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Liang X, Ren H, Han F, Liang R, Zhao J, Liu H. The new direction of drug development: Degradation of undruggable targets through targeting chimera technology. Med Res Rev 2024; 44:632-685. [PMID: 37983964 DOI: 10.1002/med.21992] [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: 11/30/2022] [Revised: 06/13/2023] [Accepted: 10/29/2023] [Indexed: 11/22/2023]
Abstract
Imbalances in protein and noncoding RNA levels in vivo lead to the occurrence of many diseases. In addition to the use of small molecule inhibitors and agonists to restore these imbalances, recently emerged targeted degradation technologies provide a new direction for disease treatment. Targeted degradation technology directly degrades target proteins or RNA by utilizing the inherent degradation pathways, thereby eliminating the functions of pathogenic proteins (or RNA) to treat diseases. Compared with traditional therapies, targeted degradation technology which avoids the principle of traditional inhibitor occupation drive, has higher efficiency and selectivity, and widely expands the range of drug targets. It is one of the most promising and hottest areas for future drug development. Herein, we systematically introduced the in vivo degradation systems applied to degrader design: ubiquitin-proteasome system, lysosomal degradation system, and RNA degradation system. We summarized the development progress, structural characteristics, and limitations of novel chimeric design technologies based on different degradation systems. In addition, due to the lack of clear ligand-binding pockets, about 80% of disease-associated proteins cannot be effectively intervened with through traditional therapies. We deeply elucidated how to use targeted degradation technology to discover and design molecules for representative undruggable targets including transcription factors, small GTPases, and phosphatases. Overall, this review provides a comprehensive and systematic overview of targeted degradation technology-related research advances and a new guidance for the chimeric design of undruggable targets.
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Affiliation(s)
- Xuewu Liang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Hairu Ren
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Fengyang Han
- School of Pharmacy, Fudan University, Shanghai, China
| | - Renwen Liang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Jiayan Zhao
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Hong Liu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
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2
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Pekarek L, Zimmer MM, Gribling-Burrer AS, Buck S, Smyth R, Caliskan N. Cis-mediated interactions of the SARS-CoV-2 frameshift RNA alter its conformations and affect function. Nucleic Acids Res 2022; 51:728-743. [PMID: 36537211 PMCID: PMC9881162 DOI: 10.1093/nar/gkac1184] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/11/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
The RNA genome of SARS-CoV-2 contains a frameshift stimulatory element (FSE) that allows access to an alternative reading frame through -1 programmed ribosomal frameshifting (PRF). -1PRF in the 1a/1b gene is essential for efficient viral replication and transcription of the viral genome. -1PRF efficiency relies on the presence of conserved RNA elements within the FSE. One of these elements is a three-stemmed pseudoknot, although alternative folds of the frameshift site might have functional roles as well. Here, by complementing ensemble and single-molecule structural analysis of SARS-CoV-2 frameshift RNA variants with functional data, we reveal a conformational interplay of the 5' and 3' immediate regions with the FSE and show that the extended FSE exists in multiple conformations. Furthermore, limiting the base pairing of the FSE with neighboring nucleotides can favor or impair the formation of the alternative folds, including the pseudoknot. Our results demonstrate that co-existing RNA structures can function together to fine-tune SARS-CoV-2 gene expression, which will aid efforts to design specific inhibitors of viral frameshifting.
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Affiliation(s)
- Lukas Pekarek
- Helmholtz Institute for RNA-based Infection Research (HIRI-HZI), Würzburg, Germany
| | | | | | | | - Redmond Smyth
- Correspondence may also be addressed to Redmond Smyth.
| | - Neva Caliskan
- To whom correspondence should be addressed. Tel: +49 931 318 5298;
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3
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Identifying Inhibitors of −1 Programmed Ribosomal Frameshifting in a Broad Spectrum of Coronaviruses. Viruses 2022; 14:v14020177. [PMID: 35215770 PMCID: PMC8876150 DOI: 10.3390/v14020177] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/30/2021] [Accepted: 01/10/2022] [Indexed: 02/06/2023] Open
Abstract
Recurrent outbreaks of novel zoonotic coronavirus (CoV) diseases in recent years have highlighted the importance of developing therapeutics with broad-spectrum activity against CoVs. Because all CoVs use −1 programmed ribosomal frameshifting (−1 PRF) to control expression of key viral proteins, the frameshift signal in viral mRNA that stimulates −1 PRF provides a promising potential target for such therapeutics. To test the viability of this strategy, we explored whether small-molecule inhibitors of −1 PRF in SARS-CoV-2 also inhibited −1 PRF in a range of bat CoVs—the most likely source of future zoonoses. Six inhibitors identified in new and previous screens against SARS-CoV-2 were evaluated against the frameshift signals from a panel of representative bat CoVs as well as MERS-CoV. Some drugs had strong activity against subsets of these CoV-derived frameshift signals, while having limited to no effect on −1 PRF caused by frameshift signals from other viruses used as negative controls. Notably, the serine protease inhibitor nafamostat suppressed −1 PRF significantly for multiple CoV-derived frameshift signals. These results suggest it is possible to find small-molecule ligands that inhibit −1 PRF specifically in a broad spectrum of CoVs, establishing frameshift signals as a viable target for developing pan-coronaviral therapeutics.
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A Novel Frameshifting Inhibitor Having Antiviral Activity against Zoonotic Coronaviruses. Viruses 2021; 13:v13081639. [PMID: 34452503 PMCID: PMC8402677 DOI: 10.3390/v13081639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/12/2022] Open
Abstract
Recent outbreaks of zoonotic coronaviruses, such as Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have caused tremendous casualties and great economic shock. Although some repurposed drugs have shown potential therapeutic efficacy in clinical trials, specific therapeutic agents targeting coronaviruses have not yet been developed. During coronavirus replication, a replicase gene cluster, including RNA-dependent RNA polymerase (RdRp), is alternatively translated via a process called -1 programmed ribosomal frameshift (−1 PRF) by an RNA pseudoknot structure encoded in viral RNAs. The coronavirus frameshifting has been identified previously as a target for antiviral therapy. In this study, the frameshifting efficiencies of MERS-CoV, SARS-CoV and SARS-CoV-2 were determined using an in vitro −1 PRF assay system. Our group has searched approximately 9689 small molecules to identify potential −1 PRF inhibitors. Herein, we found that a novel compound, 2-(5-acetylthiophen-2yl)furo[2,3-b]quinoline (KCB261770), inhibits the frameshifting of MERS-CoV and effectively suppresses viral propagation in MERS-CoV-infected cells. The inhibitory effects of 87 derivatives of furo[2,3-b]quinolines were also examined showing less prominent inhibitory effect when compared to compound KCB261770. We demonstrated that KCB261770 inhibits the frameshifting without suppressing cap-dependent translation. Furthermore, this compound was able to inhibit the frameshifting, to some extent, of SARS-CoV and SARS-CoV-2. Therefore, the novel compound 2-(5-acetylthiophen-2yl)furo[2,3-b]quinoline may serve as a promising drug candidate to interfere with pan-coronavirus frameshifting.
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5
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Atkins JF, O’Connor KM, Bhatt PR, Loughran G. From Recoding to Peptides for MHC Class I Immune Display: Enriching Viral Expression, Virus Vulnerability and Virus Evasion. Viruses 2021; 13:1251. [PMID: 34199077 PMCID: PMC8310308 DOI: 10.3390/v13071251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/11/2021] [Accepted: 06/19/2021] [Indexed: 01/02/2023] Open
Abstract
Many viruses, especially RNA viruses, utilize programmed ribosomal frameshifting and/or stop codon readthrough in their expression, and in the decoding of a few a UGA is dynamically redefined to specify selenocysteine. This recoding can effectively increase viral coding capacity and generate a set ratio of products with the same N-terminal domain(s) but different C-terminal domains. Recoding can also be regulatory or generate a product with the non-universal 21st directly encoded amino acid. Selection for translation speed in the expression of many viruses at the expense of fidelity creates host immune defensive opportunities. In contrast to host opportunism, certain viruses, including some persistent viruses, utilize recoding or adventitious frameshifting as part of their strategy to evade an immune response or specific drugs. Several instances of recoding in small intensively studied viruses escaped detection for many years and their identification resolved dilemmas. The fundamental importance of ribosome ratcheting is consistent with the initial strong view of invariant triplet decoding which however did not foresee the possibility of transitory anticodon:codon dissociation. Deep level dynamics and structural understanding of recoding is underway, and a high level structure relevant to the frameshifting required for expression of the SARS CoV-2 genome has just been determined.
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Affiliation(s)
- John F. Atkins
- Schools of Biochemistry and Microbiology, University College Cork, T12 XF62 Cork, Ireland; (K.M.O.); (P.R.B.); (G.L.)
| | - Kate M. O’Connor
- Schools of Biochemistry and Microbiology, University College Cork, T12 XF62 Cork, Ireland; (K.M.O.); (P.R.B.); (G.L.)
| | - Pramod R. Bhatt
- Schools of Biochemistry and Microbiology, University College Cork, T12 XF62 Cork, Ireland; (K.M.O.); (P.R.B.); (G.L.)
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Gary Loughran
- Schools of Biochemistry and Microbiology, University College Cork, T12 XF62 Cork, Ireland; (K.M.O.); (P.R.B.); (G.L.)
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Kelly JA, Woodside MT, Dinman JD. Programmed -1 Ribosomal Frameshifting in coronaviruses: A therapeutic target. Virology 2021; 554:75-82. [PMID: 33387787 PMCID: PMC7833279 DOI: 10.1016/j.virol.2020.12.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 01/15/2023]
Abstract
Human population growth, climate change, and globalization are accelerating the emergence of novel pathogenic viruses. In the past two decades alone, three such members of the coronavirus family have posed serious threats, spurring intense efforts to understand their biology as a way to identify targetable vulnerabilities. Coronaviruses use a programmed -1 ribosomal frameshift (-1 PRF) mechanism to direct synthesis of their replicase proteins. This is a critical switch in their replication program that can be therapeutically targeted. Here, we discuss how nearly half a century of research into -1 PRF have provided insight into the virological importance of -1 PRF, the molecular mechanisms that drive it, and approaches that can be used to manipulate it towards therapeutic outcomes with particular emphasis on SARS-CoV-2.
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Affiliation(s)
- Jamie A Kelly
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
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7
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Haniff H, Tong Y, Liu X, Chen JL, Suresh BM, Andrews RJ, Peterson JM, O’Leary CA, Benhamou RI, Moss WN, Disney MD. Targeting the SARS-CoV-2 RNA Genome with Small Molecule Binders and Ribonuclease Targeting Chimera (RIBOTAC) Degraders. ACS CENTRAL SCIENCE 2020; 6:1713-1721. [PMID: 33140033 PMCID: PMC7553039 DOI: 10.1021/acscentsci.0c00984] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Indexed: 05/07/2023]
Abstract
COVID-19 is a global pandemic, thus requiring multiple strategies to develop modalities against it. Herein, we designed multiple bioactive small molecules that target a functional structure within the SARS-CoV-2's RNA genome, the causative agent of COVID-19. An analysis to characterize the structure of the RNA genome provided a revised model of the SARS-CoV-2 frameshifting element, in particular its attenuator hairpin. By studying an RNA-focused small molecule collection, we identified a drug-like small molecule (C5) that avidly binds to the revised attenuator hairpin structure with a K d of 11 nM. The compound stabilizes the hairpin's folded state and impairs frameshifting in cells. The ligand was further elaborated into a ribonuclease targeting chimera (RIBOTAC) to recruit a cellular ribonuclease to destroy the viral genome (C5-RIBOTAC) and into a covalent molecule (C5-Chem-CLIP) that validated direct target engagement and demonstrated its specificity for the viral RNA, as compared to highly expressed host mRNAs. The RIBOTAC lead optimization strategy improved the bioactivity of the compound at least 10-fold. Collectively, these studies demonstrate that the SARS-CoV-2 RNA genome should be considered druggable.
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Affiliation(s)
- Hafeez
S. Haniff
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Yuquan Tong
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Xiaohui Liu
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Jonathan L. Chen
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Blessy M. Suresh
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Ryan J. Andrews
- Roy
J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Jake M. Peterson
- Roy
J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Collin A. O’Leary
- Roy
J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Raphael I. Benhamou
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
| | - Walter N. Moss
- Roy
J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Matthew D. Disney
- The
Scripps Research Institute, Department of Chemistry, Jupiter, Florida 33458, United States
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8
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Khrustalev VV, Giri R, Khrustaleva TA, Kapuganti SK, Stojarov AN, Poboinev VV. Translation-Associated Mutational U-Pressure in the First ORF of SARS-CoV-2 and Other Coronaviruses. Front Microbiol 2020; 11:559165. [PMID: 33072018 PMCID: PMC7536284 DOI: 10.3389/fmicb.2020.559165] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022] Open
Abstract
Within 4 months of the ongoing COVID-19 pandemic caused by SARS-CoV-2, more than 250 nucleotide mutations have been detected in ORF1ab of the virus isolated from infected persons from different parts of the globe. These observations open up an obvious question about the rate and direction of mutational pressure for further vaccine and therapeutics designing. In this study, we did a comparative analysis of ORF1a and ORF1b by using the first isolate (Wuhan strain) as the parent sequence. We observed that most of the nucleotide mutations are C to U transitions. The rate of synonymous C to U transitions is significantly higher than the rate of non-synonymous ones, indicating negative selection on amino acid substitutions. Further, trends in nucleotide usage bias have been investigated in 49 coronaviruses species. A strong bias in nucleotide usage in fourfold degenerate sites toward uracil residues is seen in ORF1ab of all the studied coronaviruses: both in the ORF1a and in the ORF1b translated thanks to the programmed ribosomal frameshifting that has an efficiency of 14 – 45% in different species. A more substantial mutational U-pressure is observed in ORF1a than in ORF1b perhaps because ORF1a is translated more frequently than ORF1b. Mutational U-pressure is there even in ORFs that are not translated from genomic RNA plus strands, but the bias is weaker than in ORF1ab. Unlike other nucleotide mutations, mutational U-pressure caused by cytosine deamination, mostly occurring during the RNA plus strand replication and also translation, cannot be corrected by the proof-reading machinery of coronaviruses. The knowledge generated on the mutational U-pressure that becomes stronger during translation of viral RNA plus strands has implications for vaccine and nucleoside analog development for treating COVID-19 and other coronavirus infections.
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Affiliation(s)
| | - Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, India
| | - Tatyana Aleksandrovna Khrustaleva
- Biochemical Group of Multidisciplinary Diagnostic Laboratory, Institute of Physiology of the National Academy of Sciences of Belarus, Minsk, Belarus
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9
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Penn WD, Harrington HR, Schlebach JP, Mukhopadhyay S. Regulators of Viral Frameshifting: More Than RNA Influences Translation Events. Annu Rev Virol 2020; 7:219-238. [PMID: 32600156 DOI: 10.1146/annurev-virology-012120-101548] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Programmed ribosomal frameshifting (PRF) is a conserved translational recoding mechanism found in all branches of life and viruses. In bacteria, archaea, and eukaryotes PRF is used to downregulate protein production by inducing a premature termination of translation, which triggers messenger RNA (mRNA) decay. In viruses, PRF is used to drive the production of a new protein while downregulating the production of another protein, thus maintaining a stoichiometry optimal for productive infection. Traditionally, PRF motifs have been defined by the characteristics of two cis elements: a slippery heptanucleotide sequence followed by an RNA pseudoknot or stem-loop within the mRNA. Recently, additional cis and new trans elements have been identified that regulate PRF in both host and viral translation. These additional factors suggest PRF is an evolutionarily conserved process whose function and regulation we are just beginning to understand.
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Affiliation(s)
- Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | - Haley R Harrington
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
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10
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Chang KC, Salawu EO, Chang YY, Wen JD, Yang LW. Resolution-exchanged structural modeling and simulations jointly unravel that subunit rolling underlies the mechanism of programmed ribosomal frameshifting. Bioinformatics 2019; 35:945-952. [PMID: 30169551 DOI: 10.1093/bioinformatics/bty762] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/26/2018] [Accepted: 08/28/2018] [Indexed: 12/20/2022] Open
Abstract
MOTIVATION Programmed ribosomal frameshifting (PRF) is widely used by viruses and bacteria to produce different proteins from a single mRNA template. How steric hindrance of a PRF-stimulatory mRNA structure transiently modifies the conformational dynamics of the ribosome, and thereby allows tRNA slippage, remains elusive. RESULTS Here, we leverage linear response theories and resolution-exchanged simulations to construct a structural/dynamics model that connects and rationalizes existing structural, single-molecule and mutagenesis data by resolution-exchanged structural modelling and simulations. Our combined theoretical techniques provide a temporal and spatial description of PRF with unprecedented mechanistic details. We discover that ribosomal unfolding of the PRF-stimulating pseudoknot exerts resistant forces on the mRNA entrance of the ribosome, and thereby drives 30S subunit rolling. Such motion distorts tRNAs, leads to tRNA slippage, and in turn serves as a delicate control of cis-element's unwinding forces over PRF. AVAILABILITY AND IMPLEMENTATION All the simulation scripts and computational implementations of our methods/analyses (including linear response theory) are included in the bioStructureM suite, provided through GitHub at https://github.com/Yuan-Yu/bioStructureM. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Kai-Chun Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Emmanuel Oluwatobi Salawu
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan.,TIGP Bioinformatics Program, Institute of Information Sciences, Academia Sinica, Taipei, Taiwan
| | - Yuan-Yu Chang
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Jin-Der Wen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Lee-Wei Yang
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan.,TIGP Bioinformatics Program, Institute of Information Sciences, Academia Sinica, Taipei, Taiwan.,Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan
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11
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Abstract
Innovation follows discovery. If the 20th century was a golden age of discovery in the biomolecular biosciences, the current century may be remembered by the explosion of beneficial devices and therapies conceived by the bioengineers of the era. Much as the development of solid-state electronic components made possible the information revolution, the rational combining of millions of basic molecular control modules will enable the development of highly sophisticated biomachines that will make today's smartphones appear rudimentary. The molecular toolbox is already well-stocked, particularly in our ability to manipulate DNA, control transcription, generate functionally novel hybrid proteins, and expand the genetic code to include unnatural amino acids. This review focuses on how RNA-based regulatory modules that direct alternative readings of the genetic code can be employed as basic circuit components to expand our ability to control gene expression.
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Affiliation(s)
- Jonathan D Dinman
- From the Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
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12
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mRNA-Mediated Duplexes Play Dual Roles in the Regulation of Bidirectional Ribosomal Frameshifting. Int J Mol Sci 2018; 19:ijms19123867. [PMID: 30518074 PMCID: PMC6321510 DOI: 10.3390/ijms19123867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 11/26/2018] [Accepted: 11/30/2018] [Indexed: 11/17/2022] Open
Abstract
In contrast to -1 programmed ribosomal frameshifting (PRF) stimulation by an RNA pseudoknot downstream of frameshifting sites, a refolding upstream RNA hairpin juxtaposing the frameshifting sites attenuates -1 PRF in human cells and stimulates +1 frameshifting in yeast. This eukaryotic functional mimicry of the internal Shine-Dalgarno (SD) sequence-mediated duplex was confirmed directly in the 70S translation system, indicating that both frameshifting regulation activities of upstream hairpin are conserved between 70S and 80S ribosomes. Unexpectedly, a downstream pseudoknot also possessed two opposing hungry codon-mediated frameshifting regulation activities: attenuation of +1 frameshifting and stimulation of a non-canonical -1 frameshifting within the +1 frameshift-prone CUUUGA frameshifting site in the absence of release factor 2 (RF2) in vitro. However, the -1 frameshifting activity of the downstream pseudoknot is not coupled with its +1 frameshifting attenuation ability. Similarly, the +1 frameshifting activity of the upstream hairpin is not required for its -1 frameshifting attenuation function Thus, each of the mRNA duplexes flanking the two ends of a ribosomal mRNA-binding channel possesses two functions in bi-directional ribosomal frameshifting regulation: frameshifting stimulation and counteracting the frameshifting activity of each other.
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13
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Dever TE, Dinman JD, Green R. Translation Elongation and Recoding in Eukaryotes. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a032649. [PMID: 29610120 DOI: 10.1101/cshperspect.a032649] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this review, we highlight the current understanding of translation elongation and recoding in eukaryotes. In addition to providing an overview of the process, recent advances in our understanding of the role of the factor eIF5A in both translation elongation and termination are discussed. We also highlight mechanisms of translation recoding with a focus on ribosomal frameshifting during elongation. We see that the balance between the basic steps in elongation and the less common recoding events is determined by the kinetics of the different processes as well as by specific sequence determinants.
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Affiliation(s)
- Thomas E Dever
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Rachel Green
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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14
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An RNA Element That Facilitates Programmed Ribosomal Readthrough in Turnip Crinkle Virus Adopts Multiple Conformations. J Virol 2016; 90:8575-91. [PMID: 27440887 DOI: 10.1128/jvi.01129-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/12/2016] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Ribosome recoding is used by RNA viruses for translational readthrough or frameshifting past termination codons for the synthesis of extension products. Recoding sites, along with downstream recoding stimulatory elements (RSEs), have long been studied in reporter constructs, because these fragments alone mediate customary levels of recoding and are thus assumed to contain complete instructions for establishment of the proper ratio of termination to recoding. RSEs from the Tombusviridae and Luteoviridae are thought to be exceptions, since they contain a long-distance RNA-RNA connection with the 3' end. This interaction has been suggested to substitute for pseudoknots, thought to be missing in tombusvirid RSEs. We provide evidence that the phylogenetically conserved RSE of the carmovirus Turnip crinkle virus (TCV) adopts an alternative, smaller structure that extends an upstream conserved hairpin and that this alternative structure is the predominant form of the RSE within nascent viral RNA in plant cells and when RNA is synthesized in vitro The TCV RSE also contains an internal pseudoknot along with the long-distance interaction, and the pseudoknot is not compatible with the phylogenetically conserved structure. Conserved residues just past the recoding site are important for recoding, and these residues are also conserved in the RSEs of gammaretroviruses. Our data demonstrate the dynamic nature of the TCV RSE and suggest that studies using reporter constructs may not be effectively recapitulating RSE-mediated recoding within viral genomes. IMPORTANCE Ribosome recoding is used by RNA viruses to enable ribosomes to extend translation past termination codons for the synthesis of longer products. Recoding sites and a downstream recoding stimulatory element (RSE) mediate expected levels of recoding when excised and placed in reporter constructs and thus are assumed to contain complete instructions for the establishment of the proper ratio of termination to recoding. We provide evidence that most of the TCV RSE adopts an alternative structure that extends an upstream conserved hairpin and that this alternative structure, and not the phylogenetically conserved structure, is the predominant form of the RSE in RNA synthesized in vitro and in plant cells. The TCV RSE also contains an internal pseudoknot that is not compatible with the phylogenetically conserved structure and an RNA bridge to the 3' end. These data suggest that the TCV RSE is structurally dynamic and that multiple conformations are likely required to regulate ribosomal readthrough.
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Lin YH, Chang KY. Rational design of a synthetic mammalian riboswitch as a ligand-responsive -1 ribosomal frame-shifting stimulator. Nucleic Acids Res 2016; 44:9005-9015. [PMID: 27521370 PMCID: PMC5062990 DOI: 10.1093/nar/gkw718] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 08/03/2016] [Indexed: 12/18/2022] Open
Abstract
Metabolite-responsive RNA pseudoknots derived from prokaryotic riboswitches have been shown to stimulate −1 programmed ribosomal frameshifting (PRF), suggesting −1 PRF as a promising gene expression platform to extend riboswitch applications in higher eukaryotes. However, its general application has been hampered by difficulty in identifying a specific ligand-responsive pseudoknot that also functions as a ligand-dependent -1 PRF stimulator. We addressed this problem by using the −1 PRF stimulation pseudoknot of SARS-CoV (SARS-PK) to build a ligand-dependent −1 PRF stimulator. In particular, the extra stem of SARS-PK was replaced by an RNA aptamer of theophylline and designed to couple theophylline binding with the stimulation of −1 PRF. Conformational and functional analyses indicate that the engineered theophylline-responsive RNA functions as a mammalian riboswitch with robust theophylline-dependent −1 PRF stimulation activity in a stable human 293T cell-line. Thus, RNA–ligand interaction repertoire provided by in vitro selection becomes accessible to ligand-specific −1 PRF stimulator engineering using SARS-PK as the scaffold for synthetic biology application.
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Affiliation(s)
- Ya-Hui Lin
- Institute of Biochemistry, National Chung-Hsing University, 250 Kuo-Kung Road, Taichung, 402 Taiwan
| | - Kung-Yao Chang
- Institute of Biochemistry, National Chung-Hsing University, 250 Kuo-Kung Road, Taichung, 402 Taiwan
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Atkins JF, Loughran G, Bhatt PR, Firth AE, Baranov PV. Ribosomal frameshifting and transcriptional slippage: From genetic steganography and cryptography to adventitious use. Nucleic Acids Res 2016; 44:7007-78. [PMID: 27436286 PMCID: PMC5009743 DOI: 10.1093/nar/gkw530] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/26/2016] [Indexed: 12/15/2022] Open
Abstract
Genetic decoding is not ‘frozen’ as was earlier thought, but dynamic. One facet of this is frameshifting that often results in synthesis of a C-terminal region encoded by a new frame. Ribosomal frameshifting is utilized for the synthesis of additional products, for regulatory purposes and for translational ‘correction’ of problem or ‘savior’ indels. Utilization for synthesis of additional products occurs prominently in the decoding of mobile chromosomal element and viral genomes. One class of regulatory frameshifting of stable chromosomal genes governs cellular polyamine levels from yeasts to humans. In many cases of productively utilized frameshifting, the proportion of ribosomes that frameshift at a shift-prone site is enhanced by specific nascent peptide or mRNA context features. Such mRNA signals, which can be 5′ or 3′ of the shift site or both, can act by pairing with ribosomal RNA or as stem loops or pseudoknots even with one component being 4 kb 3′ from the shift site. Transcriptional realignment at slippage-prone sequences also generates productively utilized products encoded trans-frame with respect to the genomic sequence. This too can be enhanced by nucleic acid structure. Together with dynamic codon redefinition, frameshifting is one of the forms of recoding that enriches gene expression.
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Affiliation(s)
- John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland School of Microbiology, University College Cork, Cork, Ireland Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Pramod R Bhatt
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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