1
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Watkins JM, Burke JM. RNase L-induced bodies sequester subgenomic flavivirus RNAs and re-establish host RNA decay. bioRxiv 2024:2024.03.25.586660. [PMID: 38585896 PMCID: PMC10996650 DOI: 10.1101/2024.03.25.586660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Subgenomic flavivirus RNAs (sfRNAs) are structured RNA elements encoded in the 3'-UTR of flaviviruses that promote viral infection by inhibiting cellular RNA decay machinery. Herein, we analyze the production of sfRNAs using single-molecule RNA fluorescence in situ hybridization (smRNA-FISH) and super-resolution microscopy during West Nile virus, Zika virus, or Dengue virus serotype 2 infection. We show that sfRNAs are initially localized diffusely in the cytosol or in processing bodies (P-bodies). However, upon activation of the host antiviral endoribonuclease, Ribonuclease L (RNase L), nearly all sfRNAs re-localize to antiviral biological condensates known as RNase L-induced bodies (RLBs). RLB-mediated sequestration of sfRNAs reduces sfRNA association with RNA decay machinery in P-bodies, which coincides with increased viral RNA decay. These findings establish a role of RLBs in promoting viral RNA decay, demonstrating the complex host-pathogen interactions at the level of RNA decay and biological condensation.
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Affiliation(s)
- J. Monty Watkins
- Department of Molecular Medicine, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States of America
- Department of Immunology and Microbiology, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States of America
- Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL, USA
| | - James M. Burke
- Department of Molecular Medicine, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States of America
- Department of Immunology and Microbiology, The Herbert Wertheim University of Florida Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States of America
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2
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Hosseini A, Lindholm HT, Chen R, Mehdipour P, Marhon SA, Ishak CA, Moore PC, Classon M, Di Gioacchino A, Greenbaum B, De Carvalho DD. Retroelement decay by the exonuclease XRN1 is a viral mimicry dependency in cancer. Cell Rep 2024; 43:113684. [PMID: 38261511 DOI: 10.1016/j.celrep.2024.113684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 10/31/2023] [Accepted: 01/03/2024] [Indexed: 01/25/2024] Open
Abstract
Viral mimicry describes the immune response induced by endogenous stimuli such as double-stranded RNA (dsRNA) from endogenous retroelements. Activation of viral mimicry has the potential to kill cancer cells or augment anti-tumor immune responses. Here, we systematically identify mechanisms of viral mimicry adaptation associated with cancer cell dependencies. Among the top hits is the RNA decay protein XRN1 as an essential gene for the survival of a subset of cancer cell lines. XRN1 dependency is mediated by mitochondrial antiviral signaling protein and protein kinase R activation and is associated with higher levels of cytosolic dsRNA, higher levels of a subset of Alus capable of forming dsRNA, and higher interferon-stimulated gene expression, indicating that cells die due to induction of viral mimicry. Furthermore, dsRNA-inducing drugs such as 5-aza-2'-deoxycytidine and palbociclib can generate a synthetic dependency on XRN1 in cells initially resistant to XRN1 knockout. These results indicate that XRN1 is a promising target for future cancer therapeutics.
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Affiliation(s)
- Amir Hosseini
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7DQ, UK
| | - Håvard T Lindholm
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Pathology, Oslo University Hospital-Rikshospitalet, 0372 Oslo, Norway
| | - Raymond Chen
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Parinaz Mehdipour
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7DQ, UK
| | - Sajid A Marhon
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Charles A Ishak
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada
| | - Paul C Moore
- Pfizer Centers for Therapeutic Innovation, South San Francisco, CA 94080, USA
| | - Marie Classon
- Pfizer Centers for Therapeutic Innovation, South San Francisco, CA 94080, USA
| | - Andrea Di Gioacchino
- Laboratoire de Physique de l'Ecole Normale Supérieure, PSL & CNRS UMR8063, Sorbonne Université, Université de Paris, Paris, France
| | - Benjamin Greenbaum
- Physiology, Biophysics & Systems Biology, Weill Cornell Medicine, Weill Cornell Medical College, New York, NY 10065, USA; Computational Oncology, Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel D De Carvalho
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada.
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3
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Chen X, Li RT, Chen RY, Shi PD, Liu ZX, Lou YN, Wu M, Zhang RR, Tang W, Li XF, Qin CF. The subgenomic flaviviral RNA suppresses RNA interference through competing with siRNAs for binding RISC components. J Virol 2024; 98:e0195423. [PMID: 38289102 PMCID: PMC10878275 DOI: 10.1128/jvi.01954-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 12/17/2023] [Indexed: 02/21/2024] Open
Abstract
During the life cycle of mosquito-borne flaviviruses, substantial subgenomic flaviviral RNA (sfRNA) is produced via incomplete degradation of viral genomic RNA by host XRN1. Zika virus (ZIKV) sfRNA has been detected in mosquito and mammalian somatic cells. Human neural progenitor cells (hNPCs) in the developing brain are the major target cells of ZIKV, and antiviral RNA interference (RNAi) plays a critical role in hNPCs. However, whether ZIKV sfRNA was produced in ZIKV-infected hNPCs as well as its function remains not known. In this study, we demonstrate that abundant sfRNA was produced in ZIKV-infected hNPCs. RNA pulldown and mass spectrum assays showed ZIKV sfRNA interacted with host proteins RHA and PACT, both of which are RNA-induced silencing complex (RISC) components. Functionally, ZIKV sfRNA can antagonize RNAi by outcompeting small interfering RNAs (siRNAs) in binding to RHA and PACT. Furthermore, the 3' stem loop (3'SL) of sfRNA was responsible for RISC components binding and RNAi inhibition, and 3'SL can enhance the replication of a viral suppressor of RNAi (VSR)-deficient virus in a RHA- and PACT-dependent manner. More importantly, the ability of binding to RISC components is conversed among multiple flaviviral 3'SLs. Together, our results identified flavivirus 3'SL as a potent VSR in RNA format, highlighting the complexity in virus-host interaction during flavivirus infection.IMPORTANCEZika virus (ZIKV) infection mainly targets human neural progenitor cells (hNPCs) and induces cell death and dysregulated cell-cycle progression, leading to microcephaly and other central nervous system abnormalities. RNA interference (RNAi) plays critical roles during ZIKV infections in hNPCs, and ZIKV has evolved to encode specific viral proteins to antagonize RNAi. Herein, we first show that abundant sfRNA was produced in ZIKV-infected hNPCs in a similar pattern to that in other cells. Importantly, ZIKV sfRNA acts as a potent viral suppressor of RNAi (VSR) by competing with siRNAs for binding RISC components, RHA and PACT. The 3'SL of sfRNA is responsible for binding RISC components, which is a conserved feature among mosquito-borne flaviviruses. As most known VSRs are viral proteins, our findings highlight the importance of viral non-coding RNAs during the antagonism of host RNAi-based antiviral innate immunity.
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Affiliation(s)
- Xiang Chen
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Rui-Ting Li
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ru-Yi Chen
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Pan-Deng Shi
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zi-Xin Liu
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ya-Nan Lou
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Mei Wu
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Rong-Rong Zhang
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Wei Tang
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiao-Feng Li
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Cheng-Feng Qin
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, China
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4
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Zhang X, Li Y, Cao Y, Wu Y, Cheng G. The Role of Noncoding RNA in the Transmission and Pathogenicity of Flaviviruses. Viruses 2024; 16:242. [PMID: 38400018 PMCID: PMC10892091 DOI: 10.3390/v16020242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/28/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
Noncoding RNAs (ncRNAs) constitute a class of RNA molecules that lack protein-coding capacity. ncRNAs frequently modulate gene expression through specific interactions with target proteins or messenger RNAs, thereby playing integral roles in a wide array of cellular processes. The Flavivirus genus comprises several significant members, such as dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV), which have caused global outbreaks, resulting in high morbidity and mortality in human populations. The life cycle of arthropod-borne flaviviruses encompasses their transmission between hematophagous insect vectors and mammalian hosts. During this process, a complex three-way interplay occurs among the pathogen, vector, and host, with ncRNAs exerting a critical regulatory influence. ncRNAs not only constitute a crucial regulatory mechanism that has emerged from the coevolution of viruses and their hosts but also hold potential as antiviral targets for controlling flavivirus epidemics. This review introduces the biogenesis of flavivirus-derived ncRNAs and summarizes the regulatory roles of ncRNAs in viral replication, vector-mediated viral transmission, antiviral innate immunity, and viral pathogenicity. A profound comprehension of the interplay between ncRNAs and flaviviruses will help formulate efficacious prophylactic and therapeutic strategies against flavivirus-related diseases.
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Affiliation(s)
- Xianwen Zhang
- Shenzhen Bay Laboratory, Institute of Infectious Diseases, Shenzhen 518000, China
| | - Yuhan Li
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China; (Y.L.); (Y.C.)
| | - Yingyi Cao
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China; (Y.L.); (Y.C.)
| | - Ying Wu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Medical School, Wuhan University, Wuhan 430072, China;
| | - Gong Cheng
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China; (Y.L.); (Y.C.)
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China
- Southwest United Graduate School, Kunming 650092, China
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5
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Jablunovsky A, Jose J. The Dynamic Landscape of Capsid Proteins and Viral RNA Interactions in Flavivirus Genome Packaging and Virus Assembly. Pathogens 2024; 13:120. [PMID: 38392858 PMCID: PMC10893219 DOI: 10.3390/pathogens13020120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The Flavivirus genus of the Flaviviridae family of enveloped single-stranded RNA viruses encompasses more than 70 members, many of which cause significant disease in humans and livestock. Packaging and assembly of the flavivirus RNA genome is essential for the formation of virions, which requires intricate coordination of genomic RNA, viral structural, and nonstructural proteins in association with virus-induced, modified endoplasmic reticulum (ER) membrane structures. The capsid (C) protein, a small but versatile RNA-binding protein, and the positive single-stranded RNA genome are at the heart of the elusive flavivirus assembly process. The nucleocapsid core, consisting of the genomic RNA encapsidated by C proteins, buds through the ER membrane, which contains viral glycoproteins prM and E organized as trimeric spikes into the lumen, forming an immature virus. During the maturation process, which involves the low pH-mediated structural rearrangement of prM and E and furin cleavage of prM in the secretory pathway, the spiky immature virus with a partially ordered nucleocapsid core becomes a smooth, mature virus with no discernible nucleocapsid. This review focuses on the mechanisms of genome packaging and assembly by examining the structural and functional aspects of C protein and viral RNA. We review the current lexicon of critical C protein features and evaluate interactions between C and genomic RNA in the context of assembly and throughout the life cycle.
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Affiliation(s)
- Anastazia Jablunovsky
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Joyce Jose
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA;
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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6
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Liu Y, Guan W, Liu H. Subgenomic Flaviviral RNAs of Dengue Viruses. Viruses 2023; 15:2306. [PMID: 38140548 PMCID: PMC10747610 DOI: 10.3390/v15122306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/15/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023] Open
Abstract
Subgenomic flaviviral RNAs (sfRNAs) are produced during flavivirus infections in both arthropod and vertebrate cells. They are undegraded products originating from the viral 3' untranslated region (3' UTR), a result of the action of the host 5'-3' exoribonuclease, Xrn1, when it encounters specific RNA structures known as Xrn1-resistant RNAs (xrRNAs) within the viral 3' UTR. Dengue viruses generate three to four distinct species of sfRNAs through the presence of two xrRNAs and two dumbbell structures (DBs). The tertiary structures of xrRNAs have been characterized to form a ringlike structure around the 5' end of the viral RNA, effectively inhibiting the activity of Xrn1. The most important role of DENV sfRNAs is to inhibit host antiviral responses by interacting with viral and host proteins, thereby influencing viral pathogenicity, replicative fitness, epidemiological fitness, and transmission. In this review, we aimed to summarize the biogenesis, structures, and functions of DENV sfRNAs, exploring their implications for viral interference.
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Affiliation(s)
- Yi Liu
- Hubei Jiangxia Laboratory, Wuhan 430200, China
| | - Wuxiang Guan
- Hubei Jiangxia Laboratory, Wuhan 430200, China
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430207, China
| | - Haibin Liu
- Hubei Jiangxia Laboratory, Wuhan 430200, China
- Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430207, China
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7
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Langeberg CJ, Kieft JS. A generalizable scaffold-based approach for structure determination of RNAs by cryo-EM. Nucleic Acids Res 2023; 51:e100. [PMID: 37791881 PMCID: PMC10639074 DOI: 10.1093/nar/gkad784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/31/2023] [Accepted: 09/24/2023] [Indexed: 10/05/2023] Open
Abstract
Single-particle cryo-electron microscopy (cryo-EM) can reveal the structures of large and often dynamic molecules, but smaller biomolecules (≤50 kDa) remain challenging targets due to their intrinsic low signal to noise ratio. Methods to help resolve small proteins have been applied but development of similar approaches to aid in structural determination of small, structured RNA elements have lagged. Here, we present a scaffold-based approach that we used to recover maps of sub-25 kDa RNA domains to 4.5-5.0 Å. While lacking the detail of true high-resolution maps, these maps are suitable for model building and preliminary structure determination. We demonstrate this method helped faithfully recover the structure of several RNA elements of known structure, and that it promises to be generalized to other RNAs without disturbing their native fold. This approach may streamline the sample preparation process and reduce the optimization required for data collection. This first-generation scaffold approach provides a robust system to aid in RNA structure determination by cryo-EM and lays the groundwork for further scaffold optimization to achieve higher resolution.
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Affiliation(s)
- Conner J Langeberg
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
- New York Structural Biology Center, New York, NY 10027, USA
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8
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Zoladek J, Nisole S. Mosquito-borne flaviviruses and type I interferon: catch me if you can! Front Microbiol 2023; 14:1257024. [PMID: 37965539 PMCID: PMC10642725 DOI: 10.3389/fmicb.2023.1257024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/11/2023] [Indexed: 11/16/2023] Open
Abstract
Mosquito-borne flaviviruses include many viruses that are important human pathogens, including Yellow fever virus, Dengue virus, Zika virus and West Nile virus. While these viruses have long been confined to tropical regions, they now pose a global public health concern, as the geographical distribution of their mosquito vectors has dramatically expanded. The constant threat of flavivirus emergence and re-emergence underlines the need for a better understanding of the relationships between these viruses and their hosts. In particular, unraveling how these viruses manage to bypass antiviral immune mechanisms could enable the design of countermeasures to limit their impact on human health. The body's first line of defense against viral infections is provided by the interferon (IFN) response. This antiviral defense mechanism takes place in two waves, namely the induction of type I IFNs triggered by viral infection, followed by the IFN signaling pathway, which leads to the synthesis of interferon-stimulated genes (ISGs), whose products inhibit viral replication. In order to spread throughout the body, viruses must race against time to replicate before this IFN-induced antiviral state hinders their dissemination. In this review, we summarize our current knowledge on the multiple strategies developed by mosquito-borne flaviviruses to interfere with innate immune detection and signaling pathways, in order to delay, if not prevent, the establishment of an antiviral response.
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Affiliation(s)
| | - Sébastien Nisole
- Viral Trafficking, Restriction and Innate Signaling, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
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9
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Eichenberger BT, Griesbach E, Mitchell J, Chao JA. Following the Birth, Life, and Death of mRNAs in Single Cells. Annu Rev Cell Dev Biol 2023; 39:253-275. [PMID: 37843928 DOI: 10.1146/annurev-cellbio-022723-024045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Recent advances in single-molecule imaging of mRNAs in fixed and living cells have enabled the lives of mRNAs to be studied with unprecedented spatial and temporal detail. These approaches have moved beyond simply being able to observe specific events and have begun to allow an understanding of how regulation is coupled between steps in the mRNA life cycle. Additionally, these methodologies are now being applied in multicellular systems and animals to provide more nuanced insights into the physiological regulation of RNA metabolism.
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Affiliation(s)
- Bastian T Eichenberger
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
- University of Basel, Basel, Switzerland
| | - Esther Griesbach
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
| | - Jessica Mitchell
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
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10
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Dilweg IW, Peer J, Olsthoorn RCL. Xrn1-resistant RNA motifs are disseminated throughout the RNA virome and are able to block scanning ribosomes. Sci Rep 2023; 13:15987. [PMID: 37749116 PMCID: PMC10520033 DOI: 10.1038/s41598-023-43001-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 09/18/2023] [Indexed: 09/27/2023] Open
Abstract
RNAs that are able to prevent degradation by the 5'-3' exoribonuclease Xrn1 have emerged as crucial structures during infection by an increasing number of RNA viruses. Several plant viruses employ the so-called coremin motif, an Xrn1-resistant RNA that is usually located in 3' untranslated regions. Investigation of its structural and sequence requirements has led to its identification in plant virus families beyond those in which the coremin motif was initially discovered. In this study, we identified coremin-like motifs that deviate from the original in the number of nucleotides present in the loop region of the 5' proximal hairpin. They are present in a number of viral families that previously did not have an Xrn1-resistant RNA identified yet, including the double-stranded RNA virus families Hypoviridae and Chrysoviridae. Through systematic mutational analysis, we demonstrated that a coremin motif carrying a 6-nucleotide loop in the 5' proximal hairpin generally requires a YGNNAD consensus for stalling Xrn1, similar to the previously determined YGAD consensus required for Xrn1 resistance of the original coremin motif. Furthermore, we determined the minimal requirements for the 3' proximal hairpin. Since some putative coremin motifs were found in intergenic regions or coding sequences, we demonstrated their capacity for inhibiting translation through an in vitro ribosomal scanning inhibition assay. Consequently, this study provides a further expansion on the number of viral families with known Xrn1-resistant elements, while adding a novel, potentially regulatory function for this structure.
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Affiliation(s)
- Ivar W Dilweg
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Jasper Peer
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - René C L Olsthoorn
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
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11
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Sarkar R, Singh RK, Roy S. Hierarchical Hydration Dynamics of RNA with Nano-Water-Pool at Its Core. J Phys Chem B 2023; 127:6903-6919. [PMID: 37506269 DOI: 10.1021/acs.jpcb.3c03553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Many functional RNAs fold into a compact, roughly globular shape by minimizing the electrostatic repulsion between their negatively charged phosphodiester backbone. The fold of such close, compact RNA architecture is often so designed that its outer surface and complex core both are predominately populated by phosphate groups loosely sequestering bases in the intermediate layers. A number of helical junctions maintain the RNA core and its nano-water-pool. While the folding of RNA is manifested by its counterion environment composed of mixed mono- and divalent salts, the concerted role of ion and water in maintaining an RNA fold is yet to be explored. In this work, detailed atomistic simulations of SAM-I and Add Adenine riboswitch aptamers, and subgenomic flavivirus RNA (sfRNA) have been performed in a physiological mixed mono- and divalent salt environment. All three RNA systems have compact folds with a core diameter of range 1-1.7 nm. The spatiotemporal heterogeneity of RNA hydration was probed in a layer-wise manner by distinguishing the core, the intermediate, and the outer layers. The layer-wise decomposition of hydrogen bonds and collective single-particle reorientational dynamics reveal a nonmonotonic relaxation pattern with the slowest relaxation observed at the intermediate layers that involves functionally important tertiary motifs. The slowness of this intermediate layer is attributed to two types of long-resident water molecules: (i) water from ion-hydration layers and (ii) structurally trapped water (distant from ions). The relaxation kinetics of the core and the surface water essentially exposed to the phosphate groups show well-separated time scales from the intermediate layers. In the slow intermediate layers, site-specific ions and water control the functional dynamics of important RNA motifs like kink-turn, observed in different structure-probing experiments. Most interestingly, we find that as the size of the RNA core increases (SAM1 core < sfRNAcore < Add adenine core), its hydration tends to show faster relaxation. The hierarchical hydration and the layer-wise base-phosphate composition uniquely portray the globular RNA to act like a soft vesicle with a quasi-dynamic nano-water-pool at its core.
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Affiliation(s)
- Raju Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Rishabh K Singh
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Susmita Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
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12
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Langeberg CJ, Kieft JS. A Generalizable Scaffold-Based Approach for Structure Determination of RNAs by Cryo-EM. bioRxiv 2023:2023.07.06.547879. [PMID: 37461535 PMCID: PMC10350027 DOI: 10.1101/2023.07.06.547879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Single-particle cryo-electron microscopy (cryo-EM) can reveal the structures of large and often dynamic molecules, but smaller biomolecules remain challenging targets due to their intrinsic low signal to noise ratio. Methods to resolve small proteins have been applied but development of similar approaches for small structured RNA elements have lagged. Here, we present a scaffold-based approach that we used to recover maps of sub-25 kDa RNA domains to 4.5 - 5.0 Å. While lacking the detail of true high-resolution maps, these are suitable for model building and preliminary structure determination. We demonstrate this method faithfully recovers the structure of several RNA elements of known structure, and it promises to be generalized to other RNAs without disturbing their native fold. This approach may streamline the sample preparation process and reduce the optimization required for data collection. This first-generation scaffold approach provides a system for RNA structure determination by cryo-EM and lays the groundwork for further scaffold optimization to achieve higher resolution.
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13
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Ruivinho C, Gama-Carvalho M. Small non-coding RNAs encoded by RNA viruses: old controversies and new lessons from the COVID-19 pandemic. Front Genet 2023; 14:1216890. [PMID: 37415603 PMCID: PMC10322155 DOI: 10.3389/fgene.2023.1216890] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/07/2023] [Indexed: 07/08/2023] Open
Abstract
The recurring outbreaks caused by emerging RNA viruses have fostered an increased interest in the research of the mechanisms that regulate viral life cycles and the pathological outcomes associated with infections. Although interactions at the protein level are well-studied, interactions mediated by RNA molecules are less explored. RNA viruses can encode small non-coding RNAs molecules (sncRNAs), including viral miRNAs (v-miRNAs), that play important roles in modulating host immune responses and viral replication by targeting viral or host transcripts. Starting from the analysis of public databases compiling the known repertoire of viral ncRNA molecules and the evolution of publications and research interests on this topic in the wake of the COVID-19 pandemic, we provide an updated view on the current knowledge on viral sncRNAs, with a focus on v-miRNAs encoded by RNA viruses, and their mechanisms of action. We also discuss the potential of these molecules as diagnostic and prognostic biomarkers for viral infections and the development of antiviral therapies targeting v-miRNAs. This review emphasizes the importance of continued research efforts to characterize sncRNAs encoded by RNA viruses, identifies the most relevant pitfalls in the study of these molecules, and highlights the paradigm changes that have occurred in the last few years regarding their biogenesis, prevalence and functional relevance in the context of host-pathogen interactions.
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14
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van Bree JW, Visser I, Duyvestyn JM, Aguilar-Bretones M, Marshall EM, van Hemert MJ, Pijlman GP, van Nierop GP, Kikkert M, Rockx BH, Miesen P, Fros JJ. Novel approaches for the rapid development of rationally designed arbovirus vaccines. One Health 2023; 16:100565. [PMID: 37363258 PMCID: PMC10288159 DOI: 10.1016/j.onehlt.2023.100565] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 05/09/2023] [Accepted: 05/12/2023] [Indexed: 06/28/2023] Open
Abstract
Vector-borne diseases, including those transmitted by mosquitoes, account for more than 17% of infectious diseases worldwide. This number is expected to rise with an increased spread of vector mosquitoes and viruses due to climate change and man-made alterations to ecosystems. Among the most common, medically relevant mosquito-borne infections are those caused by arthropod-borne viruses (arboviruses), especially members of the genera Flavivirus and Alphavirus. Arbovirus infections can cause severe disease in humans, livestock and wildlife. Severe consequences from infections include congenital malformations as well as arthritogenic, haemorrhagic or neuroinvasive disease. Inactivated or live-attenuated vaccines (LAVs) are available for a small number of arboviruses; however there are no licensed vaccines for the majority of these infections. Here we discuss recent developments in pan-arbovirus LAV approaches, from site-directed attenuation strategies targeting conserved determinants of virulence to universal strategies that utilize genome-wide re-coding of viral genomes. In addition to these approaches, we discuss novel strategies targeting mosquito saliva proteins that play an important role in virus transmission and pathogenesis in vertebrate hosts. For rapid pre-clinical evaluations of novel arbovirus vaccine candidates, representative in vitro and in vivo experimental systems are required to assess the desired specific immune responses. Here we discuss promising models to study attenuation of neuroinvasion, neurovirulence and virus transmission, as well as antibody induction and potential for cross-reactivity. Investigating broadly applicable vaccination strategies to target the direct interface of the vertebrate host, the mosquito vector and the viral pathogen is a prime example of a One Health strategy to tackle human and animal diseases.
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Affiliation(s)
- Joyce W.M. van Bree
- Laboratory of Virology, Wageningen University & Research, Wageningen, the Netherlands
| | - Imke Visser
- Department of Viroscience, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Jo M. Duyvestyn
- Department of Medical Microbiology, Leiden University Medical Centre, Leiden, the Netherlands
| | | | - Eleanor M. Marshall
- Department of Viroscience, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Martijn J. van Hemert
- Department of Medical Microbiology, Leiden University Medical Centre, Leiden, the Netherlands
| | - Gorben P. Pijlman
- Laboratory of Virology, Wageningen University & Research, Wageningen, the Netherlands
| | | | - Marjolein Kikkert
- Department of Medical Microbiology, Leiden University Medical Centre, Leiden, the Netherlands
| | - Barry H.G. Rockx
- Department of Viroscience, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500, HB, Nijmegen, the Netherlands
| | - Jelke J. Fros
- Laboratory of Virology, Wageningen University & Research, Wageningen, the Netherlands
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15
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Litov AG, Okhezin EV, Kholodilov IS, Belova OA, Karganova GG. Conserved Sequences in the 5' and 3' Untranslated Regions of Jingmenvirus Group Representatives. Viruses 2023; 15:v15040971. [PMID: 37112951 PMCID: PMC10141212 DOI: 10.3390/v15040971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/10/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
The Jingmenvirus group (JVG), with members such as Jingmen tick virus (JMTV), Alongshan virus (ALSV), Yanggou tick virus (YGTV), and Takachi virus (TAKV), is drawing attention due to evidence of it causing disease in humans and its unique genome architecture. In the current work, complete untranslated regions (UTRs) of four strains of ALSV and eight strains of YGTV were obtained. An analysis of these sequences, as well as JVG sequences from GenBank, uncovered several regions within viral UTRs that were highly conserved for all the segments and viruses. Bioinformatics predictions suggested that the UTRs of all the segments of YGTV, ALSV, and JMTV could form similar RNA structures. The most notable feature of these structures was a stable stem-loop with one (5' UTR) or two (3' UTR) AAGU tetraloops on the end of a hairpin.
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Affiliation(s)
- Alexander G Litov
- Laboratory of Biology of Arboviruses, FSASI "Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of RAS" (Institute of Poliomyelitis), 108819 Moscow, Russia
| | - Egor V Okhezin
- Laboratory of Biology of Arboviruses, FSASI "Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of RAS" (Institute of Poliomyelitis), 108819 Moscow, Russia
- Department of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Ivan S Kholodilov
- Laboratory of Biology of Arboviruses, FSASI "Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of RAS" (Institute of Poliomyelitis), 108819 Moscow, Russia
| | - Oxana A Belova
- Laboratory of Biology of Arboviruses, FSASI "Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of RAS" (Institute of Poliomyelitis), 108819 Moscow, Russia
| | - Galina G Karganova
- Laboratory of Biology of Arboviruses, FSASI "Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of RAS" (Institute of Poliomyelitis), 108819 Moscow, Russia
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16
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Chen X, Wang Y, Xu Z, Cheng ML, Ma QQ, Li RT, Wang ZJ, Zhao H, Zuo X, Li XF, Fang X, Qin CF. Zika virus RNA structure controls its unique neurotropism by bipartite binding to Musashi-1. Nat Commun 2023; 14:1134. [PMID: 36854751 PMCID: PMC9972320 DOI: 10.1038/s41467-023-36838-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 02/17/2023] [Indexed: 03/02/2023] Open
Abstract
Human RNA binding protein Musashi-1 (MSI1) plays a critical role in neural progenitor cells (NPCs) by binding to various host RNA transcripts. The canonical MSI1 binding site (MBS), A/GU(1-3)AG single-strand motif, is present in many RNA virus genomes, but only Zika virus (ZIKV) genome has been demonstrated to bind MSI1. Herein, we identified the AUAG motif and the AGAA tetraloop in the Xrn1-resistant RNA 2 (xrRNA2) as the canonical and non-canonical MBS, respectively, and both are crucial for ZIKV neurotropism. More importantly, the unique AGNN-type tetraloop is evolutionally conserved, and distinguishes ZIKV from other known viruses with putative MBSs. Integrated structural analysis showed that MSI1 binds to the AUAG motif and AGAA tetraloop of ZIKV in a bipartite fashion. Thus, our results not only identified an unusual viral RNA structure responsible for MSI recognition, but also revealed a role for the highly structured xrRNA in controlling viral neurotropism.
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Affiliation(s)
- Xiang Chen
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Yan Wang
- Beijing Advanced Innovation Center for Structural Biology and Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhonghe Xu
- Beijing Advanced Innovation Center for Structural Biology and Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Meng-Li Cheng
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Qing-Qing Ma
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Rui-Ting Li
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Zheng-Jian Wang
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Hui Zhao
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Xiaobing Zuo
- X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Xiao-Feng Li
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China
| | - Xianyang Fang
- Beijing Advanced Innovation Center for Structural Biology and Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Cheng-Feng Qin
- Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, AMMS, Beijing, 100071, China.
- Research Unit of Discovery and Tracing of Natural Focus Diseases, Chinese Academy of Medical Sciences, Beijing, 100071, China.
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17
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Lim MJ, Loh ZY, Yeo HL, Yenamandra SP, Kong M, Pang HY, Lee MH, Humaidi M, Chua C, Griffiths J, Ng LC, Hapuarachchi HC, Mailepessov D. Isolation and Genetic Characterization of Japanese Encephalitis Virus Two Decades after Its Elimination in Singapore. Viruses 2022; 14. [PMID: 36560666 DOI: 10.3390/v14122662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022] Open
Abstract
Japanese encephalitis virus (JEV) is an important arbovirus in Asia that can cause serious neurological disease. JEV is transmitted by mosquitoes in an enzootic cycle involving porcine and avian reservoirs, in which humans are accidental, dead-end hosts. JEV is currently not endemic in Singapore, after pig farming was abolished in 1992; the last known human case was reported in 2005. However, due to its location along the East-Asian Australasian Flyway (EAAF), Singapore is vulnerable to JEV re-introduction from the endemic regions. Serological and genetic evidence in the last decade suggests JEV's presence in the local fauna. In the present study, we report the genetic characterization and the first isolation of JEV from 3214 mosquito pools consisting of 41,843 Culex mosquitoes, which were trapped from April 2014 to May 2021. The findings demonstrated the presence of genotype I of JEV (n = 10), in contrast to the previous reports of the presence of genotype II of JEV in Singapore. The genetic analyses also suggested that JEV has entered Singapore on several occasions and has potentially established an enzootic cycle in the local fauna. These observations have important implications in the risk assessment and the control of Japanese encephalitis in non-endemic countries, such as Singapore, that are at risk for JEV transmission.
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18
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Krishnamoorthy P, Raj AS, Kumar P, Das N, Kumar H. Host and viral non-coding RNAs in dengue pathogenesis. Rev Med Virol 2022; 32:e2360. [PMID: 35510480 DOI: 10.1002/rmv.2360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 11/10/2022]
Abstract
Dengue virus (DENV) is a mosquito-borne flavivirus that causes frequent outbreaks in tropical countries. Due to the four different serotypes and ever-mutating RNA genome, it is challenging to develop efficient therapeutics. Early diagnosis is crucial to prevent the severe form of dengue, leading to mortality. In the past decade, rapid advancement in the high throughput sequencing technologies has shed light on the crucial regulating role of non-coding RNAs (ncRNAs), also known as the "dark matter" of the genome, in various pathological processes. In addition to the human host ncRNAs like microRNAs and circular RNAs, DENV also produces ncRNAs such as subgenomic flaviviral RNAs that can modulate the virus life cycle and regulate disease outcomes. This review outlines the advances in understanding the interplay between the human host and DENV ncRNAs, their regulation of the innate immune system of the host, and the prospects of the ncRNAs in clinical applications such as dengue diagnosis and promising therapeutics.
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Affiliation(s)
- Pandikannan Krishnamoorthy
- Department of Biological Sciences, Laboratory of Immunology and Infectious Disease Biology, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Athira S Raj
- Department of Biological Sciences, Laboratory of Immunology and Infectious Disease Biology, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Pramod Kumar
- Department of Biological Sciences, Laboratory of Immunology and Infectious Disease Biology, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Nilanjana Das
- Department of Biological Sciences, Laboratory of Immunology and Infectious Disease Biology, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Himanshu Kumar
- Department of Biological Sciences, Laboratory of Immunology and Infectious Disease Biology, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India.,Laboratory of Host Defense, WPI Immunology, Frontier Research Centre, Osaka University, Osaka, Japan
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19
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Slonchak A, Parry R, Pullinger B, Sng JDJ, Wang X, Buck TF, Torres FJ, Harrison JJ, Colmant AMG, Hobson-Peters J, Hall RA, Tuplin A, Khromykh AA. Structural analysis of 3'UTRs in insect flaviviruses reveals novel determinants of sfRNA biogenesis and provides new insights into flavivirus evolution. Nat Commun 2022; 13:1279. [PMID: 35277507 DOI: 10.1038/s41467-022-28977-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Subgenomic flaviviral RNAs (sfRNAs) are virus-derived noncoding RNAs produced by pathogenic mosquito-borne flaviviruses (MBF) to counteract the host antiviral response. To date, the ability of non-pathogenic flaviviruses to produce and utilise sfRNAs remains largely unexplored, and it is unclear what role XRN1 resistance plays in flavivirus evolution and host adaptation. Herein the production of sfRNAs by several insect-specific flaviviruses (ISFs) that replicate exclusively in mosquitoes is shown, and the secondary structures of their complete 3’UTRs are determined. The xrRNAs responsible for the biogenesis of ISF sfRNAs are also identified, and the role of these sfRNAs in virus replication is demonstrated. We demonstrate that 3’UTRs of all classical ISFs, except Anopheles spp-asscoaited viruses, and of the dual-host associated ISF Binjari virus contain duplicated xrRNAs. We also reveal novel structural elements in the 3’UTRs of dual host-associated and Anopheles-associated classical ISFs. Structure-based phylogenetic analysis demonstrates that xrRNAs identified in Anopheles spp-associated ISF are likely ancestral to xrRNAs of ISFs and MBFs. In addition, our data provide evidence that duplicated xrRNAs are selected in the evolution of flaviviruses to provide functional redundancy, which preserves the production of sfRNAs if one of the structures is disabled by mutations or misfolding. Subgenomic flaviviral RNAs (sfRNAs) are produced by pathogenic flaviviruses to counteract the host antiviral response. sfRNAs are products of incomplete degradation of viral RNA by the host exoribonuclease XRN1 which stalls on XRN1-resistant structural elements (xrRNAs) in the 3‟UTR. Here, Slonchak et al. identify xrRNAs for mosquito-specific flaviviruses, characterize their ability to stall XRN1 and produce sfRNAs, and apply structure-based phylogenetic analysis to provide evidence for evolutionary selection of these elements.
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20
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Abstract
With their categorical requirement for host ribosomes to translate mRNA, viruses provide a wealth of genetically tractable models to investigate how gene expression is remodeled post-transcriptionally by infection-triggered biological stress. By co-opting and subverting cellular pathways that control mRNA decay, modification, and translation, the global landscape of post-transcriptional processes is swiftly reshaped by virus-encoded factors. Concurrent host cell-intrinsic countermeasures likewise conscript post-transcriptional strategies to mobilize critical innate immune defenses. Here we review strategies and mechanisms that control mRNA decay, modification, and translation in animal virus-infected cells. Besides settling infection outcomes, post-transcriptional gene regulation in virus-infected cells epitomizes fundamental physiological stress responses in health and disease.
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Affiliation(s)
- Hannah M Burgess
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Elizabeth I Vink
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | - Ian Mohr
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA.,Laura and Isaac Perlmutter Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
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21
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Wang S, Chan KWK, Tan MJA, Flory C, Luo D, Lescar J, Forwood JK, Vasudevan SG. A conserved arginine in NS5 binds genomic 3' stem-loop RNA for primer-independent initiation of flavivirus RNA replication. RNA 2022; 28:177-193. [PMID: 34759006 PMCID: PMC8906541 DOI: 10.1261/rna.078949.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
The commitment to replicate the RNA genome of flaviviruses without a primer involves RNA-protein interactions that have been shown to include the recognition of the stem-loop A (SLA) in the 5' untranslated region (UTR) by the nonstructural protein NS5. We show that DENV2 NS5 arginine 888, located within the carboxy-terminal 18 residues, is completely conserved in all flaviviruses and interacts specifically with the top-loop of 3'SL in the 3'UTR which contains the pentanucleotide 5'-CACAG-3' previously shown to be critical for flavivirus RNA replication. We present virological and biochemical data showing the importance of this Arg 888 in virus viability and de novo initiation of RNA polymerase activity in vitro. Based on our binding studies, we hypothesize that ternary complex formation of NS5 with 3'SL, followed by dimerization, leads to the formation of the de novo initiation complex that could be regulated by the reversible zipping and unzipping of cis-acting RNA elements.
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Affiliation(s)
- Sai Wang
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 169857 Singapore
| | - Kitti Wing Ki Chan
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 169857 Singapore
| | - Min Jie Alvin Tan
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 169857 Singapore
| | - Charlotte Flory
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 169857 Singapore
| | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, 636921 Singapore
| | - Julian Lescar
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia
| | - Subhash G Vasudevan
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 169857 Singapore
- Department of Microbiology and Immunology, National University of Singapore, 117545 Singapore
- Institute for Glycomics, Griffith University, Gold Coast Campus, QLD 4222, Australia
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22
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Abstract
In recent years, it has become clear that RNA molecules are involved in almost all vital cellular processes and pathogenesis of human disorders. The functional diversity of RNA comes from its structural richness. Although composed of only four nucleotides, RNA molecules present a plethora of secondary and tertiary structures critical for intra and intermolecular contacts with other RNAs and ligands (proteins, small metabolites, etc.). In order to fully understand RNA function it is necessary to define its spatial structure. Crystallography, nuclear magnetic resonance and cryogenic electron microscopy have demonstrated considerable success in determining the structures of biologically important RNA molecules. However, these powerful methods require large amounts of sample. Despite their limitations, chemical synthesis and in vitro transcription are usually employed to obtain milligram quantities of RNA for structural studies, delivering simple and effective methods for large-scale production of homogenous samples. The aim of this paper is to provide an overview of methods for large-scale RNA synthesis with emphasis on chemical synthesis and in vitro transcription. We also present our own results of testing the efficiency of these approaches in order to adapt the material acquisition strategy depending on the desired RNA construct.
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23
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Campbell AJ, Anderson JR, Wilusz J. A plant-infecting subviral RNA associated with poleroviruses produces a subgenomic RNA which resists exonuclease XRN1 in vitro. Virology 2022; 566:1-8. [PMID: 34808564 PMCID: PMC9832584 DOI: 10.1016/j.virol.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 01/13/2023]
Abstract
Subviral agents are nucleic acids which lack the features for classification as a virus. Tombusvirus-like associated RNAs (tlaRNAs) are subviral positive-sense, single-stranded RNAs that replicate autonomously, yet depend on a coinfecting virus for encapsidation and transmission. TlaRNAs produce abundant subgenomic RNA (sgRNA) upon infection. Here, we investigate how the well-studied tlaRNA, ST9, produces sgRNA and its function. We found ST9 is a noncoding RNA, due to its lack of protein coding capacity. We used resistance assays with eukaryotic Exoribonuclease-1 (XRN1) to investigate sgRNA production via incomplete degradation of genomic RNA. The ST9 3' untranslated region stalled XRN1 very near the 5' sgRNA end. Thus, the XRN family of enzymes drives sgRNA accumulation in ST9-infected tissue by incomplete degradation of ST9 RNA. This work suggests tlaRNAs are not just parasites of viruses with compatible capsids, but also mutually beneficial partners that influence host cell RNA biology.
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Affiliation(s)
- A J Campbell
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, 95616, USA.
| | - John R Anderson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523, USA.
| | - Jeffrey Wilusz
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523, USA.
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24
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Ren Z, Yu Y, Chen C, Yang D, Ding T, Zhu L, Deng J, Xu Z. The Triangle Relationship Between Long Noncoding RNA, RIG-I-like Receptor Signaling Pathway, and Glycolysis. Front Microbiol 2021; 12:807737. [PMID: 34917069 PMCID: PMC8670088 DOI: 10.3389/fmicb.2021.807737] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/09/2021] [Indexed: 12/11/2022] Open
Abstract
Long noncoding RNA (LncRNA), a noncoding RNA over 200nt in length, can regulate glycolysis through metabolic pathways, glucose metabolizing enzymes, and epigenetic reprogramming. Upon viral infection, increased aerobic glycolysis providzes material and energy for viral replication. Mitochondrial antiviral signaling protein (MAVS) is the only protein-specified downstream of retinoic acid-inducible gene I (RIG-I) that bridges the gap between antiviral immunity and glycolysis. MAVS binding to RIG-I inhibits MAVS binding to Hexokinase (HK2), thereby impairing glycolysis, while excess lactate production inhibits MAVS and the downstream antiviral immune response, facilitating viral replication. LncRNAs can also regulate antiviral innate immunity by interacting with RIG-I and downstream signaling pathways and by regulating the expression of interferons and interferon-stimulated genes (ISGs). Altogether, we summarize the relationship between glycolysis, antiviral immunity, and lncRNAs and propose that lncRNAs interact with glycolysis and antiviral pathways, providing a new perspective for the future treatment against virus infection, including SARS-CoV-2.
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Affiliation(s)
- Zhihua Ren
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yueru Yu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Chaoxi Chen
- College of Life Since and Technology, Southwest Minzu University, Chengdu, China
| | - Dingyong Yang
- College of Animal Husbandry and Veterinary Medicine, Chengdu Agricultural College, Chengdu, China
| | - Ting Ding
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Junliang Deng
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhiwen Xu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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25
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Gebert LFR, Law M, MacRae IJ. A structured RNA motif locks Argonaute2:miR-122 onto the 5' end of the HCV genome. Nat Commun 2021; 12:6836. [PMID: 34824224 DOI: 10.1038/s41467-021-27177-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/27/2021] [Indexed: 12/03/2022] Open
Abstract
microRNAs (miRNAs) form regulatory networks in metazoans. Viruses engage miRNA networks in numerous ways, with Flaviviridae members exploiting direct interactions of their RNA genomes with host miRNAs. For hepatitis C virus (HCV), binding of liver-abundant miR-122 stabilizes the viral RNA and regulates viral translation. Here, we investigate the structural basis for these activities, taking into consideration that miRNAs function in complex with Argonaute (Ago) proteins. The crystal structure of the Ago2:miR-122:HCV complex reveals a structured RNA motif that traps Ago2 on the viral RNA, masking its 5’ end from enzymatic attack. The trapped Ago2 can recruit host factor PCBP2, implicated in viral translation, while binding of a second Ago2:miR-122 competes with PCBP2, creating a potential molecular switch for translational control. Combined results reveal a viral RNA structure that modulates Ago2:miR-122 dynamics and repurposes host proteins to generate a functional analog of the mRNA cap-binding complex. The RNA genome of the Hepatitis C Virus binds to the liver-specific miR122. Here the authors report the crystal structure of the Ago2:miR122:HCV complex showing that the viral RNA’s structural element traps the Ago2:miR-122 complex on the 5’ end of the viral genome to protect it from degradation.
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Niu X, Sun R, Chen Z, Yao Y, Zuo X, Chen C, Fang X. Pseudoknot length modulates the folding, conformational dynamics, and robustness of Xrn1 resistance of flaviviral xrRNAs. Nat Commun 2021; 12:6417. [PMID: 34741027 DOI: 10.1038/s41467-021-26616-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 10/04/2021] [Indexed: 01/15/2023] Open
Abstract
To understand how RNA dynamics is regulated and connected to its function, we investigate the folding, conformational dynamics and robustness of Xrn1 resistance of a set of flaviviral xrRNAs using SAXS, smFRET and in vitro enzymatic assays. Flaviviral xrRNAs form discrete ring-like 3D structures, in which the length of a conserved long-range pseudoknot (PK2) ranges from 2 bp to 7 bp. We find that xrRNAs' folding, conformational dynamics and Xrn1 resistance are strongly correlated and highly Mg2+-dependent, furthermore, the Mg2+-dependence is modulated by PK2 length variations. xrRNAs with long PK2 require less Mg2+ to stabilize their folding, exhibit reduced conformational dynamics and strong Xrn1 resistance even at low Mg2+, and tolerate mutations at key tertiary motifs at high Mg2+, which generally are destructive to xrRNAs with short PK2. These results demonstrate an unusual regulatory mechanism of RNA dynamics providing insights into the functions and future biomedical applications of xrRNAs.
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Harvey C, Klassa S, Finol E, Hall J, Hill AC. Chimeric Flaviviral RNA-siRNA Molecules Resist Degradation by The Exoribonuclease Xrn1 and Trigger Gene Silencing in Mammalian Cells. Chembiochem 2021; 22:3099-3106. [PMID: 34431199 PMCID: PMC8596575 DOI: 10.1002/cbic.202100434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Indexed: 11/11/2022]
Abstract
RNA is an emerging platform for drug delivery, but the susceptibility of RNA to nuclease degradation remains a major barrier to its implementation in vivo. Here, we engineered flaviviral Xrn1-resistant RNA (xrRNA) motifs to host small interfering RNA (siRNA) duplexes. The xrRNA-siRNA molecules self-assemble in vitro, resist degradation by the conserved eukaryotic 5' to 3' exoribonuclease Xrn1, and trigger gene silencing in 293T cells. The resistance of the molecules to Xrn1 does not translate to stability in blood serum. Nevertheless, our results demonstrate that flavivirus-derived xrRNA motifs can confer Xrn1 resistance on a model therapeutic payload and set the stage for further investigations into using the motifs as building blocks in RNA nanotechnology.
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Affiliation(s)
- Cressida Harvey
- Department of BiologyETH ZürichWolfgang-Pauli-Strasse 278093ZürichSwitzerland
| | - Sven Klassa
- Department of Chemistry and Applied BiosciencesInstitute of Pharmaceutical SciencesETH ZürichVladimir-Prelog-Weg 1-5/108093ZürichSwitzerland
| | - Esteban Finol
- Department of BiologyETH ZürichWolfgang-Pauli-Strasse 278093ZürichSwitzerland
| | - Jonathan Hall
- Department of Chemistry and Applied BiosciencesInstitute of Pharmaceutical SciencesETH ZürichVladimir-Prelog-Weg 1-5/108093ZürichSwitzerland
| | - Alyssa C. Hill
- Department of Chemistry and Applied BiosciencesInstitute of Pharmaceutical SciencesETH ZürichVladimir-Prelog-Weg 1-5/108093ZürichSwitzerland
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Abstract
Flaviviruses such as dengue, Japanese encephalitis, West Nile, Yellow Fever and Zika virus, cause viral hemorrhagic fever and encephalitis in humans. However, antiviral therapeutics to treat or prevent flavivirus infections are not yet available. Thus, there is pressing need to develop therapeutics and vaccines that target flavivirus infections. All flaviviruses carry a positive-sense single-stranded RNA genome, which encodes ten proteins; three structural proteins form the virus shell, and seven nonstructural (NS) proteins are involved in replication of the viral genome. While all NS proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) are part of a functional membrane-bound replication complex, enzymatic activities required for flaviviral replication reside in only two NS proteins, NS3 and NS5. NS3 functions as a protease, helicase, and triphosphatase, and NS5 as a capping enzyme, methyltransferase, and RNA-dependent RNA polymerase. In this chapter, we provide an overview of viral replication focusing on the structure and function of NS3 and NS5 replicases. We further describe strategies and examples of current efforts to identify potential flavivirus inhibitors against NS3 and NS5 enzymatic activities that can be developed as therapeutic agents to combat flavivirus infections.
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Affiliation(s)
- Ekaterina Knyazhanskaya
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX, United States
| | - Marc C Morais
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX, United States
| | - Kyung H Choi
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX, United States.
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Zhang S, Sun R, Perdoncini Carvalho C, Han J, Zheng L, Qu F. Replication-Dependent Biogenesis of Turnip Crinkle Virus Long Noncoding RNAs. J Virol 2021; 95:e0016921. [PMID: 34160262 PMCID: PMC8387050 DOI: 10.1128/jvi.00169-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/14/2021] [Indexed: 12/24/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) of virus origin accumulate in cells infected by many positive-strand (+) RNA viruses to bolster viral infectivity. Their biogenesis mostly utilizes exoribonucleases of host cells that degrade viral genomic or subgenomic RNAs in the 5'-to-3' direction until being stalled by well-defined RNA structures. Here, we report a viral lncRNA that is produced by a novel replication-dependent mechanism. This lncRNA corresponds to the last 283 nucleotides of the turnip crinkle virus (TCV) genome and hence is designated tiny TCV subgenomic RNA (ttsgR). ttsgR accumulated to high levels in TCV-infected Nicotiana benthamiana cells when the TCV-encoded RNA-dependent RNA polymerase (RdRp), also known as p88, was overexpressed. Both (+) and (-) strand forms of ttsgR were produced in a manner dependent on the RdRp functionality. Strikingly, templates as short as ttsgR itself were sufficient to program ttsgR amplification, as long as the TCV-encoded replication proteins p28 and p88 were provided in trans. Consistent with its replicational origin, ttsgR accumulation required a 5' terminal carmovirus consensus sequence (CCS), a sequence motif shared by genomic and subgenomic RNAs of many viruses phylogenetically related to TCV. More importantly, introducing a new CCS motif elsewhere in the TCV genome was alone sufficient to cause the emergence of another lncRNA. Finally, abolishing ttsgR by mutating its 5' CCS gave rise to a TCV mutant that failed to compete with wild-type TCV in Arabidopsis. Collectively, our results unveil a replication-dependent mechanism for the biogenesis of viral lncRNAs, thus suggesting that multiple mechanisms, individually or in combination, may be responsible for viral lncRNA production. IMPORTANCE Many positive-strand (+) RNA viruses produce long noncoding RNAs (lncRNAs) during the process of cellular infections and mobilize these lncRNAs to counteract antiviral defenses, as well as coordinate the translation of viral proteins. Most viral lncRNAs arise from 5'-to-3' degradation of longer viral RNAs being stalled at stable secondary structures. Here, we report a viral lncRNA that is produced by the replication machinery of turnip crinkle virus (TCV). This lncRNA, designated ttsgR, shares the terminal characteristics with TCV genomic and subgenomic RNAs and overaccumulates in the presence of moderately overexpressed TCV RNA-dependent RNA polymerase (RdRp). Furthermore, templates that are of similar sizes as ttsgR are readily replicated by TCV replication proteins (p28 and RdRp) provided from nonviral sources. In summary, this study establishes an approach for uncovering low abundance viral lncRNAs, and characterizes a replicating TCV lncRNA. Similar investigations on human-pathogenic (+) RNA viruses could yield novel therapeutic targets.
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Affiliation(s)
- Shaoyan Zhang
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Rong Sun
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Camila Perdoncini Carvalho
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Junping Han
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Limin Zheng
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
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Gokhale NS, Smith JR, Van Gelder RD, Savan R. RNA regulatory mechanisms that control antiviral innate immunity. Immunol Rev 2021; 304:77-96. [PMID: 34405416 DOI: 10.1111/imr.13019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/29/2021] [Accepted: 08/02/2021] [Indexed: 12/21/2022]
Abstract
From the initial sensing of viral nucleotides by pattern recognition receptors, through the induction of type I and III interferons (IFN), upregulation of antiviral effector proteins, and resolution of the inflammatory response, each step of innate immune signaling is under tight control. Though innate immunity is often associated with broad regulation at the level of gene transcription, RNA-centric post-transcriptional processes have emerged as critical mechanisms for ensuring a proper antiviral response. Here, we explore the diverse RNA regulatory mechanisms that modulate the innate antiviral immune response, with a focus on RNA sensing by RIG-I-like receptors (RLR), interferon (IFN) and IFN signaling pathways, viral pathogenesis, and host genetic variation that contributes to these processes. We address the post-transcriptional interactions with RNA-binding proteins, non-coding RNAs, transcript elements, and modifications that control mRNA stability, as well as alternative splicing events that modulate the innate immune antiviral response.
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Affiliation(s)
- Nandan S Gokhale
- Department of Immunology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Julian R Smith
- Department of Immunology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Rachel D Van Gelder
- Department of Immunology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Ram Savan
- Department of Immunology, School of Medicine, University of Washington, Seattle, Washington, USA
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Choksupmanee O, Tangkijthavorn W, Hodge K, Trisakulwattana K, Phornsiricharoenphant W, Narkthong V, Tulakarnwong S, Ngamphiw C, Tongsima S, Chimnaronk S. Specific Interaction of DDX6 with an RNA Hairpin in the 3' UTR of the Dengue Virus Genome Mediates G 1 Phase Arrest. J Virol 2021; 95:e0051021. [PMID: 34132569 DOI: 10.1128/JVI.00510-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The extent to which viral genomic RNAs interact with host factors and contribute to host response and disease pathogenesis is not well known. Here, we report that the human RNA helicase DDX6 specifically binds to the viral most conserved RNA hairpin in the A3 element in the dengue 3' UTR, with nanomolar affinities. DDX6 CLIP confirmed the interaction in HuH-7 cells infected by dengue virus serotype 2. This interaction requires three conserved residues-Lys307, Lys367, and Arg369-as well as the unstructured extension in the C-terminal domain of DDX6. Interestingly, alanine substitution of these three basic residues resulted in RNA-independent ATPase activity, suggesting a mechanism by which RNA-binding and ATPase activities are coupled in DEAD box helicases. Furthermore, we applied a cross-omics gene enrichment approach to suggest that DDX6 is functionally related to cell cycle regulation and viral pathogenicity. Indeed, infected cells exhibited cell cycle arrest in G1 phase and a decrease in the early S phase. Exogenous expression of intact DDX6, but not A3-binding-deficient mutants, alleviated these effects by rescue of the DNA preinitiation complex expression. Disruption of the DDX6-binding site was found in dengue and Zika live-attenuated vaccine strains. Our results suggested that dengue virus has evolved an RNA aptamer against DDX6 to alter host cell states and defined DDX6 as a new regulator of G1/S transition. IMPORTANCE Dengue virus (DENV) is transmitted by mosquitoes to humans, infecting 390 million individuals per year globally. About 20% of infected patients shows a spectrum of clinical manifestation, ranging from a mild flu-like syndrome, to dengue fever, to life-threatening severe dengue diseases, including dengue hemorrhagic fever and dengue shock syndrome. There is currently no specific treatment for dengue diseases, and the molecular mechanism underlying dengue pathogenesis remains poorly understood. In this study, we combined biochemical, bioinformatics, high-content analysis and RNA sequencing approaches to characterize a highly conserved interface of the RNA genome of DENV with a human factor named DDX6 in infected cells. The significance of our research is in identifying the mechanism for a viral strategy to alter host cell fates, which conceivably allows us to generate a model for live-attenuated vaccine and the design of new therapeutic reagent for dengue diseases.
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Gunawardene CD, Im JSH, White KA. RNA Structure Protects the 5'-end of an Uncapped Tombusvirus RNA Genome from Xrn Digestion. J Virol 2021;:JVI0103421. [PMID: 34346764 DOI: 10.1128/JVI.01034-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One of the many challenges faced by RNA viruses is the maintenance of their genomes during infections of host cells. Members of the family Tombusviridae are plus-strand RNA viruses with unmodified triphosphorylated genomic 5'-termini. The tombusvirus Carnation Italian ringspot virus was used to investigate how it protects its RNA genome from attack by 5'-end-targeting degradation enzymes. In vivo and in vitro assays were employed to determine the role of genomic RNA structure in conferring protection from the 5'-to-3' exoribonuclease Xrn. The results revealed that (i) the CIRV RNA genome is more resistant to Xrn than its sg mRNAs, (ii) the genomic 5'UTR folds into a compact RNA structure that effectively and independently prevents Xrn access, (iii) the RNA structure limiting 5'-access is formed by secondary and tertiary interactions that function cooperatively, (iv) the structure is also able to block access of RNA pyrophosphohydrolase to the genomic 5'-terminus, and (v) the RNA structure does not stall an actively digesting Xrn. Based on its proficiency at impeding Xrn 5'-access, we have termed this 5'-terminal structure an Xrn-evading RNA or xeRNA. These and other findings demonstrate that the 5'UTR of the CIRV RNA genome folds into a complex structural conformation that helps to protect its unmodified 5'-terminus from enzymatic decay during infections. IMPORTANCE The plus-strand RNA genomes of plant viruses in the large family Tombusviridae are not 5'-capped. Here we explored how a species in the type genus Tombusvirus protects its genomic 5'-end from cellular nuclease attack. Our results revealed that the 5'-terminal sequence of the CIRV genome folds into a complex RNA structure that limits access of the 5'-to-3' exoribonuclease Xrn, thereby protecting it from processive degradation. The RNA conformation also impeded access of RNA pyrophosphohydrolase, which converts 5'-triphosphorylated RNA termini into 5'-monophosphorylated forms, the preferred substrate for Xrn. This study represents the first report of a genome-encoded higher-order RNA structure independently conferring resistance to cellular 5'-end-attacking enzymes in an RNA plant virus.
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33
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Akiyama BM, Graham ME, O Donoghue Z, Beckham JD, Kieft JS. Three-dimensional structure of a flavivirus dumbbell RNA reveals molecular details of an RNA regulator of replication. Nucleic Acids Res 2021; 49:7122-7138. [PMID: 34133732 PMCID: PMC8266583 DOI: 10.1093/nar/gkab462] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 05/07/2021] [Accepted: 05/17/2021] [Indexed: 11/14/2022] Open
Abstract
Mosquito-borne flaviviruses (MBFVs) including dengue, West Nile, yellow fever, and Zika viruses have an RNA genome encoding one open reading frame flanked by 5' and 3' untranslated regions (UTRs). The 3' UTRs of MBFVs contain regions of high sequence conservation in structured RNA elements known as dumbbells (DBs). DBs regulate translation and replication of the viral RNA genome, functions proposed to depend on the formation of an RNA pseudoknot. To understand how DB structure provides this function, we solved the x-ray crystal structure of the Donggang virus DB to 2.1Å resolution and used structural modeling to reveal the details of its three-dimensional fold. The structure confirmed the predicted pseudoknot and molecular modeling revealed how conserved sequences form a four-way junction that appears to stabilize the pseudoknot. Single-molecule FRET suggests that the DB pseudoknot is a stable element that can regulate the switch between translation and replication during the viral lifecycle by modulating long-range RNA conformational changes.
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Affiliation(s)
- Benjamin M Akiyama
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA
| | - Monica E Graham
- Department of Immunology and Microbiology, Aurora, CO 80045, USA
| | - Zoe O Donoghue
- Department of Immunology and Microbiology, Aurora, CO 80045, USA
| | - J David Beckham
- Department of Immunology and Microbiology, Aurora, CO 80045, USA.,Department of Medicine Division of Infectious Diseases, Aurora, CO 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA.,RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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34
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35
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Vicens Q, Kieft JS. Shared properties and singularities of exoribonuclease-resistant RNAs in viruses. Comput Struct Biotechnol J 2021; 19:4373-4380. [PMID: 34471487 PMCID: PMC8374639 DOI: 10.1016/j.csbj.2021.07.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 11/29/2022] Open
Abstract
What viral RNA genomes lack in size, they make up for in intricacy. Elaborate RNA structures embedded in viral genomes can hijack essential cellular mechanisms aiding virus propagation. Exoribonuclease-resistant RNAs (xrRNAs) are an emerging class of viral elements, which resist degradation by host cellular exoribonucleases to produce viral RNAs with diverse roles during infection. Detailed three-dimensional structural studies of xrRNAs from flaviviruses and a subset of plant viruses led to a mechanistic model in which xrRNAs block enzymatic digestion using a ring-like structure that encircles the 5' end of the resistant structure. In this mini-review, we describe the state of our understanding of the phylogenetic distribution of xrRNAs, their structures, and their conformational dynamics. Because xrRNAs have now been found in several major superfamilies of RNA viruses, they may represent a more widely used strategy than currently appreciated. Could xrRNAs represent a 'molecular clock' that would help us understand virus evolution and pathogenicity? The more we study xrRNAs in viruses, the closer we get to finding xrRNAs within cellular RNAs.
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Affiliation(s)
- Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
| | - Jeffrey S. Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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Fonseka HYY, Javidi A, Oliveira LFL, Micheletti C, Stan G. Unfolding and Translocation of Knotted Proteins by Clp Biological Nanomachines: Synergistic Contribution of Primary Sequence and Topology Revealed by Molecular Dynamics Simulations. J Phys Chem B 2021; 125:7335-7350. [PMID: 34110163 DOI: 10.1021/acs.jpcb.1c00898] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We use Langevin dynamics simulations to model, at an atomistic resolution, how various natively knotted proteins are unfolded in repeated allosteric translocating cycles of the ClpY ATPase. We consider proteins representative of different topologies, from the simplest knot (trefoil 31), to the three-twist 52 knot, to the most complex stevedore, 61, knot. We harness the atomistic detail of the simulations to address aspects that have so far remained largely unexplored, such as sequence-dependent effects on the ruggedness of the landscape traversed during knot sliding. Our simulations reveal the combined effect on translocation of the knotted protein structure, i.e., backbone topology and geometry, and primary sequence, i.e., side chain size and interactions, and show that the latter can dominate translocation hindrance. In addition, we observe that due to the interplay between the knotted topology and intramolecular contacts the transmission of tension along the polypeptide chain occurs very differently from that of homopolymers. Finally, by considering native and non-native interactions, we examine how the disruption or formation of such contacts can affect the translocation processivity and concomitantly create multiple unfolding pathways with very different activation barriers.
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Affiliation(s)
| | - Alex Javidi
- Data Sciences, Janssen Research and Development, Spring House, Pennsylvania 19477, United States
| | - Luiz F L Oliveira
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Cristian Micheletti
- Molecular and Statistical Biophysics, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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37
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Zhao M, Woodside MT. Mechanical strength of RNA knot in Zika virus protects against cellular defenses. Nat Chem Biol 2021. [PMID: 34253909 DOI: 10.1038/s41589-021-00829-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 06/03/2021] [Indexed: 12/21/2022]
Abstract
Unusual knot-like structures recently discovered in viral exoribonuclease-resistant RNAs (xrRNAs) prevent digestion by host RNases to create subgenomic RNAs enhancing infection and pathogenicity. xrRNAs are proposed to prevent digestion through mechanical resistance to unfolding. However, their unfolding force has not been measured, and the factors determining RNase resistance are unclear. Furthermore, how these knots fold remains unknown. Unfolding a Zika virus xrRNA with optical tweezers revealed that it was the most mechanically stable RNA yet observed. The knot formed by threading the 5' end into a three-helix junction before pseudoknot interactions closed a ring around it. The pseudoknot and tertiary contacts stabilizing the threaded 5' end were both required to generate extreme force resistance, whereas removing a 5'-end contact produced a low-force knot lacking RNase resistance. These results indicate mechanical resistance plays a central functional role, with the fraction of molecules forming extremely high-force knots determining the RNase resistance level.
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38
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Abstract
SARS-CoV-2 is an RNA virus whose success as a pathogen relies on its abilities to repurpose host RNA-binding proteins (RBPs) and to evade antiviral RBPs. To uncover the SARS-CoV-2 RNA interactome, we here develop a robust ribonucleoprotein (RNP) capture protocol and identify 109 host factors that directly bind to SARS-CoV-2 RNAs. Applying RNP capture on another coronavirus, HCoV-OC43, revealed evolutionarily conserved interactions between coronaviral RNAs and host proteins. Transcriptome analyses and knockdown experiments delineated 17 antiviral RBPs, including ZC3HAV1, TRIM25, PARP12, and SHFL, and 8 proviral RBPs, such as EIF3D and CSDE1, which are responsible for co-opting multiple steps of the mRNA life cycle. This also led to the identification of LARP1, a downstream target of the mTOR signaling pathway, as an antiviral host factor that interacts with the SARS-CoV-2 RNAs. Overall, this study provides a comprehensive list of RBPs regulating coronaviral replication and opens new avenues for therapeutic interventions.
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Affiliation(s)
- Sungyul Lee
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Young-Suk Lee
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea; Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Yeon Choi
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Ahyeon Son
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Youngran Park
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Kyung-Min Lee
- International Vaccine Institute, Seoul, Republic of Korea
| | - Jeesoo Kim
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jong-Seo Kim
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - V Narry Kim
- Center for RNA Research, Institute for Basic Science, Seoul, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul, Republic of Korea.
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Choi KH. The Role of the Stem-Loop A RNA Promoter in Flavivirus Replication. Viruses 2021; 13:1107. [PMID: 34207869 DOI: 10.3390/v13061107] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/22/2022] Open
Abstract
An essential challenge in the lifecycle of RNA viruses is identifying and replicating the viral genome amongst all the RNAs present in the host cell cytoplasm. Yet, how the viral polymerase selectively recognizes and copies the viral RNA genome is poorly understood. In flaviviruses, the 5′-end of the viral RNA genome contains a 70 nucleotide-long stem-loop, called stem-loop A (SLA), which functions as a promoter for genome replication. During replication, flaviviral polymerase NS5 specifically recognizes SLA to both initiate viral RNA synthesis and to methylate the 5′ guanine cap of the nascent RNA. While the sequences of this region vary between different flaviviruses, the three-way junction arrangement of secondary structures is conserved in SLA, suggesting that viruses recognize a common structural feature to replicate the viral genome rather than a particular sequence. To better understand the molecular basis of genome recognition by flaviviruses, we recently determined the crystal structures of flavivirus SLAs from dengue virus (DENV) and Zika virus (ZIKV). In this review, I will provide an overview of (1) flaviviral genome replication; (2) structures of viral SLA promoters and NS5 polymerases; and (3) and describe our current model of how NS5 polymerases specifically recognize the SLA at the 5′ terminus of the viral genome to initiate RNA synthesis at the 3′ terminus.
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Zammit A, Helwerda L, Olsthoorn RCL, Verbeek FJ, Gultyaev AP. A database of flavivirus RNA structures with a search algorithm for pseudoknots and triple base interactions. Bioinformatics 2021; 37:956-962. [PMID: 32866223 PMCID: PMC8128465 DOI: 10.1093/bioinformatics/btaa759] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 08/19/2020] [Accepted: 08/24/2020] [Indexed: 12/13/2022] Open
Abstract
Motivation The Flavivirus genus includes several important pathogens, such as Zika, dengue and yellow fever virus. Flavivirus RNA genomes contain a number of functionally important structures in their 3′ untranslated regions (3′UTRs). Due to the diversity of sequences and topologies of these structures, their identification is often difficult. In contrast, predictions of such structures are important for understanding of flavivirus replication cycles and development of antiviral strategies. Results We have developed an algorithm for structured pattern search in RNA sequences, including secondary structures, pseudoknots and triple base interactions. Using the data on known conserved flavivirus 3′UTR structures, we constructed structural descriptors which covered the diversity of patterns in these motifs. The descriptors and the search algorithm were used for the construction of a database of flavivirus 3′UTR structures. Validating this approach, we identified a number of domains matching a general pattern of exoribonuclease Xrn1-resistant RNAs in the growing group of insect-specific flaviviruses. Availability and implementation The Leiden Flavivirus RNA Structure Database is available at https://rna.liacs.nl. The search algorithm is available at https://github.com/LeidenRNA/SRHS. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Alan Zammit
- Group Imaging & Bioinformatics, Leiden Institute of Advanced Computer Science (LIACS), Leiden University, 2300 RA Leiden, The Netherlands
| | - Leon Helwerda
- Group Imaging & Bioinformatics, Leiden Institute of Advanced Computer Science (LIACS), Leiden University, 2300 RA Leiden, The Netherlands
| | - René C L Olsthoorn
- Group Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | - Fons J Verbeek
- Group Imaging & Bioinformatics, Leiden Institute of Advanced Computer Science (LIACS), Leiden University, 2300 RA Leiden, The Netherlands
| | - Alexander P Gultyaev
- Group Imaging & Bioinformatics, Leiden Institute of Advanced Computer Science (LIACS), Leiden University, 2300 RA Leiden, The Netherlands.,Department of Viroscience, Erasmus Medical Center, Rotterdam, 3000 CA, The Netherlands
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van den Elsen K, Quek JP, Luo D. Molecular Insights into the Flavivirus Replication Complex. Viruses 2021; 13:956. [PMID: 34064113 DOI: 10.3390/v13060956] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/17/2021] [Accepted: 05/17/2021] [Indexed: 12/11/2022] Open
Abstract
Flaviviruses are vector-borne RNA viruses, many of which are clinically relevant human viral pathogens, such as dengue, Zika, Japanese encephalitis, West Nile and yellow fever viruses. Millions of people are infected with these viruses around the world each year. Vaccines are only available for some members of this large virus family, and there are no effective antiviral drugs to treat flavivirus infections. The unmet need for vaccines and therapies against these flaviviral infections drives research towards a better understanding of the epidemiology, biology and immunology of flaviviruses. In this review, we discuss the basic biology of the flavivirus replication process and focus on the molecular aspects of viral genome replication. Within the virus-induced intracellular membranous compartments, flaviviral RNA genome replication takes place, starting from viral poly protein expression and processing to the assembly of the virus RNA replication complex, followed by the delivery of the progeny viral RNA to the viral particle assembly sites. We attempt to update the latest understanding of the key molecular events during this process and highlight knowledge gaps for future studies.
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Abstract
The activity of a conditional guide RNA (cgRNA) is dependent on the presence or absence of an RNA trigger, enabling cell-selective regulation of CRISPR/Cas function. cgRNAs are programmable at two levels, with the target-binding sequence controlling the target of Cas activity (edit, silence, or induce a gene of choice) and the trigger-binding sequence controlling the scope of Cas activity (subset of cells expressing the trigger RNA). Allosteric cgRNA mechanisms enable independent design of the target and trigger sequences, providing the flexibility to select the regulatory target and scope independently. Building on prior advances in dynamic RNA nanotechnology that demonstrated the cgRNA concept, here we set the goal of engineering high-performance allosteric cgRNA mechanisms for the mammalian setting, pursuing both ON → OFF logic (conditional inactivation by an RNA trigger) and OFF → ON logic (conditional activation by an RNA trigger). For each mechanism, libraries of orthogonal cgRNA/trigger pairs were designed using NUPACK. In HEK 293T cells expressing cgRNAs, triggers, and inducing dCas9: (1) a library of four ON → OFF "terminator switch" cgRNAs exhibit a median fold-change of ≈50×, a median fractional dynamic range of ≈20%, and a median crosstalk modulus of ≈9%; (2) a library of three OFF → ON "split-terminator switch" cgRNAs exhibit a median fold-change of ≈150×, a median fractional dynamic range of ≈50%, and a median crosstalk modulus of ≈4%. Further, we demonstrate that xrRNA elements that protect viral RNAs from degradation by exoribonucleases can dramatically enhance the performance of RNA synthetic biology. The high-performance allosteric cgRNAs demonstrated here for ON → OFF and OFF → ON logic in mammalian cells provide a foundation for pursuing applications of programmable cell-selective regulation.
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Affiliation(s)
- Lisa M Hochrein
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Heyun Li
- Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Niles A Pierce
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Division of Engineering & Applied Science, California Institute of Technology, Pasadena, California 91125, United States
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Markiewicz L, Drazkowska K, Sikorski PJ. Tricks and threats of RNA viruses - towards understanding the fate of viral RNA. RNA Biol 2021; 18:669-687. [PMID: 33618611 PMCID: PMC8078519 DOI: 10.1080/15476286.2021.1875680] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/22/2020] [Accepted: 01/09/2021] [Indexed: 12/24/2022] Open
Abstract
Human innate cellular defence pathways have evolved to sense and eliminate pathogens, of which, viruses are considered one of the most dangerous. Their relatively simple structure makes the identification of viral invasion a difficult task for cells. In the course of evolution, viral nucleic acids have become one of the strongest and most reliable early identifiers of infection. When considering RNA virus recognition, RNA sensing is the central mechanism in human innate immunity, and effectiveness of this sensing is crucial for triggering an appropriate antiviral response. Although human cells are armed with a variety of highly specialized receptors designed to respond only to pathogenic viral RNA, RNA viruses have developed an array of mechanisms to avoid being recognized by human interferon-mediated cellular defence systems. The repertoire of viral evasion strategies is extremely wide, ranging from masking pathogenic RNA through end modification, to utilizing sophisticated techniques to deceive host cellular RNA degrading enzymes, and hijacking the most basic metabolic pathways in host cells. In this review, we aim to dissect human RNA sensing mechanisms crucial for antiviral immune defences, as well as the strategies adopted by RNA viruses to avoid detection and degradation by host cells. We believe that understanding the fate of viral RNA upon infection, and detailing the molecular mechanisms behind virus-host interactions, may be helpful for developing more effective antiviral strategies; which are urgently needed to prevent the far-reaching consequences of widespread, highly pathogenic viral infections.
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Jansen S, Smlatic E, Copmans D, Debaveye S, Tangy F, Vidalain PO, Neyts J, Dallmeier K. Identification of host factors binding to dengue and Zika virus subgenomic RNA by efficient yeast three-hybrid screens of the human ORFeome. RNA Biol 2021; 18:732-744. [PMID: 33459164 PMCID: PMC8086697 DOI: 10.1080/15476286.2020.1868754] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 10/26/2022] Open
Abstract
Flaviviruses such as the dengue (DENV) and the Zika virus (ZIKV) are important human pathogens causing around 100 million symptomatic infections each year. During infection, small subgenomic flavivirus RNAs (sfRNAs) are formed inside the infected host cell as a result of incomplete degradation of the viral RNA genome by cellular exoribonuclease XRN1. Although the full extent of sfRNA functions is to be revealed, these non-coding RNAs are key virulence factors and their detrimental effects on multiple cellular processes seem to consistently involve molecular interactions with RNA-binding proteins (RBPs). Discovery of such sfRNA-binding host-factors has followed established biochemical pull-down approaches skewed towards highly abundant proteins hampering proteome-wide coverage. Yeast three-hybrid (Y3H) systems represent an attractive alternative approach. To facilitate proteome-wide screens for RBP, we revisited and improved existing RNA-Y3H methodology by (1) implementing full-length ORF libraries in combination with (2) efficient yeast mating to increase screening depth and sensitivity, and (3) stringent negative controls to eliminate over-representation of non-specific RNA-binders. These improvements were validated employing the well-characterized interaction between DDX6 (DEAD-box helicase 6) and sfRNA of DENV as paradigm. Our advanced Y3H system was used to screen for human proteins binding to DENV and ZIKV sfRNA, resulting in a list of 69 putative sfRNA-binders, including several previously reported as well as numerous novel RBP host factors. Our methodology requiring no sophisticated infrastructure or analytic pipeline may be employed for the discovery of meaningful RNA-protein interactions at large scale in other fields.
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Affiliation(s)
- Sander Jansen
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Enisa Smlatic
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
- Division of Paediatric Infectious Diseases, Ludwig-Maximilians-University Munich, Dr. Von Hauner Children’s Hospital, Munich, Germany
| | - Daniëlle Copmans
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
- KU Leuven Department of Pharmaceutical and Pharmacological Sciences, Laboratory for Molecular Biodiscovery, Leuven, Belgium
| | - Sarah Debaveye
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Frédéric Tangy
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS, Paris, France
| | - Pierre-Olivier Vidalain
- Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS, Paris, France
- CIRI, Centre International de Recherche en Infectiologie, Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, Lyon, France
| | - Johan Neyts
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Kai Dallmeier
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
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Dilweg IW, Bouabda A, Dalebout T, Gultyaev AP, Bredenbeek PJ, Olsthoorn RCL. Xrn1-resistant RNA structures are well-conserved within the genus flavivirus. RNA Biol 2021; 18:709-717. [PMID: 33064973 PMCID: PMC8078501 DOI: 10.1080/15476286.2020.1830238] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 12/18/2022] Open
Abstract
Subgenomic RNAs are produced by several RNA viruses through incomplete degradation of their genomic RNA by the exoribonuclease Xrn1, and have been shown to be essential for viral growth and pathogenicity. Within the flavivirus genus of the Flaviviridae family, two distinct classes of Xrn1-resistant RNA motifs have been proposed; one for mosquito-borne and insect-specific flaviviruses, and one for tick-borne flaviviruses and no-known-vector flaviviruses. We investigated tick-borne and no-known-vector flavivirus Xrn1-resistant RNA motifs through systematic in vitro mutational analysis and showed that both classes actually possess very similar structural configurations, including a double pseudoknot and a base-triple at identical, conserved locations. For the no-known-vector flavivirus Modoc virus, we show that in vivo generation of subgenomic flaviviral RNA was affected by mutations targeted at nucleotides involved in the structural features of flaviviral Xrn1-resistant RNA motifs that were defined in this work. Our results suggest that throughout the genus flavivirus Xrn1-resistant RNA motifs adopt the same topologically conserved structure.
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Affiliation(s)
- Ivar W. Dilweg
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Assia Bouabda
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tim Dalebout
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Alexander P. Gultyaev
- Leiden Institute of Advanced Computer Science, Leiden University, Leiden, The Netherlands
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Peter J. Bredenbeek
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - R. C. L. Olsthoorn
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
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Abstract
After infection by flaviviruses like Zika and West Nile virus, eukaryotic hosts employ the well-conserved endoribonuclease Xrn1 to degrade the viral genomic RNA. Within the 3' untranslated regions, this enzyme encounters intricate Xrn1-resistant structures. This results in the accumulation of subgenomic flaviviral RNAs, an event that improves viral growth and aggravates viral pathogenicity. Xrn1-resistant RNAs have been established throughout the flaviviral genus, but not yet throughout the entire Flaviviridae family. In this work, we use previously determined characteristics of these structures to identify homologous sequences in many members of the genera pegivirus, hepacivirus and pestivirus. We used structural alignment and mutational analyses to establish that these sequences indeed represent Xrn1-resistant RNA and that they employ the general features of the flaviviral xrRNAs, consisting of a double pseudoknot formed by five base-paired regions stitched together by a crucial triple base interaction. Furthermore, we demonstrate that the pestivirus Bungowannah virus produces subgenomic RNA in vivo. Altogether, these results indicate that viruses make use of a universal Xrn1-resistant RNA throughout the Flaviviridae family.
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Affiliation(s)
- Ivar W Dilweg
- Leiden Institute of Chemistry, Leiden University, RA, Leiden, The Netherlands
| | - Anya Savina
- Leiden Institute of Chemistry, Leiden University, RA, Leiden, The Netherlands
| | - Susanne Köthe
- Friedrich-Loeffler-Institut, Institute of Diagnostic Virology, Greifswald, Germany
| | - Alexander P Gultyaev
- Leiden Institute of Advanced Computer Science, Leiden University, RA, Leiden, The Netherlands.,Department of Viroscience, Erasmus Medical Center, CA, Rotterdam, The Netherlands
| | - Peter J Bredenbeek
- Department of Medical Microbiology, Leiden University Medical Center, RC, Leiden, The Netherlands
| | - René C L Olsthoorn
- Leiden Institute of Chemistry, Leiden University, RA, Leiden, The Netherlands
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Ramos-Lorente S, Romero-López C, Berzal-Herranz A. Information Encoded by the Flavivirus Genomes beyond the Nucleotide Sequence. Int J Mol Sci 2021; 22:3738. [PMID: 33916729 PMCID: PMC8038387 DOI: 10.3390/ijms22073738] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 02/05/2023] Open
Abstract
The genus Flavivirus comprises numerous, small, single positive-stranded RNA viruses, many of which are important human pathogens. To store all the information required for their successful propagation, flaviviruses use discrete structural genomic RNA elements to code for functional information by the establishment of dynamic networks of long-range RNA-RNA interactions that promote specific folding. These structural elements behave as true cis-acting, non-coding RNAs (ncRNAs) and have essential regulatory roles in the viral cycle. These include the control of the formation of subgenomic RNAs, known as sfRNAs, via the prevention of the complete degradation of the RNA genome. These sfRNAs are important in ensuring viral fitness. This work summarizes our current knowledge of the functions performed by the genome conformations and the role of RNA-RNA interactions in these functions. It also reviews the role of RNA structure in the production of sfRNAs across the genus Flavivirus, and their existence in related viruses.
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Affiliation(s)
| | - Cristina Romero-López
- Instituto de Parasitología y Biomedicina López-Neyra (IPBLN-CSIC), Av. Conocimiento 17, Armilla, 18016 Granada, Spain;
| | - Alfredo Berzal-Herranz
- Instituto de Parasitología y Biomedicina López-Neyra (IPBLN-CSIC), Av. Conocimiento 17, Armilla, 18016 Granada, Spain;
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Xie S, Zhang H, Liang Z, Yang X, Cao R. AXL, an Important Host Factor for DENV and ZIKV Replication. Front Cell Infect Microbiol 2021; 11:575346. [PMID: 33954117 PMCID: PMC8092360 DOI: 10.3389/fcimb.2021.575346] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022] Open
Abstract
Flaviviruses, as critically important pathogens, are still major public health problems all over the world. For instance, the evolution of ZIKV led to large-scale outbreaks in the Yap island in 2007. DENV was considered by the World Health Organization (WHO) as one of the 10 threats to global health in 2019. Enveloped viruses hijack a variety of host factors to complete its replication cycle. Phosphatidylserine (PS) receptor, AXL, is considered to be a candidate receptor for flavivirus invasion. In this review, we discuss the molecular structure of ZIKV and DENV, and how they interact with AXL to successfully invade host cells. A more comprehensive understanding of the molecular mechanisms of flavivirus-AXL interaction will provide crucial insights into the virus infection process and the development of anti-flavivirus therapeutics.
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Affiliation(s)
- Shengda Xie
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Huiru Zhang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Zhenjie Liang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xingmiao Yang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Ruibing Cao
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
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De Falco L, Silva NM, Santos NC, Huber RG, Martins IC. The Pseudo-Circular Genomes of Flaviviruses: Structures, Mechanisms, and Functions of Circularization. Cells 2021; 10:642. [PMID: 33805761 DOI: 10.3390/cells10030642] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/19/2021] [Accepted: 03/02/2021] [Indexed: 11/23/2022] Open
Abstract
The circularization of viral genomes fulfills various functions, from evading host defense mechanisms to promoting specific replication and translation patterns supporting viral proliferation. Here, we describe the genomic structures and associated host factors important for flaviviruses genome circularization and summarize their functional roles. Flaviviruses are relatively small, single-stranded, positive-sense RNA viruses with genomes of approximately 11 kb in length. These genomes contain motifs at their 5′ and 3′ ends, as well as in other regions, that are involved in circularization. These motifs are highly conserved throughout the Flavivirus genus and occur both in mature virions and within infected cells. We provide an overview of these sequence motifs and RNA structures involved in circularization, describe their linear and circularized structures, and discuss the proteins that interact with these circular structures and that promote and regulate their formation, aiming to clarify the key features of genome circularization and understand how these affect the flaviviruses life cycle.
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Girardi E, Pfeffer S, Baumert TF, Majzoub K. Roadblocks and fast tracks: How RNA binding proteins affect the viral RNA journey in the cell. Semin Cell Dev Biol 2021; 111:86-100. [PMID: 32847707 PMCID: PMC7443355 DOI: 10.1016/j.semcdb.2020.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022]
Abstract
As obligate intracellular parasites with limited coding capacity, RNA viruses rely on host cells to complete their multiplication cycle. Viral RNAs (vRNAs) are central to infection. They carry all the necessary information for a virus to synthesize its proteins, replicate and spread and could also play essential non-coding roles. Regardless of its origin or tropism, vRNA has by definition evolved in the presence of host RNA Binding Proteins (RBPs), which resulted in intricate and complicated interactions with these factors. While on one hand some host RBPs recognize vRNA as non-self and mobilize host antiviral defenses, vRNA must also co-opt other host RBPs to promote viral infection. Focusing on pathogenic RNA viruses, we will review important scenarios of RBP-vRNA interactions during which host RBPs recognize, modify or degrade vRNAs. We will then focus on how vRNA hijacks the largest ribonucleoprotein complex (RNP) in the cell, the ribosome, to selectively promote the synthesis of its proteins. We will finally reflect on how novel technologies are helping in deepening our understanding of vRNA-host RBPs interactions, which can be ultimately leveraged to combat everlasting viral threats.
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Affiliation(s)
- Erika Girardi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Sebastien Pfeffer
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Thomas F Baumert
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Université de Strasbourg, 67000, Strasbourg, France; Pole Hépatodigestif, Institut Hopitalo-universitaire, Hopitaux Universitaires de Strasbourg, 67000 Strasbourg, France
| | - Karim Majzoub
- Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Université de Strasbourg, 67000, Strasbourg, France.
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