1
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Li T, Liu M, Gu Z, Su X, Liu Y, Lin J, Zhang Y, Shen QT. Structures of the mumps virus polymerase complex via cryo-electron microscopy. Nat Commun 2024; 15:4189. [PMID: 38760379 PMCID: PMC11101452 DOI: 10.1038/s41467-024-48389-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 04/26/2024] [Indexed: 05/19/2024] Open
Abstract
The viral polymerase complex, comprising the large protein (L) and phosphoprotein (P), is crucial for both genome replication and transcription in non-segmented negative-strand RNA viruses (nsNSVs), while structures corresponding to these activities remain obscure. Here, we resolved two L-P complex conformations from the mumps virus (MuV), a typical member of nsNSVs, via cryogenic-electron microscopy. One conformation presents all five domains of L forming a continuous RNA tunnel to the methyltransferase domain (MTase), preferably as a transcription state. The other conformation has the appendage averaged out, which is inaccessible to MTase. In both conformations, parallel P tetramers are revealed around MuV L, which, together with structures of other nsNSVs, demonstrates the diverse origins of the L-binding X domain of P. Our study links varying structures of nsNSV polymerase complexes with genome replication and transcription and points to a sliding model for polymerase complexes to advance along the RNA templates.
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Affiliation(s)
- Tianhao Li
- School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Mingdong Liu
- School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Zhanxi Gu
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Synthetic Biology, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Xin Su
- School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, 200438, China
| | - Yunhui Liu
- School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jinzhong Lin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, 200438, China
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Qing-Tao Shen
- School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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2
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Musa AO, Faber SR, Forrest K, Smith KP, Sengupta S, López CB. Identification of distinct genotypes in circulating RSV A strains based on variants on the virus replication-associated genes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590570. [PMID: 38712045 PMCID: PMC11071361 DOI: 10.1101/2024.04.22.590570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Respiratory syncytial virus is a common cause of respiratory infection that often leads to hospitalization of infected younger children and older adults. RSV is classified into two strains, A and B, each with several subgroups or genotypes. One issue with the definition of these subgroups is the lack of a unified method of identification or genotyping. We propose that genotyping strategies based on the genes coding for replication-associated proteins could provide critical information on the replication capacity of the distinct subgroup, while clearly distinguishing genotypes. Here, we analyzed the virus replication-associated genes N, P, M2, and L from de novo assembled RSV A sequences obtained from 31 newly sequenced samples from hospitalized patients in Philadelphia and 78 additional publicly available sequences from different geographic locations within the US. In-depth analysis and annotation of the protein variants in L and the other replication-associated proteins N, P, M2-1, and M2-2 identified the polymerase protein L as a robust target for genotyping RSV subgroups. Importantly, our analysis revealed non-synonymous variations in L that were consistently accompanied by conserved changes in its co-factor P or the M2-2 protein, suggesting associations and interactions between specific domains of these proteins. These results highlight L as an alternative to other RSV genotyping targets and demonstrate the value of in-depth analyses and annotations of RSV sequences as it can serve as a foundation for subsequent in vitro and clinical studies on the efficiency of the polymerase and fitness of different virus isolates.
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Affiliation(s)
- Abdulafiz O. Musa
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Center for Womeńs Infectious Diseases Research, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Sydney R. Faber
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Center for Womeńs Infectious Diseases Research, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Kaitlyn Forrest
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Neonatology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Kenneth P. Smith
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Infectious Disease Diagnostics Laboratory, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Shaon Sengupta
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Neonatology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Carolina B. López
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Center for Womeńs Infectious Diseases Research, Washington University School of Medicine, Saint Louis, Missouri, USA
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3
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Xie J, Ouizougun-Oubari M, Wang L, Zhai G, Wu D, Lin Z, Wang M, Ludeke B, Yan X, Nilsson T, Gao L, Huang X, Fearns R, Chen S. Structural basis for dimerization of a paramyxovirus polymerase complex. Nat Commun 2024; 15:3163. [PMID: 38605025 PMCID: PMC11009304 DOI: 10.1038/s41467-024-47470-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/26/2024] [Indexed: 04/13/2024] Open
Abstract
The transcription and replication processes of non-segmented, negative-strand RNA viruses (nsNSVs) are catalyzed by a multi-functional polymerase complex composed of the large protein (L) and a cofactor protein, such as phosphoprotein (P). Previous studies have shown that the nsNSV polymerase can adopt a dimeric form, however, the structure of the dimer and its function are poorly understood. Here we determine a 2.7 Å cryo-EM structure of human parainfluenza virus type 3 (hPIV3) L-P complex with the connector domain (CD') of a second L built, while reconstruction of the rest of the second L-P obtains a low-resolution map of the ring-like L core region. This study reveals detailed atomic features of nsNSV polymerase active site and distinct conformation of hPIV3 L with a unique β-strand latch. Furthermore, we report the structural basis of L-L dimerization, with CD' located at the putative template entry of the adjoining L. Disruption of the L-L interface causes a defect in RNA replication that can be overcome by complementation, demonstrating that L dimerization is necessary for hPIV3 genome replication. These findings provide further insight into how nsNSV polymerases perform their functions, and suggest a new avenue for rational drug design.
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Affiliation(s)
- Jin Xie
- Roche Pharma Research and Early Development, Lead Discovery, Roche Innovation Center Shanghai, 201203, Shanghai, China
| | - Mohamed Ouizougun-Oubari
- Department of Virology, Immunology & Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA
| | - Li Wang
- Roche Pharma Research and Early Development, Infectious Diseases, Roche Innovation Center Shanghai, 201203, Shanghai, China
| | - Guanglei Zhai
- Roche Pharma Research and Early Development, Lead Discovery, Roche Innovation Center Shanghai, 201203, Shanghai, China
| | - Daitze Wu
- Roche Pharma Research and Early Development, Infectious Diseases, Roche Innovation Center Shanghai, 201203, Shanghai, China
| | - Zhaohu Lin
- Roche Pharma Research and Early Development, Lead Discovery, Roche Innovation Center Shanghai, 201203, Shanghai, China
| | - Manfu Wang
- Wuxi Biortus Biosciences Co. Ltd., 214437, Jiangyin, Jiangsu, China
| | - Barbara Ludeke
- Department of Virology, Immunology & Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA
| | - Xiaodong Yan
- Wuxi Biortus Biosciences Co. Ltd., 214437, Jiangyin, Jiangsu, China
| | - Tobias Nilsson
- Roche Pharma Research and Early Development, Infectious Diseases, Roche Innovation Center Basel, Basel, 4070, Switzerland
| | - Lu Gao
- Roche Pharma Research and Early Development, Infectious Diseases, Roche Innovation Center Shanghai, 201203, Shanghai, China.
| | - Xinyi Huang
- Roche Pharma Research and Early Development, Lead Discovery, Roche Innovation Center Shanghai, 201203, Shanghai, China.
| | - Rachel Fearns
- Department of Virology, Immunology & Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA.
| | - Shuai Chen
- Roche Pharma Research and Early Development, Lead Discovery, Roche Innovation Center Shanghai, 201203, Shanghai, China.
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4
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Cao D, Gao Y, Chen Z, Gooneratne I, Roesler C, Mera C, D'Cunha P, Antonova A, Katta D, Romanelli S, Wang Q, Rice S, Lemons W, Ramanathan A, Liang B. Structures of the promoter-bound respiratory syncytial virus polymerase. Nature 2024; 625:611-617. [PMID: 38123676 PMCID: PMC10794133 DOI: 10.1038/s41586-023-06867-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023]
Abstract
The respiratory syncytial virus (RSV) polymerase is a multifunctional RNA-dependent RNA polymerase composed of the large (L) protein and the phosphoprotein (P). It transcribes the RNA genome into ten viral mRNAs and replicates full-length viral genomic and antigenomic RNAs1. The RSV polymerase initiates RNA synthesis by binding to the conserved 3'-terminal RNA promoters of the genome or antigenome2. However, the lack of a structure of the RSV polymerase bound to the RNA promoter has impeded the mechanistic understanding of RSV RNA synthesis. Here we report cryogenic electron microscopy structures of the RSV polymerase bound to its genomic and antigenomic viral RNA promoters, representing two of the first structures of an RNA-dependent RNA polymerase in complex with its RNA promoters in non-segmented negative-sense RNA viruses. The overall structures of the promoter-bound RSV polymerases are similar to that of the unbound (apo) polymerase. Our structures illustrate the interactions between the RSV polymerase and the RNA promoters and provide the structural basis for the initiation of RNA synthesis at positions 1 and 3 of the RSV promoters. These structures offer a deeper understanding of the pre-initiation state of the RSV polymerase and could aid in antiviral research against RSV.
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Affiliation(s)
- Dongdong Cao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Yunrong Gao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Zhenhang Chen
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Inesh Gooneratne
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Claire Roesler
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Cristopher Mera
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Paul D'Cunha
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Anna Antonova
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Deepak Katta
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Sarah Romanelli
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Qi Wang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Samantha Rice
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Wesley Lemons
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Anita Ramanathan
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.
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5
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Meng XY, Jiang QQ, Yu XD, Zhang QY, Ke F. Eukaryotic translation elongation factor 1 alpha (eEF1A) inhibits Siniperca chuatsi rhabdovirus (SCRV) infection through two distinct mechanisms. J Virol 2023; 97:e0122623. [PMID: 37861337 PMCID: PMC10688370 DOI: 10.1128/jvi.01226-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 09/22/2023] [Indexed: 10/21/2023] Open
Abstract
IMPORTANCE Although a virus can regulate many cellular responses to facilitate its replication by interacting with host proteins, the host can also restrict virus infection through these interactions. In the present study, we showed that the host eukaryotic translation elongation factor 1 alpha (eEF1A), an essential protein in the translation machinery, interacted with two proteins of a fish rhabdovirus, Siniperca chuatsi rhabdovirus (SCRV), and inhibited virus infection via two different mechanisms: (i) inhibiting the formation of crucial viral protein complexes required for virus transcription and replication and (ii) promoting the ubiquitin-proteasome degradation of viral protein. We also revealed the functional regions of eEF1A that are involved in the two processes. Such a host protein inhibiting a rhabdovirus infection in two ways is rarely reported. These findings provided new information for the interactions between host and fish rhabdovirus.
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Affiliation(s)
- Xian-Yu Meng
- Institute of Hydrobiology, College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
| | - Qi-Qi Jiang
- Institute of Hydrobiology, College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
| | - Xue-Dong Yu
- Institute of Hydrobiology, College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
| | - Qi-Ya Zhang
- Institute of Hydrobiology, College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
- The Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Fei Ke
- Institute of Hydrobiology, College of Modern Agriculture Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Wuhan, China
- The Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
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6
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Yu X, Abeywickrema P, Bonneux B, Behera I, Anson B, Jacoby E, Fung A, Adhikary S, Bhaumik A, Carbajo RJ, De Bruyn S, Miller R, Patrick A, Pham Q, Piassek M, Verheyen N, Shareef A, Sutto-Ortiz P, Ysebaert N, Van Vlijmen H, Jonckers THM, Herschke F, McLellan JS, Decroly E, Fearns R, Grosse S, Roymans D, Sharma S, Rigaux P, Jin Z. Structural and mechanistic insights into the inhibition of respiratory syncytial virus polymerase by a non-nucleoside inhibitor. Commun Biol 2023; 6:1074. [PMID: 37865687 PMCID: PMC10590419 DOI: 10.1038/s42003-023-05451-4] [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: 08/07/2023] [Accepted: 10/11/2023] [Indexed: 10/23/2023] Open
Abstract
The respiratory syncytial virus polymerase complex, consisting of the polymerase (L) and phosphoprotein (P), catalyzes nucleotide polymerization, cap addition, and cap methylation via the RNA dependent RNA polymerase, capping, and Methyltransferase domains on L. Several nucleoside and non-nucleoside inhibitors have been reported to inhibit this polymerase complex, but the structural details of the exact inhibitor-polymerase interactions have been lacking. Here, we report a non-nucleoside inhibitor JNJ-8003 with sub-nanomolar inhibition potency in both antiviral and polymerase assays. Our 2.9 Å resolution cryo-EM structure revealed that JNJ-8003 binds to an induced-fit pocket on the capping domain, with multiple interactions consistent with its tight binding and resistance mutation profile. The minigenome and gel-based de novo RNA synthesis and primer extension assays demonstrated that JNJ-8003 inhibited nucleotide polymerization at the early stages of RNA transcription and replication. Our results support that JNJ-8003 binding modulates a functional interplay between the capping and RdRp domains, and this molecular insight could accelerate the design of broad-spectrum antiviral drugs.
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Affiliation(s)
- Xiaodi Yu
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA.
| | - Pravien Abeywickrema
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Brecht Bonneux
- Janssen Infectious Diseases and Vaccines, 2340, Beerse, Belgium
- University of Antwerp, Antwerp, Belgium
| | - Ishani Behera
- Johnson & Johnson Innovative Medicine, Brisbane, CA, 94005, USA
| | - Brandon Anson
- Johnson & Johnson Innovative Medicine, Brisbane, CA, 94005, USA
| | - Edgar Jacoby
- Johnson & Johnson Innovative Medicine, Beerse, Belgium
| | - Amy Fung
- Johnson & Johnson Innovative Medicine, Brisbane, CA, 94005, USA
| | - Suraj Adhikary
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Anusarka Bhaumik
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Rodrigo J Carbajo
- Johnson & Johnson Innovative Medicine, Janssen-Cilag, Discovery Chemistry S.A. Río Jarama, 75A, 45007, Toledo, Spain
| | | | - Robyn Miller
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Aaron Patrick
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Quyen Pham
- Johnson & Johnson Innovative Medicine, Brisbane, CA, 94005, USA
| | - Madison Piassek
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Nick Verheyen
- Janssen Infectious Diseases and Vaccines, 2340, Beerse, Belgium
| | - Afzaal Shareef
- Department of Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA
| | | | - Nina Ysebaert
- Janssen Infectious Diseases and Vaccines, 2340, Beerse, Belgium
| | | | | | | | - Jason S McLellan
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB, UMR 7257, Marseille, France
| | - Rachel Fearns
- Department of Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, 02118, USA
| | | | - Dirk Roymans
- Janssen Infectious Diseases and Vaccines, 2340, Beerse, Belgium
| | - Sujata Sharma
- Johnson & Johnson Innovative Medicine, Spring House, Pennsylvania, PA, 19477, USA
| | - Peter Rigaux
- Janssen Infectious Diseases and Vaccines, 2340, Beerse, Belgium
| | - Zhinan Jin
- Johnson & Johnson Innovative Medicine, Brisbane, CA, 94005, USA.
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7
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Peng Q, Yuan B, Cheng J, Wang M, Gao S, Bai S, Zhao X, Qi J, Gao GF, Shi Y. Molecular mechanism of de novo replication by the Ebola virus polymerase. Nature 2023; 622:603-610. [PMID: 37699521 DOI: 10.1038/s41586-023-06608-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 09/05/2023] [Indexed: 09/14/2023]
Abstract
Non-segmented negative-strand RNA viruses, including Ebola virus (EBOV), rabies virus, human respiratory syncytial virus and pneumoviruses, can cause respiratory infections, haemorrhagic fever and encephalitis in humans and animals, and are considered a substantial health and economic burden worldwide1. Replication and transcription of the viral genome are executed by the large (L) polymerase, which is a promising target for the development of antiviral drugs. Here, using the L polymerase of EBOV as a representative, we show that de novo replication of L polymerase is controlled by the specific 3' leader sequence of the EBOV genome in an enzymatic assay, and that formation of at least three base pairs can effectively drive the elongation process of RNA synthesis independent of the specific RNA sequence. We present the high-resolution structures of the EBOV L-VP35-RNA complex and show that the 3' leader RNA binds in the template entry channel with a distinctive stable bend conformation. Using mutagenesis assays, we confirm that the bend conformation of the RNA is required for the de novo replication activity and reveal the key residues of the L protein that stabilize the RNA conformation. These findings provide a new mechanistic understanding of RNA synthesis for polymerases of non-segmented negative-strand RNA viruses, and reveal important targets for the development of antiviral drugs.
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Affiliation(s)
- Qi Peng
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Bin Yuan
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinlong Cheng
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Siwei Gao
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Suran Bai
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xuejin Zhao
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jianxun Qi
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
- Beijing Life Science Academy, Beijing, China.
| | - George F Gao
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
- Beijing Life Science Academy, Beijing, China.
- Center for Influenza Research and Early-warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Disease (CEEID), Chinese Academy of Sciences, Beijing, China.
- Research Unit of Adaptive Evolution and Control of Emerging Viruses, Chinese Academy of Medical Sciences, Beijing, China.
| | - Yi Shi
- International Institute of Vaccine Research and Innovation (iVac), Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
- Beijing Life Science Academy, Beijing, China.
- Center for Influenza Research and Early-warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Disease (CEEID), Chinese Academy of Sciences, Beijing, China.
- Research Unit of Adaptive Evolution and Control of Emerging Viruses, Chinese Academy of Medical Sciences, Beijing, China.
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8
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Abstract
The nonsegmented, negative-strand RNA viruses (nsNSVs), also known as the order Mononegavirales, have a genome consisting of a single strand of negative-sense RNA. Integral to the nsNSV replication cycle is the viral polymerase, which is responsible for transcribing the viral genome, to produce an array of capped and polyadenylated messenger RNAs, and replicating it to produce new genomes. To perform the different steps that are necessary for these processes, the nsNSV polymerases undergo a series of coordinated conformational transitions. While much is still to be learned regarding the intersection of nsNSV polymerase dynamics, structure, and function, recently published polymerase structures, combined with a history of biochemical and molecular biology studies, have provided new insights into how nsNSV polymerases function as dynamic machines. In this review, we consider each of the steps involved in nsNSV transcription and replication and suggest how these relate to solved polymerase structures.
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Affiliation(s)
- Mohamed Ouizougun-Oubari
- Department of Virology, Immunology & Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts, USA;
| | - Rachel Fearns
- Department of Virology, Immunology & Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts, USA;
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9
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Gupta N, Ogino M, Watkins DE, Yu T, Green TJ, Ogino T. Discontinuous L-binding motifs in the transactivation domain of the vesicular stomatitis virus P protein are required for terminal de novo transcription initiation by the L protein. J Virol 2023; 97:e0024623. [PMID: 37578231 PMCID: PMC10506490 DOI: 10.1128/jvi.00246-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 06/18/2023] [Indexed: 08/15/2023] Open
Abstract
The phospho- (P) protein, the co-factor of the RNA polymerase large (L) protein, of vesicular stomatitis virus (VSV, a prototype of nonsegmented negative-strand RNA viruses) plays pivotal roles in transcription and replication. However, the precise mechanism underlying the transcriptional transactivation by the P protein has remained elusive. Here, using an in vitro transcription system and a series of deletion mutants of the P protein, we mapped a region encompassing residues 51-104 as a transactivation domain (TAD) that is critical for terminal de novo initiation, the initial step of synthesis of the leader RNA and anti-genome/genome, with the L protein. Site-directed mutagenesis revealed that conserved amino acid residues in three discontinuous L-binding sites within the TAD are essential for the transactivation activity of the P protein or important for maintaining its full activity. Importantly, relative inhibitory effects of TAD point mutations on synthesis of the full-length leader RNA and mRNAs from the 3'-terminal leader region and internal genes, respectively, of the genome were similar to those on terminal de novo initiation. Furthermore, any of the examined TAD mutations did not alter the gradient pattern of mRNAs synthesized from internal genes, nor did they induce the production of readthrough transcripts. These results suggest that these TAD mutations impact mainly terminal de novo initiation but rarely other steps (e.g., elongation, termination, internal initiation) of single-entry stop-start transcription. Consistently, the mutations of the essential or important amino acid residues within the P TAD were lethal or deleterious to VSV replication in host cells. IMPORTANCE RNA-dependent RNA polymerase L proteins of nonsegmented negative-strand RNA viruses belonging to the Mononegavirales order require their cognate co-factor P proteins or their counterparts for genome transcription and replication. However, exact roles of these co-factor proteins in modulating functions of L proteins during transcription and replication remain unknown. In this study, we revealed that three discrete L-binding motifs within a transactivation domain of the P protein of vesicular stomatitis virus, a prototypic nonsegmented negative-strand RNA virus, are required for terminal de novo initiation mediated by the L protein, which is the first step of synthesis of the leader RNA as well as genome/anti-genome.
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Affiliation(s)
- Nirmala Gupta
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Minako Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Dean E. Watkins
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Tiffany Yu
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
| | - Todd J. Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Tomoaki Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, USA
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10
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Risso-Ballester J, Rameix-Welti MA. Spatial resolution of virus replication: RSV and cytoplasmic inclusion bodies. Adv Virus Res 2023; 116:1-43. [PMID: 37524479 DOI: 10.1016/bs.aivir.2023.06.001] [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] [Indexed: 08/02/2023]
Abstract
Respiratory Syncytial Virus (RSV) is a major cause of respiratory illness in young children, elderly and immunocompromised individuals worldwide representing a severe burden for health systems. The urgent development of vaccines or specific antivirals against RSV is impaired by the lack of knowledge regarding its replication mechanisms. RSV is a negative-sense single-stranded RNA (ssRNA) virus belonging to the Mononegavirales order (MNV) which includes other viruses pathogenic to humans as Rabies (RabV), Ebola (EBOV), or measles (MeV) viruses. Transcription and replication of viral genomes occur within cytoplasmatic virus-induced spherical inclusions, commonly referred as inclusion bodies (IBs). Recently IBs were shown to exhibit properties of membrane-less organelles (MLO) arising by liquid-liquid phase separation (LLPS). Compartmentalization of viral RNA synthesis steps in viral-induced MLO is indeed a common feature of MNV. Strikingly these key compartments still remain mysterious. Most of our current knowledge on IBs relies on the use of fluorescence microscopy. The ability to fluorescently label IBs in cells has been key to uncover their dynamics and nature. The generation of recombinant viruses expressing a fluorescently-labeled viral protein and the immunolabeling or the expression of viral fusion proteins known to be recruited in IBs are some of the tools used to visualize IBs in infected cells. In this chapter, microscope techniques and the most relevant studies that have shed light on RSV IBs fundamental aspects, including biogenesis, organization and dynamics are being discussed and brought to light with the investigations carried out on other MNV.
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Affiliation(s)
| | - Marie-Anne Rameix-Welti
- Institut Pasteur, Université Paris-Saclay, Université de Versailles St. Quentin, UMR 1173 (2I), INSERM, Paris, France; Assistance Publique des Hôpitaux de Paris, Hôpital Ambroise Paré, Laboratoire de Microbiologie, DMU15, Paris, France.
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11
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Kleiner VA, O Fischmann T, Howe JA, Beshore DC, Eddins MJ, Hou Y, Mayhood T, Klein D, Nahas DD, Lucas BJ, Xi H, Murray E, Ma DY, Getty K, Fearns R. Conserved allosteric inhibitory site on the respiratory syncytial virus and human metapneumovirus RNA-dependent RNA polymerases. Commun Biol 2023; 6:649. [PMID: 37337079 DOI: 10.1038/s42003-023-04990-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 05/26/2023] [Indexed: 06/21/2023] Open
Abstract
Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in infants, elderly, and immunocompromised adults1-3. Therapeutic small molecule inhibitors that bind to the RSV polymerase and inhibit viral replication are being developed, but their binding sites and molecular mechanisms of action remain largely unknown4. Here we report a conserved allosteric inhibitory site identified on the L polymerase proteins of RSV and HMPV that can be targeted by a dual-specificity, non-nucleoside inhibitor, termed MRK-1. Cryo-EM structures of the inhibitor in complexes with truncated RSV and full-length HMPV polymerase proteins provide a structural understanding of how MRK-1 is active against both viruses. Functional analyses indicate that MRK-1 inhibits conformational changes necessary for the polymerase to engage in RNA synthesis initiation and to transition into an elongation mode. Competition studies reveal that the MRK-1 binding pocket is distinct from that of a capping inhibitor with an overlapping resistance profile, suggesting that the polymerase conformation bound by MRK-1 may be distinct from that involved in mRNA capping. These findings should facilitate optimization of dual RSV and HMPV replication inhibitors and provide insights into the molecular mechanisms underlying their polymerase activities.
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Affiliation(s)
- Victoria A Kleiner
- Department of Virology, Immunology & Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA
| | | | | | | | | | - Yan Hou
- MRL, Merck & Co., Inc., Rahway, NJ, USA
| | | | | | | | | | - He Xi
- MRL, Merck & Co., Inc., Rahway, NJ, USA
| | | | | | | | - Rachel Fearns
- Department of Virology, Immunology & Microbiology, National Emerging Infectious Diseases Laboratories, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA.
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12
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Shepherd JG, Davis C, Streicker DG, Thomson EC. Emerging Rhabdoviruses and Human Infection. BIOLOGY 2023; 12:878. [PMID: 37372162 PMCID: PMC10294888 DOI: 10.3390/biology12060878] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023]
Abstract
Rhabdoviridae is a large viral family, with members infecting a diverse range of hosts including, vertebrate species, arthropods, and plants. The predominant human pathogen within the family is Rabies lyssavirus, the main cause of human rabies. While rabies is itself a neglected disease, there are other, less well studied, rhabdoviruses known to cause human infection. The increasing application of next-generation sequencing technology to clinical samples has led to the detection of several novel or rarely detected rhabdoviruses associated with febrile illness. Many of these viruses have been detected in low- and middle-income countries where the extent of human infection and the burden of disease remain largely unquantified. This review describes the rhabdoviruses other than Rabies lyssavirus that have been associated with human infection. The discovery of the Bas Congo virus and Ekpoma virus is discussed, as is the re-emergence of species such as Le Dantec virus, which has recently been detected in Africa 40 years after its initial isolation. Chandipura virus and the lyssaviruses that are known to cause human rabies are also described. Given their association with human disease, the viruses described in this review should be prioritised for further study.
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Affiliation(s)
- James G. Shepherd
- Centre for Virus Research, MRC-University of Glasgow, Glasgow G61 1QH, UK; (C.D.); (D.G.S.)
| | - Chris Davis
- Centre for Virus Research, MRC-University of Glasgow, Glasgow G61 1QH, UK; (C.D.); (D.G.S.)
| | - Daniel G. Streicker
- Centre for Virus Research, MRC-University of Glasgow, Glasgow G61 1QH, UK; (C.D.); (D.G.S.)
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Emma C. Thomson
- Centre for Virus Research, MRC-University of Glasgow, Glasgow G61 1QH, UK; (C.D.); (D.G.S.)
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13
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Zhao Z, Wang B, Wu S, Zhang Z, Chen Y, Zhang J, Wang Y, Zhu D, Li Y, Xu J, Hou L, Chen W. Regulated control of virus replication by 4-hydroxytamoxifen-induced splicing. Front Microbiol 2023; 14:1112580. [PMID: 36992923 PMCID: PMC10040539 DOI: 10.3389/fmicb.2023.1112580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/14/2023] [Indexed: 03/14/2023] Open
Abstract
Designing a modified virus that can be controlled to replicate will facilitate the study of pathogenic mechanisms of virus and virus–host interactions. Here, we report a universal switch element that enables precise control of virus replication after exposure to a small molecule. Inteins mediate a traceless protein splicing–ligation process, and we generate a series of modified vesicular stomatitis virus (VSV) with intein insertion into the nucleocapsid, phosphoprotein, or large RNA-dependent RNA polymerase of VSV. Two recombinant VSV, LC599 and LY1744, were screened for intein insertion in the large RNA-dependent RNA polymerase of VSV, and their replication was regulated in a dose-dependent manner with the small molecule 4-hydroxytamoxifen, which induces intein splicing to restore the VSV replication. Furthermore, in the presence of 4-hydroxytamoxifen, the intein-modified VSV LC599 replicated efficiently in an animal model like a prototype of VSV. Thus, we present a simple and highly adaptable tool for regulating virus replication.
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Affiliation(s)
| | - Busen Wang
- Beijing Institute of Biotechnology, Beijing, China
| | - Shipo Wu
- Beijing Institute of Biotechnology, Beijing, China
| | - Zhe Zhang
- Beijing Institute of Biotechnology, Beijing, China
| | - Yi Chen
- Beijing Institute of Biotechnology, Beijing, China
| | | | - Yudong Wang
- Beijing Institute of Biotechnology, Beijing, China
| | - Danni Zhu
- Beijing Institute of Biotechnology, Beijing, China
- Qingdao Special Servicemen Recuperation Center of PLA Navy, Qingdao, Shandong, China
| | - Yao Li
- Beijing Institute of Biotechnology, Beijing, China
| | - Jinghan Xu
- Beijing Institute of Biotechnology, Beijing, China
| | - Lihua Hou
- Beijing Institute of Biotechnology, Beijing, China
- *Correspondence: Lihua Hou, ; Wei Chen,
| | - Wei Chen
- Beijing Institute of Biotechnology, Beijing, China
- *Correspondence: Lihua Hou, ; Wei Chen,
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14
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Sutto-Ortiz P, Eléouët JF, Ferron F, Decroly E. Biochemistry of the Respiratory Syncytial Virus L Protein Embedding RNA Polymerase and Capping Activities. Viruses 2023; 15:v15020341. [PMID: 36851554 PMCID: PMC9960070 DOI: 10.3390/v15020341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/12/2023] [Accepted: 01/21/2023] [Indexed: 01/27/2023] Open
Abstract
The human respiratory syncytial virus (RSV) is a negative-sense, single-stranded RNA virus. It is the major cause of severe acute lower respiratory tract infection in infants, the elderly population, and immunocompromised individuals. There is still no approved vaccine or antiviral treatment against RSV disease, but new monoclonal prophylactic antibodies are yet to be commercialized, and clinical trials are in progress. Hence, urgent efforts are needed to develop efficient therapeutic treatments. RSV RNA synthesis comprises viral transcription and replication that are catalyzed by the large protein (L) in coordination with the phosphoprotein polymerase cofactor (P), the nucleoprotein (N), and the M2-1 transcription factor. The replication/transcription is orchestrated by the L protein, which contains three conserved enzymatic domains: the RNA-dependent RNA polymerase (RdRp), the polyribonucleotidyl transferase (PRNTase or capping), and the methyltransferase (MTase) domain. These activities are essential for the RSV replicative cycle and are thus considered as attractive targets for the development of therapeutic agents. In this review, we summarize recent findings about RSV L domains structure that highlight how the enzymatic activities of RSV L domains are interconnected, discuss the most relevant and recent antivirals developments that target the replication/transcription complex, and conclude with a perspective on identified knowledge gaps that enable new research directions.
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Affiliation(s)
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, F78350 Jouy en Josas, France
| | - François Ferron
- Aix Marseille Université, CNRS, AFMB, UMR, 7257 Marseille, France
- European Virus Bioinformatics Center, Leutragraben 1, 07743 Jena, Germany
| | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB, UMR, 7257 Marseille, France
- Correspondence:
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15
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IRF2 Cooperates with Phosphoprotein of Spring Viremia of Carp Virus to Suppress Antiviral Response in Zebrafish. J Virol 2022; 96:e0131422. [PMID: 36314827 PMCID: PMC9683000 DOI: 10.1128/jvi.01314-22] [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: 11/24/2022] Open
Abstract
IFN regulatory factor (IRF) 2 belongs to the IRF1 subfamily, and its functions are not yet fully understood. In this study, we showed that IRF2a was a negative regulator of the interferon (IFN) response induced by spring viremia of carp virus (SVCV). Irf2a-/- knockout zebrafish were less susceptible to SVCV than wild-type fish. Transcriptomic analysis reveals that differentially expressed genes (DEGs) in the irf2a-/- and irf2a+/+ cells derived caudal fins were mainly involved in cytokine-cytokine receptor interaction, mitogen-activated protein kinase (MAPK) signaling pathway, and transforming growth factor-beta (TGF-beta) signaling pathway. Interestingly, the basal expression levels of interferon stimulating genes (ISGs), including pkz, mx, apol, and stat1 were higher in the irf2a-/- cells than irf2a+/+ cells, suggesting that they may contribute to the increased viral resistance of the irf2a-/- cells. Overexpression of IRF2a inhibited the activation of ifnφ1 and ifnφ3 induced by SVCV and poly(I:C) in the epithelioma papulosum cyprini (EPC) cells. Further, it was found that SVCV phosphoprotein (SVCV-P) could interact with IRF2a to promote IRF2a nuclear translocation and protein stability via suppressing K48-linked ubiquitination of IRF2a. Both IRF2a and SVCV-P not only destabilized STAT1a but reduced its translocation into the nucleus. Our work demonstrates that IRF2a cooperates with SVCV-P to suppress host antiviral response against viral infection in zebrafish. IMPORTANCE Interferon regulatory factors (IRFs) are central in the regulation of interferon-mediated antiviral immunity. Here, we reported that IRF2a suppressed interferon response and promoted virus replication in zebrafish. The suppressive effects were enhanced by the phosphoprotein of the spring viremia of carp virus (SVCV) via inhibition of K48-linked ubiquitination of IRF2a. IRF2a and SVCV phosphoprotein cooperated to degrade STAT1 and block its nuclear translocation. Our work demonstrated that IRFs and STATs were targeted by the virus through posttranslational modifications to repress interferon-mediated antiviral response in lower vertebrates.
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16
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Borna Disease Virus 1 Phosphoprotein Forms a Tetramer and Interacts with Host Factors Involved in DNA Double-Strand Break Repair and mRNA Processing. Viruses 2022; 14:v14112358. [PMID: 36366462 PMCID: PMC9692295 DOI: 10.3390/v14112358] [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: 09/23/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 01/31/2023] Open
Abstract
Determining the structural organisation of viral replication complexes and unravelling the impact of infection on cellular homeostasis represent important challenges in virology. This may prove particularly useful when confronted with viruses that pose a significant threat to human health, that appear unique within their family, or for which knowledge is scarce. Among Mononegavirales, bornaviruses (family Bornaviridae) stand out due to their compact genomes and their nuclear localisation for replication. The recent recognition of the zoonotic potential of several orthobornaviruses has sparked a surge of interest in improving our knowledge on this viral family. In this work, we provide a complete analysis of the structural organisation of Borna disease virus 1 (BoDV-1) phosphoprotein (P), an important cofactor for polymerase activity. Using X-ray diffusion and diffraction experiments, we revealed that BoDV-1 P adopts a long coiled-coil α-helical structure split into two parts by an original β-strand twist motif, which is highly conserved across the members of whole Orthobornavirus genus and may regulate viral replication. In parallel, we used BioID to determine the proximal interactome of P in living cells. We confirmed previously known interactors and identified novel proteins linked to several biological processes such as DNA repair or mRNA metabolism. Altogether, our study provides important structure/function cues, which may improve our understanding of BoDV-1 pathogenesis.
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17
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Yuan B, Peng Q, Cheng J, Wang M, Zhong J, Qi J, Gao GF, Shi Y. Structure of the Ebola virus polymerase complex. Nature 2022; 610:394-401. [PMID: 36171293 PMCID: PMC9517992 DOI: 10.1038/s41586-022-05271-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022]
Abstract
Filoviruses, including Ebola virus, pose an increasing threat to the public health. Although two therapeutic monoclonal antibodies have been approved to treat the Ebola virus disease1,2, there are no approved broadly reactive drugs to control diverse filovirus infection. Filovirus has a large polymerase (L) protein and the cofactor viral protein 35 (VP35), which constitute the basic functional unit responsible for virus genome RNA synthesis3. Owing to its conservation, the L–VP35 polymerase complex is a promising target for broadly reactive antiviral drugs. Here we determined the structure of Ebola virus L protein in complex with tetrameric VP35 using cryo-electron microscopy (state 1). Structural analysis revealed that Ebola virus L possesses a filovirus-specific insertion element that is essential for RNA synthesis, and that VP35 interacts extensively with the N-terminal region of L by three protomers of the VP35 tetramer. Notably, we captured the complex structure in a second conformation with the unambiguous priming loop and supporting helix away from polymerase active site (state 2). Moreover, we demonstrated that the century-old drug suramin could inhibit the activity of the Ebola virus polymerase in an enzymatic assay. The structure of the L–VP35–suramin complex reveals that suramin can bind at the highly conserved NTP entry channel to prevent substrates from entering the active site. These findings reveal the mechanism of Ebola virus replication and may guide the development of more powerful anti-filovirus drugs. Structural studies of the Ebola virus polymerase complex provide insights into its function and demonstrate the structural basis of its inhibition by suramin.
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Affiliation(s)
- Bin Yuan
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Qi Peng
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinlong Cheng
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jin Zhong
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.,CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - George F Gao
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China. .,Center for Influenza Research and Early-Warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Disease (CEEID), Chinese Academy of Sciences, Beijing, China. .,Research Unit of Adaptive Evolution and Control of Emerging Viruses, Chinese Academy of Medical Sciences, Beijing, China.
| | - Yi Shi
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China. .,Center for Influenza Research and Early-Warning (CASCIRE), CAS-TWAS Center of Excellence for Emerging Infectious Disease (CEEID), Chinese Academy of Sciences, Beijing, China. .,Research Unit of Adaptive Evolution and Control of Emerging Viruses, Chinese Academy of Medical Sciences, Beijing, China.
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18
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Jenni S, Horwitz JA, Bloyet LM, Whelan SPJ, Harrison SC. Visualizing molecular interactions that determine assembly of a bullet-shaped vesicular stomatitis virus particle. Nat Commun 2022; 13:4802. [PMID: 35970826 PMCID: PMC9378655 DOI: 10.1038/s41467-022-32223-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/18/2022] [Indexed: 11/09/2022] Open
Abstract
Vesicular stomatitis virus (VSV) is a negative-strand RNA virus with a non-segmented genome, closely related to rabies virus. Both have characteristic bullet-like shapes. We report the structure of intact, infectious VSV particles determined by cryogenic electron microscopy. By compensating for polymorphism among viral particles with computational classification, we obtained a reconstruction of the shaft ("trunk") at 3.5 Å resolution, with lower resolution for the rounded tip. The ribonucleoprotein (RNP), genomic RNA complexed with nucleoprotein (N), curls into a dome-like structure with about eight gradually expanding turns before transitioning into the regular helical trunk. Two layers of matrix (M) protein link the RNP with the membrane. Radial inter-layer subunit contacts are fixed within single RNA-N-M1-M2 modules, but flexible lateral and axial interactions allow assembly of polymorphic virions. Together with published structures of recombinant N in various states, our results suggest a mechanism for membrane-coupled self-assembly of VSV and its relatives.
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Affiliation(s)
- Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Joshua A Horwitz
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA.,Molecular Pharmacology and Virology Group, PureTech Health LLC, Boston, MA, 02210, USA
| | - Louis-Marie Bloyet
- Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA.,Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - Sean P J Whelan
- Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA.,Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA. .,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, 02115, USA. .,Laboratory of Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA.
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19
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Sourimant J, Lieber CM, Yoon JJ, Toots M, Govindarajan M, Udumula V, Sakamoto K, Natchus MG, Patti J, Vernachio J, Plemper RK. Orally efficacious lead of the AVG inhibitor series targeting a dynamic interface in the respiratory syncytial virus polymerase. SCIENCE ADVANCES 2022; 8:eabo2236. [PMID: 35749502 PMCID: PMC9232112 DOI: 10.1126/sciadv.abo2236] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Respiratory syncytial virus (RSV) is a leading cause of lower respiratory infections in infants and the immunocompromised, yet no efficient therapeutic exists. We have identified the AVG class of allosteric inhibitors of RSV RNA synthesis. Here, we demonstrate through biolayer interferometry and in vitro RNA-dependent RNA polymerase (RdRP) assays that AVG compounds bind to the viral polymerase, stalling the polymerase in initiation conformation. Resistance profiling revealed a unique escape pattern, suggesting a discrete docking pose. Affinity mapping using photoreactive AVG analogs identified the interface of polymerase core, capping, and connector domains as a molecular target site. A first-generation lead showed nanomolar potency against RSV in human airway epithelium organoids but lacked in vivo efficacy. Docking pose-informed synthetic optimization generated orally efficacious AVG-388, which showed potent efficacy in the RSV mouse model when administered therapeutically. This study maps a druggable target in the RSV RdRP and establishes clinical potential of the AVG chemotype against RSV disease.
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Affiliation(s)
- Julien Sourimant
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Carolin M. Lieber
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Jeong-Joong Yoon
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | - Mart Toots
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
| | | | - Venkata Udumula
- Emory Institute for Drug Development, Emory University, Atlanta, GA 30322, USA
| | - Kaori Sakamoto
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Michael G. Natchus
- Emory Institute for Drug Development, Emory University, Atlanta, GA 30322, USA
| | - Joseph Patti
- Aviragen Therapeutics Inc, Alpharetta, GA 30009, USA
| | | | - Richard K. Plemper
- Center for Translational Antiviral Research, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA
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20
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Cressey TN, Shareef AM, Kleiner VA, Noton SL, Byrne PO, McLellan JS, Mühlberger E, Fearns R. Distinctive features of the respiratory syncytial virus priming loop compared to other non-segmented negative strand RNA viruses. PLoS Pathog 2022; 18:e1010451. [PMID: 35731802 PMCID: PMC9255747 DOI: 10.1371/journal.ppat.1010451] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/05/2022] [Accepted: 05/20/2022] [Indexed: 11/23/2022] Open
Abstract
De novo initiation by viral RNA-dependent RNA polymerases often requires a polymerase priming residue, located within a priming loop, to stabilize the initiating NTPs. Polymerase structures from three different non-segmented negative strand RNA virus (nsNSV) families revealed putative priming loops in different conformations, and an aromatic priming residue has been identified in the rhabdovirus polymerase. In a previous study of the respiratory syncytial virus (RSV) polymerase, we found that Tyr1276, the L protein aromatic amino acid residue that most closely aligns with the rhabdovirus priming residue, is not required for RNA synthesis but two nearby residues, Pro1261 and Trp1262, were required. In this study, we examined the roles of Pro1261 and Trp1262 in RNA synthesis initiation. Biochemical studies showed that substitution of Pro1261 inhibited RNA synthesis initiation without inhibiting back-priming, indicating a defect in initiation. Biochemical and minigenome experiments showed that the initiation defect incurred by a P1261A substitution could be rescued by factors that would be expected to increase the stability of the initiation complex, specifically increased NTP concentration, manganese, and a more efficient promoter sequence. These findings indicate that Pro1261 of the RSV L protein plays a role in initiation, most likely in stabilizing the initiation complex. However, we found that substitution of the corresponding proline residue in a filovirus polymerase had no effect on RNA synthesis initiation or elongation. These results indicate that despite similarities between the nsNSV polymerases, there are differences in the features required for RNA synthesis initiation. RSV has a significant impact on human health. It is the major cause of respiratory disease in infants and exerts a significant toll on the elderly and immunocompromised. RSV is a member of the Mononegavirales, the non-segmented, negative strand RNA viruses (nsNSVs). Like other viruses in this order, RSV encodes an RNA dependent RNA polymerase, which is responsible for transcribing and replicating the viral genome. Due to its essential role during the viral replication cycle, the polymerase is a promising candidate target for antiviral inhibitors and so a greater understanding of the mechanistic basis of its activities could aid antiviral drug development. In this study, we identified an amino acid residue within the RSV polymerase that appears to stabilize the RNA synthesis initiation complex and showed that it plays a role in both transcription and RNA replication. However, the corresponding residue in a different nsNSV polymerase does not appear to play a similar role. This work reveals a key feature of the RSV polymerase but identifies differences with the polymerases of other related viruses.
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Affiliation(s)
- Tessa N. Cressey
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
| | - Afzaal M. Shareef
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
| | - Victoria A. Kleiner
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
| | - Sarah L. Noton
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
| | - Patrick O. Byrne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jason S. McLellan
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Elke Mühlberger
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
| | - Rachel Fearns
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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Hsp90 Activity Is Necessary for the Maturation of Rabies Virus Polymerase. Int J Mol Sci 2022; 23:ijms23136946. [PMID: 35805948 PMCID: PMC9266396 DOI: 10.3390/ijms23136946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/21/2022] [Accepted: 06/21/2022] [Indexed: 11/17/2022] Open
Abstract
Mononegavirales is an order of viruses with a genome in the form of a non-segmented negative-strand RNA that encodes several proteins. The functional polymerase complex of these viruses is composed of two proteins: a large protein (L) and a phosphoprotein (P). The replication of viruses from this order depends on Hsp90 chaperone activity. Previous studies have demonstrated that Hsp90 inhibition results in the degradation of mononegaviruses L protein, with exception of the rabies virus, for which the degradation of P protein was observed. Here, we demonstrated that Hsp90 inhibition does not affect the expression of rabies L and P proteins, but it inhibits binding of the P protein and L protein into functional viral polymerase. Rabies and the vesicular stomatitis virus, but not the measles virus, L proteins can be expressed independently of the presence of a P protein and in the presence of an Hsp90 inhibitor. Our results suggest that the interaction of L proteins with P proteins and Hsp90 in the process of polymerase maturation may be a process specific to particular viruses.
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22
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Locations and in situ structure of the polymerase complex inside the virion of vesicular stomatitis virus. Proc Natl Acad Sci U S A 2022; 119:e2111948119. [PMID: 35476516 PMCID: PMC9170060 DOI: 10.1073/pnas.2111948119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Unlike fellow nonsegmented negative-strand RNA viruses, exemplified by the devastating Nipah, Ebola, rabies, and measles viruses, vesicular stomatitis virus (VSV) can be considered beneficial, as it is widely used as a vector for anticancer therapy and vaccine development. In these RNA viruses, transcription and replication of the viral genome depend on an RNA-dependent RNA polymerase. Here, we determined the in situ structure of the VSV polymerase complex, consisting of a large protein (L) and a phosphoprotein (P), by cryo-electron tomography and subtomogram averaging. Approximately 55 polymerase complexes are packaged in each bullet-shaped virion through flexible interactions with nucleoproteins. Our results provide insights into the mechanism of L packaging during virus assembly and efficient initiation of transcription during infection. The polymerase complex of nonsegmented negative-strand RNA viruses primarily consists of a large (L) protein and a phosphoprotein (P). L is a multifunctional enzyme carrying out RNA-dependent RNA polymerization and all other steps associated with transcription and replication, while P is the nonenzymatic cofactor, regulating the function and conformation of L. The structure of a purified vesicular stomatitis virus (VSV) polymerase complex containing L and associated P segments has been determined; however, the location and manner of the attachments of L and P within each virion are unknown, limiting our mechanistic understanding of VSV RNA replication and transcription and hindering engineering efforts of this widely used anticancer and vaccine vector. Here, we have used cryo-electron tomography to visualize the VSV virion, revealing the attachment of the ring-shaped L molecules to VSV nucleocapsid proteins (N) throughout the cavity of the bullet-shaped nucleocapsid. Subtomogram averaging and three-dimensional classification of regions containing N and the matrix protein (M) have yielded the in situ structure of the polymerase complex. On average, ∼55 polymerase complexes are packaged in each virion. The capping domain of L interacts with two neighboring N molecules through flexible attachments. P, which exists as a dimer, bridges separate N molecules and the connector and C-terminal domains of L. Our data provide the structural basis for recruitment of L to N by P in virus assembly and for flexible attachments between L and N, which allow a quick response of L in primary transcription upon cell entry.
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Ogino M, Green TJ, Ogino T. GDP polyribonucleotidyltransferase domain of vesicular stomatitis virus polymerase regulates leader-promoter escape and polyadenylation-coupled termination during stop-start transcription. PLoS Pathog 2022; 18:e1010287. [PMID: 35108335 PMCID: PMC8843114 DOI: 10.1371/journal.ppat.1010287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 02/14/2022] [Accepted: 01/19/2022] [Indexed: 11/23/2022] Open
Abstract
The unconventional mRNA capping enzyme (GDP polyribonucleotidyltransferase, PRNTase) domain of the vesicular stomatitis virus (VSV) L protein possesses a dual-functional "priming-capping loop" that governs terminal de novo initiation for leader RNA synthesis and capping of monocistronic mRNAs during the unique stop-start transcription cycle. Here, we investigated the roles of basic amino acid residues on a helix structure directly connected to the priming-capping loop in viral RNA synthesis and identified single point mutations that cause previously unreported defective phenotypes at different steps of stop-start transcription. Mutations of residue R1183 (R1183A and R1183K) dramatically reduced the leader RNA synthesis activity by hampering early elongation, but not terminal de novo initiation or productive elongation, suggesting that the mutations negatively affect escape from the leader promoter. On the other hand, mutations of residue R1178 (R1178A and R1178K) decreased the efficiency of polyadenylation-coupled termination of mRNA synthesis at the gene junctions, but not termination of leader RNA synthesis at the leader-to-N-gene junction, resulting in the generation of larger amounts of aberrant polycistronic mRNAs. In contrast, both the R1183 and R1178 residues are not essential for cap-forming activities. The R1183K mutation was lethal to VSV, whereas the R1178K mutation attenuated VSV and triggered the production of the polycistronic mRNAs in infected cells. These observations suggest that the PRNTase domain plays multiple roles in conducting accurate stop-start transcription beyond its known role in pre-mRNA capping. Vesicular stomatitis virus (VSV), an animal rhabdovirus closely related to rabies virus, has served as a paradigm for understanding the basic molecular mechanisms of transcription and replication by rhabdoviruses (e.g., rabies) and other non-segmented negative strand (NNS) RNA viruses, such as measles and Ebola. NNS RNA viral polymerases sequentially synthesize the non-coding leader RNA and monocistronic mRNAs from the 3′-terminal leader region and internal genes, respectively, on their genomes by the stop-start transcription mechanism. A hallmark of NNS RNA viral polymerases is the presence of a unique enzymatic domain, called GDP polyribonucleotidyltransferase (PRNTase), which catalyzes pre-mRNA 5′-capping, one of the essential mRNA modifications. Our recent study revealed that the VSV PRNTase domain directs transcription initiation at the 3′-end of the genome as well as pre-mRNA capping with the dual functional priming-capping loop during stop-start transcription. Here, we further show that a helix structure flanked by the priming-capping loop regulates not only transcription elongation at an early phase of leader RNA synthesis but also polyadenylation-coupled transcription termination at gene junctions. These findings indicate that the PRNTase domain acts as a key regulatory domain for stop-start transcription as well as a catalytic domain for pre-mRNA capping.
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Affiliation(s)
- Minako Ogino
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Todd J. Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Tomoaki Ogino
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, Ohio, United States of America
- * E-mail:
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Dong X, Wang X, Xie M, Wu W, Chen Z. Structural Basis of Human Parainfluenza Virus 3 Unassembled Nucleoprotein in Complex with Its Viral Chaperone. J Virol 2022; 96:e0164821. [PMID: 34730394 PMCID: PMC8791282 DOI: 10.1128/jvi.01648-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 10/30/2021] [Indexed: 11/20/2022] Open
Abstract
Human parainfluenza virus 3 (HPIV3) belongs to the Paramyxoviridae, causing annual worldwide epidemics of respiratory diseases, especially in newborns and infants. The core components consist of just three viral proteins: nucleoprotein (N), phosphoprotein (P), and RNA polymerase (L), playing essential roles in replication and transcription of HPIV3 as well as other paramyxoviruses. Viral genome encapsidated by N is as a template and recognized by RNA-dependent RNA polymerase complex composed of L and P. The offspring RNA also needs to assemble with N to form nucleocapsids. The N is one of the most abundant viral proteins in infected cells and chaperoned in the RNA-free form (N0) by P before encapsidation. In this study, we presented the structure of unassembled HPIV3 N0 in complex with the N-terminal portion of the P, revealing the molecular details of the N0 and the conserved N0-P interaction. Combined with biological experiments, we showed that the P binds to the C-terminal domain of N0 mainly by hydrophobic interaction and maintains the unassembled conformation of N by interfering with the formation of N-RNA oligomers, which might be a target for drug development. Based on the complex structure, we developed a method to obtain the monomeric N0. Furthermore, we designed a P-derived fusion peptide with 10-fold higher affinity, which hijacked the N and interfered with the binding of the N to RNA significantly. Finally, we proposed a model of conformational transition of N from the unassembled state to the assembled state, which helped to further understand viral replication. IMPORTANCE Human parainfluenza virus 3 (HPIV3) causes annual epidemics of respiratory diseases, especially in newborns and infants. For the replication of HPIV3 and other paramyxoviruses, only three viral proteins are required: phosphoprotein (P), RNA polymerase (L), and nucleoprotein (N). Here, we report the crystal structure of the complex of N and its chaperone P. We describe in detail how P acts as a chaperone to maintain the unassembled conformation of N. Our analysis indicated that the interaction between P and N is conserved and mediated by hydrophobicity, which can be used as a target for drug development. We obtained a high-affinity P-derived peptide inhibitor, specifically targeted N, and greatly interfered with the binding of the N to RNA, thereby inhibiting viral encapsidation and replication. In summary, our results provide new insights into the paramyxovirus genome replication and nucleocapsid assembly and lay the basis for drug development.
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Affiliation(s)
- Xiaofei Dong
- State Key Laboratory of Agrobiotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xue Wang
- State Key Laboratory of Agrobiotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Mengjia Xie
- State Key Laboratory of Agrobiotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wei Wu
- State Key Laboratory of Agrobiotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Zhongzhou Chen
- State Key Laboratory of Agrobiotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing, China
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25
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Comparison of RNA synthesis initiation properties of non-segmented negative strand RNA virus polymerases. PLoS Pathog 2021; 17:e1010151. [PMID: 34914795 PMCID: PMC8717993 DOI: 10.1371/journal.ppat.1010151] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/30/2021] [Accepted: 11/26/2021] [Indexed: 11/19/2022] Open
Abstract
It is generally thought that the promoters of non-segmented, negative strand RNA viruses (nsNSVs) direct the polymerase to initiate RNA synthesis exclusively opposite the 3´ terminal nucleotide of the genome RNA by a de novo (primer independent) initiation mechanism. However, recent studies have revealed that there is diversity between different nsNSVs with pneumovirus promoters directing the polymerase to initiate at positions 1 and 3 of the genome, and ebolavirus polymerases being able to initiate at position 2 on the template. Studies with other RNA viruses have shown that polymerases that engage in de novo initiation opposite position 1 typically have structural features to stabilize the initiation complex and ensure efficient and accurate initiation. This raised the question of whether different nsNSV polymerases have evolved fundamentally different structural properties to facilitate initiation at different sites on their promoters. Here we examined the functional properties of polymerases of respiratory syncytial virus (RSV), a pneumovirus, human parainfluenza virus type 3 (PIV-3), a paramyxovirus, and Marburg virus (MARV), a filovirus, both on their cognate promoters and on promoters of other viruses. We found that in contrast to the RSV polymerase, which initiated at positions 1 and 3 of its promoter, the PIV-3 and MARV polymerases initiated exclusively at position 1 on their cognate promoters. However, all three polymerases could recognize and initiate from heterologous promoters, with the promoter sequence playing a key role in determining initiation site selection. In addition to examining de novo initiation, we also compared the ability of the RSV and PIV-3 polymerases to engage in back-priming, an activity in which the promoter template is folded into a secondary structure and nucleotides are added to the template 3´ end. This analysis showed that whereas the RSV polymerase was promiscuous in back-priming activity, the PIV-3 polymerase generated barely detectable levels of back-primed product, irrespective of promoter template sequence. Overall, this study shows that the polymerases from these three nsNSV families are fundamentally similar in their initiation properties, but have differences in their abilities to engage in back-priming.
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26
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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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27
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Abstract
Arenaviruses initiate infection by delivering a transcriptionally competent ribonucleoprotein (RNP) complex into the cytosol of host cells. The arenavirus RNP consists of the large (L) RNA-dependent RNA polymerase (RdRP) bound to a nucleoprotein (NP)-encapsidated genomic RNA (viral RNA [vRNA]) template. During transcription and replication, L must transiently displace RNA-bound NP to allow for template access into the RdRP active site. Concomitant with RNA replication, new subunits of NP must be added to the nascent complementary RNAs (cRNA) as they emerge from the product exit channel of L. Interactions between L and NP thus play a central role in arenavirus gene expression. We developed an approach to purify recombinant functional RNPs from mammalian cells in culture using a synthetic vRNA and affinity-tagged L and NP. Negative-stain electron microscopy of purified RNPs revealed they adopt diverse and flexible structures, like RNPs of other Bunyavirales members. Monodispersed L-NP and trimeric ring-like NP complexes were also obtained in excess of flexible RNPs, suggesting that these heterodimeric structures self-assemble in the absence of suitable RNA templates. This work allows for further biochemical analysis of the interaction between arenavirus L and NP proteins and provides a framework for future high-resolution structural analyses of this replication-associated complex. IMPORTANCE Arenaviruses are rodent-borne pathogens that can cause severe disease in humans. All arenaviruses begin the infection cycle with delivery of the virus replication machinery into the cytoplasm of the host cell. This machinery consists of an RNA-dependent RNA polymerase-which copies the viral genome segments and synthesizes all four viral mRNAs-bound to the two nucleoprotein-encapsidated genomic RNAs. How this complex assembles remains a mystery. Our findings provide direct evidence for the formation of diverse intracellular arenavirus replication complexes using purification strategies for the polymerase, nucleoprotein, and genomic RNA of Machupo virus, which causes Bolivian hemorrhagic fever in humans. We demonstrate that the polymerase and nucleoprotein assemble into higher-order structures within cells, providing a model for the molecular events of arenavirus RNA synthesis. These findings provide a framework for probing the architectures and functions of the arenavirus replication machinery and thus advancing antiviral strategies targeting this essential complex.
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Kakuk B, Kiss AA, Torma G, Csabai Z, Prazsák I, Mizik M, Megyeri K, Tombácz D, Boldogkői Z. Nanopore Assay Reveals Cell-Type-Dependent Gene Expression of Vesicular Stomatitis Indiana Virus and Differential Host Cell Response. Pathogens 2021; 10:pathogens10091196. [PMID: 34578228 PMCID: PMC8468008 DOI: 10.3390/pathogens10091196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
Vesicular stomatitis Indiana virus (VSIV) of genus Vesiculovirus, species IndianaVesiculovirus (formerly as Vesicular stomatitis virus, VSV) causes a disease in livestock that is very similar to the foot and mouth disease, thereby an outbreak may lead to significant economic loss. Long-read sequencing (LRS) -based approaches already reveal a hidden complexity of the transcriptomes in several viruses. This technique has been utilized for the sequencing of the VSIV genome, but our study is the first for the application of this technique for the profiling of the VSIV transcriptome. Since LRS is able to sequence full-length RNA molecules, it thereby provides more accurate annotation of the transcriptomes than the traditional short-read sequencing methods. The objectives of this study were to assemble the complete transcriptome of using nanopore sequencing, to ascertain cell-type specificity and dynamics of viral gene expression, and to evaluate host gene expression changes induced by the viral infection. We carried out a time-course analysis of VSIV gene expression in human glioblastoma and primate fibroblast cell lines using a nanopore-based LRS approach and applied both amplified and direct cDNA sequencing (as well as cap-selection) for a fraction of samples. Our investigations revealed that, although the VSIV genome is simple, it generates a relatively complex transcriptomic architecture. In this study, we also demonstrated that VSIV transcripts vary in structure and exhibit differential gene expression patterns in the two examined cell types.
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Affiliation(s)
- Balázs Kakuk
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - András Attila Kiss
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - Gábor Torma
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - Zsolt Csabai
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - István Prazsák
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - Máté Mizik
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - Klára Megyeri
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary;
| | - Dóra Tombácz
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
| | - Zsolt Boldogkői
- Department of Medical Biology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary; (B.K.); (A.A.K.); (G.T.); (Z.C.); (I.P.); (M.M.); (D.T.)
- Correspondence:
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Malogolovkin A, Gasanov N, Egorov A, Weener M, Ivanov R, Karabelsky A. Combinatorial Approaches for Cancer Treatment Using Oncolytic Viruses: Projecting the Perspectives through Clinical Trials Outcomes. Viruses 2021; 13:1271. [PMID: 34209981 PMCID: PMC8309967 DOI: 10.3390/v13071271] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 02/06/2023] Open
Abstract
Recent cancer immunotherapy breakthroughs have fundamentally changed oncology and revived the fading hope for a cancer cure. The immune checkpoint inhibitors (ICI) became an indispensable tool for the treatment of many malignant tumors. Alongside ICI, the application of oncolytic viruses in clinical trials is demonstrating encouraging outcomes. Dozens of combinations of oncolytic viruses with conventional radiotherapy and chemotherapy are widely used or studied, but it seems quite complicated to highlight the most effective combinations. Our review summarizes the results of clinical trials evaluating oncolytic viruses with or without genetic alterations in combination with immune checkpoint blockade, cytokines, antigens and other oncolytic viruses as well. This review is focused on the efficacy and safety of virotherapy and the most promising combinations based on the published clinical data, rather than presenting all oncolytic virus variations, which are discussed in comprehensive literature reviews. We briefly revise the research landscape of oncolytic viruses and discuss future perspectives in virus immunotherapy, in order to provide an insight for novel strategies of cancer treatment.
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Affiliation(s)
- Alexander Malogolovkin
- Gene Therapy Department, Sirius University of Science and Technology, Olympic Avenue, 1, 354340 Sochi, Russia; (N.G.); (A.E.); (M.W.); (R.I.)
| | | | | | | | | | - Alexander Karabelsky
- Gene Therapy Department, Sirius University of Science and Technology, Olympic Avenue, 1, 354340 Sochi, Russia; (N.G.); (A.E.); (M.W.); (R.I.)
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30
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Gibbons JS, Khadka S, Williams CG, Wang L, Schneller SW, Liu C, Tufariello JM, Basler CF. Mechanisms of anti-vesicular stomatitis virus activity of deazaneplanocin and its 3-brominated analogs. Antiviral Res 2021; 191:105088. [PMID: 34019950 DOI: 10.1016/j.antiviral.2021.105088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/02/2021] [Accepted: 05/10/2021] [Indexed: 12/30/2022]
Abstract
3-deazaneplanocin A (DzNep) and its 3-brominated analogs inhibit replication of several RNA viruses. This antiviral activity is attributed to inhibition of S-adenosyl homocysteine hydrolase (SAHase) and consequently inhibition of viral methyltransferases, impairing translation of viral transcripts. The L-enantiomers of some derivatives retain antiviral activity despite dramatically reduced inhibition of SAHase in vitro. To better understand the mechanisms by which these compounds exert their antiviral effects, we compared DzNep, its 3-bromo-derivative, CL123, and the related enantiomers, CL4033 and CL4053, for their activities towards the model negative-sense RNA virus vesicular stomatitis virus (VSV). In cell culture, DzNep, CL123 and CL4033 each exhibited 50 percent inhibitory concentrations (IC50s) in the nanomolar range whereas the IC50 for the L-form, CL4053, was 34-85 times higher. When a CL123-resistant mutant (VSVR) was selected, it exhibited cross-resistance to each of the neplanocin analogs, but retained sensitivity to the adenosine analog BCX4430, an RNA chain terminator. Sequencing of VSVR identified a mutation in the C-terminal domain (CTD) of the viral large (L) protein, a domain implicated in regulation of L protein methyltransferase activity. CL123 inhibited VSV viral mRNA 5' cap methylation, impaired viral protein synthesis and decreased association of viral mRNAs with polysomes. Modest impacts on viral transcription were also demonstrated. VSVR exhibited partial resistance in each of these assays but its replication was impaired, relative to the parent VSV, in the absence of the inhibitors. These data suggest that DzNep, CL123 and CL4033 inhibit VSV through impairment of viral mRNA cap methylation and that the L-form, CL4053, based on the cross-resistance of VSVR, may act by a similar mechanism.
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Affiliation(s)
- Joyce Sweeney Gibbons
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA; Department of Chemistry, Georgia State University, Atlanta, GA, USA
| | - Sudip Khadka
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA; Department of Molecular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Caroline G Williams
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Lin Wang
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA; Department of Molecular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Stewart W Schneller
- Molette Laboratory for Drug Discovery, Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA
| | - Chong Liu
- Molette Laboratory for Drug Discovery, Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA
| | - JoAnn M Tufariello
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Christopher F Basler
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA.
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Sutto-Ortiz P, Tcherniuk S, Ysebaert N, Abeywickrema P, Noël M, Decombe A, Debart F, Vasseur JJ, Canard B, Roymans D, Rigaux P, Eléouët JF, Decroly E. The methyltransferase domain of the Respiratory Syncytial Virus L protein catalyzes cap N7 and 2'-O-methylation. PLoS Pathog 2021; 17:e1009562. [PMID: 33956914 PMCID: PMC8130918 DOI: 10.1371/journal.ppat.1009562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 05/18/2021] [Accepted: 04/15/2021] [Indexed: 12/15/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a negative sense single-stranded RNA virus and one of the main causes of severe lower respiratory tract infections in infants and young children. RSV RNA replication/transcription and capping are ensured by the viral Large (L) protein. The L protein contains a polymerase domain associated with a polyribonucleotidyl transferase domain in its N-terminus, and a methyltransferase (MTase) domain followed by the C-terminal domain (CTD) enriched in basic amino acids at its C-terminus. The MTase-CTD of Mononegavirales forms a clamp to accommodate RNA that is subsequently methylated on the cap structure and depending on the virus, on internal positions. These enzymatic activities are essential for efficient viral mRNA translation into proteins, and to prevent the recognition of uncapped viral RNA by innate immunity sensors. In this work, we demonstrated that the MTase-CTD of RSV, as well as the full-length L protein in complex with phosphoprotein (P), catalyzes the N7- and 2’-O-methylation of the cap structure of a short RNA sequence that corresponds to the 5’ end of viral mRNA. Using different experimental systems, we showed that the RSV MTase-CTD methylates the cap structure with a preference for N7-methylation as first reaction. However, we did not observe cap-independent internal methylation, as recently evidenced for the Ebola virus MTase. We also found that at μM concentrations, sinefungin, a S-adenosylmethionine analogue, inhibits the MTase activity of the RSV L protein and of the MTase-CTD domain. Altogether, these results suggest that the RSV MTase domain specifically recognizes viral RNA decorated by a cap structure and catalyzes its methylation, which is required for translation and innate immune system subversion. Respiratory syncytial virus (RSV) is responsible of infant bronchiolitis and severe lower respiratory tract infections in infants and young children, and the leading cause of hospitalization in children under one year of age. However, we still lack a vaccine and therapeutics against this important pathogen. The main enzymatic activities involved in RSV propagation are embedded in the Large (L) protein that contains the polymerase domain and also all the activities required for RNA cap structure synthesis and methylation. These post-transcriptional RNA modifications play a key role in virus replication because cap N7-methylation is required for viral RNA translation into proteins, and 2’-O-methylation hides viral RNA from innate immunity detection. Viral methyltransferase (MTase) activities are now considered potential antiviral targets because their inhibition might limit the virus production and strengthen early virus detection by innate immunity sensors. In this work, we compared the enzymatic activities of the MTase expressed as a single domain or in the context of the full-length L protein. We demonstrated that the MTase protein catalyzes the specific methylation of the cap structure at both N7- and 2’-O-positions, and we obtained the proof of concept that a S-adenosylmethionine analogue can inhibit the MTase activity of the L protein.
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Affiliation(s)
| | - Sergey Tcherniuk
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, Jouy en Josas, France
| | - Nina Ysebaert
- Janssen Infectious Diseases and Vaccines, Beerse, Belgium
| | | | - Mathieu Noël
- IBMM, Université de Montpellier, ENSCM, CNRS, UMR 5247, Montpellier, France
| | - Alice Decombe
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Françoise Debart
- IBMM, Université de Montpellier, ENSCM, CNRS, UMR 5247, Montpellier, France
| | | | - Bruno Canard
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Dirk Roymans
- Janssen Infectious Diseases and Vaccines, Beerse, Belgium
| | - Peter Rigaux
- Janssen Infectious Diseases and Vaccines, Beerse, Belgium
| | - Jean-François Eléouët
- Unité de Virologie et Immunologie Moléculaires, INRAE, Université Paris Saclay, Jouy en Josas, France
| | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
- * E-mail:
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32
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Structural Insights into the Respiratory Syncytial Virus RNA Synthesis Complexes. Viruses 2021; 13:v13050834. [PMID: 34063087 PMCID: PMC8147935 DOI: 10.3390/v13050834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 12/13/2022] Open
Abstract
RNA synthesis in respiratory syncytial virus (RSV), a negative-sense (-) nonsegmented RNA virus, consists of viral gene transcription and genome replication. Gene transcription includes the positive-sense (+) viral mRNA synthesis, 5'-RNA capping and methylation, and 3' end polyadenylation. Genome replication includes (+) RNA antigenome and (-) RNA genome synthesis. RSV executes the viral RNA synthesis using an RNA synthesis ribonucleoprotein (RNP) complex, comprising four proteins, the nucleoprotein (N), the large protein (L), the phosphoprotein (P), and the M2-1 protein. We provide an overview of the RSV RNA synthesis and the structural insights into the RSV gene transcription and genome replication process. We propose a model of how the essential four proteins coordinate their activities in different RNA synthesis processes.
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Abstract
Vesicular stomatitis virus (VSV) is a member of the order Mononegavirales, which consists of viruses with a genome of nonsegmented negative-sense (NNS) RNA. Many insights into the molecular biology of NNS viruses were first made in VSV, which is often studied as a prototype for members of this order. Like other NNS viruses, the VSV RNA polymerase consists of a complex of the large protein (L) and phosphoprotein (P). Recent discoveries have produced a model in which the N-terminal disordered segment of P (PNTD) coordinates the C-terminal accessory domains to produce a "compacted" L conformation. Despite this advancement, the role of the three phosphorylation sites in PNTD has remained unknown. Using nuclear magnetic resonance spectroscopy to analyze the interactions between PNTD and the L protein C-terminal domain (LCTD), we demonstrated our ability to sensitively test for changes in the interface between the two proteins. This method showed that the binding site for PNTD on LCTD is longer than was previously appreciated. We demonstrated that phosphorylation of PNTD modulates its interaction with LCTD and used a minigenome reporter system to validate the functional significance of the PNTD-LCTD interaction. Using an electron microscopy approach, we showed that L bound to phosphorylated PNTD displays increased conformational heterogeneity in solution. Taken as a whole, our studies suggest a model in which phosphorylation of PNTD modulates its cofactor and conformational regulatory activities with L.IMPORTANCE Polymerase-cofactor interactions like those addressed in this study are absolute requirements for mononegavirus RNA synthesis. Despite cofactor phosphorylation being present in most of these interactions, what effect if any it has on this protein-protein interaction had not been addressed. Our study is the first to address the effects of phosphorylation on P during its interactions with L in residue-by-residue detail. As phosphorylation is the biologically relevant state of the cofactor, our demonstration of its effects on L conformation suggest that the structural picture of L during infection might be more complex than previously appreciated.
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Abstract
RNA viruses include many important human and animal pathogens, such as the influenza viruses, respiratory syncytial virus, Ebola virus, measles virus and rabies virus. The genomes of these viruses consist of single or multiple RNA segments that assemble with oligomeric viral nucleoprotein into ribonucleoprotein complexes. Replication and transcription of the viral genome is performed by ~250-450 kDa viral RNA-dependent RNA polymerases that also contain capping or cap-snatching activity. In this Review, we compare recent high-resolution X-ray and cryoelectron microscopy structures of RNA polymerases of negative-sense RNA viruses with segmented and non-segmented genomes, including orthomyxoviruses, peribunyaviruses, phenuiviruses, arenaviruses, rhabdoviruses, pneumoviruses and paramyxoviruses. In addition, we discuss how structural insights into these enzymes contribute to our understanding of the molecular mechanisms of viral transcription and replication, and how we can use these insights to identify targets for antiviral drug design.
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Abstract
Mononegavirales, known as nonsegmented negative-sense (NNS) RNA viruses, are a class of pathogenic and sometimes deadly viruses that include rabies virus (RABV), human respiratory syncytial virus (HRSV), and Ebola virus (EBOV). Unfortunately, no effective vaccines and antiviral therapeutics against many Mononegavirales are currently available. Viral polymerases have been attractive and major antiviral therapeutic targets. Therefore, Mononegavirales polymerases have been extensively investigated for their structures and functions. Mononegavirales, known as nonsegmented negative-sense (NNS) RNA viruses, are a class of pathogenic and sometimes deadly viruses that include rabies virus (RABV), human respiratory syncytial virus (HRSV), and Ebola virus (EBOV). Unfortunately, no effective vaccines and antiviral therapeutics against many Mononegavirales are currently available. Viral polymerases have been attractive and major antiviral therapeutic targets. Therefore, Mononegavirales polymerases have been extensively investigated for their structures and functions. Mononegavirales mimic RNA synthesis of their eukaryotic counterparts by utilizing multifunctional RNA polymerases to replicate entire viral genomes and transcribe viral mRNAs from individual viral genes as well as synthesize 5′ methylated cap and 3′ poly(A) tail of the transcribed viral mRNAs. The catalytic subunit large protein (L) and cofactor phosphoprotein (P) constitute the Mononegavirales polymerases. In this review, we discuss the shared and unique features of RNA synthesis, the monomeric multifunctional enzyme L, and the oligomeric multimodular adapter P of Mononegavirales. We outline the structural analyses of the Mononegavirales polymerases since the first structure of the vesicular stomatitis virus (VSV) L protein determined in 2015 and highlight multiple high-resolution cryo-electron microscopy (cryo-EM) structures of the polymerases of Mononegavirales, namely, VSV, RABV, HRSV, human metapneumovirus (HMPV), and human parainfluenza virus (HPIV), that have been reported in recent months (2019 to 2020). We compare the structures of those polymerases grouped by virus family, illustrate the similarities and differences among those polymerases, and reveal the potential RNA synthesis mechanisms and models of highly conserved Mononegavirales. We conclude by the discussion of remaining questions, evolutionary perspectives, and future directions.
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36
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Riedel C, Hennrich AA, Conzelmann KK. Components and Architecture of the Rhabdovirus Ribonucleoprotein Complex. Viruses 2020; 12:v12090959. [PMID: 32872471 PMCID: PMC7552012 DOI: 10.3390/v12090959] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/27/2020] [Accepted: 08/27/2020] [Indexed: 12/14/2022] Open
Abstract
Rhabdoviruses, as single-stranded, negative-sense RNA viruses within the order Mononegavirales, are characterised by bullet-shaped or bacteroid particles that contain a helical ribonucleoprotein complex (RNP). Here, we review the components of the RNP and its higher-order structural assembly.
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Affiliation(s)
- Christiane Riedel
- Institute of Virology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
- Correspondence:
| | - Alexandru A. Hennrich
- Max von Pettenkofer-Institute Virology, Faculty of Medicine, and Gene Center, LMU Munich, 81377 Munich, Germany; (A.A.H.); (K.-K.C.)
| | - Karl-Klaus Conzelmann
- Max von Pettenkofer-Institute Virology, Faculty of Medicine, and Gene Center, LMU Munich, 81377 Munich, Germany; (A.A.H.); (K.-K.C.)
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37
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Nevers Q, Albertini AA, Lagaudrière-Gesbert C, Gaudin Y. Negri bodies and other virus membrane-less replication compartments. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118831. [PMID: 32835749 PMCID: PMC7442162 DOI: 10.1016/j.bbamcr.2020.118831] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 12/25/2022]
Abstract
Viruses reshape the organization of the cell interior to achieve different steps of their cellular cycle. Particularly, viral replication and assembly often take place in viral factories where specific viral and cellular proteins as well as nucleic acids concentrate. Viral factories can be either membrane-delimited or devoid of any cellular membranes. In the latter case, they are referred as membrane-less replication compartments. The most emblematic ones are the Negri bodies, which are inclusion bodies that constitute the hallmark of rabies virus infection. Interestingly, Negri bodies and several other viral replication compartments have been shown to arise from a liquid-liquid phase separation process and, thus, constitute a new class of liquid organelles. This is a paradigm shift in the field of virus replication. Here, we review the different aspects of membrane-less virus replication compartments with a focus on the Mononegavirales order and discuss their interactions with the host cell machineries and the cytoskeleton. We particularly examine the interplay between viral factories and the cellular innate immune response, of which several components also form membrane-less condensates in infected cells. Viral factories harbor essential steps of the viral cycle. Some viral factories are devoid of membranes and have liquid organelle properties. Liquid viral factories concentrate cellular factors required for replication. Innate immunity sensors and several ISGs are found in membrane-less condensates. A subtle interplay exists between liquid viral factories and innate immunity actors.
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Affiliation(s)
- Quentin Nevers
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Aurélie A Albertini
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Cécile Lagaudrière-Gesbert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Yves Gaudin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France.
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Luo M, Terrell JR, Mcmanus SA. Nucleocapsid Structure of Negative Strand RNA Virus. Viruses 2020; 12:E835. [PMID: 32751700 PMCID: PMC7472042 DOI: 10.3390/v12080835] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/23/2020] [Accepted: 07/27/2020] [Indexed: 12/14/2022] Open
Abstract
Negative strand RNA viruses (NSVs) include many important human pathogens, such as influenza virus, Ebola virus, and rabies virus. One of the unique characteristics that NSVs share is the assembly of the nucleocapsid and its role in viral RNA synthesis. In NSVs, the single strand RNA genome is encapsidated in the linear nucleocapsid throughout the viral replication cycle. Subunits of the nucleocapsid protein are parallelly aligned along the RNA genome that is sandwiched between two domains composed of conserved helix motifs. The viral RNA-dependent-RNA polymerase (vRdRp) must recognize the protein-RNA complex of the nucleocapsid and unveil the protected genomic RNA in order to initiate viral RNA synthesis. In addition, vRdRp must continuously translocate along the protein-RNA complex during elongation in viral RNA synthesis. This unique mechanism of viral RNA synthesis suggests that the nucleocapsid may play a regulatory role during NSV replication.
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Affiliation(s)
- Ming Luo
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA; (J.R.T.); (S.A.M.)
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39
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Structural and Functional Characterization of the Phosphoprotein Central Domain of Spring Viremia of Carp Virus. J Virol 2020; 94:JVI.00855-20. [PMID: 32434890 DOI: 10.1128/jvi.00855-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 05/18/2020] [Indexed: 11/20/2022] Open
Abstract
Spring viremia of carp virus (SVCV) is a highly pathogenic Vesiculovirus in the common carp. The phosphoprotein (P protein) of SVCV is a multifunctional protein that acts as a polymerase cofactor and an antagonist of cellular interferon (IFN) response. Here, we report the 1.5-Å-resolution crystal structure of the P protein central domain (PCD) of SVCV (SVCVPCD). The PCD monomer consists of two β sheets, an α helix, and another two β sheets. Two PCD monomers pack together through their hydrophobic surfaces to form a dimer. The mutations of residues on the hydrophobic surfaces of PCD disrupt the dimer formation to different degrees and affect the expression of host IFN consistently. Therefore, the oligomeric state formation of the P protein of SVCV is an important mechanism to negatively regulate host IFN response.IMPORTANCE SVCV can cause spring viremia of carp with up to 90% lethality, and it is the homologous virus of the notorious vesicular stomatitis virus (VSV). There are currently no drugs that effectively cure this disease. P proteins of negative-strand RNA viruses (NSVs) play an essential role in many steps during the replication cycle and an additional role in immunosuppression as a cofactor. All P proteins of NSVs are oligomeric, but the studies on the role of this oligomerization mainly focus on the process of virus transcription or replication, and there are few studies on the role of PCD in immunosuppression. Here, we present the crystal structure of SVCVPCD A new mechanism of immune evasion is clarified by exploring the relationship between SVCVPCD and host IFN response from a structural biology point of view. These findings may provide more accurate target sites for drug design against SVCV and provide new insights into the function of NSVPCD.
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40
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Oligomerization of the Vesicular Stomatitis Virus Phosphoprotein Is Dispensable for mRNA Synthesis but Facilitates RNA Replication. J Virol 2020; 94:JVI.00115-20. [PMID: 32321813 PMCID: PMC7307139 DOI: 10.1128/jvi.00115-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/15/2020] [Indexed: 12/18/2022] Open
Abstract
All NNS RNA viruses, including the human pathogens rabies, measles, respiratory syncytial virus, Nipah, and Ebola, possess an essential L-protein cofactor, required to access the N-RNA template and coordinate the various enzymatic activities of L. The polymerase cofactors share a similar modular organization of a soluble N-binding domain and a template-binding domain separated by a central oligomerization domain. Using a prototype of NNS RNA virus gene expression, vesicular stomatitis virus (VSV), we determined the importance of P oligomerization. We find that oligomerization of VSV P is not required for any step of viral mRNA synthesis but is required for efficient RNA replication. We present evidence that this likely occurs through the stage of loading soluble N onto the nascent RNA strand as it exits the polymerase during RNA replication. Interfering with the oligomerization of P may represent a general strategy to interfere with NNS RNA virus replication. Nonsegmented negative-strand (NNS) RNA viruses possess a ribonucleoprotein template in which the genomic RNA is sequestered within a homopolymer of nucleocapsid protein (N). The viral RNA-dependent RNA polymerase (RdRP) resides within an approximately 250-kDa large protein (L), along with unconventional mRNA capping enzymes: a GDP:polyribonucleotidyltransferase (PRNT) and a dual-specificity mRNA cap methylase (MT). To gain access to the N-RNA template and orchestrate the LRdRP, LPRNT, and LMT, an oligomeric phosphoprotein (P) is required. Vesicular stomatitis virus (VSV) P is dimeric with an oligomerization domain (OD) separating two largely disordered regions followed by a globular C-terminal domain that binds the template. P is also responsible for bringing new N protomers onto the nascent RNA during genome replication. We show VSV P lacking the OD (PΔOD) is monomeric but is indistinguishable from wild-type P in supporting mRNA transcription in vitro. Recombinant virus VSV-PΔOD exhibits a pronounced kinetic delay in progeny virus production. Fluorescence recovery after photobleaching demonstrates that PΔOD diffuses 6-fold more rapidly than the wild type within viral replication compartments. A well-characterized defective interfering particle of VSV (DI-T) that is only competent for RNA replication requires significantly higher levels of N to drive RNA replication in the presence of PΔOD. We conclude P oligomerization is not required for mRNA synthesis but enhances genome replication by facilitating RNA encapsidation. IMPORTANCE All NNS RNA viruses, including the human pathogens rabies, measles, respiratory syncytial virus, Nipah, and Ebola, possess an essential L-protein cofactor, required to access the N-RNA template and coordinate the various enzymatic activities of L. The polymerase cofactors share a similar modular organization of a soluble N-binding domain and a template-binding domain separated by a central oligomerization domain. Using a prototype of NNS RNA virus gene expression, vesicular stomatitis virus (VSV), we determined the importance of P oligomerization. We find that oligomerization of VSV P is not required for any step of viral mRNA synthesis but is required for efficient RNA replication. We present evidence that this likely occurs through the stage of loading soluble N onto the nascent RNA strand as it exits the polymerase during RNA replication. Interfering with the oligomerization of P may represent a general strategy to interfere with NNS RNA virus replication.
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41
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Jensen MR, Yabukarski F, Communie G, Condamine E, Mas C, Volchkova V, Tarbouriech N, Bourhis JM, Volchkov V, Blackledge M, Jamin M. Structural Description of the Nipah Virus Phosphoprotein and Its Interaction with STAT1. Biophys J 2020; 118:2470-2488. [PMID: 32348724 PMCID: PMC7231922 DOI: 10.1016/j.bpj.2020.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 03/31/2020] [Accepted: 04/06/2020] [Indexed: 12/25/2022] Open
Abstract
The structural characterization of modular proteins containing long intrinsically disordered regions intercalated with folded domains is complicated by their conformational diversity and flexibility and requires the integration of multiple experimental approaches. Nipah virus (NiV) phosphoprotein, an essential component of the viral RNA transcription/replication machine and a component of the viral arsenal that hijacks cellular components and counteracts host immune responses, is a prototypical model for such modular proteins. Curiously, the phosphoprotein of NiV is significantly longer than the corresponding protein of other paramyxoviruses. Here, we combine multiple biophysical methods, including x-ray crystallography, NMR spectroscopy, and small angle x-ray scattering, to characterize the structure of this protein and provide an atomistic representation of the full-length protein in the form of a conformational ensemble. We show that full-length NiV phosphoprotein is tetrameric, and we solve the crystal structure of its tetramerization domain. Using NMR spectroscopy and small angle x-ray scattering, we show that the long N-terminal intrinsically disordered region and the linker connecting the tetramerization domain to the C-terminal X domain exchange between multiple conformations while containing short regions of residual secondary structure. Some of these transient helices are known to interact with partners, whereas others represent putative binding sites for yet unidentified proteins. Finally, using NMR spectroscopy and isothermal titration calorimetry, we map a region of the phosphoprotein, comprising residues between 110 and 140 and common to the V and W proteins, that binds with weak affinity to STAT1 and confirm the involvement of key amino acids of the viral protein in this interaction. This provides new, to our knowledge, insights into how the phosphoprotein and the nonstructural V and W proteins of NiV perform their multiple functions.
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Affiliation(s)
| | - Filip Yabukarski
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Guillaume Communie
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Eric Condamine
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Caroline Mas
- Integrated Structural Biology Grenoble CNRS, CEA, University Grenoble Alpes, EMBL, Grenoble, France
| | - Valentina Volchkova
- Molecular Basis of Viral Pathogenicity, Centre International de Recherche en Infectiologie, INSERMU1111-CNRS UMR5308, Université Claude Bernard Lyon 1, ENS de Lyon, Lyon, France
| | - Nicolas Tarbouriech
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Jean-Marie Bourhis
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Viktor Volchkov
- Molecular Basis of Viral Pathogenicity, Centre International de Recherche en Infectiologie, INSERMU1111-CNRS UMR5308, Université Claude Bernard Lyon 1, ENS de Lyon, Lyon, France
| | - Martin Blackledge
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Marc Jamin
- Institut de Biologie Structurale, University Grenoble Alpes, CEA, CNRS, Grenoble, France.
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Cao D, Liang B. Cryo-Electron Microscopy Structures of the Pneumoviridae Polymerases. Viral Immunol 2020; 34:18-26. [PMID: 32429800 DOI: 10.1089/vim.2020.0018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The resolution revolution of cryo-electron microscopy (cryo-EM) has made a significant impact on the structural analysis of the Pneumoviridae multifunctional RNA polymerases. In recent months, several high-resolution structures of apo RNA polymerases of Pneumoviridae, which includes the human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV), have been determined by single-particle cryo-EM. These structures illustrated high similarities and minor differences between the Pneumoviridae polymerases and revealed the potential mechanisms of the Pneumoviridae RNA synthesis.
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Affiliation(s)
- Dongdong Cao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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43
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Guseva S, Milles S, Jensen MR, Schoehn G, Ruigrok RWH, Blackledge M. Structure, dynamics and phase separation of measles virus RNA replication machinery. Curr Opin Virol 2020; 41:59-67. [DOI: 10.1016/j.coviro.2020.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/08/2020] [Accepted: 05/14/2020] [Indexed: 12/20/2022]
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44
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Vesicular Stomatitis Virus Phosphoprotein Dimerization Domain Is Dispensable for Virus Growth. J Virol 2020; 94:JVI.01789-19. [PMID: 31852780 DOI: 10.1128/jvi.01789-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/06/2019] [Indexed: 02/08/2023] Open
Abstract
The phosphoprotein (P) of the nonsegmented negative-sense RNA viruses is a multimeric modular protein that is essential for RNA transcription and replication. Despite great variability in length and sequence, the architecture of this protein is conserved among the different viral families, with a long N-terminal intrinsically disordered region comprising a nucleoprotein chaperone module, a central multimerization domain (PMD), connected by a disordered linker to a C-terminal nucleocapsid-binding domain. The P protein of vesicular stomatitis virus (VSV) forms dimers, and here we investigate the importance of its dimerization domain, PMD, for viral gene expression and virus growth. A truncated P protein lacking the central dimerization domain (PΔMD) loses its ability to form dimers both in vitro and in a yeast two-hybrid system but conserves its ability to bind N. In a minireplicon system, the truncated monomeric protein performs almost as well as the full-length dimeric protein, while a recombinant virus harboring the same truncation in the P protein has been rescued and follows replication kinetics similar to those seen with the wild-type virus, showing that the dimerization domain of P is dispensable for viral gene expression and virus replication in cell culture. Because RNA viruses have high mutation rates, it is unlikely that a structured domain such as a VSV dimerization domain would persist in the absence of a function(s), but our work indicates that it is not required for the functioning of the RNA polymerase machinery or for the assembly of new viruses.IMPORTANCE The phosphoprotein (P) is an essential and conserved component of all nonsegmented negative-sense RNA viruses, including some major human pathogens (e.g., rabies virus, measles virus, respiratory syncytial virus [RSV], Ebola virus, and Nipah virus). P is a modular protein with intrinsically disordered regions and folded domains that plays specific and similar roles in the replication of the different viruses and, in some cases, hijacks cell components to the advantage of the virus and is involved in immune evasion. All P proteins are multimeric, but the role of this multimerization is still unclear. Here, we demonstrate that the dimerization domain of VSV P is dispensable for the expression of virally encoded proteins and for virus growth in cell culture. This provides new insights into and raises questions about the functioning of the RNA-synthesizing machinery of the nonsegmented negative-sense RNA viruses.
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Insight into the multifunctional RNA synthesis machine of rabies virus. Proc Natl Acad Sci U S A 2020; 117:3895-3897. [PMID: 31992635 DOI: 10.1073/pnas.2000120117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Rabies virus (RABV) and other viruses with single-segment, negative-sense, RNA genomes have a multi-functional polymerase protein (L) that carries out the various reactions required for transcription and replication. Many of these viruses are serious human pathogens, and L is a potential target for antiviral therapeutics. Drugs that inhibit polymerases of HCV and HIV-1 provide successful precedents. The structure described here of the RABV L protein in complex with its P-protein cofactor shows a conformation poised for initiation of transcription or replication. Channels in the molecule and the relative positions of catalytic sites suggest that L couples a distinctive capping reaction with priming and initiation of transcription, and that replication and transcription have different priming configurations and different product exit sites. Nonsegmented negative-stranded (NNS) RNA viruses, among them the virus that causes rabies (RABV), include many deadly human pathogens. The large polymerase (L) proteins of NNS RNA viruses carry all of the enzymatic functions required for viral messenger RNA (mRNA) transcription and replication: RNA polymerization, mRNA capping, and cap methylation. We describe here a complete structure of RABV L bound with its phosphoprotein cofactor (P), determined by electron cryo-microscopy at 3.3 Å resolution. The complex closely resembles the vesicular stomatitis virus (VSV) L-P, the one other known full-length NNS-RNA L-protein structure, with key local differences (e.g., in L-P interactions). Like the VSV L-P structure, the RABV complex analyzed here represents a preinitiation conformation. Comparison with the likely elongation state, seen in two structures of pneumovirus L-P complexes, suggests differences between priming/initiation and elongation complexes. Analysis of internal cavities within RABV L suggests distinct template and product entry and exit pathways during transcription and replication.
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