1
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Deng X, Yu YV, Jin YN. Non-canonical translation in cancer: significance and therapeutic potential of non-canonical ORFs, m 6A-modification, and circular RNAs. Cell Death Discov 2024; 10:412. [PMID: 39333489 PMCID: PMC11437038 DOI: 10.1038/s41420-024-02185-y] [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: 05/12/2024] [Revised: 09/13/2024] [Accepted: 09/18/2024] [Indexed: 09/29/2024] Open
Abstract
Translation is a decoding process that synthesizes proteins from RNA, typically mRNA. The conventional translation process consists of four stages: initiation, elongation, termination, and ribosome recycling. Precise control over the translation mechanism is crucial, as dysregulation in this process is often linked to human diseases such as cancer. Recent discoveries have unveiled translation mechanisms that extend beyond typical well-characterized components like the m7G cap, poly(A)-tail, or translation factors like eIFs. These mechanisms instead utilize atypical elements, such as non-canonical ORF, m6A-modification, and circular RNA, as key components for protein synthesis. Collectively, these mechanisms are classified as non-canonical translations. It is increasingly clear that non-canonical translation mechanisms significantly impact the various regulatory pathways of cancer, including proliferation, tumorigenicity, and the behavior of cancer stem cells. This review explores the involvement of a variety of non-canonical translation mechanisms in cancer biology and provides insights into potential therapeutic strategies for cancer treatment.
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Affiliation(s)
- Xiaoyi Deng
- Department of Neurology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei, China
| | - Yanxun V Yu
- Department of Neurology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, Hubei, China
| | - Youngnam N Jin
- Department of Neurology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei, China.
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, Hubei, China.
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2
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Shen R, Yao Q, Tan X, Ren W, Zhong D, Zhang X, Li X, Dong C, Cao X, Tian Y, Zhu JK, Lu Y. In-locus gene silencing in plants using genome editing. THE NEW PHYTOLOGIST 2024; 243:2501-2511. [PMID: 38798233 DOI: 10.1111/nph.19856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 05/03/2024] [Indexed: 05/29/2024]
Abstract
Gene silencing is crucial in crop breeding for desired trait development. RNA interference (RNAi) has been used widely but is limited by ectopic expression of transgenes and genetic instability. Introducing an upstream start codon (uATG) into the 5'untranslated region (5'UTR) of a target gene may 'silence' the target gene by inhibiting protein translation from the primary start codon (pATG). Here, we report an efficient gene silencing method by introducing a tailor-designed uATG-containing element (ATGE) into the 5'UTR of genes in plants, occupying the original start site to act as a new pATG. Using base editing to introduce new uATGs failed to silence two of the tested three rice genes, indicating complex regulatory mechanisms. Precisely inserting an ATGE adjacent to pATG achieved significant target protein downregulation. Through extensive optimization, we demonstrated this strategy substantially and consistently downregulated target protein expression. By designing a bidirectional multifunctional ATGE4, we enabled tunable knockdown from 19% to 89% and observed expected phenotypes. Introducing ATGE into Waxy, which regulates starch synthesis, generated grains with lower amylose, revealing the value for crop breeding. Together, we have developed a programmable and robust method to knock down gene expression in plants, with potential for biological mechanism exploration and crop enhancement.
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Affiliation(s)
- Rundong Shen
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Institute of Crop Sciences/National Nanfan Research Institute, Chinese Academy of Agricultural Sciences (CAAS), and Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Sanya, 572024, China
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Qi Yao
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Xinhang Tan
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Wendan Ren
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Dating Zhong
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Xuening Zhang
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xinbo Li
- Institute of Crop Sciences/National Nanfan Research Institute, Chinese Academy of Agricultural Sciences (CAAS), and Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Sanya, 572024, China
| | - Chao Dong
- Institute of Crop Sciences/National Nanfan Research Institute, Chinese Academy of Agricultural Sciences (CAAS), and Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Sanya, 572024, China
| | - Xuesong Cao
- Institute of Advanced Biotechnology, and School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yifu Tian
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Institute of Crop Sciences/National Nanfan Research Institute, Chinese Academy of Agricultural Sciences (CAAS), and Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Sanya, 572024, China
| | - Jian-Kang Zhu
- Institute of Crop Sciences/National Nanfan Research Institute, Chinese Academy of Agricultural Sciences (CAAS), and Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Sanya, 572024, China
- Institute of Advanced Biotechnology, and School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yuming Lu
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
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3
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Simon AE, Quito-Avila DF, Bera S. Expanding the Plant Virome: Umbra-Like Viruses Use Host Proteins for Movement. Annu Rev Virol 2024; 11:283-308. [PMID: 38876114 DOI: 10.1146/annurev-virology-111821-122718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Before the very recent discovery of umbra-like viruses (ULVs), the signature defining feature of all plant RNA viruses was the encoding of specialized RNA-binding movement proteins (MPs) for transiting their RNA genomes through gated plasmodesmata to establish systemic infections. The vast majority of ULVs share umbravirus-like RNA-dependent RNA polymerases and 3'-terminal structures, but they differ by not encoding cell-to-cell and long-distance MPs and by not relying on a helper virus for trans-encapsidation and plant-to-plant transmission. The recent finding that two groups of ULVs do not necessarily encode MPs is expanding our understanding of the minimum requirements for modern plant RNA viruses. ULV CY1 from citrus uses host protein PHLOEM PROTEIN 2 (PP2) for systemic movement, and related ULVs encode a capsid protein, thereby providing an explanation for the lack of helper viruses present in many ULV-infected plants. ULVs thus resemble the first viruses that infected plants, which were likely deposited from feeding organisms and would have similarly required the use of host proteins such as PP2 to exit initially infected cells.
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Affiliation(s)
- Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA;
| | - Diego F Quito-Avila
- Facultad de Ciencias de la Vida and Centro de Investigaciones Biotecnológicas del Ecuador, Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador
| | - Sayanta Bera
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA;
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4
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Rollwage L, Van Houtte H, Hossain R, Wynant N, Willems G, Varrelmann M. Recessive resistance against beet chlorosis virus is conferred by the eukaryotic translation initiation factor (iso)4E in Beta vulgaris. PLANT BIOTECHNOLOGY JOURNAL 2024; 22:2129-2141. [PMID: 38488845 PMCID: PMC11258979 DOI: 10.1111/pbi.14333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 02/16/2024] [Accepted: 02/24/2024] [Indexed: 07/21/2024]
Abstract
Eukaryotic translation initiation factors (eIFs) are important for mRNA translation but also pivotal for plant-virus interaction. Most of these plant-virus interactions were found between plant eIFs and the viral protein genome-linked (VPg) of potyviruses. In case of lost interaction due to mutation or deletion of eIFs, the viral translation and subsequent replication within its host is negatively affected, resulting in a recessive resistance. Here we report the identification of the Beta vulgaris Bv-eIF(iso)4E as a susceptibility factor towards the VPg-carrying beet chlorosis virus (genus Polerovirus). Using yeast two-hybrid and bimolecular fluorescence complementation assays, the physical interaction between Bv-eIF(iso)4E and the putative BChV-VPg was detected, while the VPg of the closely related beet mild yellowing virus (BMYV) was found to interact with the two isoforms Bv-eIF4E and Bv-eIF(iso)4E. These VPg-eIF interactions within the polerovirus-beet pathosystem were demonstrated to be highly specific, as single mutations within the predicted cap-binding pocket of Bv-eIF(iso)4E resulted in a loss of interaction. To investigate the suitability of eIFs as a resistance resource against beet infecting poleroviruses, B. vulgaris plants were genome edited by CRISPR/Cas9 resulting in knockouts of different eIFs. A simultaneous knockout of the identified BMYV-interaction partners Bv-eIF4E and Bv-eIF(iso)4E was not achieved, but Bv-eIF(iso)4EKO plants showed a significantly lowered BChV accumulation and decrease in infection rate from 100% to 28.86%, while no influence on BMYV accumulation was observed. Still, these observations support that eIFs are promising candidate genes for polerovirus resistance breeding in sugar beet.
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5
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Mahé M, Rios-Fuller T, Katsara O, Schneider RJ. Non-canonical mRNA translation initiation in cell stress and cancer. NAR Cancer 2024; 6:zcae026. [PMID: 38828390 PMCID: PMC11140632 DOI: 10.1093/narcan/zcae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 05/08/2024] [Accepted: 05/29/2024] [Indexed: 06/05/2024] Open
Abstract
The now well described canonical mRNA translation initiation mechanism of m7G 'cap' recognition by cap-binding protein eIF4E and assembly of the canonical pre-initiation complex consisting of scaffolding protein eIF4G and RNA helicase eIF4A has historically been thought to describe all cellular mRNA translation. However, the past decade has seen the discovery of alternative mechanisms to canonical eIF4E mediated mRNA translation initiation. Studies have shown that non-canonical alternate mechanisms of cellular mRNA translation initiation, whether cap-dependent or independent, serve to provide selective translation of mRNAs under cell physiological and pathological stress conditions. These conditions typically involve the global downregulation of canonical eIF4E1/cap-mediated mRNA translation, and selective translational reprogramming of the cell proteome, as occurs in tumor development and malignant progression. Cancer cells must be able to maintain physiological plasticity to acquire a migratory phenotype, invade tissues, metastasize, survive and adapt to severe microenvironmental stress conditions that involve inhibition of canonical mRNA translation initiation. In this review we describe the emerging, important role of non-canonical, alternate mechanisms of mRNA translation initiation in cancer, particularly in adaptation to stresses and the phenotypic cell fate changes involved in malignant progression and metastasis. These alternate translation initiation mechanisms provide new targets for oncology therapeutics development.
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Affiliation(s)
- Mélanie Mahé
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Tiffany Rios-Fuller
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Olga Katsara
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Robert J Schneider
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY 10016, USA
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6
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Yang R, Pan M, Guo J, Huang Y, Zhang QC, Deng T, Wang J. Mapping of the influenza A virus genome RNA structure and interactions reveals essential elements of viral replication. Cell Rep 2024; 43:113833. [PMID: 38416642 DOI: 10.1016/j.celrep.2024.113833] [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: 05/31/2023] [Revised: 12/04/2023] [Accepted: 02/02/2024] [Indexed: 03/01/2024] Open
Abstract
Influenza A virus (IAV) represents a constant public health threat. The single-stranded, segmented RNA genome of IAV is replicated in host cell nuclei as a series of 8 ribonucleoprotein complexes (vRNPs) with RNA structures known to exert essential function to support viral replication. Here, we investigate RNA secondary structures and RNA interactions networks of the IAV genome and construct an in vivo structure model for each of the 8 IAV genome segments. Our analyses reveal an overall in vivo and in virio resemblance of the IAV genome conformation but also wide disparities among long-range and intersegment interactions. Moreover, we identify a long-range RNA interaction that exerts an essential role in genome packaging. Disrupting this structure displays reduced infectivity, attenuating virus pathogenicity in mice. Our findings characterize the in vivo RNA structural landscape of the IAV genome and reveal viral RNA structures that can be targeted to develop antiviral interventions.
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Affiliation(s)
- Rui Yang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Minglei Pan
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Jiamei Guo
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Huang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiangfeng Cliff Zhang
- The State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Tao Deng
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Jianwei Wang
- NHC Key Laboratory of Systems Biology of Pathogens and Christophe Mérieux Laboratory, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China; Key Laboratory of Respiratory Disease Pathogenomics, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
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7
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Khan D, Fox PL. Host-like RNA Elements Regulate Virus Translation. Viruses 2024; 16:468. [PMID: 38543832 PMCID: PMC10976276 DOI: 10.3390/v16030468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/14/2024] [Accepted: 03/17/2024] [Indexed: 04/01/2024] Open
Abstract
Viruses are obligate, intracellular parasites that co-opt host cell machineries for propagation. Critical among these machineries are those that translate RNA into protein and their mechanisms of control. Most regulatory mechanisms effectuate their activity by targeting sequence or structural features at the RNA termini, i.e., at the 5' or 3' ends, including the untranslated regions (UTRs). Translation of most eukaryotic mRNAs is initiated by 5' cap-dependent scanning. In contrast, many viruses initiate translation at internal RNA regions at internal ribosome entry sites (IRESs). Eukaryotic mRNAs often contain upstream open reading frames (uORFs) that permit condition-dependent control of downstream major ORFs. To offset genome compression and increase coding capacity, some viruses take advantage of out-of-frame overlapping uORFs (oORFs). Lacking the essential machinery of protein synthesis, for example, ribosomes and other translation factors, all viruses utilize the host apparatus to generate virus protein. In addition, some viruses exhibit RNA elements that bind host regulatory factors that are not essential components of the translation machinery. SARS-CoV-2 is a paradigm example of a virus taking advantage of multiple features of eukaryotic host translation control: the virus mimics the established human GAIT regulatory element and co-opts four host aminoacyl tRNA synthetases to form a stimulatory binding complex. Utilizing discontinuous transcription, the elements are present and identical in all SARS-CoV-2 subgenomic RNAs (and the genomic RNA). Thus, the virus exhibits a post-transcriptional regulon that improves upon analogous eukaryotic regulons, in which a family of functionally related mRNA targets contain elements that are structurally similar but lacking sequence identity. This "thrifty" virus strategy can be exploited against the virus since targeting the element can suppress the expression of all subgenomic RNAs as well as the genomic RNA. Other 3' end viral elements include 3'-cap-independent translation elements (3'-CITEs) and 3'-tRNA-like structures. Elucidation of virus translation control elements, their binding proteins, and their mechanisms can lead to novel therapeutic approaches to reduce virus replication and pathogenicity.
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Affiliation(s)
- Debjit Khan
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paul L. Fox
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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8
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Bhatter N, Dmitriev SE, Ivanov P. Cell death or survival: Insights into the role of mRNA translational control. Semin Cell Dev Biol 2024; 154:138-154. [PMID: 37357122 PMCID: PMC10695129 DOI: 10.1016/j.semcdb.2023.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/27/2023]
Abstract
Cellular stress is an intrinsic part of cell physiology that underlines cell survival or death. The ability of mammalian cells to regulate global protein synthesis (aka translational control) represents a critical, yet underappreciated, layer of regulation during the stress response. Various cellular stress response pathways monitor conditions of cell growth and subsequently reshape the cellular translatome to optimize translational outputs. On the molecular level, such translational reprogramming involves an intricate network of interactions between translation machinery, RNA-binding proteins, mRNAs, and non-protein coding RNAs. In this review, we will discuss molecular mechanisms, signaling pathways, and targets of translational control that contribute to cellular adaptation to stress and to cell survival or death.
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Affiliation(s)
- Nupur Bhatter
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Pavel Ivanov
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA; Harvard Initiative for RNA Medicine, Boston, Massachusetts, USA.
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9
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Ojha M, Vogt J, Das NK, Redmond E, Singh K, Banna HA, Sadat T, Koirala D. Structure of saguaro cactus virus 3' translational enhancer mimics 5' cap for eIF4E binding. Proc Natl Acad Sci U S A 2024; 121:e2313677121. [PMID: 38241435 PMCID: PMC10823258 DOI: 10.1073/pnas.2313677121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 12/18/2023] [Indexed: 01/21/2024] Open
Abstract
The genomes of several plant viruses contain RNA structures at their 3' ends called cap-independent translation enhancers (CITEs) that bind the host protein factors such as mRNA 5' cap-binding protein eIF4E for promoting cap-independent genome translation. However, the structural basis of such 5' cap-binding protein recognition by the uncapped RNA remains largely unknown. Here, we have determined the crystal structure of a 3' CITE, panicum mosaic virus-like translation enhancer (PTE) from the saguaro cactus virus (SCV), using a Fab crystallization chaperone. The PTE RNA folds into a three-way junction architecture with a pseudoknot between the purine-rich R domain and pyrimidine-rich Y domain, which organizes the overall structure to protrude out a specific guanine nucleotide, G18, from the R domain that comprises a major interaction site for the eIF4E binding. The superimposable crystal structures of the wild-type, G18A, G18C, and G18U mutants suggest that the PTE scaffold is preorganized with the flipped-out G18 ready to dock into the eIF4E 5' cap-binding pocket. The binding studies with wheat and human eIF4Es using gel electrophoresis and isothermal titration calorimetry, and molecular docking computation for the PTE-eIF4E complex demonstrated that the PTE structure essentially mimics the mRNA 5' cap for eIF4E binding. Such 5' cap mimicry by the uncapped and structured viral RNA highlights how viruses can exploit RNA structures to mimic the host protein-binding partners and bypass the canonical mechanisms for their genome translation, providing opportunities for a better understanding of virus-host interactions and non-canonical translation mechanisms found in many pathogenic RNA viruses.
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Affiliation(s)
- Manju Ojha
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Jeff Vogt
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Naba Krishna Das
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Emily Redmond
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Karndeep Singh
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
- HHMI, University of Maryland Baltimore County, Baltimore, MD21250
| | - Hasan Al Banna
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Tasnia Sadat
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
| | - Deepak Koirala
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD21250
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10
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Geng G, Yu C, Yuan X. Variable eIF4E-binding sites and their synergistic effect on cap-independent translation in a novel IRES of wheat yellow mosaic virus RNA2 isolates. Int J Biol Macromol 2024; 254:128062. [PMID: 37967597 DOI: 10.1016/j.ijbiomac.2023.128062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/17/2023]
Abstract
Some viral proteins are translated cap-independently via the internal ribosome entry site (IRES), which maintains conservative characteristic among different isolates of the same virus species. However, IRES activity showed a 7-fold variance in RNA2 of wheat yellow mosaic virus (WYMV) HC and LYJN isolates in this study. Based on RNA structure probing and mutagenesis assay, the loosened middle stem of H1 and the hepta-nucleotide top loop of H2 in the LYJN isolate synergistically ensured higher IRES activity than that in the HC isolate. In addition, the conserved top loop of H1 ensured basic IRES activity in HC and LYJN isolates. WYMV RNA2 5'-UTR specifically interacted with the wheat eIF4E, accomplished by the top loop of H1 in the HC isolate or the top loop of H1 and H2 in the LYJN isolate. The high IRES activity of the WYMV RNA2 LYJN isolate was regulated by two eIF4E-binding sites, which showed a synergistic effect mediated by the proximity of the H1 and H2 top loops owing to the flexibility of the middle stem in H1. This report presents a novel evolution pattern of IRES, which altered the number of eIF4E-binding sites to regulate IRES activity.
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Affiliation(s)
- Guowei Geng
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, PR China
| | - Chengming Yu
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, PR China
| | - Xuefeng Yuan
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Shandong Province Key Laboratory of Agricultural Microbiology, Tai'an 271018, PR China.
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11
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Truniger V, Pechar GS, Aranda MA. Advances in Understanding the Mechanism of Cap-Independent Cucurbit Aphid-Borne Yellows Virus Protein Synthesis. Int J Mol Sci 2023; 24:17598. [PMID: 38139425 PMCID: PMC10744285 DOI: 10.3390/ijms242417598] [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: 10/30/2023] [Revised: 12/07/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Non-canonical translation mechanisms have been described for many viral RNAs. In the case of several plant viruses, their protein synthesis is controlled by RNA elements in their genomic 3'-ends that are able to enhance cap-independent translation (3'-CITE). The proposed general mechanism of 3'-CITEs includes their binding to eukaryotic translation initiation factors (eIFs) that reach the 5'-end and AUG start codon through 5'-3'-UTR-interactions. It was previously shown that cucurbit aphid-borne yellows virus (CABYV) has a 3'-CITE, which varies in sequence and structure depending on the phylogenetic group to which the isolate belongs, possibly as a result of adaptation to the different geographical regions. In this work, the cap-independent translation mechanisms of two CABYV 3'-CITEs belonging to the Mediterranean (CMTE) and Asian (CXTE) groups, respectively, were studied. In vivo cap-independent translation assays show that these 3'-CITEs require the presence of the CABYV short genomic 5'-UTR with at least 40% adenines in cis and an accessible 5'-end for its activity. Additionally, they suggest that the eIF4E-independent CABYV 3'-CITE activities may not require either eIF4A or the eIF4F complex, but may depend on eIF4G and PABP. By pulling down host proteins using RNA baits containing both 5'- and 3'-CABYV-UTRs, 80 RNA binding proteins were identified. These interacted preferentially with either CMTE, CXTE, or both. One of these proteins, specifically interacting with the RNA containing CMTE, was HSP70.2. Preliminary results suggested that HSP70.2 may be involved in CMTE- but not CXTE-mediated cap-independent translation activity.
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Affiliation(s)
- Verónica Truniger
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), 30100 Murcia, Spain; (G.S.P.); (M.A.A.)
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12
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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] [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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13
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Lewicka A, Roman C, Jones S, Disare M, Rice P, Piccirilli J. Crystal structure of a cap-independent translation enhancer RNA. Nucleic Acids Res 2023; 51:8891-8907. [PMID: 37548413 PMCID: PMC10484670 DOI: 10.1093/nar/gkad649] [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: 04/20/2023] [Revised: 07/14/2023] [Accepted: 07/28/2023] [Indexed: 08/08/2023] Open
Abstract
In eukaryotic messenger RNAs, the 5' cap structure binds to the translation initiation factor 4E to facilitate early stages of translation. Although many plant viruses lack the 5' cap structure, some contain cap-independent translation elements (CITEs) in their 3' untranslated region. The PTE (Panicum mosaic virus translation element) class of CITEs contains a G-rich asymmetric bulge and a C-rich helical junction that were proposed to interact via formation of a pseudoknot. SHAPE analysis of PTE homologs reveals a highly reactive guanosine residue within the G-rich region proposed to mediate eukaryotic initiation factor 4E (eIF4E) recognition. Here we have obtained the crystal structure of the PTE from Pea enation mosaic virus 2 (PEMV2) RNA in complex with our structural chaperone, Fab BL3-6. The structure reveals that the G-rich and C-rich regions interact through a complex network of interactions distinct from those expected for a pseudoknot. The motif, which contains a short parallel duplex, provides a structural mechanism for how the guanosine is extruded from the core stack to enable eIF4E recognition. Homologous PTE elements harbor a G-rich bulge and a three-way junction and exhibit covariation at crucial positions, suggesting that the PEMV2 tertiary architecture is conserved among these homologs.
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Affiliation(s)
- Anna Lewicka
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Christina Roman
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Stacey Jones
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Michael Disare
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Joseph A Piccirilli
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
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14
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Koloniuk I, Matyášová A, Brázdová S, Veselá J, Přibylová J, Várallyay E, Fránová J. Analysis of Virus-Derived siRNAs in Strawberry Plants Co-Infected with Multiple Viruses and Their Genotypes. PLANTS (BASEL, SWITZERLAND) 2023; 12:2564. [PMID: 37447124 DOI: 10.3390/plants12132564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/15/2023]
Abstract
Plants can be infected with multiple viruses. High-throughput sequencing tools have enabled numerous discoveries of multi-strain infections, when more than one viral strain or divergent genomic variant infects a single plant. Here, we investigated small interfering RNAs (siRNAs) in a single strawberry plant co-infected with several strains of strawberry mottle virus (SMoV), strawberry crinkle virus (SCV) and strawberry virus 1 (StrV-1). A range of plants infected with subsets of the initial viral species and strains that were obtained by aphid-mediated transmission were also evaluated. Using high-throughput sequencing, we characterized the small RNA fractions associated with different genotypes of these three viruses and determined small RNA hotspot regions in viral genomes. A comparison of virus-specific siRNA (vsiRNA) abundance with relative viral concentrations did not reveal any consistent agreement. Strawberry mottle virus strains exhibiting considerable variations in concentrations were found to be associated with comparable quantities of vsiRNAs. Additionally, by estimating the specificity of siRNAs to different viral strains, we observed that a substantial pool of vsiRNAs could target all SMoV strains, while strain-specific vsiRNAs predominantly targeted rhabdoviruses, SCV and StrV-1. This highlights the intricate nature and potential interference of the antiviral response within a single infected plant when multiple viruses are present.
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Affiliation(s)
- Igor Koloniuk
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
| | - Alena Matyášová
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
| | - Sára Brázdová
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
- Faculty of Agriculture, University of South Bohemia, 370 05 Ceske Budejovice, Czech Republic
| | - Jana Veselá
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
| | - Jaroslava Přibylová
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
| | - Eva Várallyay
- Genomics Research Group, Institute of Plant Protection, Department of Plant Pathology, Hungarian University of Agriculture and Life Sciences, Szent-Gyorgyi Albert Street 4, 2100 Gödöllő, Hungary
| | - Jana Fránová
- Institute of Plant Molecular Biology, Department of Plant Virology, Biology Centre CAS, 370 05 Ceske Budejovice, Czech Republic
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15
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Zhou X, Du Z, Huang X. A potential long-range RNA-RNA interaction in the HIV-1 RNA. J Biomol Struct Dyn 2023; 41:14968-14976. [PMID: 36863767 DOI: 10.1080/07391102.2023.2184639] [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: 07/03/2022] [Accepted: 02/19/2023] [Indexed: 03/04/2023]
Abstract
It is well-established that viral and cellular mRNAs alike harbour functional long-range intra-molecular RNA-RNA interactions. Despite the biological importance of such interactions, their identification and characterization remain challenging. Here we present a computational method for the identification of certain kinds of long-range intra-molecular RNA-RNA interactions involving the loop nucleotides of a hairpin loop. Using the computational method, we analysed 4272 HIV-1 genomic mRNAs. A potential long-range intra-molecular RNA-RNA interaction within the HIV-1 genomic RNA was identified. The long-range interaction is mediated by a kissing loop structure between two stem-loops of the previously reported SHAPE-based secondary structure of the entire HIV-1 genome. Structural modelling studies were carried out to show that the kissing loop structure not only is sterically feasible, but also contains a conserved RNA structural motif often found in compact RNA pseudoknots. The computational method should be generally applicable to the identification of potential long-range intra-molecular RNA-RNA interactions in any viral or cellular mRNA sequence.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Xia Zhou
- School of Chemical and Biomolecular Sciences, Southern Illinois University at Carbondale, Carbondale, IL, USA
| | - Zhihua Du
- School of Chemical and Biomolecular Sciences, Southern Illinois University at Carbondale, Carbondale, IL, USA
| | - Xiaolan Huang
- School of Computing, Southern Illinois University at Carbondale, Carbondale, IL, USA
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16
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Liu Y, Cui J, Hoffman AR, Hu JF. Eukaryotic translation initiation factor eIF4G2 opens novel paths for protein synthesis in development, apoptosis and cell differentiation. Cell Prolif 2023; 56:e13367. [PMID: 36547008 PMCID: PMC9977666 DOI: 10.1111/cpr.13367] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/21/2022] [Accepted: 11/04/2022] [Indexed: 12/24/2022] Open
Abstract
Protein translation is a critical regulatory event involved in nearly all physiological and pathological processes. Eukaryotic translation initiation factors are dedicated to translation initiation, the most highly regulated stage of protein synthesis. Eukaryotic translation initiation factor 4G2 (eIF4G2, also called p97, NAT1 and DAP5), an eIF4G family member that lacks the binding sites for 5' cap binding protein eIF4E, is widely considered to be a key factor for internal ribosome entry sites (IRESs)-mediated cap-independent translation. However, recent findings demonstrate that eIF4G2 also supports many other translation initiation pathways. In this review, we summarize the role of eIF4G2 in a variety of cap-independent and -dependent translation initiation events. Additionally, we also update recent findings regarding the role of eIF4G2 in apoptosis, cell survival, cell differentiation and embryonic development. These studies reveal an emerging new picture of how eIF4G2 utilizes diverse translational mechanisms to regulate gene expression.
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Affiliation(s)
- Yudi Liu
- Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education, Cancer Center, First Hospital, Jilin University, Changchun, Jilin, P.R. China
| | - Jiuwei Cui
- Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education, Cancer Center, First Hospital, Jilin University, Changchun, Jilin, P.R. China
| | - Andrew R Hoffman
- Stanford University Medical School, VA Palo Alto Health Care System, Palo Alto, California, USA
| | - Ji-Fan Hu
- Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education, Cancer Center, First Hospital, Jilin University, Changchun, Jilin, P.R. China.,Stanford University Medical School, VA Palo Alto Health Care System, Palo Alto, California, USA
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17
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Bera S, Ilyas M, Mikkelsen AA, Simon AE. Conserved Structure Associated with Different 3′CITEs Is Important for Translation of Umbraviruses. Viruses 2023; 15:v15030638. [PMID: 36992347 PMCID: PMC10051134 DOI: 10.3390/v15030638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/17/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
The cap-independent translation of plus-strand RNA plant viruses frequently depends on 3′ structures to attract translation initiation factors that bind ribosomal subunits or bind directly to ribosomes. Umbraviruses are excellent models for studying 3′ cap-independent translation enhancers (3′CITEs), as umbraviruses can have different 3′CITEs in the central region of their lengthy 3′UTRs, and most also have a particular 3′CITE (the T-shaped structure or 3′TSS) near their 3′ ends. We discovered a novel hairpin just upstream of the centrally located (known or putative) 3′CITEs in all 14 umbraviruses. These CITE-associated structures (CASs) have conserved sequences in their apical loops and at the stem base and adjacent positions. In 11 umbraviruses, CASs are preceded by two small hairpins joined by a putative kissing loop interaction (KL). Converting the conserved 6-nt apical loop to a GNRA tetraloop in opium poppy mosaic virus (OPMV) and pea enation mosaic virus 2 (PEMV2) enhanced translation of genomic (g)RNA, but not subgenomic (sg)RNA reporter constructs, and significantly repressed virus accumulation in Nicotiana benthamiana. Other alterations throughout OPMV CAS also repressed virus accumulation and only enhanced sgRNA reporter translation, while mutations in the lower stem repressed gRNA reporter translation. Similar mutations in the PEMV2 CAS also repressed accumulation but did not significantly affect gRNA or sgRNA reporter translation, with the exception of deletion of the entire hairpin, which only reduced translation of the gRNA reporter. OPMV CAS mutations had little effect on the downstream BTE 3′CITE or upstream KL element, while PEMV2 CAS mutations significantly altered KL structures. These results introduce an additional element associated with different 3′CITEs that differentially affect the structure and translation of different umbraviruses.
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18
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Kim B, Seol J, Kim YK, Lee JB. Single-molecule visualization of mRNA circularization during translation. Exp Mol Med 2023; 55:283-289. [PMID: 36720916 PMCID: PMC9981743 DOI: 10.1038/s12276-023-00933-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/04/2022] [Accepted: 12/04/2022] [Indexed: 02/02/2023] Open
Abstract
Translation is mediated by precisely orchestrated sequential interactions among translation initiation components, mRNA, and ribosomes. Biochemical, structural, and genetic techniques have revealed the fundamental mechanism that determines what occurs and when, where and in what order. Most mRNAs are circularized via the eIF4E-eIF4G-PABP interaction, which stabilizes mRNAs and enhances translation by recycling ribosomes. However, studies using single-molecule fluorescence imaging have allowed for the visualization of complex data that opposes the traditional "functional circularization" theory. Here, we briefly introduce single-molecule techniques applied to studies on mRNA circularization and describe the results of in vitro and live-cell imaging. Finally, we discuss relevant insights and questions gained from single-molecule research related to translation.
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Affiliation(s)
- Byungju Kim
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jincheol Seol
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, 37673, Republic of Korea
| | - Yoon Ki Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Jong-Bong Lee
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang, 37673, Republic of Korea.
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, 37673, Republic of Korea.
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19
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Bwalya J, Kim KH. The Crucial Role of Chloroplast-Related Proteins in Viral Genome Replication and Host Defense against Positive-Sense Single-Stranded RNA Viruses. THE PLANT PATHOLOGY JOURNAL 2023; 39:28-38. [PMID: 36760047 PMCID: PMC9929168 DOI: 10.5423/ppj.rw.10.2022.0139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
Plant viruses are responsible for worldwide production losses of numerous economically important crops. The most common plant RNA viruses are positivesense single-stranded RNA viruses [(+)ss RNA viruses]. These viruses have small genomes that encode a limited number of proteins. The viruses depend on their host's machinery for the replication of their RNA genome, assembly, movement, and attraction to the vectors for dispersal. Recently researchers have reported that chloroplast proteins are crucial for replicating (+)ss plant RNA viruses. Some chloroplast proteins, including translation initiation factor [eIF(iso)4E] and 75 DEAD-box RNA helicase RH8, help viruses fulfill their infection cycle in plants. In contrast, other chloroplast proteins such as PAP2.1, PSaC, and ATPsyn-α play active roles in plant defense against viruses. This is also consistent with the idea that reactive oxygen species, salicylic acid, jasmonic acid, and abscisic acid are produced in chloroplast. However, knowledge of molecular mechanisms and functions underlying these chloroplast host factors during the virus infection is still scarce and remains largely unknown. Our review briefly summarizes the latest knowledge regarding the possible role of chloroplast in plant virus replication, emphasizing chloroplast-related proteins. We have highlighted current advances regarding chloroplast-related proteins' role in replicating plant (+)ss RNA viruses.
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Affiliation(s)
- John Bwalya
- Department of Agriculture Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Kook-Hyung Kim
- Department of Agriculture Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826,
Korea
- Research of Institute Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
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20
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Novel 3' Proximal Replication Elements in Umbravirus Genomes. Viruses 2022; 14:v14122615. [PMID: 36560619 PMCID: PMC9780821 DOI: 10.3390/v14122615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022] Open
Abstract
The 3' untranslated regions (UTRs) of positive-strand RNA plant viruses commonly contain elements that promote viral replication and translation. The ~700 nt 3'UTR of umbravirus pea enation mosaic virus 2 (PEMV2) contains three 3' cap-independent translation enhancers (3'CITEs), including one (PTE) found in members of several genera in the family Tombusviridae and another (the 3'TSS) found in numerous umbraviruses and several carmoviruses. In addition, three 3' terminal replication elements are found in nearly every umbravirus and carmovirus. For this report, we have identified a set of three hairpins and a putative pseudoknot, collectively termed "Trio", that are exclusively found in a subset of umbraviruses and are located just upstream of the 3'TSS. Modification of these elements had no impact on viral translation in wheat germ extracts or in translation of luciferase reporter constructs in vivo. In contrast, Trio hairpins were critical for viral RNA accumulation in Arabidopsis thaliana protoplasts and for replication of a non-autonomously replicating replicon using a trans-replication system in Nicotiana benthamiana leaves. Trio and other 3' terminal elements involved in viral replication are highly conserved in umbraviruses possessing different classes of upstream 3'CITEs, suggesting conservation of replication mechanisms among umbraviruses despite variation in mechanisms for translation enhancement.
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21
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Lappe RR, Elmore MG, Lozier ZR, Jander G, Miller WA, Whitham SA. Metagenomic identification of novel viruses of maize and teosinte in North America. BMC Genomics 2022; 23:767. [DOI: 10.1186/s12864-022-09001-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/10/2022] [Indexed: 11/25/2022] Open
Abstract
Abstract
Background
Maize-infecting viruses are known to inflict significant agronomic yield loss throughout the world annually. Identification of known or novel causal agents of disease prior to outbreak is imperative to preserve food security via future crop protection efforts. Toward this goal, a large-scale metagenomic approach utilizing high throughput sequencing (HTS) was employed to identify novel viruses with the potential to contribute to yield loss of graminaceous species, particularly maize, in North America.
Results
Here we present four novel viruses discovered by HTS and individually validated by Sanger sequencing. Three of these viruses are RNA viruses belonging to either the Betaflexiviridae or Tombusviridae families. Additionally, a novel DNA virus belonging to the Geminiviridae family was discovered, the first Mastrevirus identified in North American maize.
Conclusions
Metagenomic studies of crop and crop-related species such as this may be useful for the identification and surveillance of known and novel viral pathogens of crops. Monitoring related species may prove useful in identifying viruses capable of infecting crops due to overlapping insect vectors and viral host-range to protect food security.
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22
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Miras M, Aranda MA, Truniger V. Different RNA Elements Control Viral Protein Synthesis in Polerovirus Isolates Evolved in Separate Geographical Regions. Int J Mol Sci 2022; 23:ijms232012503. [PMID: 36293360 PMCID: PMC9603980 DOI: 10.3390/ijms232012503] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/13/2022] [Accepted: 10/15/2022] [Indexed: 12/05/2022] Open
Abstract
Most plant viruses lack the 5′-cap and 3′-poly(A) structures, which are common in their host mRNAs, and are crucial for translation initiation. Thus, alternative translation initiation mechanisms were identified for viral mRNAs, one of these being controlled by an RNA element in their 3′-ends that is able to enhance mRNA cap-independent translation (3′-CITE). The 3′-CITEs are modular and transferable RNA elements. In the case of poleroviruses, the mechanism of translation initiation of their RNAs in the host cell is still unclear; thus, it was studied for one of its members, cucurbit aphid-borne yellows virus (CABYV). We determined that efficient CABYV RNA translation requires the presence of a 3′-CITE in its 3′-UTR. We showed that this 3′-CITE requires the presence of the 5′-UTR in cis for its eIF4E-independent activity. Efficient virus multiplication depended on 3′-CITE activity. In CABYV isolates belonging to the three phylogenetic groups identified so far, the 3′-CITEs differ, and recombination prediction analyses suggest that these 3′-CITEs have been acquired through recombination with an unknown donor. Since these isolates have evolved in different geographical regions, this may suggest that their respective 3′-CITEs are possibly better adapted to each region. We propose that translation of other polerovirus genomes may also be 3′-CITE-dependent.
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Affiliation(s)
- Manuel Miras
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), 30100 Murcia, Spain
- Department of Molecular Physiology, Heinrich Heine University of Düsseldorf, 40225 Düsseldorf, Germany
| | - Miguel A. Aranda
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), 30100 Murcia, Spain
| | - Verónica Truniger
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), 30100 Murcia, Spain
- Correspondence:
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23
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Berzal-Herranz A, Berzal-Herranz B, Ramos-Lorente SE, Romero-López C. The Genomic 3′ UTR of Flaviviruses Is a Translation Initiation Enhancer. Int J Mol Sci 2022; 23:ijms23158604. [PMID: 35955738 PMCID: PMC9369090 DOI: 10.3390/ijms23158604] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 07/24/2022] [Accepted: 07/31/2022] [Indexed: 12/21/2022] Open
Abstract
Viruses rely on the cellular machinery of host cells to synthesize their proteins, and have developed different mechanisms enabling them to compete with cellular mRNAs for access to it. The genus Flavivirus is a large group of positive, single-stranded RNA viruses that includes several important human pathogens, such as West Nile, Dengue and Zika virus. The genome of flaviviruses bears a type 1 cap structure at its 5′ end, needed for the main translation initiation mechanism. Several members of the genus also use a cap-independent translation mechanism. The present work provides evidence that the WNV 5′ end also promotes a cap-independent translation initiation mechanism in mammalian and insect cells, reinforcing the hypothesis that this might be a general strategy of flaviviruses. In agreement with previous reports, we show that this mechanism depends on the presence of the viral genomic 3′ UTR. The results also show that the 3′ UTR of the WNV genome enhances translation of the cap-dependent mechanism. Interestingly, WNV 3′ UTR can be replaced by the 3′ UTR of other flaviviruses and the translation enhancing effect is maintained, suggesting a molecular mechanism that does not involve direct RNA-RNA interactions to be at work. In addition, the deletion of specific structural elements of the WNV 3′ UTR leads to increased cap-dependent and cap-independent translation. These findings suggest the 3′ UTR to be involved in a fine-tuned translation regulation mechanism.
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24
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Quito-Avila DF, Reyes-Proaño EG, Mendoza A, Margaria P, Menzel W, Bera S, Simon AE. Two new umbravirus-like associated RNAs (ulaRNAs) discovered in maize and johnsongrass from Ecuador. Arch Virol 2022; 167:2093-2098. [PMID: 35821148 DOI: 10.1007/s00705-022-05525-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/22/2022] [Indexed: 11/02/2022]
Abstract
Two new umbravirus-like associated RNAs (ulaRNAs) were found, respectively, in maize and Johnsongrass samples from Ecuador. The complete sequences consist of 3,053 and 3,025 nucleotides, respectively, and contain four open reading frames (ORFs). Their genome sequences were 58% identical to each other and 28 to 60% identical to the most closely related viruses. Phylogenetic analysis using full genome sequences and amino acid sequence of the RNA-dependent-RNA polymerase (RdRp) placed both sequences in a clade sharing the most recent common ancestor with ulaRNAs from sugarcane and maize, suggesting that they belong to a monophyletic grass-infecting lineage. Their terminal regions exhibit features common to umbraviruses and ulaRNAs.
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Affiliation(s)
- Diego F Quito-Avila
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Km 30.5 Vía Perimetral Campus Gustavo Galindo, Guayaquil, Ecuador. .,Centro de Investigaciones Biotecnológicas del Ecuador, CIBE, Escuela Superior Politécnica del Litoral, Km 30.5 Vía Perimetral Campus Gustavo Galindo, Guayaquil, Ecuador.
| | - Edison G Reyes-Proaño
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Km 30.5 Vía Perimetral Campus Gustavo Galindo, Guayaquil, Ecuador
| | - Alma Mendoza
- INIAP, Estación Experimental Portoviejo, Km 12, Via a Santa Ana, Manabí, Ecuador
| | - Paolo Margaria
- Plant Virus Department, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7 B, Braunschweig, Germany
| | - Wulf Menzel
- Plant Virus Department, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7 B, Braunschweig, Germany
| | - Sayanta Bera
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD, 20742, USA
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD, 20742, USA
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25
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Sáez Moreno D, Udi Q, Azeredo J, Domingues L. Towards T7 RNA polymerase (T7RNAP)-based expression system in yeast: challenges and opportunities. Bioengineered 2022; 13:14947-14959. [PMID: 37105766 DOI: 10.1080/21655979.2023.2180579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
During the last decades, we have witnessed unprecedented advances in biological engineering and synthetic biology. These disciplines aim to take advantage of gene pathway regulation and gene expression in different organisms, to enable cells to perform desired functions. Yeast has been widely utilized as a model for the study of eukaryotic protein expression while bacteriophage T7RNAP and its promoter constitute the preferred system for prokaryotic protein expression (such as pET-based expression systems). The ability to integrate a T7RNAP-based expression system in yeast could allow for a better understanding of gene regulation in eukaryotic cells, and potentially increase the efficiency and processivity of yeast as an expression system. However, the attempts for the creation of such a system have been unsuccessful to date. This review aims to: (i) summarize the efforts that, for many years, have been devoted to the creation of a T7RNAP-based yeast expression system and ii) provide an overview of the latest advances in knowledge of eukaryotic transcription and translation that could lead to the construction of a successful T7RNAP expression system in yeast. The completion of this new expression system would allow to further expand the toolkit of yeast in synthetic biology and ultimately contribute to boost yeast usage as a key cell factory in sustainable biorefinery and circular economy.
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Affiliation(s)
- David Sáez Moreno
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
| | - Qimron Udi
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Joana Azeredo
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal
- LABBELS-Associate Laboratory, 4835-198, Guimarães, Braga, Portugal
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Biziaev NS, Egorova TV, Alkalaeva EZ. Dynamics of Eukaryotic mRNA Structure during Translation. Mol Biol 2022. [DOI: 10.1134/s0026893322030037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Conserved RNA secondary structure in Cherry virus A 5'-UTR associated with translation regulation. Virol J 2022; 19:91. [PMID: 35619168 PMCID: PMC9137147 DOI: 10.1186/s12985-022-01824-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 05/18/2022] [Indexed: 11/14/2022] Open
Abstract
Background A variety of cis-acting RNA elements with structures in the 5′- or 3′-untranslated region (UTR) of viral genomes play key roles in viral translation. Cherry virus A (CVA) is a member of the genus Capillovirus in the family Betaflexiviridae. It has a positive single-stranded RNA genome of ~ 7400 nucleotides (nt). The length of the CVA 5′-UTR is ~ 100 nt; however, the function of this long UTR has not yet been reported. Methods Molecular and phylogenetic analyses were performed on 75 CVA sequences, which could be divided into four groups, and the RNA secondary structure was predicted in four CVA 5′-UTR types. These four CVA 5′-UTR types were then inserted upstream of the firefly luciferase reporter gene FLuc (FLuc), and in vitro translation of the corresponding transcripts was evaluated using wheat germ extract (WGE). Then, in-line structure probing was performed to reveal the conserved RNA structures in CVA-5′UTR. Results The four CVA 5′-UTR types appeared to have a conserved RNA structure, and the FLuc construct containing these four CVA 5′-UTR types increased the translation of FLuc by 2–3 folds, suggesting weak translation enhancement activity. Mutations in CVA 5′-UTR suppressed translation, suggesting that the conserved RNA structure was important for function. Conclusion The conserved RNA secondary structure was identified by structural evolution analysis of different CVA isolates and was found to regulate translation.
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Powell P, Bhardwaj U, Goss D. Eukaryotic initiation factor 4F promotes a reorientation of eukaryotic initiation factor 3 binding on the 5' and the 3' UTRs of barley yellow dwarf virus mRNA. Nucleic Acids Res 2022; 50:4988-4999. [PMID: 35446425 PMCID: PMC9122605 DOI: 10.1093/nar/gkac284] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/06/2022] [Accepted: 04/13/2022] [Indexed: 11/14/2022] Open
Abstract
Viral mRNAs that lack a 5′ m7GTP cap and a 3′ poly-A tail rely on structural elements in their untranslated regions (UTRs) to form unique RNA-protein complexes that regulate viral translation. Recent studies of the barley yellow dwarf virus (BYDV) have revealed eukaryotic initiation factor 3 (eIF3) plays a significant role in facilitating communication between its 5′ and 3′ UTRs by binding both UTRs simultaneously. This report uses in vitro translation assays, fluorescence anisotropy binding assays, and selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) footprinting to identify secondary structures that are selectively interacting with eIF3. SHAPE data also show that eIF3 alters its interaction with BYDV structures when another factor crucial for BYDV translation, eIF4F, is introduced by the 3′ BYDV translational enhancer (BTE). The observed BTE and eIF4F-induced shift of eIF3 position on the 5’ UTR and the translational effects of altering eIF3-binding structures (SLC and SLII) support a new model for BYDV translation initiation that requires the reorientation of eIF3 on BYDV UTRs. This eIF3 function in BYDV translation initiation is both reminiscent of and distinct from eIF3–RNA interactions found in other non-canonically translating mRNAs (e.g. HCV). This characterization of a new role in translation initiation expands the known functionality of eIF3 and may be broadly applicable to other non-canonically translating mRNAs.
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Affiliation(s)
- Paul Powell
- Department of Chemistry, Hunter College, CUNY, New York, NY 10065, USA.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Usha Bhardwaj
- Department of Chemistry, Hunter College, CUNY, New York, NY 10065, USA
| | - Dixie Goss
- Department of Chemistry, Hunter College, CUNY, New York, NY 10065, USA.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA.,Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
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Leppek K, Byeon GW, Kladwang W, Wayment-Steele HK, Kerr CH, Xu AF, Kim DS, Topkar VV, Choe C, Rothschild D, Tiu GC, Wellington-Oguri R, Fujii K, Sharma E, Watkins AM, Nicol JJ, Romano J, Tunguz B, Diaz F, Cai H, Guo P, Wu J, Meng F, Shi S, Participants E, Dormitzer PR, Solórzano A, Barna M, Das R. Combinatorial optimization of mRNA structure, stability, and translation for RNA-based therapeutics. Nat Commun 2022; 13:1536. [PMID: 35318324 PMCID: PMC8940940 DOI: 10.1038/s41467-022-28776-w] [Citation(s) in RCA: 109] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 02/07/2022] [Indexed: 02/07/2023] Open
Abstract
Therapeutic mRNAs and vaccines are being developed for a broad range of human diseases, including COVID-19. However, their optimization is hindered by mRNA instability and inefficient protein expression. Here, we describe design principles that overcome these barriers. We develop an RNA sequencing-based platform called PERSIST-seq to systematically delineate in-cell mRNA stability, ribosome load, as well as in-solution stability of a library of diverse mRNAs. We find that, surprisingly, in-cell stability is a greater driver of protein output than high ribosome load. We further introduce a method called In-line-seq, applied to thousands of diverse RNAs, that reveals sequence and structure-based rules for mitigating hydrolytic degradation. Our findings show that highly structured "superfolder" mRNAs can be designed to improve both stability and expression with further enhancement through pseudouridine nucleoside modification. Together, our study demonstrates simultaneous improvement of mRNA stability and protein expression and provides a computational-experimental platform for the enhancement of mRNA medicines.
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Affiliation(s)
- Kathrin Leppek
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Gun Woo Byeon
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Wipapat Kladwang
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
| | | | - Craig H Kerr
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Adele F Xu
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Do Soon Kim
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
| | - Ved V Topkar
- Program in Biophysics, Stanford University, Stanford, CA, 94305, USA
| | - Christian Choe
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Daphna Rothschild
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Gerald C Tiu
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | | | - Kotaro Fujii
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
| | - Eesha Sharma
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
| | - Andrew M Watkins
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
| | - John J Nicol
- Eterna Massive Open Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Jonathan Romano
- Eterna Massive Open Laboratory, Stanford University, Stanford, CA, 94305, USA
- Department of Computer Science and Engineering, State University of New York at Buffalo, Buffalo, New York, 14260, USA
| | - Bojan Tunguz
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA
- NVIDIA Corporation, 2788 San Tomas Expy, Santa Clara, CA, 95051, USA
| | - Fernando Diaz
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Hui Cai
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Pengbo Guo
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Jiewei Wu
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Fanyu Meng
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Shuai Shi
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
| | - Eterna Participants
- Eterna Massive Open Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Philip R Dormitzer
- Pfizer Vaccine Research and Development, Pearl River, NY, USA
- GlaxoSmithKline, 1000 Winter St., Waltham, MA, 02453, USA
| | | | - Maria Barna
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA.
- Program in Biophysics, Stanford University, Stanford, CA, 94305, USA.
- Eterna Massive Open Laboratory, Stanford University, Stanford, CA, 94305, USA.
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30
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Identification of Novel 5' and 3' Translation Enhancers in Umbravirus-Like Coat Protein-Deficient RNA Replicons. J Virol 2022; 96:e0173621. [PMID: 35297668 DOI: 10.1128/jvi.01736-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Translation of plant plus-strand RNA viral genomes that lack a 5' cap frequently requires the use of cap-independent translation enhancers (CITEs) located in or near the 3' untranslated region (UTR). 3'CITEs are grouped based on secondary structure and ability to interact with different translation initiation factors or ribosomal subunits, which assemble a complex at the 3' end that is nearly always transferred to the 5' end via a long-distance kissing-loop interaction between sequences in the 3'CITE and 5' hairpins. We report here the identification of a novel 3'CITE in coat protein-deficient RNA replicons that are related to umbraviruses. Umbra-like associated RNAs (ulaRNAs), such as citrus yellow vein-associated virus (CYVaV), are a new type of subviral RNA that do not encode movement proteins, coat proteins, or silencing suppressors but can independently replicate using their encoded RNA-dependent RNA polymerase. An extended hairpin structure containing multiple internal loops in the 3' UTR of CYVaV is strongly conserved in the most closely related ulaRNAs and structurally resembles an I-shaped structure (ISS) 3'CITE. However, unlike ISS, the CYVaV structure binds to eIF4G and no long-distance interaction is discernible between the CYVaV ISS-like structure and sequences at or near the 5' end. We also report that the ∼30-nucleotide (nt) 5' terminal hairpin of CYVaV and related ulaRNAs can enhance translation of reporter constructs when associated with either the CYVaV 3'CITE or the 3'CITEs of umbravirus pea enation mosaic virus (PEMV2) and even independent of a 3'CITE. These findings introduce a new type of 3'CITE and provide the first information on translation of ulaRNAs. IMPORTANCE Umbra-like associated RNAs (ulaRNAs) are a recently discovered type of subviral RNA that use their encoded RNA-dependent RNA polymerase for replication but do not encode any coat proteins, movement proteins, or silencing suppressors yet can be found in plants in the absence of any discernible helper virus. We report the first analysis of their translation using class 2 ulaRNA citrus yellow vein-associated virus (CYVaV). CYVaV uses a novel eIF4G-binding I-shaped structure as its 3' cap-independent translation enhancer (3'CITE), which does not connect with the 5' end by a long-distance RNA:RNA interaction that is typical of 3'CITEs. ulaRNA 5' terminal hairpins can also enhance translation in association with cognate 3'CITEs or those of related ulaRNAs and, to a lesser extent, with 3'CITEs of umbraviruses, or even independent of a 3'CITE. These findings introduce a new type of 3'CITE and provide the first information on translation of ulaRNAs.
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Short 5' Untranslated Region Enables Optimal Translation of Plant Virus Tricistronic RNA via Leaky Scanning. J Virol 2022; 96:e0214421. [PMID: 35262378 DOI: 10.1128/jvi.02144-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Regardless of the general model of translation in eukaryotic cells, a number of studies suggested that many mRNAs encode multiple proteins. Leaky scanning, which supplies ribosomes to downstream open reading frames (ORFs) by readthrough of upstream ORFs, has great potential to translate polycistronic mRNAs. However, the mRNA elements controlling leaky scanning and their biological relevance have rarely been elucidated, with exceptions such as the Kozak sequence. Here, we have analyzed the strategy of a plant RNA virus to translate three movement proteins from a single RNA molecule through leaky scanning. The in planta and in vitro results indicate thatthe significantly shorter 5' untranslated region (UTR) of the most upstream ORF promotes leaky scanning, potentially fine-tuning the translation efficiency of the three proteins in a single RNA molecule to optimize viral propagation. Our results suggest that the remarkably short length of the leader sequence, like the Kozak sequence, is a translational regulatory element with a biologically important role, as previous studies have shown biochemically. IMPORTANCE Potexvirus, a group of plant viruses, infect a variety of crops, including cultivated crops. It has been thought that the three transition proteins that are essential for the cell-to-cell transfer of potexviruses are translated from two subgenomic RNAs, sgRNA1 and sgRNA2. However, sgRNA2 has not been clearly detected. In this study, we have shown that sgRNA1, but not sgRNA2, is the major translation template for the three movement proteins. In addition, we determined the transcription start site of sgRNA1 in flexiviruses and found that the efficiency of leaky scanning caused by the short 5' UTR of sgRNA1, a widely conserved feature, regulates the translation of the three movement proteins. When we tested the infection of viruses with mutations introduced into the length of the 5' UTR, we found that the movement efficiency of the virus was affected. Our results provide important additional information on the protein translation strategy of flexiviruses, including Potexvirus, and provide a basis for research on their control as well as the need to reevaluate the short 5' UTR as a translational regulatory element with an important role in vivo.
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Johnson PZ, Kasprzak WK, Shapiro BA, Simon AE. Structural characterization of a new subclass of panicum mosaic virus-like 3' cap-independent translation enhancer. Nucleic Acids Res 2022; 50:1601-1619. [PMID: 35104872 PMCID: PMC8860577 DOI: 10.1093/nar/gkac007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 12/29/2021] [Accepted: 01/29/2022] [Indexed: 11/29/2022] Open
Abstract
Canonical eukaryotic mRNA translation requires 5'cap recognition by initiation factor 4E (eIF4E). In contrast, many positive-strand RNA virus genomes lack a 5'cap and promote translation by non-canonical mechanisms. Among plant viruses, PTEs are a major class of cap-independent translation enhancers located in/near the 3'UTR that recruit eIF4E to greatly enhance viral translation. Previous work proposed a single form of PTE characterized by a Y-shaped secondary structure with two terminal stem-loops (SL1 and SL2) atop a supporting stem containing a large, G-rich asymmetric loop that forms an essential pseudoknot (PK) involving C/U residues located between SL1 and SL2. We found that PTEs with less than three consecutive cytidylates available for PK formation have an upstream stem-loop that forms a kissing loop interaction with the apical loop of SL2, important for formation/stabilization of PK. PKs found in both subclasses of PTE assume a specific conformation with a hyperreactive guanylate (G*) in SHAPE structure probing, previously found critical for binding eIF4E. While PTE PKs were proposed to be formed by Watson-Crick base-pairing, alternative chemical probing and 3D modeling indicate that the Watson-Crick faces of G* and an adjacent guanylate have high solvent accessibilities. Thus, PTE PKs are likely composed primarily of non-canonical interactions.
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Affiliation(s)
- Philip Z Johnson
- Department of Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD 20742, USA
| | - Wojciech K Kasprzak
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Bruce A Shapiro
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD 20742, USA
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33
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Translation of Plant RNA Viruses. Viruses 2021; 13:v13122499. [PMID: 34960768 PMCID: PMC8708638 DOI: 10.3390/v13122499] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 12/01/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
Plant RNA viruses encode essential viral proteins that depend on the host translation machinery for their expression. However, genomic RNAs of most plant RNA viruses lack the classical characteristics of eukaryotic cellular mRNAs, such as mono-cistron, 5′ cap structure, and 3′ polyadenylation. To adapt and utilize the eukaryotic translation machinery, plant RNA viruses have evolved a variety of translation strategies such as cap-independent translation, translation recoding on initiation and termination sites, and post-translation processes. This review focuses on advances in cap-independent translation and translation recoding in plant viruses.
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34
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Lin X, Fonseca MAS, Breunig JJ, Corona RI, Lawrenson K. In vivo discovery of RNA proximal proteins via proximity-dependent biotinylation. RNA Biol 2021; 18:2203-2217. [PMID: 34006179 PMCID: PMC8648264 DOI: 10.1080/15476286.2021.1917215] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/16/2021] [Accepted: 04/10/2021] [Indexed: 12/12/2022] Open
Abstract
RNA molecules function as messenger RNAs (mRNAs) that encode proteins and noncoding transcripts that serve as adaptor molecules, structural components, and regulators of genome organization and gene expression. Their function and regulation are largely mediated by RNA binding proteins (RBPs). Here we present RNA proximity labelling (RPL), an RNA-centric method comprising the endonuclease-deficient Type VI CRISPR-Cas protein dCas13b fused to engineered ascorbate peroxidase APEX2. RPL discovers target RNA proximal proteins in vivo via proximity-based biotinylation. RPL applied to U1 identified proteins involved in both U1 canonical and noncanonical functions. Profiling of poly(A) tail proximal proteins uncovered expected categories of RBPs and provided additional evidence for 5'-3' proximity and unexplored subcellular localizations of poly(A)+ RNA. Our results suggest that RPL allows rapid identification of target RNA binding proteins in native cellular contexts, and is expected to pave the way for discovery of novel RNA-protein interactions important for health and disease.
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Affiliation(s)
- Xianzhi Lin
- Cedars-Sinai Medical Center, Women’s Cancer Research Program at Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Marcos A. S. Fonseca
- Cedars-Sinai Medical Center, Women’s Cancer Research Program at Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Joshua J. Breunig
- Cedars-Sinai Medical Center, Board of Governors Regenerative Medicine Institute, Los Angeles, CA, USA
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Cedars-Sinai Medical Center, Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Rosario I. Corona
- Cedars-Sinai Medical Center, Women’s Cancer Research Program at Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Kate Lawrenson
- Cedars-Sinai Medical Center, Women’s Cancer Research Program at Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Cedars-Sinai Medical Center, Center for Bioinformatics and Functional Genomics, Samuel Oschin Comprehensive Cancer Institute, Los Angeles, CA, USA
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Bao C, Ermolenko DN. Ribosome as a Translocase and Helicase. BIOCHEMISTRY (MOSCOW) 2021; 86:992-1002. [PMID: 34488575 PMCID: PMC8294220 DOI: 10.1134/s0006297921080095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
During protein synthesis, ribosome moves along mRNA to decode one codon after the other. Ribosome translocation is induced by a universally conserved protein, elongation factor G (EF-G) in bacteria and elongation factor 2 (EF-2) in eukaryotes. EF-G-induced translocation results in unwinding of the intramolecular secondary structures of mRNA by three base pairs at a time that renders the translating ribosome a processive helicase. Professor Alexander Sergeevich Spirin has made numerous seminal contributions to understanding the molecular mechanism of translocation. Here, we review Spirin's insights into the ribosomal translocation and recent advances in the field that stemmed from Spirin's pioneering work. We also discuss key remaining challenges in studies of translocase and helicase activities of the ribosome.
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Affiliation(s)
- Chen Bao
- Department of Biochemistry & Biophysics, School of Medicine and Dentistry and Center for RNA Biology, University of Rochester, Rochester, NY, USA.
| | - Dmitri N Ermolenko
- Department of Biochemistry & Biophysics, School of Medicine and Dentistry and Center for RNA Biology, University of Rochester, Rochester, NY, USA.
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Brown SL, Garrison DJ, May JP. Phase separation of a plant virus movement protein and cellular factors support virus-host interactions. PLoS Pathog 2021; 17:e1009622. [PMID: 34543360 PMCID: PMC8483311 DOI: 10.1371/journal.ppat.1009622] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 09/30/2021] [Accepted: 09/13/2021] [Indexed: 12/27/2022] Open
Abstract
Both cellular and viral proteins can undergo phase separation and form membraneless compartments that concentrate biomolecules. The p26 movement protein from single-stranded, positive-sense Pea enation mosaic virus 2 (PEMV2) separates into a dense phase in nucleoli where p26 and related orthologues must interact with fibrillarin (Fib2) as a pre-requisite for systemic virus movement. Using in vitro assays, viral ribonucleoprotein complexes containing p26, Fib2, and PEMV2 genomic RNAs formed droplets that may provide the basis for self-assembly in planta. Mutating basic p26 residues (R/K-G) blocked droplet formation and partitioning into Fib2 droplets or the nucleolus and prevented systemic movement of a Tobacco mosaic virus (TMV) vector in Nicotiana benthamiana. Mutating acidic residues (D/E-G) reduced droplet formation in vitro, increased nucleolar retention 6.5-fold, and prevented systemic movement of TMV, thus demonstrating that p26 requires electrostatic interactions for droplet formation and charged residues are critical for nucleolar trafficking and virus movement. p26 readily partitioned into stress granules (SGs), which are membraneless compartments that assemble by clustering of the RNA binding protein G3BP following stress. G3BP is upregulated during PEMV2 infection and over-expression of G3BP restricted PEMV2 RNA accumulation >20-fold. Deletion of the NTF2 domain that is required for G3BP condensation restored PEMV2 RNA accumulation >4-fold, demonstrating that phase separation enhances G3BP antiviral activity. These results indicate that p26 partitions into membraneless compartments with either proviral (Fib2) or antiviral (G3BP) factors.
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Affiliation(s)
- Shelby L. Brown
- Department of Cell and Molecular Biology and Biochemistry, School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Dana J. Garrison
- Department of Cell and Molecular Biology and Biochemistry, School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Jared P. May
- Department of Cell and Molecular Biology and Biochemistry, School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
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Langeberg CJ, Sherlock ME, MacFadden A, Kieft JS. An expanded class of histidine-accepting viral tRNA-like structures. RNA (NEW YORK, N.Y.) 2021; 27:653-664. [PMID: 33811147 PMCID: PMC8127992 DOI: 10.1261/rna.078550.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/30/2021] [Indexed: 05/12/2023]
Abstract
Structured RNA elements are common in the genomes of RNA viruses, often playing critical roles during viral infection. Some viral RNA elements use forms of tRNA mimicry, but the diverse ways this mimicry can be achieved are poorly understood. Histidine-accepting tRNA-like structures (TLSHis) are examples found at the 3' termini of some positive-sense single-stranded RNA (+ssRNA) viruses where they interact with several host proteins, induce histidylation of the RNA genome, and facilitate processes important for infection, to include genome replication. As only five TLSHis examples had been reported, we explored the possible larger phylogenetic distribution and diversity of this TLS class using bioinformatic approaches. We identified many new examples of TLSHis, yielding a rigorous consensus sequence and secondary structure model that we validated by chemical probing of representative TLSHis RNAs. We confirmed new examples as authentic TLSHis by demonstrating their ability to be histidylated in vitro, then used mutational analyses to imply a tertiary interaction that is likely analogous to the D- and T-loop interaction found in canonical tRNAs. These results expand our understanding of how diverse RNA sequences achieve tRNA-like structure and function in the context of viral RNA genomes and lay the groundwork for high-resolution structural studies of tRNA mimicry by histidine-accepting TLSs.
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Affiliation(s)
- Conner J Langeberg
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Madeline E Sherlock
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Andrea MacFadden
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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38
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Opium Poppy Mosaic Virus Has an Xrn-Resistant, Translated Subgenomic RNA and a BTE 3' CITE. J Virol 2021; 95:JVI.02109-20. [PMID: 33597210 DOI: 10.1128/jvi.02109-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/08/2021] [Indexed: 12/30/2022] Open
Abstract
Opium poppy mosaic virus (OPMV) is a recently discovered umbravirus in the family Tombusviridae OPMV has a plus-sense genomic RNA (gRNA) of 4,241 nucleotides (nt) from which replication protein p35 and p35 extension product p98, the RNA-dependent RNA polymerase (RdRp), are expressed. Movement proteins p27 (long distance) and p28 (cell to cell) are expressed from a 1,440-nt subgenomic RNA (sgRNA2). A highly conserved structure was identified just upstream from the sgRNA2 transcription start site in all umbraviruses, which includes a carmovirus consensus sequence, denoting generation by an RdRp-mediated mechanism. OPMV also has a second sgRNA of 1,554 nt (sgRNA1) that starts just downstream of a canonical exoribonuclease-resistant sequence (xrRNAD). sgRNA1 codes for a 30-kDa protein in vitro that is in frame with p28 and cannot be synthesized in other umbraviruses. Eliminating sgRNA1 or truncating the p30 open reading frame (ORF) without affecting p28 substantially reduced accumulation of OPMV gRNA, suggesting a functional role for the protein. The 652-nt 3' untranslated region of OPMV contains two 3' cap-independent translation enhancers (3' CITEs), a T-shaped structure (TSS) near its 3' end, and a Barley yellow dwarf virus-like translation element (BTE) in the central region. Only the BTE is functional in luciferase reporter constructs containing gRNA or sgRNA2 5' sequences in vivo, which differs from how umbravirus 3' CITEs were used in a previous study. Similarly to most 3' CITEs, the OPMV BTE links to the 5' end via a long-distance RNA-RNA interaction. Analysis of 14 BTEs revealed additional conserved sequences and structural features beyond the previously identified 17-nt conserved sequence.IMPORTANCE Opium poppy mosaic virus (OPMV) is an umbravirus in the family Tombusviridae We determined that OPMV accumulates two similarly sized subgenomic RNAs (sgRNAs), with the smaller known to code for proteins expressed from overlapping open reading frames. The slightly larger sgRNA1 has a 5' end just upstream from a previously predicted xrRNAD site, identifying this sgRNA as an unusually long product produced by exoribonuclease trimming. Although four umbraviruses have similar predicted xrRNAD sites, only sgRNA1 of OPMV can code for a protein that is an extension product of umbravirus ORF4. Inability to generate the sgRNA or translate this protein was associated with reduced gRNA accumulation in vivo We also characterized the OPMV BTE structure, a 3' cap-independent translation enhancer (3' CITE). Comparisons of 13 BTEs with the OPMV BTE revealed additional stretches of sequence similarity beyond the 17-nt signature sequence, as well as conserved structural features not previously recognized in these 3' CITEs.
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Paudel DB, Sanfaçon H. Mapping of sequences in the 5' region and 3' UTR of tomato ringspot virus RNA2 that facilitate cap-independent translation of reporter transcripts in vitro. PLoS One 2021; 16:e0249928. [PMID: 33836032 PMCID: PMC8034749 DOI: 10.1371/journal.pone.0249928] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/26/2021] [Indexed: 12/18/2022] Open
Abstract
Tomato ringspot virus (ToRSV, genus Nepovirus, family Secoviridae, order Picornavirales) is a bipartite positive-strand RNA virus, with each RNA encoding one large polyprotein. ToRSV RNAs are linked to a 5'-viral genome-linked protein (VPg) and have a 3' polyA tail, suggesting a non-canonical cap-independent translation initiation mechanism. The 3' untranslated regions (UTRs) of RNA1 and RNA2 are unusually long (~1.5 kb) and share several large stretches of sequence identities. Several putative in-frame start codons are present in the 5' regions of the viral RNAs, which are also highly conserved between the two RNAs. Using reporter transcripts containing the 5' region and 3' UTR of the RNA2 of ToRSV Rasp1 isolate (ToRSV-Rasp1) and in vitro wheat germ extract translation assays, we provide evidence that translation initiates exclusively at the first AUG, in spite of a poor codon context. We also show that both the 5' region and 3' UTR of RNA2 are required for efficient cap-independent translation of these transcripts. We identify translation-enhancing elements in the 5' proximal coding region of the RNA2 polyprotein and in the RNA2 3' UTR. Cap-dependent translation of control reporter transcripts was inhibited when RNAs consisting of the RNA2 3' UTR were supplied in trans. Taken together, our results suggest the presence of a CITE in the ToRSV-Rasp1 RNA2 3' UTR that recruits one or several translation factors and facilitates efficient cap-independent translation together with the 5' region of the RNA. Non-overlapping deletion mutagenesis delineated the putative CITE to a 200 nts segment (nts 773-972) of the 1547 nt long 3' UTR. We conclude that the general mechanism of ToRSV RNA2 translation initiation is similar to that previously reported for the RNAs of blackcurrant reversion virus, another nepovirus. However, the position, sequence and predicted structures of the translation-enhancing elements differed between the two viruses.
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Affiliation(s)
- Dinesh Babu Paudel
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Hélène Sanfaçon
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, Canada
- * E-mail:
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40
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Liu J, Carino E, Bera S, Gao F, May JP, Simon AE. Structural Analysis and Whole Genome Mapping of a New Type of Plant Virus Subviral RNA: Umbravirus-Like Associated RNAs. Viruses 2021; 13:646. [PMID: 33918656 PMCID: PMC8068935 DOI: 10.3390/v13040646] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 03/31/2021] [Accepted: 04/03/2021] [Indexed: 12/13/2022] Open
Abstract
We report the biological and structural characterization of umbravirus-like associated RNAs (ulaRNAs), a new category of coat-protein dependent subviral RNA replicons that infect plants. These RNAs encode an RNA-dependent RNA polymerase (RdRp) following a -1 ribosomal frameshift event, are 2.7-4.6 kb in length, and are related to umbraviruses, unlike similar RNA replicons that are related to tombusviruses. Three classes of ulaRNAs are proposed, with citrus yellow vein associated virus (CYVaV) placed in Class 2. With the exception of CYVaV, Class 2 and Class 3 ulaRNAs encode an additional open reading frame (ORF) with movement protein-like motifs made possible by additional sequences just past the RdRp termination codon. The full-length secondary structure of CYVaV was determined using Selective 2' Hydroxyl Acylation analyzed by Primer Extension (SHAPE) structure probing and phylogenic comparisons, which was used as a template for determining the putative structures of the other Class 2 ulaRNAs, revealing a number of distinctive structural features. The ribosome recoding sites of nearly all ulaRNAs, which differ significantly from those of umbraviruses, may exist in two conformations and are highly efficient. The 3' regions of Class 2 and Class 3 ulaRNAs have structural elements similar to those of nearly all umbraviruses, and all Class 2 ulaRNAs have a unique, conserved 3' cap-independent translation enhancer. CYVaV replicates independently in protoplasts, demonstrating that the reported sequence is full-length. Additionally, CYVaV contains a sequence in its 3' UTR that confers protection to nonsense mediated decay (NMD), thus likely obviating the need for umbravirus ORF3, a known suppressor of NMD. This initial characterization lays down a road map for future investigations into these novel virus-like RNAs.
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Affiliation(s)
- Jingyuan Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA; (J.L.); (E.C.); (S.B.)
| | - Elizabeth Carino
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA; (J.L.); (E.C.); (S.B.)
| | - Sayanta Bera
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA; (J.L.); (E.C.); (S.B.)
| | - Feng Gao
- Silvec Biologics, Rockville, MD 20850, USA;
| | - Jared P. May
- Department of Cell and Molecular Biology and Biochemistry, University of Missouri-Kansas City, Kansas City, MO 64110, USA;
| | - Anne E. Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA; (J.L.); (E.C.); (S.B.)
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41
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Moradi Z, Maghdoori H, Nazifi E, Mehrvar M. Complete Genomic Characterization of Two Beet Soil-Borne Virus Isolates from Turkey: Implications of Comparative Analysis of Genome Sequences. THE PLANT PATHOLOGY JOURNAL 2021; 37:152-161. [PMID: 33866757 PMCID: PMC8053846 DOI: 10.5423/ppj.oa.12.2020.0223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/26/2021] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Sugar beet (Beta vulgaris L.) is known as a key product for agriculture in several countries across the world. Beet soil-borne virus (BSBV) triggers substantial economic damages to sugar beet by reducing the quantity of the yield and quality of the beet sugars. We conducted the present study to report the complete genome sequences of two BSBV isolates in Turkey for the first time. The genome organization was identical to those previously established BSBV isolates. The tripartite genome of BSBV-TR1 and -TR3 comprised a 5,835-nucleotide (nt) RNA1, a 3,454-nt RNA2, and a 3,005-nt RNA3 segment. According to sequence identity analyses, Turkish isolates were most closely related to the BSBV isolate reported from Iran (97.83-98.77% nt identity). The BSBV isolates worldwide (n = 9) were phylogenetically classified into five (RNA-coat protein read through gene [CPRT], TGB1, and TGB2 segments), four (RNA-rep), or three (TGB3) lineages. In genetic analysis, the TGB3 revealed more genetic variability (Pi = 0.034) compared with other regions. Population selection analysis revealed that most of the codons were generally under negative selection or neutral evolution in the BSBV isolates studied. However, positive selection was detected at codon 135 in the TGB1, which could be an adaptation in order to facilitate the movement and overcome the host plant resistance genes. We expect that the information on genome properties and genetic variability of BSBV, particularly in TGB3, TGB1, and CPRT genes, assist in developing effective control measures in order to prevent severe losses and make amendments in management strategies.
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Affiliation(s)
- Zohreh Moradi
- Department of Plant Pathology, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, P.O. Box 578, Sari,
Iran
| | - Hossein Maghdoori
- Department of Plant Pathology, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O. Box 91779-1163, Mashhad,
Iran
| | - Ehsan Nazifi
- Department of Biology, Faculty of Basic Sciences, University of Mazandaran, P.O. Box 47416-95447, Babolsar,
Iran
| | - Mohsen Mehrvar
- Department of Plant Pathology, Faculty of Agriculture, Ferdowsi University of Mashhad, P.O. Box 91779-1163, Mashhad,
Iran
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Leppek K, Byeon GW, Kladwang W, Wayment-Steele HK, Kerr CH, Xu AF, Kim DS, Topkar VV, Choe C, Rothschild D, Tiu GC, Wellington-Oguri R, Fujii K, Sharma E, Watkins AM, Nicol JJ, Romano J, Tunguz B, Participants E, Barna M, Das R. Combinatorial optimization of mRNA structure, stability, and translation for RNA-based therapeutics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.03.29.437587. [PMID: 33821271 PMCID: PMC8020971 DOI: 10.1101/2021.03.29.437587] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Therapeutic mRNAs and vaccines are being developed for a broad range of human diseases, including COVID-19. However, their optimization is hindered by mRNA instability and inefficient protein expression. Here, we describe design principles that overcome these barriers. We develop a new RNA sequencing-based platform called PERSIST-seq to systematically delineate in-cell mRNA stability, ribosome load, as well as in-solution stability of a library of diverse mRNAs. We find that, surprisingly, in-cell stability is a greater driver of protein output than high ribosome load. We further introduce a method called In-line-seq, applied to thousands of diverse RNAs, that reveals sequence and structure-based rules for mitigating hydrolytic degradation. Our findings show that "superfolder" mRNAs can be designed to improve both stability and expression that are further enhanced through pseudouridine nucleoside modification. Together, our study demonstrates simultaneous improvement of mRNA stability and protein expression and provides a computational-experimental platform for the enhancement of mRNA medicines.
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Affiliation(s)
- Kathrin Leppek
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Gun Woo Byeon
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Wipapat Kladwang
- Department of Biochemistry, Stanford University, California 94305, USA
| | | | - Craig H Kerr
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Adele F Xu
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Do Soon Kim
- Department of Biochemistry, Stanford University, California 94305, USA
| | - Ved V Topkar
- Program in Biophysics, Stanford University, Stanford, California 94305, USA
| | - Christian Choe
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
| | - Daphna Rothschild
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Gerald C Tiu
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | | | - Kotaro Fujii
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Eesha Sharma
- Department of Biochemistry, Stanford University, California 94305, USA
| | - Andrew M Watkins
- Department of Biochemistry, Stanford University, California 94305, USA
| | | | - Jonathan Romano
- Eterna Massive Open Laboratory
- Department of Computer Science and Engineering, State University of New York at Buffalo, Buffalo, New York, 14260, USA
| | - Bojan Tunguz
- Department of Biochemistry, Stanford University, California 94305, USA
| | | | - Maria Barna
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, California 94305, USA
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May JP, Simon AE. Targeting of viral RNAs by Upf1-mediated RNA decay pathways. Curr Opin Virol 2020; 47:1-8. [PMID: 33341474 DOI: 10.1016/j.coviro.2020.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/25/2022]
Abstract
Viral RNAs are susceptible to co-translational RNA decay pathways mediated by the RNA helicase Upstream frameshift 1 (Upf1). Upf1 is a key component in nonsense-mediated decay (NMD), Staufen1-mediated mRNA decay (SMD), and structure-mediated RNA decay (SRD) pathways, among others. Diverse families of viruses have features that predispose them to Upf1 targeting, but have evolved means to escape decay through the action of cis-acting or trans-acting viral factors. Studies aimed at understanding how viruses are subjected to and circumvent NMD have increased our understanding of NMD target selection of host mRNAs. This review focuses on the knowledge gained from studying NMD in viral systems as well as related Upf1-dependent pathways and how these pathways restrict virus replication.
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Affiliation(s)
- Jared P May
- Department of Cell and Molecular Biology and Biochemistry, School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD, USA.
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44
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Prats AC, David F, Diallo LH, Roussel E, Tatin F, Garmy-Susini B, Lacazette E. Circular RNA, the Key for Translation. Int J Mol Sci 2020; 21:E8591. [PMID: 33202605 PMCID: PMC7697609 DOI: 10.3390/ijms21228591] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/06/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
It was thought until the 1990s that the eukaryotic translation machinery was unable to translate a circular RNA. However internal ribosome entry sites (IRESs) and m6A-induced ribosome engagement sites (MIRESs) were discovered, promoting 5' end-independent translation initiation. Today a new family of so-called "noncoding" circular RNAs (circRNAs) has emerged, revealing the pivotal role of 5' end-independent translation. CircRNAs have a strong impact on translational control via their sponge function, and form a new mRNA family as they are translated into proteins with pathophysiological roles. While there is no more doubt about translation of covalently closed circRNA, the linearity of canonical mRNA is only theoretical: it has been shown for more than thirty years that polysomes exhibit a circular form and mRNA functional circularization has been demonstrated in the 1990s by the interaction of initiation factor eIF4G with poly(A) binding protein. More recently, additional mechanisms of 3'-5' interaction have been reported, including m6A modification. Functional circularization enhances translation via ribosome recycling and acceleration of the translation initiation rate. This update of covalently and noncovalently closed circular mRNA translation landscape shows that RNA with circular shape might be the rule for translation with an important impact on disease development and biotechnological applications.
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Affiliation(s)
- Anne-Catherine Prats
- Institut des Maladies Métaboliques et Cardiovasculaires, UMR 1048, Inserm, Université de Toulouse UT3, 1, Avenue Jean Poulhes, BP 84225, 31432 Toulouse CEDEX 4, France; (F.D.); (L.H.D.); (E.R.); (F.T.); (B.G.-S.); (E.L.)
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45
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Nobuta R, Machida K, Sato M, Hashimoto S, Toriumi Y, Nakajima S, Suto D, Imataka H, Inada T. eIF4G-driven translation initiation of downstream ORFs in mammalian cells. Nucleic Acids Res 2020; 48:10441-10455. [PMID: 32941651 PMCID: PMC7544200 DOI: 10.1093/nar/gkaa728] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 12/24/2022] Open
Abstract
Comprehensive genome-wide analysis has revealed the presence of translational elements in the 3′ untranslated regions (UTRs) of human transcripts. However, the mechanisms by which translation is initiated in 3′ UTRs and the physiological function of their products remain unclear. This study showed that eIF4G drives the translation of various downstream open reading frames (dORFs) in 3′ UTRs. The 3′ UTR of GCH1, which encodes GTP cyclohydrolase 1, contains an internal ribosome entry site (IRES) that initiates the translation of dORFs. An in vitro reconstituted translation system showed that the IRES in the 3′ UTR of GCH1 required eIF4G and conventional translation initiation factors, except eIF4E, for AUG-initiated translation of dORFs. The 3′ UTR of GCH1-mediated translation was resistant to the mTOR inhibitor Torin 1, which inhibits cap-dependent initiation by increasing eIF4E-unbound eIF4G. eIF4G was also required for the activity of various elements, including polyU and poliovirus type 2, a short element thought to recruit ribosomes by base-pairing with 18S rRNA. These findings indicate that eIF4G mediates translation initiation of various ORFs in mammalian cells, suggesting that the 3′ UTRs of mRNAs may encode various products.
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Affiliation(s)
- Risa Nobuta
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Kodai Machida
- Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan
| | - Misaki Sato
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Satoshi Hashimoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yasuhito Toriumi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shizuka Nakajima
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Daiki Suto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Hiroaki Imataka
- Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
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Carino EJ, Scheets K, Miller WA. The RNA of Maize Chlorotic Mottle Virus, an Obligatory Component of Maize Lethal Necrosis Disease, Is Translated via a Variant Panicum Mosaic Virus-Like Cap-Independent Translation Element. J Virol 2020; 94:e01005-20. [PMID: 32847851 PMCID: PMC7592216 DOI: 10.1128/jvi.01005-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/30/2020] [Indexed: 11/29/2022] Open
Abstract
Maize chlorotic mottle virus (MCMV) combines with a potyvirus in maize lethal necrosis disease (MLND), a serious emerging disease worldwide. To inform resistance strategies, we characterized the translation initiation mechanism of MCMV. We report that MCMV RNA contains a cap-independent translation element (CITE) in its 3' untranslated region (UTR). The MCMV 3' CITE (MTE) was mapped to nucleotides 4164 to 4333 in the genomic RNA. 2'-Hydroxyl acylation analyzed by primer extension (SHAPE) probing revealed that the MTE is a distinct variant of the panicum mosaic virus-like 3' CITE (PTE). Like the PTE, electrophoretic mobility shift assays (EMSAs) indicated that eukaryotic translation initiation factor 4E (eIF4E) binds the MTE despite the absence of an m7GpppN cap structure, which is normally required for eIF4E to bind RNA. Using a luciferase reporter system, mutagenesis to disrupt and restore base pairing revealed that the MTE interacts with the 5' UTRs of both genomic RNA and subgenomic RNA1 via long-distance kissing stem-loop interaction to facilitate translation. The MTE stimulates a relatively low level of translation and has a weak, if any, pseudoknot, which is present in the most active PTEs, mainly because the MTE lacks the pyrimidine-rich tract that base pairs to a G-rich bulge to form the pseudoknot. However, most mutations designed to form a pseudoknot decreased translation activity. Mutations in the viral genome that reduced or restored translation prevented and restored virus replication, respectively, in maize protoplasts and in plants. In summary, the MTE differs from the canonical PTE but falls into a structurally related class of 3' CITEs.IMPORTANCE In the past decade, maize lethal necrosis disease has caused massive crop losses in East Africa. It has also emerged in China and parts of South America. Maize chlorotic mottle virus (MCMV) infection is required for this disease. While some tolerant maize lines have been identified, there are no known resistance genes that confer immunity to MCMV. In order to improve resistance strategies against MCMV, we focused on how the MCMV genome is translated, the first step of gene expression by all positive-strand RNA viruses. We identified a structure (cap-independent translation element) in the 3' untranslated region of the viral RNA genome that allows the virus to usurp a host translation initiation factor, eIF4E, in a way that differs from host mRNA interactions with the translational machinery. This difference indicates eIF4E may be a soft target for engineering of-or breeding for-resistance to MCMV.
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Affiliation(s)
- Elizabeth J Carino
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, USA
- Interdepartmental Genetics and Genomics Program, Iowa State University, Ames, Iowa, USA
| | - Kay Scheets
- Department of Plant Biology, Ecology and Evolution, Oklahoma State University, Stillwater, Oklahoma, USA
| | - W Allen Miller
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa, USA
- Interdepartmental Genetics and Genomics Program, Iowa State University, Ames, Iowa, USA
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47
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Wu Q, Wright M, Gogol MM, Bradford WD, Zhang N, Bazzini AA. Translation of small downstream ORFs enhances translation of canonical main open reading frames. EMBO J 2020; 39:e104763. [PMID: 32744758 PMCID: PMC7459409 DOI: 10.15252/embj.2020104763] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 12/26/2022] Open
Abstract
In addition to canonical open reading frames (ORFs), thousands of translated small ORFs (containing less than 100 codons) have been identified in untranslated mRNA regions (UTRs) across eukaryotes. Small ORFs in 5′ UTRs (upstream (u)ORFs) often repress translation of the canonical ORF within the same mRNA. However, the function of translated small ORFs in the 3′ UTRs (downstream (d)ORFs) is unknown. Contrary to uORFs, we find that translation of dORFs enhances translation of their corresponding canonical ORFs. This translation stimulatory effect of dORFs depends on the number of dORFs, but not the length or peptide they encode. We propose that dORFs represent a new, strong, and universal translation regulatory mechanism in vertebrates.
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Affiliation(s)
- Qiushuang Wu
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Matthew Wright
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | | | | | - Ning Zhang
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Ariel A Bazzini
- Stowers Institute for Medical Research, Kansas City, MO, USA.,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
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48
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Gupta A, Bansal M. RNA-mediated translation regulation in viral genomes: computational advances in the recognition of sequences and structures. Brief Bioinform 2020; 21:1151-1163. [PMID: 31204430 PMCID: PMC7109810 DOI: 10.1093/bib/bbz054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 03/24/2019] [Accepted: 04/15/2019] [Indexed: 12/30/2022] Open
Abstract
RNA structures are widely distributed across all life forms. The global conformation of these structures is defined by a variety of constituent structural units such as helices, hairpin loops, kissing-loop motifs and pseudoknots, which often behave in a modular way. Their ubiquitous distribution is associated with a variety of functions in biological processes. The location of these structures in the genomes of RNA viruses is often coordinated with specific processes in the viral life cycle, where the presence of the structure acts as a checkpoint for deciding the eventual fate of the process. These structures have been found to adopt complex conformations and exert their effects by interacting with ribosomes, multiple host translation factors and small RNA molecules like miRNA. A number of such RNA structures have also been shown to regulate translation in viruses at the level of initiation, elongation or termination. The role of various computational studies in the preliminary identification of such sequences and/or structures and subsequent functional analysis has not been fully appreciated. This review aims to summarize the processes in which viral RNA structures have been found to play an active role in translational regulation, their global conformational features and the bioinformatics/computational tools available for the identification and prediction of these structures.
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Affiliation(s)
- Asmita Gupta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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Ermolenko DN, Mathews DH. Making ends meet: New functions of mRNA secondary structure. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1611. [PMID: 32597020 DOI: 10.1002/wrna.1611] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 11/10/2022]
Abstract
The 5' cap and 3' poly(A) tail of mRNA are known to synergistically regulate mRNA translation and stability. Recent computational and experimental studies revealed that both protein-coding and non-coding RNAs will fold with extensive intramolecular secondary structure, which will result in close distances between the sequence ends. This proximity of the ends is a sequence-independent, universal property of most RNAs. Only low-complexity sequences without guanosines are without secondary structure and exhibit end-to-end distances expected for RNA random coils. The innate proximity of RNA ends might have important biological implications that remain unexplored. In particular, the inherent compactness of mRNA might regulate translation initiation by facilitating the formation of protein complexes that bridge mRNA 5' and 3' ends. Additionally, the proximity of mRNA ends might mediate coupling of 3' deadenylation to 5' end mRNA decay. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems Translation > Translation Regulation.
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Affiliation(s)
- Dmitri N Ermolenko
- Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
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Borden KLB, Volpon L. The diversity, plasticity, and adaptability of cap-dependent translation initiation and the associated machinery. RNA Biol 2020; 17:1239-1251. [PMID: 32496897 PMCID: PMC7549709 DOI: 10.1080/15476286.2020.1766179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Translation initiation is a critical facet of gene expression with important impacts that underlie cellular responses to stresses and environmental cues. Its dysregulation in many diseases position this process as an important area for the development of new therapeutics. The gateway translation factor eIF4E is typically considered responsible for ‘global’ or ‘canonical’ m7G cap-dependent translation. However, eIF4E impacts translation of specific transcripts rather than the entire translatome. There are many alternative cap-dependent translation mechanisms that also contribute to the translation capacity of the cell. We review the diversity of these, juxtaposing more recently identified mechanisms with eIF4E-dependent modalities. We also explore the multiplicity of functions played by translation factors, both within and outside protein synthesis, and discuss how these differentially contribute to their ultimate physiological impacts. For comparison, we discuss some modalities for cap-independent translation. In all, this review highlights the diverse mechanisms that engage and control translation in eukaryotes.
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Affiliation(s)
- Katherine L B Borden
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
| | - Laurent Volpon
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
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