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Kleiner VA, Fearns R. How does the polymerase of non-segmented negative strand RNA viruses commit to transcription or genome replication? J Virol 2024; 98:e0033224. [PMID: 39078194 PMCID: PMC11334523 DOI: 10.1128/jvi.00332-24] [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] [Indexed: 07/31/2024] Open
Abstract
The Mononegavirales, or non-segmented negative-sense RNA viruses (nsNSVs), includes significant human pathogens, such as respiratory syncytial virus, parainfluenza virus, measles virus, Ebola virus, and rabies virus. Although these viruses differ widely in their pathogenic properties, they are united by each having a genome consisting of a single strand of negative-sense RNA. Consistent with their shared genome structure, the nsNSVs have evolved similar ways to transcribe their genome into mRNAs and replicate it to produce new genomes. Importantly, both mRNA transcription and genome replication are performed by a single virus-encoded polymerase. A fundamental and intriguing question is: how does the nsNSV polymerase commit to being either an mRNA transcriptase or a replicase? The polymerase must become committed to one process or the other either before it interacts with the genome template or in its initial interactions with the promoter sequence at the 3´ end of the genomic RNA. This review examines the biochemical, molecular biology, and structural biology data regarding the first steps of transcription and RNA replication that have been gathered over several decades for different families of nsNSVs. These findings are discussed in relation to possible models that could explain how an nsNSV polymerase initiates and commits to either transcription or genome replication.
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Affiliation(s)
- Victoria A. Kleiner
- Department of Virology, Immunology & Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts, USA
| | - Rachel Fearns
- Department of Virology, Immunology & Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts, USA
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2
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Haas GD, Schmitz KS, Azarm KD, Johnson KN, Klain WR, Freiberg AN, Cox RM, Plemper RK, Lee B. Tetracistronic Minigenomes Elucidate a Functional Promoter for Ghana Virus and Unveils Cedar Virus Replicase Promiscuity for all Henipaviruses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589704. [PMID: 38659760 PMCID: PMC11042316 DOI: 10.1101/2024.04.16.589704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Batborne henipaviruses, such as Nipah virus and Hendra virus, represent a major threat to global health due to their propensity for spillover, severe pathogenicity, and high mortality rate in human hosts. Coupled with the absence of approved vaccines or therapeutics, work with the prototypical species and uncharacterized, emergent species is restricted to high biocontainment facilities. There is a scarcity of such specialized spaces for research, and often the scope and capacity of research which can be conducted at BSL-4 is limited. Therefore, there is a pressing need for innovative life-cycle modeling systems to enable comprehensive research within lower biocontainment settings. This work showcases tetracistronic, transcription and replication competent minigenomes for Nipah virus, Hendra virus, Cedar virus, and Ghana virus, which encode viral proteins facilitating budding, fusion, and receptor binding. We validate the functionality of all encoded viral proteins and demonstrate a variety of applications to interrogate the viral life cycle. Notably, we found that the Cedar virus replicase exhibits remarkable promiscuity, efficiently rescuing minigenomes from all tested henipaviruses. We also apply this technology to GhV, an emergent species which has so far not been isolated in culture. We demonstrate that the reported sequence of GhV is incomplete, but that this missing sequence can be substituted with analogous sequences from other henipaviruses. Use of our GhV system establishes the functionality of the GhV replicase and identifies two antivirals which are highly efficacious against the GhV polymerase.
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Affiliation(s)
- Griffin D. Haas
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Kristopher D. Azarm
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Kendra N. Johnson
- Department of Pathology, University of Texas Medical Branch, Galveston, TX
| | - William R. Klain
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Robert M. Cox
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Richard K. Plemper
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA
| | - Benhur Lee
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY
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3
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Zou G, Cao S, Gao Z, Yie J, Wu JZ. Current state and challenges in respiratory syncytial virus drug discovery and development. Antiviral Res 2024; 221:105791. [PMID: 38160942 DOI: 10.1016/j.antiviral.2023.105791] [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: 11/21/2023] [Revised: 12/22/2023] [Accepted: 12/23/2023] [Indexed: 01/03/2024]
Abstract
Human respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTI) in young children and elderly people worldwide. Recent significant progress in our understanding of the structure and function of RSV proteins has led to the discovery of several clinical candidates targeting RSV fusion and replication. These include both the development of novel small molecule interventions and the isolation of potent monoclonal antibodies. In this review, we summarize the state-of-the-art of RSV drug discovery, with a focus on the characteristics of the candidates that reached the clinical stage of development. We also discuss the lessons learned from failed and discontinued clinical developments and highlight the challenges that remain for development of RSV therapies.
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Affiliation(s)
- Gang Zou
- Shanghai Ark Biopharmaceutical Co., Ltd, Shanghai, 201203, China.
| | - Sushan Cao
- Shanghai Ark Biopharmaceutical Co., Ltd, Shanghai, 201203, China
| | - Zhao Gao
- Shanghai Ark Biopharmaceutical Co., Ltd, Shanghai, 201203, China
| | - Junming Yie
- Shanghai Ark Biopharmaceutical Co., Ltd, Shanghai, 201203, China
| | - Jim Zhen Wu
- Shanghai Ark Biopharmaceutical Co., Ltd, Shanghai, 201203, China
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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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Sabsay KR, te Velthuis AJW. Negative and ambisense RNA virus ribonucleocapsids: more than protective armor. Microbiol Mol Biol Rev 2023; 87:e0008223. [PMID: 37750733 PMCID: PMC10732063 DOI: 10.1128/mmbr.00082-23] [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] [Indexed: 09/27/2023] Open
Abstract
SUMMARYNegative and ambisense RNA viruses are the causative agents of important human diseases such as influenza, measles, Lassa fever, and Ebola hemorrhagic fever. The viral genome of these RNA viruses consists of one or more single-stranded RNA molecules that are encapsidated by viral nucleocapsid proteins to form a ribonucleoprotein complex (RNP). This RNP acts as protection, as a scaffold for RNA folding, and as the context for viral replication and transcription by a viral RNA polymerase. However, the roles of the viral nucleoproteins extend beyond these functions during the viral infection cycle. Recent advances in structural biology techniques and analysis methods have provided new insights into the formation, function, dynamics, and evolution of negative sense virus nucleocapsid proteins, as well as the role that they play in host innate immune responses against viral infection. In this review, we discuss the various roles of nucleocapsid proteins, both in the context of RNPs and in RNA-free states, as well as the open questions that remain.
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Affiliation(s)
- Kimberly R. Sabsay
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA
| | - Aartjan J. W. te Velthuis
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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6
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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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7
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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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