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Abram QH, Landry BN, Wang AB, Kothe RF, Hauch HC, Sagan SM. The myriad roles of RNA structure in the flavivirus life cycle. RNA Biol 2024; 21:14-30. [PMID: 38797925 PMCID: PMC11135854 DOI: 10.1080/15476286.2024.2357857] [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] [Accepted: 05/16/2024] [Indexed: 05/29/2024] Open
Abstract
As positive-sense RNA viruses, the genomes of flaviviruses serve as the template for all stages of the viral life cycle, including translation, replication, and infectious particle production. Yet, they encode just 10 proteins, suggesting that the structure and dynamics of the viral RNA itself helps shepherd the viral genome through these stages. Herein, we highlight advances in our understanding of flavivirus RNA structural elements through the lens of their impact on the viral life cycle. We highlight how RNA structures impact translation, the switch from translation to replication, negative- and positive-strand RNA synthesis, and virion assembly. Consequently, we describe three major themes regarding the roles of RNA structure in flavivirus infections: 1) providing a layer of specificity; 2) increasing the functional capacity; and 3) providing a mechanism to support genome compaction. While the interactions described herein are specific to flaviviruses, these themes appear to extend more broadly across RNA viruses.
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Affiliation(s)
- Quinn H. Abram
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Breanna N. Landry
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Alex B. Wang
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Ronja F. Kothe
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Hannah C.H. Hauch
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
| | - Selena M. Sagan
- Department of Biochemistry, McGill University, Montreal, QC, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada
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Boon PLS, Martins AS, Lim XN, Enguita FJ, Santos NC, Bond PJ, Wan Y, Martins IC, Huber RG. Dengue Virus Capsid Protein Facilitates Genome Compaction and Packaging. Int J Mol Sci 2023; 24:ijms24098158. [PMID: 37175867 PMCID: PMC10179140 DOI: 10.3390/ijms24098158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Dengue virus (DENV) is a single-stranded (+)-sense RNA virus that infects humans and mosquitoes, posing a significant health risk in tropical and subtropical regions. Mature virions are composed of an icosahedral shell of envelope (E) and membrane (M) proteins circumscribing a lipid bilayer, which in turn contains a complex of the approximately 11 kb genomic RNA with capsid (C) proteins. Whereas the structure of the envelope is clearly defined, the structure of the packaged genome in complex with C proteins remains elusive. Here, we investigated the interactions of C proteins with viral RNA, in solution and inside mature virions, via footprinting and cross-linking experiments. We demonstrated that C protein interaction with DENV genomes saturates at an RNA:C protein ratio below 1:250. Moreover, we also showed that the length of the RNA genome interaction sites varies, in a multimodal distribution, consistent with the C protein binding to each RNA site mostly in singlets or pairs (and, in some instances, higher numbers). We showed that interaction sites are preferentially sites with low base pairing, as previously measured by 2'-acetylation analyzed by primer extension (SHAPE) reactivity indicating structuredness. We found a clear association pattern emerged: RNA-C protein binding sites are strongly associated with long-range RNA-RNA interaction sites, particularly inside virions. This, in turn, explains the need for C protein in viral genome packaging: the protein has a chief role in coordinating these key interactions, promoting proper packaging of viral RNA. Such sites are, thus, highly consequential for viral assembly, and, as such, may be targeted in future drug development strategies against these and related viruses.
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Affiliation(s)
- Priscilla L S Boon
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
- Department of Biological Sciences (DBS), National University of Singapore (NUS), 16 Science Drive 4, Singapore 117558, Singapore
| | - Ana S Martins
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Xin Ni Lim
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
| | - Francisco J Enguita
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Nuno C Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Peter J Bond
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
- Department of Biological Sciences (DBS), National University of Singapore (NUS), 16 Science Drive 4, Singapore 117558, Singapore
| | - Yue Wan
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
| | - Ivo C Martins
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Roland G Huber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
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Allan MF, Brivanlou A, Rouskin S. RNA levers and switches controlling viral gene expression. Trends Biochem Sci 2023; 48:391-406. [PMID: 36710231 DOI: 10.1016/j.tibs.2022.12.002] [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: 09/12/2022] [Revised: 11/27/2022] [Accepted: 12/15/2022] [Indexed: 01/29/2023]
Abstract
RNA viruses are diverse and abundant pathogens that are responsible for numerous human diseases. RNA viruses possess relatively compact genomes and have therefore evolved multiple mechanisms to maximize their coding capacities, often by encoding overlapping reading frames. These reading frames are then decoded by mechanisms such as alternative splicing and ribosomal frameshifting to produce multiple distinct proteins. These solutions are enabled by the ability of the RNA genome to fold into 3D structures that can mimic cellular RNAs, hijack host proteins, and expose or occlude regulatory protein-binding motifs to ultimately control key process in the viral life cycle. We highlight recent findings focusing on less conventional mechanisms of gene expression and new discoveries on the role of RNA structures.
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Affiliation(s)
- Matthew F Allan
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Amir Brivanlou
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Silvi Rouskin
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
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Circular RNAs: Non-Canonical Observations on Non-Canonical RNAs. Cells 2023; 12:cells12020323. [PMID: 36672257 PMCID: PMC9856604 DOI: 10.3390/cells12020323] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
The existence of circular RNA (circRNA) research in mainstream science can be attributed to the contemporary synergism of big data and keen attention to detail by several research groups worldwide. Since the re-emergence of these non-canonical RNA transcripts, seminal advances have been made in understanding their biogenesis, interactome, and functions in diverse fields and a myriad of human diseases. However, most research outputs to date have focused on the ability of highly stable circRNAs to interact with, and impact signalling through, microRNAs. This is likely to be the result of seminal papers in the field ascribing a few remarkable circRNAs as "miRNA sponges". However, the stoichiometric ratio between the (often-lowly-expressed) circRNA and their (commonly-more-abundant) target is rarely in favour of a biologically relevant and functional consequence of these interactions. It is time for yet another revolution in circRNA research to uncover functions beyond their documented ability to bind miRNAs. This Special Issue aims to highlight non-canonical functions for this non-canonical family of RNA molecules.
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Yang SL, Ponti RD, Wan Y, Huber RG. Computational and Experimental Approaches to Study the RNA Secondary Structures of RNA Viruses. Viruses 2022; 14:v14081795. [PMID: 36016417 PMCID: PMC9415818 DOI: 10.3390/v14081795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/12/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Most pandemics of recent decades can be traced to RNA viruses, including HIV, SARS, influenza, dengue, Zika, and SARS-CoV-2. These RNA viruses impose considerable social and economic burdens on our society, resulting in a high number of deaths and high treatment costs. As these RNA viruses utilize an RNA genome, which is important for different stages of the viral life cycle, including replication, translation, and packaging, studying how the genome folds is important to understand virus function. In this review, we summarize recent advances in computational and high-throughput RNA structure-mapping approaches and their use in understanding structures within RNA virus genomes. In particular, we focus on the genome structures of the dengue, Zika, and SARS-CoV-2 viruses due to recent significant outbreaks of these viruses around the world.
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Affiliation(s)
- Siwy Ling Yang
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
| | - Riccardo Delli Ponti
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
| | - Yue Wan
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
- Correspondence: (Y.W.); (R.G.H.)
| | - Roland G. Huber
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
- Correspondence: (Y.W.); (R.G.H.)
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Delli Ponti R, Wang J, Wan Y, Huber RG. RNAvigator: A Pipeline to Identify Candidates for Functional RNA Structure Elements. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2022.878679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Identifying structural elements in long and complex RNAs, such as long non-coding and RNA viruses, can shed light on the functionality and mechanisms of such RNAs. Here we present RNAvigator, a tool able to identify elements of structural importance by using experimental SHAPE data or SHAPE-like predictions in conjunction with stability and entropy assessments. RNAvigator recognizes regions that are the most stable, unambiguous, and structured on RNA molecules, and thus potentially functional. When relying on predictions, RNAvigator uses the CROSS algorithm, a neural network trained on experimental data that achieved an AUC of 0.74 on hepatitis C virus SHAPE-MaP data and which was able to improve the predictive power of Superfold. By using RNAvigator, we can identify known functional regions on the complete hepatitis C virus genome, including the regulatory regions CRE and IRES, and the 3’ UTR of dengue virus, a region known for the presence of structural elements essential for its replication, and functional regions of long non-coding RNAs such as XIST and HOTAIR. We envision that RNAvigator will be a useful tool for studying long and complex RNA molecules using known chemical probing data or, if they are not available, by employing predicted profiles.
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