1
|
Parry RH, Slonchak A, Campbell LJ, Newton ND, Debat HJ, Gifford RJ, Khromykh AA. A novel tamanavirus ( Flaviviridae) of the European common frog ( Rana temporaria) from the UK. J Gen Virol 2023; 104:001927. [PMID: 38059479 PMCID: PMC10770923 DOI: 10.1099/jgv.0.001927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/19/2023] [Indexed: 12/08/2023] Open
Abstract
Flavivirids are small, enveloped, positive-sense RNA viruses from the family Flaviviridae with genomes of ~9-13 kb. Metatranscriptomic analyses of metazoan organisms have revealed a diversity of flavivirus-like or flavivirid viral sequences in fish and marine invertebrate groups. However, no flavivirus-like virus has been identified in amphibians. To remedy this, we investigated the virome of the European common frog (Rana temporaria) in the UK, utilizing high-throughput sequencing at six catch locations. De novo assembly revealed a coding-complete virus contig of a novel flavivirid ~11.2 kb in length. The virus encodes a single ORF of 3456 aa and 5' and 3' untranslated regions (UTRs) of 227 and 666 nt, respectively. We named this virus Rana tamanavirus (RaTV), as BLASTp analysis of the polyprotein showed the closest relationships to Tamana bat virus (TABV) and Cyclopterus lumpus virus from Pteronotus parnellii and Cyclopterus lumpus, respectively. Phylogenetic analysis of the RaTV polyprotein compared to Flavivirus and Flavivirus-like members indicated that RaTV was sufficiently divergent and basal to the vertebrate Tamanavirus clade. In addition to the Mitcham strain, partial but divergent RaTV, sharing 95.64-97.39 % pairwise nucleotide identity, were also obtained from the Poole and Deal samples, indicating that RaTV is widespread in UK frog samples. Bioinformatic analyses of predicted secondary structures in the 3'UTR of RaTV showed the presence of an exoribonuclease-resistant RNA (xrRNA) structure standard in flaviviruses and TABV. To examine this biochemically, we conducted an in vitro Xrn1 digestion assay showing that RaTV probably forms a functional Xrn1-resistant xrRNA.
Collapse
Affiliation(s)
- Rhys H. Parry
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Andrii Slonchak
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
- Australian Infectious Diseases Research Centre (AIDRC), Brisbane, QLD, Australia
| | - Lewis J. Campbell
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Institute of Zoology, Zoological Society of London, London, UK
- Environment and Sustainability Institute, University of Exeter, Penryn, UK
| | - Natalee D. Newton
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
- Australian Infectious Diseases Research Centre (AIDRC), Brisbane, QLD, Australia
| | - Humberto J. Debat
- Instituto de Patología Vegetal, Centro de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria (IPAVE-CIAP-INTA), Córdoba X5020ICA, Argentina
- Unidad de Fitopatología y Modelización Agrícola (UFYMA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba X5020ICA, Argentina
| | | | - Alexander A. Khromykh
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
- Australian Infectious Diseases Research Centre (AIDRC), Brisbane, QLD, Australia
- AIDRC Global Virus Network Centre of Excellence, Brisbane, QLD, Australia
| |
Collapse
|
2
|
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] [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.
Collapse
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
| |
Collapse
|
3
|
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] [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.
Collapse
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
| |
Collapse
|
4
|
Langeberg CJ, Kieft JS. A Generalizable Scaffold-Based Approach for Structure Determination of RNAs by Cryo-EM. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 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] [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.
Collapse
|
5
|
Effects of the noncoding subgenomic RNA of red clover necrotic mosaic virus in virus infection. J Virol 2021; 96:e0181521. [PMID: 34851690 PMCID: PMC8826918 DOI: 10.1128/jvi.01815-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In recent years, a new class of viral noncoding subgenomic RNA (ncsgRNA) has been identified. This RNA is generated as a stable degradation product via an exoribonuclease-resistant RNA (xrRNA) structure, which blocks the progression of 5′→3′ exoribonuclease on viral RNAs in infected cells. Here, we assess the effects of the ncsgRNA of red clover necrotic mosaic virus (RCNMV), called SR1f, in infected plants. We demonstrate the following: (i) the absence of SR1f reduces symptoms and decreases viral RNA accumulation in Nicotiana benthamiana and Arabidopsis thaliana plants; (ii) SR1f has an essential function other than suppression of RNA silencing; and (iii) the cytoplasmic exoribonuclease involved in mRNA turnover, XRN4, is not required for SR1f production or virus infection. A comparative transcriptomic analysis in N. benthamiana infected with wild-type RCNMV or an SR1f-deficient mutant RCNMV revealed that wild-type RCNMV infection, which produces SR1f and much higher levels of virus, has a greater and more significant impact on cellular gene expression than the SR1f-deficient mutant. Upregulated pathways include plant hormone signaling, plant-pathogen interaction, MAPK signaling, and several metabolic pathways, while photosynthesis-related genes were downregulated. We compare this to host genes known to participate in infection by other tombusvirids. Viral reads revealed a 10- to 100-fold ratio of positive to negative strand, and the abundance of reads of both strands mapping to the 3′ region of RCNMV RNA1 support the premature transcription termination mechanism of synthesis for the coding sgRNA. These results provide a framework for future studies of the interactions and functions of noncoding RNAs of plant viruses. IMPORTANCE Knowledge of how RNA viruses manipulate host and viral gene expression is crucial to our understanding of infection and disease. Unlike viral protein-host interactions, little is known about the control of gene expression by viral RNA. Here, we begin to address this question by investigating the noncoding subgenomic RNA (ncsgRNA) of red clover necrotic mosaic virus (RCNMV), called SR1f. Similar exoribonuclease-resistant RNAs of flaviviruses are well studied, but the roles of plant viral ncsgRNAs, and how they arise, are poorly understood. Surprisingly, we find the likely exonuclease candidate, XRN4, is not required to generate SR1f, and we assess the effects of SR1f on virus accumulation and symptom development. Finally, we compare the effects of infection by wild-type RCNMV versus an SR1f-deficient mutant on host gene expression in Nicotiana benthamiana, which reveals that ncsgRNAs such as SR1f are key players in virus-host interactions to facilitate productive infection.
Collapse
|
6
|
Pseudoknot length modulates the folding, conformational dynamics, and robustness of Xrn1 resistance of flaviviral xrRNAs. Nat Commun 2021; 12:6417. [PMID: 34741027 PMCID: PMC8571300 DOI: 10.1038/s41467-021-26616-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [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.
Collapse
|
7
|
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] [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.
Collapse
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
| |
Collapse
|
8
|
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] [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.
Collapse
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
| |
Collapse
|
9
|
Dilweg IW, Savina A, Köthe S, Gultyaev AP, Bredenbeek PJ, Olsthoorn RCL. All genera of Flaviviridae host a conserved Xrn1-resistant RNA motif. RNA Biol 2021; 18:2321-2329. [PMID: 33858294 PMCID: PMC8632102 DOI: 10.1080/15476286.2021.1907044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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.
Collapse
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
| |
Collapse
|
10
|
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] [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.
Collapse
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;
| |
Collapse
|