1
|
Williams HM, Thorkelsson SR, Vogel D, Milewski M, Busch C, Cusack S, Grünewald K, Quemin EJ, Rosenthal M. Structural insights into viral genome replication by the severe fever with thrombocytopenia syndrome virus L protein. Nucleic Acids Res 2023; 51:1424-1442. [PMID: 36651274 PMCID: PMC9943659 DOI: 10.1093/nar/gkac1249] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/29/2022] [Accepted: 12/14/2022] [Indexed: 01/19/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a phenuivirus that has rapidly become endemic in several East Asian countries. The large (L) protein of SFTSV, which includes the RNA-dependent RNA polymerase (RdRp), is responsible for catalysing viral genome replication and transcription. Here, we present 5 cryo-electron microscopy (cryo-EM) structures of the L protein in several states of the genome replication process, from pre-initiation to late-stage elongation, at a resolution of up to 2.6 Å. We identify how the L protein binds the 5' viral RNA in a hook-like conformation and show how the distal 5' and 3' RNA ends form a duplex positioning the 3' RNA terminus in the RdRp active site ready for initiation. We also observe the L protein stalled in the early and late stages of elongation with the RdRp core accommodating a 10-bp product-template duplex. This duplex ultimately splits with the template binding to a designated 3' secondary binding site. The structural data and observations are complemented by in vitro biochemical and cell-based mini-replicon assays. Altogether, our data provide novel key insights into the mechanism of viral genome replication by the SFTSV L protein and will aid drug development against segmented negative-strand RNA viruses.
Collapse
Affiliation(s)
| | | | - Dominik Vogel
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | - Morlin Milewski
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | - Carola Busch
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
| | | | - Kay Grünewald
- Centre for Structural Systems Biology, Leibniz Institute of Virology, Hamburg, Germany,University of Hamburg, Hamburg, Germany
| | - Emmanuelle R J Quemin
- Centre for Structural Systems Biology, Leibniz Institute of Virology, Hamburg, Germany
| | - Maria Rosenthal
- To whom correspondence should be addressed. Tel: +49 40 285380 930;
| |
Collapse
|
2
|
Bunyaviral N Proteins Localize at RNA Processing Bodies and Stress Granules: The Enigma of Cytoplasmic Sources of Capped RNA for Cap Snatching. Viruses 2022; 14:v14081679. [PMID: 36016301 PMCID: PMC9414089 DOI: 10.3390/v14081679] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/18/2022] [Accepted: 07/26/2022] [Indexed: 11/17/2022] Open
Abstract
Most cytoplasmic-replicating negative-strand RNA viruses (NSVs) initiate genome transcription by cap snatching. The source of host mRNAs from which the cytoplasmic NSVs snatch capped-RNA leader sequences has remained elusive. Earlier reports have pointed towards cytoplasmic-RNA processing bodies (P body, PB), although several questions have remained unsolved. Here, the nucleocapsid (N) protein of plant- and animal-infecting members of the order Bunyavirales, in casu Tomato spotted wilt virus (TSWV), Rice stripe virus (RSV), Sin nombre virus (SNV), Crimean-Congo hemorrhagic fever virus (CCHFV) and Schmallenberg virus (SBV) have been expressed and localized in cells of their respective plant and animal hosts. All N proteins localized to PBs as well as stress granules (SGs), but extensively to docking stages of PB and SG. TSWV and RSV N proteins also co-localized with Ran GTPase-activating protein 2 (RanGAP2), a nucleo-cytoplasmic shuttling factor, in the perinuclear region, and partly in the nucleus when co-expressed with its WPP domain containing a nuclear-localization signal. Upon silencing of PB and SG components individually or concomitantly, replication levels of a TSWV minireplicon, as measured by the expression of a GFP reporter gene, ranged from a 30% reduction to a four-fold increase. Upon the silencing of RanGAP homologs in planta, replication of the TSWV minireplicon was reduced by 75%. During in vivo cap-donor competition experiments, TSWV used transcripts destined to PB and SG, but also functional transcripts engaged in translation. Altogether, the results implicate a more complex situation in which, besides PB, additional cytoplasmic sources are used during transcription/cap snatching of cytoplasmic-replicating and segmented NSVs.
Collapse
|
3
|
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.
Collapse
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.
| |
Collapse
|
4
|
Xu Y, Fu S, Tao X, Zhou X. Rice stripe virus: Exploring Molecular Weapons in the Arsenal of a Negative-Sense RNA Virus. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:351-371. [PMID: 34077238 DOI: 10.1146/annurev-phyto-020620-113020] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Rice stripe disease caused by Rice stripe virus (RSV) is one of the most devastating plant viruses of rice and causes enormous losses in production. RSV is transmitted from plant to plant by the small brown planthopper (Laodelphax striatellus) in a circulative-propagative manner. The recent reemergence of this pathogen in East Asia since 2000 has made RSV one of the most studied plant viruses over the past two decades. Extensive studies of RSV have resulted in substantial advances regarding fundamental aspects of the virus infection. Here, we compile and analyze recent information on RSV with a special emphasis on the strategies that RSV has adopted to establish infections. These advances include RSV replication and movement in host plants and the small brown planthopper vector, innate immunity defenses against RSV infection, epidemiology, and recent advances in the management of rice stripe disease. Understanding these issues will facilitate the design of novel antiviral therapies for management and contribute to a more detailed understanding of negative-sense virus-host interactions at the molecular level.
Collapse
Affiliation(s)
- Yi Xu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuai Fu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
| | - Xiaorong Tao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China;
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing 210095, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| |
Collapse
|
5
|
Bolus S, Braithwaite KS, Grinstead SC, Fuentes-Bueno I, Beiriger R, Falk BW, Mollov D. Completion of Maize Stripe Virus Genome Sequence and Analysis of Diverse Isolates. Front Microbiol 2021; 12:684599. [PMID: 34194416 PMCID: PMC8238005 DOI: 10.3389/fmicb.2021.684599] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 04/26/2021] [Indexed: 01/25/2023] Open
Abstract
Maize stripe virus is a pathogen of corn and sorghum in subtropical and tropical regions worldwide. We used high-throughput sequencing to obtain the complete nucleotide sequence for the reference genome of maize stripe virus and to sequence the genomes of ten additional isolates collected from the United States or Papua New Guinea. Genetically, maize stripe virus is most closely related to rice stripe virus. We completed and characterized the RNA1 sequence for maize stripe virus, which revealed a large open reading frame encoding a putative protein with ovarian tumor-like cysteine protease, endonuclease, and RNA-dependent RNA polymerase domains. Phylogenetic and amino acid identity analyses among geographically diverse isolates revealed evidence for reassortment in RNA3 that was correlated with the absence of RNA5. This study yielded a complete and updated genetic description of the tenuivirus maize stripe virus and provided insight into potential mechanisms underpinning its diversity.
Collapse
Affiliation(s)
- Stephen Bolus
- National Germplasm Resources Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD, United States
| | | | - Samuel C Grinstead
- National Germplasm Resources Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD, United States
| | - Irazema Fuentes-Bueno
- National Germplasm Resources Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD, United States
| | - Robert Beiriger
- Institute of Food and Agricultural Sciences, University of Florida, Belle Glade, FL, United States
| | - Bryce W Falk
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Dimitre Mollov
- National Germplasm Resources Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD, United States
| |
Collapse
|
6
|
Kormelink R, Verchot J, Tao X, Desbiez C. The Bunyavirales: The Plant-Infecting Counterparts. Viruses 2021; 13:v13050842. [PMID: 34066457 PMCID: PMC8148189 DOI: 10.3390/v13050842] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 12/18/2022] Open
Abstract
Negative-strand (-) RNA viruses (NSVs) comprise a large and diverse group of viruses that are generally divided in those with non-segmented and those with segmented genomes. Whereas most NSVs infect animals and humans, the smaller group of the plant-infecting counterparts is expanding, with many causing devastating diseases worldwide, affecting a large number of major bulk and high-value food crops. In 2018, the taxonomy of segmented NSVs faced a major reorganization with the establishment of the order Bunyavirales. This article overviews the major plant viruses that are part of the order, i.e., orthospoviruses (Tospoviridae), tenuiviruses (Phenuiviridae), and emaraviruses (Fimoviridae), and provides updates on the more recent ongoing research. Features shared with the animal-infecting counterparts are mentioned, however, special attention is given to their adaptation to plant hosts and vector transmission, including intra/intercellular trafficking and viral counter defense to antiviral RNAi.
Collapse
Affiliation(s)
- Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Jeanmarie Verchot
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Xiaorong Tao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | | |
Collapse
|
7
|
Olschewski S, Cusack S, Rosenthal M. The Cap-Snatching Mechanism of Bunyaviruses. Trends Microbiol 2020; 28:293-303. [PMID: 31948728 DOI: 10.1016/j.tim.2019.12.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 12/09/2019] [Indexed: 11/25/2022]
Abstract
In common with all segmented negative-sense RNA viruses, bunyavirus transcripts contain heterologous sequences at their 5' termini originating from capped host cell RNAs. These heterologous sequences are acquired by a so-called cap-snatching mechanism. Whereas for nuclear replicating influenza virus the source of capped primers as well as the cap-binding and endonuclease activities of the viral polymerase needed for cap snatching have been functionally and structurally well characterized, our knowledge on the expected counterparts of cytoplasmic replicating bunyaviruses is still limited and controversial. This review focuses on the cap-snatching mechanism of bunyaviruses in the light of recent structural and functional data.
Collapse
Affiliation(s)
- Silke Olschewski
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, Hamburg, Germany
| | | | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine, Department of Virology, Hamburg, Germany.
| |
Collapse
|
8
|
Gogrefe N, Reindl S, Günther S, Rosenthal M. Structure of a functional cap-binding domain in Rift Valley fever virus L protein. PLoS Pathog 2019; 15:e1007829. [PMID: 31136637 PMCID: PMC6555543 DOI: 10.1371/journal.ppat.1007829] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/07/2019] [Accepted: 05/08/2019] [Indexed: 11/25/2022] Open
Abstract
Rift Valley fever virus (RVFV) belongs to the family of Phenuiviridae within the order of Bunyavirales. The virus may cause fatal disease both in livestock and humans, and therefore, is of great economical and public health relevance. In analogy to the influenza virus polymerase complex, the bunyavirus L protein is assumed to bind to and cleave off cap structures of cellular mRNAs to prime viral transcription. However, even though the presence of an endonuclease in the N-terminal domain of the L protein has been demonstrated for several bunyaviruses, there is no evidence for a cap-binding site within the L protein. We solved the structure of a C-terminal 117 amino acid-long domain of the RVFV L protein by X-ray crystallography. The overall fold of the domain shows high similarity to influenza virus PB2 cap-binding domain and the putative non-functional cap-binding domain of reptarenaviruses. Upon co-crystallization with m7GTP, we detected the cap-analogue bound between two aromatic side chains as it has been described for other cap-binding proteins. We observed weak but specific interaction with m7GTP rather than GTP in vitro using isothermal titration calorimetry. The importance of m7GTP-binding residues for viral transcription was validated using a RVFV minigenome system. In summary, we provide structural and functional evidence for a cap-binding site located within the L protein of a virus from the Bunyavirales order. Rift Valley fever virus (RVFV) is endemic to sub-Saharan Africa and the Arabian Peninsula and leads to abortions in and death of ruminants. The virus can also be transmitted to humans causing febrile illness up to hemorrhagic fever with the possibility of fatal outcome. As there is currently no human vaccine or specific treatment available and because of the high epidemic potential, WHO has listed RVFV on its R&D Blueprint for urgent development of medical countermeasures. In order to amplify, the virus needs to transcribe and replicate the viral genome inside the cell cytoplasm. For transcription, the virus uses a process called cap-snatching, which is essentially depending on two functions presumed to reside within the large viral L protein: the ability to bind cap-structures and the activity of cleaving them off from cellular mRNA. Both functions could serve as specific targets for antiviral drug design. We identified and solved the structure of the cap-binding domain of RVFV and provide the first evidence for the presence of a functional cap-binding site in the L protein of bunyaviruses. Comparison with cap-binding proteins of related viruses revealed similarities and important differences critical for the development of potential broad-spectrum antivirals.
Collapse
Affiliation(s)
- Nadja Gogrefe
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Sophia Reindl
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Stephan Günther
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.,German Center for Infection Research (DZIF), Partner site Hamburg-Lübeck-Borstel-Riems, Germany
| | - Maria Rosenthal
- Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| |
Collapse
|