang S, Sun X, Zhang D, Sun X, Zhang A, Jin M. Influenza A Virus PA Antagonizes Interferon-β by Interacting with Interferon Regulatory Factor 3. Front Immunol 2017; 8:1051. [PMID: 28955326 PMCID: PMC5600993 DOI: 10.3389/fimmu.2017.01051] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 08/14/2017] [Indexed: 01/07/2023] Open
Abstract
The influenza A virus (IAV) can be recognized by retinoic acid-inducible gene I (RIG-I) to activate the type I interferon response and induce antiviral effects. The virus has evolved several strategies to evade the innate immune response, including non-structural protein 1 (NS1) and its polymerase subunits. The mechanism by which NS1 inhibits interferon-β (IFN-β) is well understood, whereas the mechanism by which polymerase acid protein (PA) inhibits IFN-β remains to be elucidated. In this study, we observed that the IAV PA protein could inhibit the production of IFN-β and interferon-stimulated genes induced by Sendai virus through interferon regulatory factor 3 (IRF3), but not through nuclear factor-kappaB (NF-kappaB). In addition, PA inhibited IFN-β induction by RIG-I, melanoma differentiation-associated gene 5, mitochondria antiviral signaling protein, TANK-binding kinase 1, inhibitor of nuclear factor kappa-B kinase-ε (IKKε), and IRF3 overexpression. Furthermore, PA interacted with IRF3 to block its activation. The N-terminal endonuclease activity of PA was responsible for its interaction with IRF3 and inhibition of the IFN-β signaling pathway. In summary, our data reveal the mechanism by which IAV PA inhibits the IFN-β signaling pathway, providing a new mechanism by which the virus antagonizes the antiviral signaling pathway.
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Affiliation(s)
- Chenyang Yi
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Zongzheng Zhao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Shengyu Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Xin Sun
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Dan Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Xiaomei Sun
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Anding Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
| | - Meilin Jin
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, China
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26
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Reich S, Guilligay D, Cusack S. An in vitro fluorescence based study of initiation of RNA synthesis by influenza B polymerase. Nucleic Acids Res 2017; 45:3353-3368. [PMID: 28126917 PMCID: PMC5399792 DOI: 10.1093/nar/gkx043] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 01/17/2017] [Indexed: 12/20/2022] Open
Abstract
Influenza polymerase replicates, via a complementary RNA intermediate (cRNA), and transcribes the eight viral RNA (vRNA) genome segments. To initiate RNA synthesis it is bound to the conserved 5΄ and 3΄ extremities of the vRNA or cRNA (the ‘promoter’). 5΄-3΄ base-pairing in the distal promoter region is essential to position the template RNA at the polymerase active site, as shown by a new crystal structure with the 3΄ end threading through the template entry tunnel. We develop fluorescence polarization assays to quantify initiation of cap-primed (transcription) or unprimed (replication) RNA synthesis by recombinant influenza B polymerase bound to the vRNA or cRNA promoter. The rate-limiting step is formation of a primed initiation complex with minimally ApG required to stabilize the 3΄ end of the template within the active-site. Polymerase bound to the vRNA promoter initiates RNA synthesis terminally, while the cRNA promoter directs internal initiation at a significantly lower rate. Progression to elongation requires breaking the promoter 5΄-3΄ base-pairing region and favourable compensation by the emerging template-product base-pairs. The RNA synthesis assay is adaptable to high-throughput screening for polymerase inhibitors. In a pilot study, we find that initiation at the cRNA promoter is unusually susceptible to inhibition by 2΄F-2΄dNTPs.
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Affiliation(s)
- Stefan Reich
- Grenoble Outstation, European Molecular Biology Laboratory, Grenoble 38042, France.,Unit of Virus-Host Cell Interactions, EMBL-UGA-CNRS, Grenoble 38042, France
| | - Delphine Guilligay
- Unit of Virus-Host Cell Interactions, EMBL-UGA-CNRS, Grenoble 38042, France
| | - Stephen Cusack
- Grenoble Outstation, European Molecular Biology Laboratory, Grenoble 38042, France.,Unit of Virus-Host Cell Interactions, EMBL-UGA-CNRS, Grenoble 38042, France
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27
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Dong LH, Cao XR. Studies of the Interaction of Influenza Virus RNA Polymerase PA N with Endonuclease Inhibitors. Interdiscip Sci 2017. [PMID: 28631174 DOI: 10.1007/s12539-017-0239-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Influenza virus is a major causative agent of respiratory viral infections, and RNA polymerase catalyzes its replication and transcription activities in infected cell nuclei. Since it is highly conserved in all virus strains, RNA polymerase becomes a key target of anti-influenza virus agents. Although experimental studies have revealed the good inhibitory activity of endonuclease inhibitors to RNA polymerase, the mechanism is still unclear. In this study, the docking and molecular dynamics simulations have been performed to explore the interaction of three kinds of endonuclease inhibitors with the subunit (PAN) of RNA polymerase. Our calculations indicate that all these endonuclease inhibitors can bind to the binding pocket of PAN, in which the electronegative oxygen atoms of the inhibitors form a chelated structure with the two Mn2+ cations of the active center. The most important interaction between these inhibitors and PAN is electrostatic interaction. The electron density of the chelate oxygen atoms determines the magnitude of the electrostatic energy, and the chelated structure and orientation of inhibitors depend largely on the distance between the chelate oxygen atoms.
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Affiliation(s)
- Li-Hua Dong
- School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan, 250200, China.
| | - Xiao-Rong Cao
- School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan, 250200, China
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28
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Pflug A, Lukarska M, Resa-Infante P, Reich S, Cusack S. Structural insights into RNA synthesis by the influenza virus transcription-replication machine. Virus Res 2017; 234:103-117. [PMID: 28115197 DOI: 10.1016/j.virusres.2017.01.013] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 12/31/2016] [Accepted: 01/13/2017] [Indexed: 12/22/2022]
Abstract
Influenza virus is a segmented, negative strand RNA virus with each genome segment being packaged in a distinct ribonucleoprotein particle (RNP). The RNP consists of the heterotrimeric viral RNA-dependent RNA polymerase bound to the conserved 5' and 3' ends of the genome segment (the viral promoter) with the rest of the viral RNA (vRNA) being covered by multiple copies of nucleoprotein. This review focusses on the new insights that recent crystal structures have given into the detailed molecular mechanisms by which the polymerase performs both transcription and replication of the vRNA genome. Promoter binding, in particular that of 5' end, is essential to allosterically activate all polymerase functions. Transcription is initiated by the hijacking of nascent, capped host transcripts by the process of 'cap-snatching', for which the viral polymerase makes an essential interaction with the C-terminal domain (CTD) of cellular RNA polymerase II. The structures allow a coherent mechanistic model of the subsequent cap-snatching, cap-dependent priming, elongation and self-polyadenylation steps of viral mRNA synthesis. During replication, the vRNA is copied without modification into complementary RNA (cRNA) which is packaged into cRNPs. A priming loop located in the polymerase active site is required for the unprimed synthesis of cRNA from vRNA, but is not required for cRNA to vRNA replication due to differences in the mode of initiation of RNA synthesis. Overall a picture emerges of influenza polymerase being a highly complex, flexible and dynamic machine. The challenge remains to understand in more detail how it functions within the RNP and how interacting host factors modulate its activity in the cellular context. Finally, these detailed insights have opened up new opportunities for structure-based antiviral drug design targeting multiple aspects of polymerase function.
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Affiliation(s)
- Alexander Pflug
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Maria Lukarska
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Patricia Resa-Infante
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Stefan Reich
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
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29
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Stevaert A, Naesens L. The Influenza Virus Polymerase Complex: An Update on Its Structure, Functions, and Significance for Antiviral Drug Design. Med Res Rev 2016; 36:1127-1173. [PMID: 27569399 PMCID: PMC5108440 DOI: 10.1002/med.21401] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/18/2016] [Accepted: 06/24/2016] [Indexed: 12/11/2022]
Abstract
Influenza viruses cause seasonal epidemics and pandemic outbreaks associated with significant morbidity and mortality, and a huge cost. Since resistance to the existing anti‐influenza drugs is rising, innovative inhibitors with a different mode of action are urgently needed. The influenza polymerase complex is widely recognized as a key drug target, given its critical role in virus replication and high degree of conservation among influenza A (of human or zoonotic origin) and B viruses. We here review the major progress that has been made in recent years in unravelling the structure and functions of this protein complex, enabling structure‐aided drug design toward the core regions of the PA endonuclease, PB1 polymerase, or cap‐binding PB2 subunit. Alternatively, inhibitors may target a protein–protein interaction site, a cellular factor involved in viral RNA synthesis, the viral RNA itself, or the nucleoprotein component of the viral ribonucleoprotein. The latest advances made for these diverse pharmacological targets have yielded agents in advanced (i.e., favipiravir and VX‐787) or early clinical testing, besides several experimental inhibitors in various stages of development, which are all covered here.
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Affiliation(s)
| | - Lieve Naesens
- Rega Institute for Medical Research, KU Leuven, Leuven, Belgium.
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30
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Roch FF, Hinterkörner G, Menke J, Tang GQ, Cusack S, Butzendobler B, Buschmann H, Datta K, Wolkerstorfer A. An RNA Hybridization Assay for Screening Influenza A Virus Polymerase Inhibitors Using the Entire Ribonucleoprotein Complex. Assay Drug Dev Technol 2016; 13:488-506. [PMID: 26461433 DOI: 10.1089/adt.2015.668] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Novel antiviral drugs, which are less prone to resistance development, are desirable alternatives to the currently approved drugs for the treatment of potentially serious influenza virus infections. The viral polymerase is highly conserved and serves as an attractive target for antiviral drugs since potent inhibitors would directly stop viral replication at an early stage. Recent structural studies on the functional domains of the heterotrimeric influenza polymerase, which comprises subunits PA, PB1, and PB2, opened the way to a structure-based approach for optimizing inhibitors of viral replication. These strategies, however, are limited by the use of isolated protein fragments instead of employing the entire ribonucleoprotein complex (RNP), which represents the functional form of the influenza polymerase in infected cells. In this study, we have established a screening assay for efficient and reliable analysis of potential influenza polymerase inhibitors of various molecular targets such as monoselective polymerase inhibitors targeting the endonuclease site, the cap-binding domain, and the polymerase active site, respectively. By utilizing whole viral RNPs and a radioactivity-free endpoint detection with the capability for efficient compound screening while offering high-content information on potential inhibitors to drive medicinal chemistry program in a reliable manner, this biochemical assay provides significant advantages over the currently available conventional assays. We propose that this assay can eventually be adapted for coinstantaneous analysis and subsequent optimization of two or more different chemical scaffold classes targeting multiple active sites within the polymerase complex, thus enabling the evaluation of drug combinations and characterization of molecules with dual functionality.
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Affiliation(s)
| | | | - John Menke
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
| | - Guo-Qing Tang
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
| | - Stephen Cusack
- 3 Grenoble Outstation, European Molecular Biology Laboratory , Grenoble, France
| | | | | | - Kausiki Datta
- 2 Virology Discovery, Hoffmann-La Roche, Inc. , Nutley, New Jersey
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31
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New Insight into Metal Ion-Driven Catalysis of Nucleic Acids by Influenza PA-Nter. PLoS One 2016; 11:e0156972. [PMID: 27300442 PMCID: PMC4907508 DOI: 10.1371/journal.pone.0156972] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 05/23/2016] [Indexed: 11/24/2022] Open
Abstract
PA subunit of influenza RNA-dependent RNA polymerase deserves constantly increasing attention due to its essential role in influenza life cycle. N-terminal domain of PA (PA-Nter) harbors endonuclease activity, which is indispensable in viral transcription and replication. Interestingly, existing literature reports on in vitro ion preferences of the enzyme are contradictory. Some show PA-Nter activity exclusively with Mn2+, whereas others report Mg2+ as a natural cofactor. To clarify it, we performed a series of experiments with varied ion concentrations and substrate type. We observed cleavage in the presence of both ions, with a slight preference for manganese, however PA-Nter activity highly depended on the amount of residual, co-purified ions. Furthermore, to quantify cleavage reaction rate, we applied fluorescence cross-correlation spectroscopy (FCCS), providing highly sensitive and real-time monitoring of single molecules. Using nanomolar ssDNA in the regime of enzyme excess, we estimated the maximum reaction rate at 0.81± 0.38 and 1.38± 0.34 nM/min for Mg2+ and Mn2+, respectively. However, our calculations of PA-Nter ion occupancy, based on thermodynamic data, suggest Mg2+ to be a canonical metal in PA-Nter processing of RNA in vivo. Presented studies constitute a step toward better understanding of PA-Nter ion-dependent activity, which will possibly contribute to new successful inhibitor design in the future.
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32
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Identification and characterization of influenza variants resistant to a viral endonuclease inhibitor. Proc Natl Acad Sci U S A 2016; 113:3669-74. [PMID: 26976575 DOI: 10.1073/pnas.1519772113] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The influenza endonuclease is an essential subdomain of the viral RNA polymerase. It processes host pre-mRNAs to serve as primers for viral mRNA and is an attractive target for antiinfluenza drug discovery. Compound L-742,001 is a prototypical endonuclease inhibitor, and we found that repeated passaging of influenza virus in the presence of this drug did not lead to the development of resistant mutant strains. Reduced sensitivity to L-742,001 could only be induced by creating point mutations via a random mutagenesis strategy. These mutations mapped to the endonuclease active site where they can directly impact inhibitor binding. Engineered viruses containing the mutations showed resistance to L-742,001 both in vitro and in vivo, with only a modest reduction in fitness. Introduction of the mutations into a second virus also increased its resistance to the inhibitor. Using the isolated wild-type and mutant endonuclease domains, we used kinetics, inhibitor binding and crystallography to characterize how the two most significant mutations elicit resistance to L-742,001. These studies lay the foundation for the development of a new class of influenza therapeutics with reduced potential for the development of clinical endonuclease inhibitor-resistant influenza strains.
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Thierry E, Guilligay D, Kosinski J, Bock T, Gaudon S, Round A, Pflug A, Hengrung N, El Omari K, Baudin F, Hart DJ, Beck M, Cusack S. Influenza Polymerase Can Adopt an Alternative Configuration Involving a Radical Repacking of PB2 Domains. Mol Cell 2016; 61:125-37. [PMID: 26711008 PMCID: PMC4712189 DOI: 10.1016/j.molcel.2015.11.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/13/2015] [Accepted: 11/05/2015] [Indexed: 01/26/2023]
Abstract
Influenza virus polymerase transcribes or replicates the segmented RNA genome (vRNA) into respectively viral mRNA or full-length copies and initiates RNA synthesis by binding the conserved 3' and 5' vRNA ends (the promoter). In recent structures of promoter-bound polymerase, the cap-binding and endonuclease domains are configured for cap snatching, which generates capped transcription primers. Here, we present a FluB polymerase structure with a bound complementary cRNA 5' end that exhibits a major rearrangement of the subdomains within the C-terminal two-thirds of PB2 (PB2-C). Notably, the PB2 nuclear localization signal (NLS)-containing domain translocates ∼90 Å to bind to the endonuclease domain. FluA PB2-C alone and RNA-free FluC polymerase are similarly arranged. Biophysical and cap-dependent endonuclease assays show that in solution the polymerase explores different conformational distributions depending on which RNA is bound. The inherent flexibility of the polymerase allows it to adopt alternative conformations that are likely important during polymerase maturation into active progeny RNPs.
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Affiliation(s)
- Eric Thierry
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Delphine Guilligay
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Jan Kosinski
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Thomas Bock
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stephanie Gaudon
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Adam Round
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Alexander Pflug
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Narin Hengrung
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK; Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Kamel El Omari
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Florence Baudin
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France; Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Darren J Hart
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Martin Beck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stephen Cusack
- European Molecular Biology Laboratory Grenoble Outstation and Unit of Virus Host-Cell Interactions, University Grenoble Alpes-CNRS-EMBL, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
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34
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Gaglia MM, Rycroft CH, Glaunsinger BA. Transcriptome-Wide Cleavage Site Mapping on Cellular mRNAs Reveals Features Underlying Sequence-Specific Cleavage by the Viral Ribonuclease SOX. PLoS Pathog 2015; 11:e1005305. [PMID: 26646420 PMCID: PMC4672902 DOI: 10.1371/journal.ppat.1005305] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 11/03/2015] [Indexed: 11/18/2022] Open
Abstract
Many viruses express factors that reduce host gene expression through widespread degradation of cellular mRNA. An example of this class of proteins is the mRNA-targeting endoribonuclease SOX from the gamma-herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV). Previous studies indicated that cleavage of messenger RNAs (mRNA) by SOX occurs at specific locations defined by the sequence of the target RNA, which is at odds with the down-regulation of a large portion of cellular transcripts. In this study, we address this paradox by using high-throughput sequencing of cleavage intermediates combined with a custom bioinformatics-based analysis pipeline to identify SOX cleavage sites across the mRNA transcriptome. These data, coupled with targeted mutagenesis, reveal that while cleavage sites are specific and reproducible, they are defined by a degenerate sequence motif containing a small number of conserved residues rather than a strong consensus sequence. This degenerate element is well represented in both human and KSHV mRNA, and its presence correlates with RNA destabilization by SOX. This represents a new endonuclease targeting strategy, in which use of a degenerate targeting element enables RNA cleavage at specific locations without restricting the range of targets. Furthermore, it shows that strong target selectivity can be achieved without a high degree of sequence specificity.
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Affiliation(s)
- Marta Maria Gaglia
- Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, United States of America
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail: (MMG); (BAG)
| | - Chris H. Rycroft
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Mathematics, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Britt A. Glaunsinger
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail: (MMG); (BAG)
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35
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Bavagnoli L, Cucuzza S, Campanini G, Rovida F, Paolucci S, Baldanti F, Maga G. The novel influenza A virus protein PA-X and its naturally deleted variant show different enzymatic properties in comparison to the viral endonuclease PA. Nucleic Acids Res 2015; 43:9405-17. [PMID: 26384413 PMCID: PMC4627086 DOI: 10.1093/nar/gkv926] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 09/07/2015] [Indexed: 12/18/2022] Open
Abstract
The PA protein of Influenza A virus (IAV) encoded by segment 3 acts as a specialized RNA endonuclease in the transcription of the viral genome. The same genomic segment encodes for a second shorter protein, termed PA-X, with the first 191 N-terminal aminoacids (aa) identical to PA, but with a completely different C-ter domain of 61 aa, due to a ribosomal frameshifting. In addition, it has been shown that several IAV isolates encode for a naturally truncated PA-X variant, PAXΔC20, missing the last 20 aa. The biochemical properties of PA-X and PAXΔC20 have been poorly investigated so far. Here, we have carried out an enzymatic characterization of PA-X and its naturally deleted form, in comparison with PA from the human IAV strain A/WSN/33 (H1N1). Our results showed, to the best of our knowledge for the first time, that PA-X possesses an endonucleolytic activity. Both PA and PA-X preferentially cut single stranded RNA regions, but with some differences. In addition, we showed that PAXΔC20 has severely reduced nuclease activity. These results point to a previously undetected role of the last C-ter 20 aa for the catalytic activity of PA-X and support distinct roles for these proteins in the viral life cycle.
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Affiliation(s)
- Laura Bavagnoli
- Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy
| | - Stefano Cucuzza
- Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy
| | - Giulia Campanini
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, P.le Golgi 2, 27100 Pavia, Italy
| | - Francesca Rovida
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, P.le Golgi 2, 27100 Pavia, Italy
| | - Stefania Paolucci
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, P.le Golgi 2, 27100 Pavia, Italy
| | - Fausto Baldanti
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, P.le Golgi 2, 27100 Pavia, Italy
| | - Giovanni Maga
- Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy
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36
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Koppstein D, Ashour J, Bartel DP. Sequencing the cap-snatching repertoire of H1N1 influenza provides insight into the mechanism of viral transcription initiation. Nucleic Acids Res 2015; 43:5052-64. [PMID: 25901029 PMCID: PMC4446424 DOI: 10.1093/nar/gkv333] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/01/2015] [Indexed: 12/15/2022] Open
Abstract
The influenza polymerase cleaves host RNAs ∼10–13 nucleotides downstream of their 5′ ends and uses this capped fragment to prime viral mRNA synthesis. To better understand this process of cap snatching, we used high-throughput sequencing to determine the 5′ ends of A/WSN/33 (H1N1) influenza mRNAs. The sequences provided clear evidence for nascent-chain realignment during transcription initiation and revealed a strong influence of the viral template on the frequency of realignment. After accounting for the extra nucleotides inserted through realignment, analysis of the capped fragments indicated that the different viral mRNAs were each prepended with a common set of sequences and that the polymerase often cleaved host RNAs after a purine and often primed transcription on a single base pair to either the terminal or penultimate residue of the viral template. We also developed a bioinformatic approach to identify the targeted host transcripts despite limited information content within snatched fragments and found that small nuclear RNAs and small nucleolar RNAs contributed the most abundant capped leaders. These results provide insight into the mechanism of viral transcription initiation and reveal the diversity of the cap-snatched repertoire, showing that noncoding transcripts as well as mRNAs are used to make influenza mRNAs.
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Affiliation(s)
- David Koppstein
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Whitehead Institute of Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA Howard Hughes Medical Institute, Whitehead Institute of Biomedical Research, Cambridge, MA 02142, USA
| | - Joseph Ashour
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Whitehead Institute of Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - David P Bartel
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Whitehead Institute of Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA Howard Hughes Medical Institute, Whitehead Institute of Biomedical Research, Cambridge, MA 02142, USA
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37
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Stevaert A, Nurra S, Pala N, Carcelli M, Rogolino D, Shepard C, Domaoal RA, Kim B, Alfonso-Prieto M, Marras SAE, Sechi M, Naesens L. An integrated biological approach to guide the development of metal-chelating inhibitors of influenza virus PA endonuclease. Mol Pharmacol 2015; 87:323-37. [PMID: 25477342 PMCID: PMC11037440 DOI: 10.1124/mol.114.095588] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/04/2014] [Indexed: 04/26/2024] Open
Abstract
The influenza virus PA endonuclease, which cleaves capped cellular pre-mRNAs to prime viral mRNA synthesis, is a promising target for novel anti-influenza virus therapeutics. The catalytic center of this enzyme resides in the N-terminal part of PA (PA-Nter) and contains two (or possibly one or three) Mg(2+) or Mn(2+) ions, which are critical for its catalytic function. There is great interest in PA inhibitors that are optimally designed to occupy the active site and chelate the metal ions. We focused here on a series of β-diketo acid (DKA) and DKA-bioisosteric compounds containing different scaffolds, and determined their structure-activity relationship in an enzymatic assay with PA-Nter, in order to build a three-dimensional pharmacophore model. In addition, we developed a molecular beacon (MB)-based PA-Nter assay that enabled us to compare the inhibition of Mn(2+) versus Mg(2+), the latter probably being the biologically relevant cofactor. This real-time MB assay allowed us to measure the enzyme kinetics of PA-Nter or perform high-throughput screening. Several DKA derivatives were found to cause strong inhibition of PA-Nter, with IC50 values comparable to that of the prototype L-742,001 (i.e., below 2 μM). Among the different compounds tested, L-742,001 appeared unique in having equal activity against either Mg(2+) or Mn(2+). Three compounds ( 10: , with a pyrrole scaffold, and 40: and 41: , with an indole scaffold) exhibited moderate antiviral activity in cell culture (EC99 values 64-95 μM) and were proven to affect viral RNA synthesis. Our approach of integrating complementary enzymatic, cellular, and mechanistic assays should guide ongoing development of improved influenza virus PA inhibitors.
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Affiliation(s)
- Annelies Stevaert
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Salvatore Nurra
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Nicolino Pala
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Mauro Carcelli
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Dominga Rogolino
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Caitlin Shepard
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Robert A Domaoal
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Baek Kim
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Mercedes Alfonso-Prieto
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Salvatore A E Marras
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Mario Sechi
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
| | - Lieve Naesens
- Rega Institute for Medical Research, KU Leuven-University of Leuven, Leuven, Belgium (A.S., L.N.); Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy (S.N., N.P., M.S.); Department of Chemistry, University of Parma, Parma, Italy (M.C., D.R.); Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia (C.S., R.D., B.K.); Department of Pharmacy, Kyung-Hee University, Seoul, South Korea (B.K.); Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania (M.A.P.); and Public Health Research Institute, Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey (S.M.)
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Reich S, Guilligay D, Pflug A, Malet H, Berger I, Crépin T, Hart D, Lunardi T, Nanao M, Ruigrok RWH, Cusack S. Structural insight into cap-snatching and RNA synthesis by influenza polymerase. Nature 2014; 516:361-6. [PMID: 25409151 DOI: 10.1038/nature14009] [Citation(s) in RCA: 328] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/29/2014] [Indexed: 12/11/2022]
Abstract
Influenza virus polymerase uses a capped primer, derived by 'cap-snatching' from host pre-messenger RNA, to transcribe its RNA genome into mRNA and a stuttering mechanism to generate the poly(A) tail. By contrast, genome replication is unprimed and generates exact full-length copies of the template. Here we use crystal structures of bat influenza A and human influenza B polymerases (FluA and FluB), bound to the viral RNA promoter, to give mechanistic insight into these distinct processes. In the FluA structure, a loop analogous to the priming loop of flavivirus polymerases suggests that influenza could initiate unprimed template replication by a similar mechanism. Comparing the FluA and FluB structures suggests that cap-snatching involves in situ rotation of the PB2 cap-binding domain to direct the capped primer first towards the endonuclease and then into the polymerase active site. The polymerase probably undergoes considerable conformational changes to convert the observed pre-initiation state into the active initiation and elongation states.
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Affiliation(s)
- Stefan Reich
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Delphine Guilligay
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Alexander Pflug
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Hélène Malet
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Imre Berger
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Thibaut Crépin
- University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Darren Hart
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Thomas Lunardi
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Max Nanao
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Rob W H Ruigrok
- University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
| | - Stephen Cusack
- 1] European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France [2] University Grenoble Alpes-Centre National de la Recherche Scientifique-EMBL Unit of Virus Host-Cell Interactions, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France
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Abstract
The influenza A virus causes a highly contagious respiratory disease that significantly impacts our economy and health. Its replication and transcription is catalyzed by the viral RNA polymerase. This enzyme is also crucial for the virus, because it is involved in the adaptation of zoonotic strains. It is thus of major interest for the development of antiviral therapies and is being intensively studied. In this article, we will discuss recent advances that have improved our knowledge of the structure of the RNA polymerase and how mutations in the polymerase help the virus to spread effectively among new hosts.
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Affiliation(s)
- Thomas M Stubbs
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK ; Babraham Institute, Brabraham Research Campus, Cambridge, CB22 3AT, UK
| | - Aartjan Jw Te Velthuis
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
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Deep sequencing reveals the eight facets of the influenza A/HongKong/1/1968 (H3N2) virus cap-snatching process. Sci Rep 2014; 4:6181. [PMID: 25154590 PMCID: PMC4143772 DOI: 10.1038/srep06181] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/31/2014] [Indexed: 11/08/2022] Open
Abstract
The influenza A virus RNA polymerase cleaves the 5′ end of host pre-mRNAs and uses the capped RNA fragments as primers for viral mRNA synthesis. We performed deep sequencing of the 5′ ends of viral mRNAs from all genome segments transcribed in both human (A549) and mouse (M-1) cells infected with the influenza A/HongKong/1/1968 (H3N2) virus. In addition to information on RNA motifs present, our results indicate that the host primers are divergent between the viral transcripts. We observed differences in length distributions, nucleotide motifs and the identity of the host primers between the viral mRNAs. Mapping the reads to known transcription start sites indicates that the virus targets the most abundant host mRNAs, which is likely caused by the higher expression of these genes. Our findings suggest negligible competition amongst RdRp:vRNA complexes for individual host mRNA templates during cap-snatching and provide a better understanding of the molecular mechanism governing the first step of transcription of this influenza strain.
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41
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te Velthuis AJW. Common and unique features of viral RNA-dependent polymerases. Cell Mol Life Sci 2014; 71:4403-20. [PMID: 25080879 PMCID: PMC4207942 DOI: 10.1007/s00018-014-1695-z] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/29/2014] [Accepted: 07/28/2014] [Indexed: 12/12/2022]
Abstract
Eukaryotes and bacteria can be infected with a wide variety of RNA viruses. On average, these pathogens share little sequence similarity and use different replication and transcription strategies. Nevertheless, the members of nearly all RNA virus families depend on the activity of a virally encoded RNA-dependent polymerase for the condensation of nucleotide triphosphates. This review provides an overview of our current understanding of the viral RNA-dependent polymerase structure and the biochemistry and biophysics that is involved in replicating and transcribing the genetic material of RNA viruses.
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Affiliation(s)
- Aartjan J W te Velthuis
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC, Leiden, The Netherlands,
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42
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Hu J, Liu X. Crucial role of PA in virus life cycle and host adaptation of influenza A virus. Med Microbiol Immunol 2014; 204:137-49. [PMID: 25070354 DOI: 10.1007/s00430-014-0349-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 07/16/2014] [Indexed: 02/01/2023]
Abstract
The PA protein is the third subunit of the polymerase complex of influenza A virus. Compared with the other two polymerase subunits (PB2 and PB1), its precise functions are less defined. However, in recent years, advances in protein expression and crystallization technologies and also the reverse genetics, greatly accelerate our understanding of the essential role of PA in virus infection. Here, we first review the current literature on this remarkably multifunctional viral protein regarding virus life cycle, including viral RNA transcription and replication, viral genome packaging and assembly. We then discuss the various roles of PA in host adaption in avian species and mammals, general virus-host interaction, and host protein synthesis shutoff. We also review the recent findings about the novel proteins derived from PA. Finally, we discuss the prospects of PA as a target for the development of new antiviral approaches and drugs.
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Affiliation(s)
- Jiao Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, 48 East Wenhui Road, Yangzhou, 225009, Jiangsu Province, China
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Bat-derived influenza-like viruses H17N10 and H18N11. Trends Microbiol 2014; 22:183-91. [PMID: 24582528 PMCID: PMC7127364 DOI: 10.1016/j.tim.2014.01.010] [Citation(s) in RCA: 242] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/26/2014] [Accepted: 01/30/2014] [Indexed: 11/24/2022]
Abstract
Bat-derived influenza-like virus hemagglutinin and neuraminidase lack canonical functions and structures. Putative functional modules/domains in other bat-derived influenza-like proteins are conserved. Potential genomic reassortments with canonical influenza virus cannot be ruled out and should be assessed.
Shorebirds and waterfowls are believed to be the reservoir hosts for influenza viruses, whereas swine putatively act as mixing vessels. The recent identification of two influenza-like virus genomes (designated H17N10 and H18N11) from bats has challenged this notion. A crucial question concerns the role bats might play in influenza virus ecology. Structural and functional studies of the two major surface envelope proteins, hemagglutinin (HA) and neuraminidase (NA), demonstrate that neither has canonical HA or NA functions found in influenza viruses. However, putative functional modules and domains in other encoded proteins are conserved, and the N-terminal domain of the H17N10 polymerase subunit PA has a classical structure and function. Therefore, potential genomic reassortments of such influenza-like viruses with canonical influenza viruses cannot be excluded at this point and should be assessed.
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Xiao S, Klein ML, LeBard DN, Levine BG, Liang H, MacDermaid CM, Alfonso-Prieto M. Magnesium-Dependent RNA Binding to the PA Endonuclease Domain of the Avian Influenza Polymerase. J Phys Chem B 2014; 118:873-89. [DOI: 10.1021/jp408383g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Shiyan Xiao
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Michael L. Klein
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - David N. LeBard
- Department of Chemistry, Yeshiva University, New York, New York 10033, United States
| | - Benjamin G. Levine
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, United States
| | - Haojun Liang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Christopher M. MacDermaid
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Mercedes Alfonso-Prieto
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
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Guilligay D, Kadlec J, Crépin T, Lunardi T, Bouvier D, Kochs G, Ruigrok RWH, Cusack S. Comparative structural and functional analysis of orthomyxovirus polymerase cap-snatching domains. PLoS One 2014; 9:e84973. [PMID: 24454773 PMCID: PMC3893164 DOI: 10.1371/journal.pone.0084973] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/28/2013] [Indexed: 11/19/2022] Open
Abstract
Orthomyxovirus Influenza A virus (IAV) heterotrimeric polymerase performs transcription of viral mRNAs by cap-snatching, which involves generation of capped primers by host pre-mRNA binding via the PB2 subunit cap-binding site and cleavage 10–13 nucleotides from the 5′ cap by the PA subunit endonuclease. Thogotoviruses, tick-borne orthomyxoviruses that includes Thogoto (THOV), Dhori (DHOV) and Jos (JOSV) viruses, are thought to perform cap-snatching by cleaving directly after the cap and thus have no heterogeneous, host-derived sequences at the 5′ extremity of their mRNAs. Based on recent work identifying the cap-binding and endonuclease domains in IAV polymerase, we determined the crystal structures of two THOV PB2 domains, the putative cap-binding and the so-called ‘627-domain’, and the structures of the putative endonuclease domains (PA-Nter) of THOV and DHOV. Despite low sequence similarity, corresponding domains have the same fold confirming the overall architectural similarity of orthomyxovirus polymerases. However the putative Thogotovirus cap-snatching domains in PA and PB2 have non-conservative substitutions of key active site residues. Biochemical analysis confirms that, unlike the IAV domains, the THOV and DHOV PA-Nter domains do not bind divalent cations and have no endonuclease activity and the THOV central PB2 domain does not bind cap analogues. On the other hand, sequence analysis suggests that other, non-influenza, orthomyxoviruses, such as salmon anemia virus (isavirus) and Quaranfil virus likely conserve active cap-snatching domains correlating with the reported occurrence of heterogeneous, host-derived sequences at the 5′ end of the mRNAs of these viruses. These results highlight the unusual nature of transcription initiation by Thogotoviruses.
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Affiliation(s)
- Delphine Guilligay
- University Grenoble Alpes, Unit of Virus Host-Cell Interactions, Grenoble, France
- Centre National de la Recherche Scientifique, Unit of Virus Host-Cell Interactions, Grenoble, France
- European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Jan Kadlec
- European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Thibaut Crépin
- University Grenoble Alpes, Unit of Virus Host-Cell Interactions, Grenoble, France
- Centre National de la Recherche Scientifique, Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Thomas Lunardi
- European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Denis Bouvier
- University Grenoble Alpes, Unit of Virus Host-Cell Interactions, Grenoble, France
- Centre National de la Recherche Scientifique, Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Georg Kochs
- Institute for Virology, University Medical Center Freiburg, Freiburg, Germany
| | - Rob W. H. Ruigrok
- University Grenoble Alpes, Unit of Virus Host-Cell Interactions, Grenoble, France
- Centre National de la Recherche Scientifique, Unit of Virus Host-Cell Interactions, Grenoble, France
| | - Stephen Cusack
- European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, Grenoble, France
- * E-mail:
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46
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The N-terminal domain of PA from bat-derived influenza-like virus H17N10 has endonuclease activity. J Virol 2013; 88:1935-41. [PMID: 24284327 DOI: 10.1128/jvi.03270-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza imposes a great burden on society, not only in its seasonal appearance that affects both humans and domesticated animals but also through the constant threat of potential pandemics. Migratory birds are considered to be the reservoir hosts for influenza viruses, but other animals must also be considered. The recently identified influenza-like virus genome, from H17N10 in bats, was shown to be markedly different from genomes of other known influenza viruses, as both its surface glycoproteins hemagglutinin (HA) and neuraminidase (NA) do not have canonical functions. However, no studies on other individual proteins from this particular virus have been reported until now. Here, we describe the structure of the N-terminal domain of PA from H17N10 influenza-like virus at 2.7-Å resolution and show that it has a fold similar to those of homologous PA domains present in more familiar influenza A virus strains. Moreover, we demonstrate that it possesses endonuclease activity and that the histidine residue in the active site is essential for this activity. Although this particular influenza virus subtype is probably not infectious for humans (even its virus state has not been confirmed in bats, as only the genome has been sequenced), reassortment of canonical influenza viruses with certain segments from H17N10 cannot be ruled out at this stage. Therefore, further studies are urgently needed for the sake of influenza prevention and control.
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