1
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Jones CP, Ferré-D’Amaré AR. Structural switching dynamically controls the doubly pseudoknotted Rous sarcoma virus-programmed ribosomal frameshifting element. Proc Natl Acad Sci U S A 2025; 122:e2418418122. [PMID: 40172966 PMCID: PMC12002268 DOI: 10.1073/pnas.2418418122] [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: 09/09/2024] [Accepted: 02/26/2025] [Indexed: 04/04/2025] Open
Abstract
A hallmark of retrovirus replication is the translation of two different polyproteins from one RNA through programmed -1 frameshifting. This is a mechanism in which the actively translating ribosome is induced to slip in the 5' direction at a defined codon and then continues translating in the new reading frame. Programmed frameshifting controls the stoichiometry of viral proteins and is therefore under stringent evolutionary selection. Forty years ago, the first frameshifting stimulatory element was discovered in the Rous sarcoma virus. The ~120 nt RNA segment was predicted to contain a pseudoknot, but its 3D structure has remained elusive. Now, we have determined cryoEM and X-ray crystallographic structures of this classic retroviral element, finding that it adopts a butterfly-like double-pseudoknot fold. One "wing" contains a dynamic pyrimidine-rich helix, observed crystallographically in two conformations and in a third conformation via cryoEM. The other wing encompasses the predicted pseudoknot, which interacts with a second unexpected pseudoknot through a toggle residue, A2546. This key purine switches conformations between structural states and tunes the stability of interacting residues in the two wings. We find that its mutation can modulate frameshifting by as much as 50-fold, likely by altering the relative abundance of different structural states in the conformational ensemble of the RNA. Taken together, our structure-function analyses reveal how a dynamic double pseudoknot junction stimulates frameshifting by taking advantage of conformational heterogeneity, supporting a multistate model in which high Shannon entropy enhances frameshifting efficiency.
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Affiliation(s)
- Christopher P. Jones
- Laboratory of Nucleic Acids, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD20892-8012
| | - Adrian R. Ferré-D’Amaré
- Laboratory of Nucleic Acids, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD20892-8012
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2
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Abstract
Protein synthesis by the ribosome is the final stage of biological information transfer and represents an irreversible commitment to gene expression. Accurate translation of messenger RNA is therefore essential to all life, and spontaneous errors by the translational machinery are highly infrequent (∼1/100,000 codons). Programmed -1 ribosomal frameshifting (-1PRF) is a mechanism in which the elongating ribosome is induced at high frequency to slip backward by one nucleotide at a defined position and to continue translation in the new reading frame. This is exploited as a translational regulation strategy by hundreds of RNA viruses, which rely on -1PRF during genome translation to control the stoichiometry of viral proteins. While early investigations of -1PRF focused on virological and biochemical aspects, the application of X-ray crystallography and cryo-electron microscopy (cryo-EM), and the advent of deep sequencing and single-molecule approaches have revealed unexpected structural diversity and mechanistic complexity. Molecular players from several model systems have now been characterized in detail, both in isolation and, more recently, in the context of the elongating ribosome. Here we provide a summary of recent advances and discuss to what extent a general model for -1PRF remains a useful way of thinking.
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Affiliation(s)
- Chris H Hill
- York Structural Biology Laboratory, York Biomedical Research Institute, Department of Biology, University of York, York, United Kingdom;
| | - Ian Brierley
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom;
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3
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Allan MF, Brivanlou A, Rouskin S. RNA levers and switches controlling viral gene expression. Trends Biochem Sci 2023; 48:391-406. [PMID: 36710231 DOI: 10.1016/j.tibs.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/27/2022] [Accepted: 12/15/2022] [Indexed: 01/29/2023]
Abstract
RNA viruses are diverse and abundant pathogens that are responsible for numerous human diseases. RNA viruses possess relatively compact genomes and have therefore evolved multiple mechanisms to maximize their coding capacities, often by encoding overlapping reading frames. These reading frames are then decoded by mechanisms such as alternative splicing and ribosomal frameshifting to produce multiple distinct proteins. These solutions are enabled by the ability of the RNA genome to fold into 3D structures that can mimic cellular RNAs, hijack host proteins, and expose or occlude regulatory protein-binding motifs to ultimately control key process in the viral life cycle. We highlight recent findings focusing on less conventional mechanisms of gene expression and new discoveries on the role of RNA structures.
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Affiliation(s)
- Matthew F Allan
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Amir Brivanlou
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Silvi Rouskin
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
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4
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RNA-As-Graphs Motif Atlas—Dual Graph Library of RNA Modules and Viral Frameshifting-Element Applications. Int J Mol Sci 2022; 23:ijms23169249. [PMID: 36012512 PMCID: PMC9408923 DOI: 10.3390/ijms23169249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/13/2022] [Accepted: 08/14/2022] [Indexed: 11/25/2022] Open
Abstract
RNA motif classification is important for understanding structure/function connections and building phylogenetic relationships. Using our coarse-grained RNA-As-Graphs (RAG) representations, we identify recurrent dual graph motifs in experimentally solved RNA structures based on an improved search algorithm that finds and ranks independent RNA substructures. Our expanded list of 183 existing dual graph motifs reveals five common motifs found in transfer RNA, riboswitch, and ribosomal 5S RNA components. Moreover, we identify three motifs for available viral frameshifting RNA elements, suggesting a correlation between viral structural complexity and frameshifting efficiency. We further partition the RNA substructures into 1844 distinct submotifs, with pseudoknots and junctions retained intact. Common modules are internal loops and three-way junctions, and three submotifs are associated with riboswitches that bind nucleotides, ions, and signaling molecules. Together, our library of existing RNA motifs and submotifs adds to the growing universe of RNA modules, and provides a resource of structures and substructures for novel RNA design.
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5
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Arévalo DM, Anokhina VS, Swart OLR, Miller BL. Expanding the known structure space for RNA binding: a test of 2,5-diketopiperazine. Org Biomol Chem 2022; 20:606-612. [PMID: 34927652 PMCID: PMC8900054 DOI: 10.1039/d1ob01976g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
As the importance of RNA as a therapeutic target has become increasingly recognized, the need for new chemotypes able to bind RNA has grown in significance. We hypothesized that diketopiperazines (DKPs), common substructures in natural products and protein-targeting therapeutic agents, could serve as effective scaffolds for targeting RNA. To confirm this hypothesis, we designed and synthesized two analogs, one incorporating a DKP and one not, of compounds previously demonstrated to bind an RNA critical to the life cycle of HIV-1 with high affinity and specificity. Prior to compound synthesis, calculations employing density functional methods and molecular mechanics conformational searches were used to confirm that the DKP could present functionality in a similar (albeit not identical) orientation to the non DKP-containing compound. We found that both the DKP-containing and parent compound had similar affinities to the target RNA as measured by surface plasmon resonance (SPR). Both compounds were found to have modest but equal anti-HIV activity. These results establish the feasibility of using DKPs to target RNA.
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Affiliation(s)
- Diego M. Arévalo
- Department of Chemistry, University of Rochester, Rochester, NY 14642, USA
| | - Viktoriya S. Anokhina
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14642, USA
| | - Oliver L. R. Swart
- Department of Chemistry, University of Rochester, Rochester, NY 14642, USA
| | - Benjamin L. Miller
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14642, USA,Department of Dermatology, University of Rochester, Rochester, NY 14642, USA
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6
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Benner BE, Bruce JW, Kentala JR, Murray M, Becker JT, Garcia-Miranda P, Ahlquist P, Butcher SE, Sherer NM. Perturbing HIV-1 Ribosomal Frameshifting Frequency Reveals a cis Preference for Gag-Pol Incorporation into Assembling Virions. J Virol 2022; 96:e0134921. [PMID: 34643428 PMCID: PMC8754204 DOI: 10.1128/jvi.01349-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/30/2021] [Indexed: 12/29/2022] Open
Abstract
HIV-1 virion production is driven by Gag and Gag-Pol (GP) proteins, with Gag forming the bulk of the capsid and driving budding, while GP binds Gag to deliver the essential virion enzymes protease, reverse transcriptase, and integrase. Virion GP levels are traditionally thought to reflect the relative abundances of GP and Gag in cells (∼1:20), dictated by the frequency of a -1 programmed ribosomal frameshifting (PRF) event occurring in gag-pol mRNAs. Here, we exploited a panel of PRF mutant viruses to show that mechanisms in addition to PRF regulate GP incorporation into virions. First, we show that GP is enriched ∼3-fold in virions relative to cells, with viral infectivity being better maintained at subphysiological levels of GP than when GP levels are too high. Second, we report that GP is more efficiently incorporated into virions when Gag and GP are synthesized in cis (i.e., from the same gag-pol mRNA) than in trans, suggesting that Gag/GP translation and assembly are spatially coupled processes. Third, we show that, surprisingly, virions exhibit a strong upper limit to trans-delivered GP incorporation; an adaptation that appears to allow the virus to temper defects to GP/Gag cleavage that may negatively impact reverse transcription. Taking these results together, we propose a "weighted Goldilocks" scenario for HIV-1 GP incorporation, wherein combined mechanisms of GP enrichment and exclusion buffer virion infectivity over a broad range of local GP concentrations. These results provide new insights into the HIV-1 virion assembly pathway relevant to the anticipated efficacy of PRF-targeted antiviral strategies. IMPORTANCE HIV-1 infectivity requires incorporation of the Gag-Pol (GP) precursor polyprotein into virions during the process of virus particle assembly. Mechanisms dictating GP incorporation into assembling virions are poorly defined, with GP levels in virions traditionally thought to solely reflect relative levels of Gag and GP expressed in cells, dictated by the frequency of a -1 programmed ribosomal frameshifting (PRF) event that occurs in gag-pol mRNAs. Herein, we provide experimental support for a "weighted Goldilocks" scenario for GP incorporation, wherein the virus exploits both random and nonrandom mechanisms to buffer infectivity over a wide range of GP expression levels. These mechanistic data are relevant to ongoing efforts to develop antiviral strategies targeting PRF frequency and/or HIV-1 virion maturation.
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Affiliation(s)
- Bayleigh E. Benner
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- UW—Madison Microbiology Doctoral Training Program, Madison, Wisconsin, USA
| | - James W. Bruce
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Jacob R. Kentala
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Magdalena Murray
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Jordan T. Becker
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Pablo Garcia-Miranda
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Paul Ahlquist
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Nathan M. Sherer
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
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7
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Puray-Chavez M, Lee N, Tenneti K, Wang Y, Vuong HR, Liu Y, Horani A, Huang T, Gunsten SP, Case JB, Yang W, Diamond MS, Brody SL, Dougherty J, Kutluay SB. The translational landscape of SARS-CoV-2 and infected cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2020.11.03.367516. [PMID: 33173862 PMCID: PMC7654850 DOI: 10.1101/2020.11.03.367516] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
SARS-CoV-2 utilizes a number of strategies to modulate viral and host mRNA translation. Here, we used ribosome profiling in SARS-CoV-2 infected model cell lines and primary airway cells grown at the air-liquid interface to gain a deeper understanding of the translationally regulated events in response to virus replication. We find that SARS-CoV-2 mRNAs dominate the cellular mRNA pool but are not more efficiently translated than cellular mRNAs. SARS-CoV-2 utilized a highly efficient ribosomal frameshifting strategy in comparison to HIV-1, suggesting utilization of distinct structural elements. In the highly permissive cell models, although SARS-CoV-2 infection induced the transcriptional upregulation of numerous chemokines, cytokines and interferon stimulated genes, many of these mRNAs were not translated efficiently. Impact of SARS-CoV-2 on host mRNA translation was more subtle in primary cells, with marked transcriptional and translational upregulation of inflammatory and innate immune responses and downregulation of processes involved in ciliated cell function. Together, these data reveal the key role of mRNA translation in SARS-CoV-2 replication and highlight unique mechanisms for therapeutic development.
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Affiliation(s)
- Maritza Puray-Chavez
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Nakyung Lee
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Kasyap Tenneti
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Yiqing Wang
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Hung R Vuong
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Yating Liu
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Amjad Horani
- Department of Pediatrics, Allergy, Immunology and Pulmonary Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Tao Huang
- Department of Medicine, Pulmonary and Critical Care Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Sean P Gunsten
- Department of Medicine, Pulmonary and Critical Care Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - James B Case
- Department of Medicine, Infectious Disease Division, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Wei Yang
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael S Diamond
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Department of Medicine, Infectious Disease Division, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Steven L Brody
- Department of Medicine, Pulmonary and Critical Care Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Joseph Dougherty
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Sebla B Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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8
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Anokhina VS, Miller BL. Targeting Ribosomal Frameshifting as an Antiviral Strategy: From HIV-1 to SARS-CoV-2. Acc Chem Res 2021; 54:3349-3361. [PMID: 34403258 DOI: 10.1021/acs.accounts.1c00316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Treatment of HIV-1 has largely involved targeting viral enzymes using a cocktail of inhibitors. However, resistance to these inhibitors and toxicity in the long term have pushed the field to identify new therapeutic targets. To that end, -1 programmed ribosomal frameshifting (-1 PRF) has gained attention as a potential node for therapeutic intervention. In this process, a ribosome moves one nucleotide backward in the course of translating a mRNA, revealing a new reading frame for protein synthesis. In HIV-1, -1 PRF allows the virus to regulate the ratios of enzymatic and structural proteins as needed for correct viral particle assembly. Two RNA structural elements are central to -1 PRF in HIV: a slippery sequence and a highly conserved stable hairpin called the HIV-1 frameshifting stimulatory signal (FSS). Dysregulation of -1 PRF is deleterious for the virus. Thus, -1 PRF is an attractive target for new antiviral development. It is important to note that HIV-1 is not the only virus exploiting -1 PRF for regulating production of its proteins. Coronaviruses, including the COVID-19 pandemic virus SARS-CoV-2, also rely on -1 PRF. In SARS-CoV-2 and other coronaviruses, -1 PRF is required for synthesis of RNA-dependent RNA polymerase and several other nonstructural proteins. Coronaviruses employ a more complex RNA structural element for regulating -1 PRF called a pseudoknot. The purpose of this Account is primarily to review the development of molecules targeting HIV-1 -1 PRF. These approaches are case studies illustrating how the entire pipeline from screening to the generation of high-affinity leads might be implemented. We consider both target-based and function-based screening, with a particular focus on our group's approach beginning with a resin-bound dynamic combinatorial library (RBDCL) screen. We then used rational design approaches to optimize binding affinity, selectivity, and cellular bioavailability. Our tactic is, to the best of our knowledge, the only study resulting in compounds that bind specifically to the HIV-1 FSS RNA and reduce infectivity of laboratory and drug-resistant strains of HIV-1 in human cells. Lessons learned from strategies targeting -1 PRF HIV-1 might provide solutions in the development of antivirals in areas of unmet medical need. This includes the development of new frameshift-altering therapies for SARS-CoV-2, approaches to which are very recently beginning to appear.
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Affiliation(s)
- Viktoriya S. Anokhina
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642, United States
| | - Benjamin L. Miller
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York 14642, United States
- Department of Dermatology, University of Rochester, Rochester, New York 14642, United States
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9
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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: 1.2] [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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10
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Korniy N, Samatova E, Anokhina MM, Peske F, Rodnina MV. Mechanisms and biomedical implications of -1 programmed ribosome frameshifting on viral and bacterial mRNAs. FEBS Lett 2019; 593:1468-1482. [PMID: 31222875 PMCID: PMC6771820 DOI: 10.1002/1873-3468.13478] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/14/2019] [Accepted: 05/26/2019] [Indexed: 12/11/2022]
Abstract
Some proteins are expressed as a result of a ribosome frameshifting event that is facilitated by a slippery site and downstream secondary structure elements in the mRNA. This review summarizes recent progress in understanding mechanisms of –1 frameshifting in several viral genes, including IBV 1a/1b, HIV‐1 gag‐pol, and SFV 6K, and in Escherichia coli dnaX. The exact frameshifting route depends on the availability of aminoacyl‐tRNAs: the ribosome normally slips into the –1‐frame during tRNA translocation, but can also frameshift during decoding at condition when aminoacyl‐tRNA is in limited supply. Different frameshifting routes and additional slippery sites allow viruses to maintain a constant production of their key proteins. The emerging idea that tRNA pools are important for frameshifting provides new direction for developing antiviral therapies.
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Affiliation(s)
- Natalia Korniy
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Maria M Anokhina
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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11
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Ali AM, Atmaj J, Van Oosterwijk N, Groves MR, Dömling A. Stapled Peptides Inhibitors: A New Window for Target Drug Discovery. Comput Struct Biotechnol J 2019; 17:263-281. [PMID: 30867891 PMCID: PMC6396041 DOI: 10.1016/j.csbj.2019.01.012] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/11/2022] Open
Abstract
Protein-protein interaction (PPI) is a hot topic in clinical research as protein networking has a major impact in human disease. Such PPIs are potential drugs targets, leading to the need to inhibit/block specific PPIs. While small molecule inhibitors have had some success and reached clinical trials, they have generally failed to address the flat and large nature of PPI surfaces. As a result, larger biologics were developed for PPI surfaces and they have successfully targeted PPIs located outside the cell. However, biologics have low bioavailability and cannot reach intracellular targets. A novel class -hydrocarbon-stapled α-helical peptides that are synthetic mini-proteins locked into their bioactive structure through site-specific introduction of a chemical linker- has shown promise. Stapled peptides show an ability to inhibit intracellular PPIs that previously have been intractable with traditional small molecule or biologics, suggesting that they offer a novel therapeutic modality. In this review, we highlight what stapling adds to natural-mimicking peptides, describe the revolution of synthetic chemistry techniques and how current drug discovery approaches have been adapted to stabilize active peptide conformations, including ring-closing metathesis (RCM), lactamisation, cycloadditions and reversible reactions. We provide an overview on the available stapled peptide high-resolution structures in the protein data bank, with four selected structures discussed in details due to remarkable interactions of their staple with the target surface. We believe that stapled peptides are promising drug candidates and open the doors for peptide therapeutics to reach currently "undruggable" space.
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Affiliation(s)
| | | | | | | | - Alexander Dömling
- Department of Drug Design, University of Groningen, Antonius Deusinglaan1, 9700AD Groningen, the Netherlands
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12
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Marchant J, Bax A, Summers MF. Accurate Measurement of Residual Dipolar Couplings in Large RNAs by Variable Flip Angle NMR. J Am Chem Soc 2018; 140:6978-6983. [PMID: 29757635 PMCID: PMC6021016 DOI: 10.1021/jacs.8b03298] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
NMR approaches using nucleotide-specific deuterium labeling schemes have enabled structural studies of biologically relevant RNAs of increasing size and complexity. Although local structure is well-determined using these methods, definition of global structural features, including relative orientations of independent helices, remains a challenge. Residual dipolar couplings, a potential source of orientation information, have not been obtainable for large RNAs due to poor sensitivity resulting from rapid heteronuclear signal decay. Here we report a novel multiple quantum NMR method for RDC determination that employs flip angle variation rather than a coupling evolution period. The accuracy of the method and its utility for establishing interhelical orientations are demonstrated for a 36-nucleotide RNA, for which comparative data could be obtained. Applied to a 78 kDa Rev response element from the HIV-1 virus, which has an effective rotational correlation time of ca. 160 ns, the method yields sensitivity gains of an order of magnitude or greater over existing approaches. Solution-state access to structural organization in RNAs of at least 230 nucleotides is now possible.
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Affiliation(s)
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes, Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892 , United States
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13
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Ritchie DB, Cappellano TR, Tittle C, Rezajooei N, Rouleau L, Sikkema WKA, Woodside MT. Conformational dynamics of the frameshift stimulatory structure in HIV-1. RNA (NEW YORK, N.Y.) 2017; 23:1376-1384. [PMID: 28522581 PMCID: PMC5558907 DOI: 10.1261/rna.061655.117] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/12/2017] [Indexed: 05/02/2023]
Abstract
Programmed ribosomal frameshifting (PRF) in HIV-1 is thought to be stimulated by a hairpin in the mRNA, although a pseudoknot-like triplex has also been proposed. Because the conformational dynamics of the stimulatory structure under tension applied by the ribosomal helicase during translation may play an important role in PRF, we used optical tweezers to apply tension to the HIV stimulatory structure and monitor its unfolding and refolding dynamics. The folding and unfolding kinetics and energy landscape of the hairpin were measured by ramping the force on the hairpin up and down, providing a detailed biophysical characterization. Unexpectedly, whereas unfolding reflected the simple two-state behavior typical of many hairpins, refolding was more complex, displaying significant heterogeneity. Evidence was found for multiple refolding pathways as well as previously unsuspected, partially folded intermediates. Measuring a variant mRNA containing only the sequence required to form the proposed triplex, it behaved largely in the same way. Nonetheless, very rarely, high-force unfolding events characteristic of pseudoknot-like structures were observed. The rare occurrence of the triplex suggests that the hairpin is the functional stimulatory structure. The unusual heterogeneity of the hairpin dynamics under tension suggests a possible functional role in PRF similar to the dynamics of other stimulatory structures.
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Affiliation(s)
- Dustin B Ritchie
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Tonia R Cappellano
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Collin Tittle
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Negar Rezajooei
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Logan Rouleau
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | | | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
- National Institute for Nanotechnology, National Research Council, Edmonton AB T6G 2M9, Canada
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14
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Chen YT, Chang KC, Hu HT, Chen YL, Lin YH, Hsu CF, Chang CF, Chang KY, Wen JD. Coordination among tertiary base pairs results in an efficient frameshift-stimulating RNA pseudoknot. Nucleic Acids Res 2017; 45:6011-6022. [PMID: 28334864 PMCID: PMC5449628 DOI: 10.1093/nar/gkx134] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 12/28/2022] Open
Abstract
Frameshifting is an essential process that regulates protein synthesis in many viruses. The ribosome may slip backward when encountering a frameshift motif on the messenger RNA, which usually contains a pseudoknot structure involving tertiary base pair interactions. Due to the lack of detailed molecular explanations, previous studies investigating which features of the pseudoknot are important to stimulate frameshifting have presented diverse conclusions. Here we constructed a bimolecular pseudoknot to dissect the interior tertiary base pairs and used single-molecule approaches to assess the structure targeted by ribosomes. We found that the first ribosome target stem was resistant to unwinding when the neighboring loop was confined along the stem; such constrained conformation was dependent on the presence of consecutive adenosines in this loop. Mutations that disrupted the distal base triples abolished all remaining tertiary base pairs. Changes in frameshifting efficiency correlated with the stem unwinding resistance. Our results demonstrate that various tertiary base pairs are coordinated inside a highly efficient frameshift-stimulating RNA pseudoknot and suggest a mechanism by which mechanical resistance of the pseudoknot may persistently act on translocating ribosomes.
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Affiliation(s)
- Yu-Ting Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Kai-Chun Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Hao-Teng Hu
- Institute of Biochemistry, National Chung-Hsing University, Taichung 40227, Taiwan
| | - Yi-Lan Chen
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - You-Hsin Lin
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Chiung-Fang Hsu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Cheng-Fu Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Kung-Yao Chang
- Institute of Biochemistry, National Chung-Hsing University, Taichung 40227, Taiwan
| | - Jin-Der Wen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 10617, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
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15
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Ablation of Programmed -1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus Results in Attenuated Neuropathogenicity. J Virol 2017; 91:JVI.01766-16. [PMID: 27852852 DOI: 10.1128/jvi.01766-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/07/2016] [Indexed: 12/21/2022] Open
Abstract
The alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) are arthropod-borne positive-strand RNA viruses that are capable of causing acute and fatal encephalitis in many mammals, including humans. VEEV was weaponized during the Cold War and is recognized as a select agent. Currently, there are no FDA-approved vaccines or therapeutics for these viruses. The spread of VEEV and other members of this family due to climate change-mediated vector range expansion underscores the need for research aimed at developing medical countermeasures. These viruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which has previously been shown to be important for neuropathogenesis in the related Sindbis virus. Here, the alphavirus -1 PRF signals were characterized, revealing novel -1 PRF stimulatory structures. -1 PRF attenuation mildly affected the kinetics of VEEV accumulation in cultured cells but strongly inhibited its pathogenesis in an aerosol infection mouse model. Importantly, the decreased viral titers in the brains of mice infected with the mutant virus suggest that the alphavirus TF protein is important for passage through the blood-brain barrier and/or for neuroinvasiveness. These findings suggest a novel approach to the development of safe and effective live attenuated vaccines directed against VEEV and perhaps other closely related -1 PRF-utilizing viruses. IMPORTANCE Venezuelan equine encephalitis virus (VEEV) is a select agent that has been weaponized. This arthropod-borne positive-strand RNA virus causes acute and fatal encephalitis in many mammals, including humans. There is no vaccine or other approved therapeutic. VEEV and related alphaviruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which is important for neuropathogenesis. -1 PRF attenuation strongly inhibited VEEV pathogenesis in mice, and viral replication analyses suggest that the TF protein is critical for neurological disease. These findings suggest a new approach to the development of safe and effective live attenuated vaccines directed against VEEV and other related viruses.
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16
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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: 2.3] [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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17
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Stability of HIV Frameshift Site RNA Correlates with Frameshift Efficiency and Decreased Virus Infectivity. J Virol 2016; 90:6906-6917. [PMID: 27194769 DOI: 10.1128/jvi.00149-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/13/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED Human immunodeficiency virus (HIV) replication is strongly dependent upon a programmed ribosomal frameshift. Here we investigate the relationships between the thermodynamic stability of the HIV type 1 (HIV-1) RNA frameshift site stem-loop, frameshift efficiency, and infectivity, using pseudotyped HIV-1 and HEK293T cells. The data reveal a strong correlation between frameshift efficiency and local, but not overall, RNA thermodynamic stability. Mutations that modestly increase the local stability of the frameshift site RNA stem-loop structure increase frameshift efficiency 2-fold to 3-fold in cells. Thus, frameshift efficiency is determined by the strength of the thermodynamic barrier encountered by the ribosome. These data agree with previous in vitro measurements, suggesting that there are no virus- or host-specific factors that modulate frameshifting. The data also indicate that there are no sequence-specific requirements for the frameshift site stem-loop. A linear correlation between Gag-polymerase (Gag-Pol) levels in cells and levels in virions supports the idea of a stochastic virion assembly mechanism. We further demonstrate that the surrounding genomic RNA secondary structure influences frameshift efficiency and that a mutation that commonly arises in response to protease inhibitor therapy creates a functional but inefficient secondary slippery site. Finally, HIV-1 mutants with enhanced frameshift efficiencies are significantly less infectious, suggesting that compounds that increase frameshift efficiency by as little as 2-fold may be effective at suppressing HIV-1 replication. IMPORTANCE HIV, like many retroviruses, utilizes a -1 programmed ribosomal frameshift to generate viral enzymes in the form of a Gag-Pol polyprotein precursor. Thus, frameshifting is essential for viral replication. Here, we utilized a panel of mutant HIV strains to demonstrate that in cells, frameshifting efficiency is correlated with the stability of the local thermodynamic barrier to ribosomal translocation. Increasing the stability of the frameshift site RNA increases the frameshift efficiency 2-fold to 3-fold. Mutant viruses with increased frameshift efficiencies have significantly reduced infectivity. These data suggest that this effect might be exploited in the development of novel antiviral strategies.
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18
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Goz E, Tuller T. Evidence of a Direct Evolutionary Selection for Strong Folding and Mutational Robustness Within HIV Coding Regions. J Comput Biol 2016; 23:641-50. [PMID: 27347769 DOI: 10.1089/cmb.2016.0052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A large number of studies demonstrated the importance of different HIV RNA structural elements at all stages of the viral life cycle. Nevertheless, the significance of many of these structures is unknown, and plausibly new regions containing RNA structure-mediated regulatory signals remain to be identified. An important characteristic of genomic regions carrying functionally significant secondary structures is their mutational robustness, that is, the extent to which a sequence remains constant in spite of despite mutations in terms of its underlying secondary structure. Structural robustness to mutations is expected to be important in the case of functional RNA structures in viruses with high mutation rate; it may prevent fitness loss due to disruption of possibly functional conformations, pointing to the specific significance of the corresponding genomic region. In the current work, we perform a genome-wide computational analysis to detect signals of a direct evolutionary selection for strong folding and RNA structure-based mutational robustness within HIV coding sequences. We provide evidence that specific regions of HIV structural genes undergo an evolutionary selection for strong folding; in addition, we demonstrate that HIV Rev responsive element seems to undergo a direct evolutionary selection for increased secondary structure robustness to point mutations. We believe that our analysis may enable a better understanding of viral evolutionary dynamics at the RNA structural level and may benefit to practical efforts of engineering antiviral vaccines and novel therapeutic approaches.
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Affiliation(s)
- Eli Goz
- 1 Department of Biomedical Engineering, Tel-Aviv University , Ramat Aviv, Israel .,2 SynVaccine Ltd . Ramat Hachayal, Tel Aviv, Israel
| | - Tamir Tuller
- 1 Department of Biomedical Engineering, Tel-Aviv University , Ramat Aviv, Israel .,2 SynVaccine Ltd . Ramat Hachayal, Tel Aviv, Israel .,3 Sagol School of Neuroscience, Tel-Aviv University , Ramat Aviv, Israel
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19
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Hilimire TA, Bennett RP, Stewart RA, Garcia-Miranda P, Blume A, Becker J, Sherer N, Helms ED, Butcher SE, Smith HC, Miller BL. N-Methylation as a Strategy for Enhancing the Affinity and Selectivity of RNA-binding Peptides: Application to the HIV-1 Frameshift-Stimulating RNA. ACS Chem Biol 2016; 11:88-94. [PMID: 26496521 PMCID: PMC4720131 DOI: 10.1021/acschembio.5b00682] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Human Immunodeficiency
Virus (HIV) type 1 uses a −1 programmed
ribosomal frameshift (−1 PRF) event to translate its enzymes
from the same transcript used to encode the virus’ structural
proteins. The frequency of this event is highly regulated, and significant
deviation from the normal 5–10% frequency has been demonstrated
to decrease viral infectivity. Frameshifting is primarily regulated
by the Frameshift Stimulatory Signal RNA (FSS-RNA), a thermodynamically
stable, highly conserved stem loop that has been proposed as a therapeutic
target. We describe the design, synthesis, and testing of a series
of N-methyl peptides able to bind the HIV-1 FSS RNA
stem loop with low nanomolar affinity and high selectivity. Surface
plasmon resonance (SPR) data indicates increased affinity is a reflection
of a substantially enhanced on rate. Compounds readily penetrate cell
membranes and inhibit HIV infectivity in a pseudotyped virus assay.
Viral infectivity inhibition correlates with compound-dependent changes
in the ratios of Gag and Gag-Pol in virus particles. As the first
compounds with both single digit nanomolar affinities for the FSS
RNA and an ability to inhibit HIV in cells, these studies support
the use of N-methylation for enhancing the affinity,
selectivity, and bioactivity of RNA-binding peptides.
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Affiliation(s)
| | | | | | - Pablo Garcia-Miranda
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Alex Blume
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Jordan Becker
- McArdle
Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Nathan Sherer
- McArdle
Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Eric D. Helms
- Department
of Chemistry, SUNY Geneseo, Geneseo, New York 14454, United States
| | - Samuel E. Butcher
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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20
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Zhang X, Xu X, Yang Z, Burcke AJ, Gates KS, Chen SJ, Gu LQ. Mimicking Ribosomal Unfolding of RNA Pseudoknot in a Protein Channel. J Am Chem Soc 2015; 137:15742-52. [PMID: 26595106 PMCID: PMC4886178 DOI: 10.1021/jacs.5b07910] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pseudoknots are a fundamental RNA tertiary structure with important roles in regulation of mRNA translation. Molecular force spectroscopic approaches such as optical tweezers can track the pseudoknot's unfolding intermediate states by pulling the RNA chain from both ends, but the kinetic unfolding pathway induced by this method may be different from that in vivo, which occurs during translation and proceeds from the 5' to 3' end. Here we developed a ribosome-mimicking, nanopore pulling assay for dissecting the vectorial unfolding mechanism of pseudoknots. The pseudoknot unfolding pathway in the nanopore, either from the 5' to 3' end or in the reverse direction, can be controlled by a DNA leader that is attached to the pseudoknot at the 5' or 3' ends. The different nanopore conductance between DNA and RNA translocation serves as a marker for the position and structure of the unfolding RNA in the pore. With this design, we provided evidence that the pseudoknot unfolding is a two-step, multistate, metal ion-regulated process depending on the pulling direction. Most notably, unfolding in both directions is rate-limited by the unzipping of the first helix domain (first step), which is Helix-1 in the 5' → 3' direction and Helix-2 in the 3' → 5' direction, suggesting that the initial unfolding step in either pulling direction needs to overcome an energy barrier contributed by the noncanonical triplex base-pairs and coaxial stacking interactions for the tertiary structure stabilization. These findings provide new insights into RNA vectorial unfolding mechanisms, which play an important role in biological functions including frameshifting.
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Affiliation(s)
- Xinyue Zhang
- Department of Bioengineering and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Xiaojun Xu
- Department of Physics, Department of Biochemistry, and Informatics Institute, University of Missouri, Columbia, Missouri 65211, United States
| | - Zhiyu Yang
- Department of Chemistry and Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Andrew J. Burcke
- Department of Bioengineering and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Kent S. Gates
- Department of Chemistry and Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and Informatics Institute, University of Missouri, Columbia, Missouri 65211, United States
| | - Li-Qun Gu
- Department of Bioengineering and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri 65211, United States
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21
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Chitsaz H, Aminisharifabad M. Exact Learning of RNA Energy Parameters From Structure. J Comput Biol 2015; 22:463-73. [DOI: 10.1089/cmb.2014.0164] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Hamidreza Chitsaz
- Department of Computer Science, Colorado State University, Fort Collins, Colorado
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22
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Mathew SF, Crowe-McAuliffe C, Graves R, Cardno TS, McKinney C, Poole ES, Tate WP. The highly conserved codon following the slippery sequence supports -1 frameshift efficiency at the HIV-1 frameshift site. PLoS One 2015; 10:e0122176. [PMID: 25807539 PMCID: PMC4373837 DOI: 10.1371/journal.pone.0122176] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 02/08/2015] [Indexed: 01/18/2023] Open
Abstract
HIV-1 utilises -1 programmed ribosomal frameshifting to translate structural and enzymatic domains in a defined proportion required for replication. A slippery sequence, U UUU UUA, and a stem-loop are well-defined RNA features modulating -1 frameshifting in HIV-1. The GGG glycine codon immediately following the slippery sequence (the 'intercodon') contributes structurally to the start of the stem-loop but has no defined role in current models of the frameshift mechanism, as slippage is inferred to occur before the intercodon has reached the ribosomal decoding site. This GGG codon is highly conserved in natural isolates of HIV. When the natural intercodon was replaced with a stop codon two different decoding molecules-eRF1 protein or a cognate suppressor tRNA-were able to access and decode the intercodon prior to -1 frameshifting. This implies significant slippage occurs when the intercodon is in the (perhaps distorted) ribosomal A site. We accommodate the influence of the intercodon in a model of frame maintenance versus frameshifting in HIV-1.
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Affiliation(s)
- Suneeth F. Mathew
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | | | - Ryan Graves
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Tony S. Cardno
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Cushla McKinney
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Elizabeth S. Poole
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Warren P. Tate
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
- * E-mail:
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23
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Mouzakis KD, Dethoff EA, Tonelli M, Al-Hashimi H, Butcher SE. Dynamic motions of the HIV-1 frameshift site RNA. Biophys J 2015; 108:644-54. [PMID: 25650931 PMCID: PMC4317556 DOI: 10.1016/j.bpj.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 11/11/2014] [Accepted: 12/05/2014] [Indexed: 12/13/2022] Open
Abstract
The HIV-1 frameshift site (FS) plays a critical role in viral replication. During translation, the HIV-1 FS transitions from a 3-helix to a 2-helix junction RNA secondary structure. The 2-helix junction structure contains a GGA bulge, and purine-rich bulges are common motifs in RNA secondary structure. Here, we investigate the dynamics of the HIV-1 FS 2-helix junction RNA. Interhelical motions were studied under different ionic conditions using NMR order tensor analysis of residual dipolar couplings. In 150 mM potassium, the RNA adopts a 43°(±4°) interhelical bend angle (β) and displays large amplitude, anisotropic interhelical motions characterized by a 0.52(±0.04) internal generalized degree of order (GDOint) and distinct order tensor asymmetries for its two helices (η = 0.26(±0.04) and 0.5(±0.1)). These motions are effectively quenched by addition of 2 mM magnesium (GDOint = 0.87(±0.06)), which promotes a near-coaxial conformation (β = 15°(±6°)) of the two helices. Base stacking in the bulge was investigated using the fluorescent purine analog 2-aminopurine. These results indicate that magnesium stabilizes extrahelical conformations of the bulge nucleotides, thereby promoting coaxial stacking of helices. These results are highly similar to previous studies of the HIV transactivation response RNA, despite a complete lack of sequence similarity between the two RNAs. Thus, the conformational space of these RNAs is largely determined by the topology of their interhelical junctions.
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Affiliation(s)
- Kathryn D Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Elizabeth A Dethoff
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina
| | - Marco Tonelli
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | | | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin.
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24
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Guerrero S, Batisse J, Libre C, Bernacchi S, Marquet R, Paillart JC. HIV-1 replication and the cellular eukaryotic translation apparatus. Viruses 2015; 7:199-218. [PMID: 25606970 PMCID: PMC4306834 DOI: 10.3390/v7010199] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/12/2015] [Indexed: 12/13/2022] Open
Abstract
Eukaryotic translation is a complex process composed of three main steps: initiation, elongation, and termination. During infections by RNA- and DNA-viruses, the eukaryotic translation machinery is used to assure optimal viral protein synthesis. Human immunodeficiency virus type I (HIV-1) uses several non-canonical pathways to translate its own proteins, such as leaky scanning, frameshifting, shunt, and cap-independent mechanisms. Moreover, HIV-1 modulates the host translation machinery by targeting key translation factors and overcomes different cellular obstacles that affect protein translation. In this review, we describe how HIV-1 proteins target several components of the eukaryotic translation machinery, which consequently improves viral translation and replication.
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Affiliation(s)
- Santiago Guerrero
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
| | - Julien Batisse
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
| | - Camille Libre
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
| | - Serena Bernacchi
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
| | - Roland Marquet
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
| | - Jean-Christophe Paillart
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg cedex, France.
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25
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Cantara WA, Olson ED, Musier-Forsyth K. Progress and outlook in structural biology of large viral RNAs. Virus Res 2014; 193:24-38. [PMID: 24956407 PMCID: PMC4252365 DOI: 10.1016/j.virusres.2014.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/11/2014] [Accepted: 06/12/2014] [Indexed: 02/05/2023]
Abstract
The field of viral molecular biology has reached a precipice for which pioneering studies on the structure of viral RNAs are beginning to bridge the gap. It has become clear that viral genomic RNAs are not simply carriers of hereditary information, but rather are active players in many critical stages during replication. Indeed, functions such as cap-independent translation initiation mechanisms are, in some cases, primarily driven by RNA structural determinants. Other stages including reverse transcription initiation in retroviruses, nuclear export and viral packaging are specifically dependent on the proper 3-dimensional folding of multiple RNA domains to recruit necessary viral and host factors required for activity. Furthermore, a large-scale conformational change within the 5'-untranslated region of HIV-1 has been proposed to regulate the temporal switch between viral protein synthesis and packaging. These RNA-dependent functions are necessary for replication of many human disease-causing viruses such as severe acute respiratory syndrome (SARS)-associated coronavirus, West Nile virus, and HIV-1. The potential for antiviral development is currently hindered by a poor understanding of RNA-driven molecular mechanisms, resulting from a lack of structural information on large RNAs and ribonucleoprotein complexes. Herein, we describe the recent progress that has been made on characterizing these large RNAs and provide brief descriptions of the techniques that will be at the forefront of future advances. Ongoing and future work will contribute to a more complete understanding of the lifecycles of retroviruses and RNA viruses and potentially lead to novel antiviral strategies.
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Affiliation(s)
| | | | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, Center for Retrovirus Research, Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
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26
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Belew AT, Meskauskas A, Musalgaonkar S, Advani VM, Sulima SO, Kasprzak WK, Shapiro BA, Dinman JD. Ribosomal frameshifting in the CCR5 mRNA is regulated by miRNAs and the NMD pathway. Nature 2014; 512:265-9. [PMID: 25043019 PMCID: PMC4369343 DOI: 10.1038/nature13429] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/29/2014] [Indexed: 12/17/2022]
Abstract
Programmed -1 ribosomal frameshift (-1 PRF) signals redirect translating ribosomes to slip back one base on messenger RNAs. Although well characterized in viruses, how these elements may regulate cellular gene expression is not understood. Here we describe a -1 PRF signal in the human mRNA encoding CCR5, the HIV-1 co-receptor. CCR5 mRNA-mediated -1 PRF is directed by an mRNA pseudoknot, and is stimulated by at least two microRNAs. Mapping the mRNA-miRNA interaction suggests that formation of a triplex RNA structure stimulates -1 PRF. A -1 PRF event on the CCR5 mRNA directs translating ribosomes to a premature termination codon, destabilizing it through the nonsense-mediated mRNA decay pathway. At least one additional mRNA decay pathway is also involved. Functional -1 PRF signals that seem to be regulated by miRNAs are also demonstrated in mRNAs encoding six other cytokine receptors, suggesting a novel mode through which immune responses may be fine-tuned in mammalian cells.
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Affiliation(s)
- Ashton Trey Belew
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
| | - Arturas Meskauskas
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
- Department of Biotechnology and Microbiology, Vilnius University, Vilnius, LT 03101 Lithuania
| | - Sharmishtha Musalgaonkar
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
| | - Vivek M. Advani
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
| | - Sergey O. Sulima
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
- Present Address: Present address: VIB Center for the Biology of Disease, KU Leuven, Campus Gasthuisberg, Herestraat 49, bus 602, 3000 Leuven, Belgium.,
| | - Wojciech K. Kasprzak
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, 21702 Maryland USA
| | - Bruce A. Shapiro
- Basic Research Laboratory, National Cancer Institute, Frederick, 21702 Maryland USA
| | - Jonathan D. Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, 20742 Maryland USA
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27
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Low JT, Garcia-Miranda P, Mouzakis KD, Gorelick RJ, Butcher SE, Weeks KM. Structure and dynamics of the HIV-1 frameshift element RNA. Biochemistry 2014; 53:4282-91. [PMID: 24926888 PMCID: PMC4089884 DOI: 10.1021/bi5004926] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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The
HIV-1 ribosomal frameshift element is highly structured, regulates
translation of all virally encoded enzymes, and is a promising therapeutic
target. The prior model for this motif contains two helices separated
by a three-nucleotide bulge. Modifications to this model were suggested
by SHAPE chemical probing of an entire HIV-1 RNA genome. Novel features
of the SHAPE-directed model include alternate helical conformations
and a larger, more complex structure. These structural elements also
support the presence of a secondary frameshift site within the frameshift
domain. Here, we use oligonucleotide-directed structure perturbation,
probing in the presence of formamide, and in-virion experiments to
examine these models. Our data support a model in which the frameshift
domain is anchored by a stable helix outside the conventional domain.
Less stable helices within the domain can switch from the SHAPE-predicted
to the two-helix conformation. Translational frameshifting assays
with frameshift domain mutants support a functional role for the interactions
predicted by and specific to the SHAPE-directed model. These results
reveal that the HIV-1 frameshift domain is a complex, dynamic structure
and underscore the importance of analyzing folding in the context
of full-length RNAs.
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Affiliation(s)
- Justin T Low
- Department of Chemistry, University of North Carolina , Chapel Hill, North Carolina 27599-3290, United States
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28
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Eichhorn CD, Al-Hashimi HM. Structural dynamics of a single-stranded RNA-helix junction using NMR. RNA (NEW YORK, N.Y.) 2014; 20:782-91. [PMID: 24742933 PMCID: PMC4024633 DOI: 10.1261/rna.043711.113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Many regulatory RNAs contain long single strands (ssRNA) that adjoin secondary structural elements. Here, we use NMR spectroscopy to study the dynamic properties of a 12-nucleotide (nt) ssRNA tail derived from the prequeuosine riboswitch linked to the 3' end of a 48-nt hairpin. Analysis of chemical shifts, NOE connectivity, (13)C spin relaxation, and residual dipolar coupling data suggests that the first two residues (A25 and U26) in the ssRNA tail stack onto the adjacent helix and assume an ordered conformation. The following U26-A27 step marks the beginning of an A6-tract and forms an acute pivot point for substantial motions within the tail, which increase toward the terminal end. Despite substantial internal motions, the ssRNA tail adopts, on average, an A-form helical conformation that is coaxial with the helix. Our results reveal a surprising degree of structural and dynamic complexity at the ssRNA-helix junction, which involves a fine balance between order and disorder that may facilitate efficient pseudoknot formation on ligand recognition.
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Affiliation(s)
- Catherine D. Eichhorn
- Chemical Biology Doctoral Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
- Corresponding authorE-mail
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29
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Bailey BL, Visscher K, Watkins J. A stochastic model of translation with -1 programmed ribosomal frameshifting. Phys Biol 2014; 11:016009. [PMID: 24501223 DOI: 10.1088/1478-3975/11/1/016009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Many viruses produce multiple proteins from a single mRNA sequence by encoding overlapping genes. One mechanism to decode both genes, which reside in alternate reading frames, is -1 programmed ribosomal frameshifting. Although recognized for over 25 years, the molecular and physical mechanism of -1 frameshifting remains poorly understood. We have developed a mathematical model that treats mRNA translation and associated -1 frameshifting as a stochastic process in which the transition probabilities are based on the energetics of local molecular interactions. The model predicts both the location and efficiency of -1 frameshift events in HIV-1. Moreover, we compute -1 frameshift efficiencies upon mutations in the viral mRNA sequence and variations in relative tRNA abundances, predictions that are directly testable in experiment.
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Affiliation(s)
- Brenae L Bailey
- Program in Applied Mathematics, University of Arizona, Tucson, AZ 85721, USA
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30
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Anti-frameshifting ligand reduces the conformational plasticity of the SARS virus pseudoknot. J Am Chem Soc 2014; 136:2196-9. [PMID: 24446874 DOI: 10.1021/ja410344b] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Programmed -1 ribosomal frameshifting (-1 PRF) stimulated by mRNA pseudoknots regulates gene expression in many viruses, making pseudoknots potential targets for anti-viral drugs. The mechanism by which pseudoknots trigger -1 PRF, however, remains controversial, with several competing models. Recent work showed that high -1 PRF efficiency was linked to high pseudoknot conformational plasticity via the formation of alternate conformers. We tested whether pseudoknots bound with an anti-frameshifting ligand exhibited a similar correlation between conformational plasticity and -1 PRF efficiency by measuring the effects of a ligand that was found to inhibit -1 PRF in the SARS coronavirus on the conformational dynamics of the SARS pseudoknot. Using single-molecule force spectroscopy to unfold pseudoknots mechanically, we found that the ligand binding effectively abolished the formation of alternate conformers. This result extends the connection between -1 PRF and conformational dynamics and, moreover, suggests that targeting the conformational dynamics of pseudoknots may be an effective strategy for anti-viral drug design.
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31
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Ofori LO, Hilimire TA, Bennett RP, Brown NW, Smith HC, Miller BL. High-affinity recognition of HIV-1 frameshift-stimulating RNA alters frameshifting in vitro and interferes with HIV-1 infectivity. J Med Chem 2014; 57:723-32. [PMID: 24387306 PMCID: PMC3954503 DOI: 10.1021/jm401438g] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The
life cycle of the human immunodeficiency virus type 1 (HIV-1)
has an absolute requirement for ribosomal frameshifting during protein
translation in order to produce the polyprotein precursor of the viral
enzymes. While an RNA stem-loop structure (the “HIV-1 Frameshift
Stimulating Signal”, or HIV-1 FSS) controls the frameshift
efficiency and has been hypothesized as an attractive therapeutic
target, developing compounds that selectively bind this RNA and interfere
with HIV-1 replication has proven challenging. Building on our prior
discovery of a “hit” molecule able to bind this stem-loop,
we now report the development of compounds displaying high affinity
for the HIV-1 FSS. These compounds are able to enhance frameshifting
more than 50% in a dual-luciferase assay in human embryonic kidney
cells, and they strongly inhibit the infectivity of pseudotyped HIV-1
virions.
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Affiliation(s)
- Leslie O Ofori
- Departments of Chemistry, ‡Biochemistry and Biophysics, and §Dermatology, University of Rochester , Rochester, New York 14642, United States
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32
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Mouzakis KD, Lang AL, Vander Meulen KA, Easterday PD, Butcher SE. HIV-1 frameshift efficiency is primarily determined by the stability of base pairs positioned at the mRNA entrance channel of the ribosome. Nucleic Acids Res 2012; 41:1901-13. [PMID: 23248007 PMCID: PMC3561942 DOI: 10.1093/nar/gks1254] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The human immunodeficiency virus (HIV) requires a programmed −1 ribosomal frameshift for Pol gene expression. The HIV frameshift site consists of a heptanucleotide slippery sequence (UUUUUUA) followed by a spacer region and a downstream RNA stem–loop structure. Here we investigate the role of the RNA structure in promoting the −1 frameshift. The stem–loop was systematically altered to decouple the contributions of local and overall thermodynamic stability towards frameshift efficiency. No correlation between overall stability and frameshift efficiency is observed. In contrast, there is a strong correlation between frameshift efficiency and the local thermodynamic stability of the first 3–4 bp in the stem–loop, which are predicted to reside at the opening of the mRNA entrance channel when the ribosome is paused at the slippery site. Insertion or deletions in the spacer region appear to correspondingly change the identity of the base pairs encountered 8 nt downstream of the slippery site. Finally, the role of the surrounding genomic secondary structure was investigated and found to have a modest impact on frameshift efficiency, consistent with the hypothesis that the genomic secondary structure attenuates frameshifting by affecting the overall rate of translation.
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Affiliation(s)
- Kathryn D Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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33
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Brakier-Gingras L, Charbonneau J, Butcher SE. Targeting frameshifting in the human immunodeficiency virus. Expert Opin Ther Targets 2012; 16:249-58. [PMID: 22404160 DOI: 10.1517/14728222.2012.665879] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION HIV-1 uses a programmed –1 ribosomal frameshift to generate Gag-Pol, the precursor of its enzymes, when its full-length mRNA is translated by the ribosomes of the infected cells. This change in the reading frame occurs at a so-called slippery sequence that is followed by a specific secondary structure, the frameshift stimulatory signal. This signal controls the frameshift efficiency. The synthesis of HIV-1 enzymes is critical for virus replication and therefore, the –1 ribosomal frameshift could be the target of novel antiviral drugs. AREAS COVERED Various approaches were used to select drugs interfering with the –1 frameshift of HIV-1. These include the selection and modification of chemical compounds that specifically bind to the frameshift stimulatory signal, the use of antisense oligonucleotides targeting this signal and the selection of compounds that modulate HIV-1 frameshift, by using bicistronic reporters where the expression of the second cistron depends upon HIV-1 frameshift. EXPERT OPINION The most promising approach is the selection and modification of compounds specifically targeting the HIV-1 frameshift stimulatory signal. The use of antisense oligonucleotides binding to the frameshift stimulatory signal is still questionable. The use of bicistronic reporters preferentially selects compounds that modulate the frameshift by targeting the ribosomes, which is less promising.
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34
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Lin Z, Gilbert RJC, Brierley I. Spacer-length dependence of programmed -1 or -2 ribosomal frameshifting on a U6A heptamer supports a role for messenger RNA (mRNA) tension in frameshifting. Nucleic Acids Res 2012; 40:8674-89. [PMID: 22743270 PMCID: PMC3458567 DOI: 10.1093/nar/gks629] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Programmed -1 ribosomal frameshifting is employed in the expression of a number of viral and cellular genes. In this process, the ribosome slips backwards by a single nucleotide and continues translation of an overlapping reading frame, generating a fusion protein. Frameshifting signals comprise a heptanucleotide slippery sequence, where the ribosome changes frame, and a stimulatory RNA structure, a stem-loop or RNA pseudoknot. Antisense oligonucleotides annealed appropriately 3' of a slippery sequence have also shown activity in frameshifting, at least in vitro. Here we examined frameshifting at the U6A slippery sequence of the HIV gag/pol signal and found high levels of both -1 and -2 frameshifting with stem-loop, pseudoknot or antisense oligonucleotide stimulators. By examining -1 and -2 frameshifting outcomes on mRNAs with varying slippery sequence-stimulatory RNA spacing distances, we found that -2 frameshifting was optimal at a spacer length 1-2 nucleotides shorter than that optimal for -1 frameshifting with all stimulatory RNAs tested. We propose that the shorter spacer increases the tension on the mRNA such that when the tRNA detaches, it more readily enters the -2 frame on the U6A heptamer. We propose that mRNA tension is central to frameshifting, whether promoted by stem-loop, pseudoknot or antisense oligonucleotide stimulator.
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Affiliation(s)
- Zhaoru Lin
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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35
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Abstract
Expression of retroviral replication enzymes (Pol) requires a controlled translational recoding event to bypass the stop codon at the end of gag. This recoding event occurs either by direct suppression of termination via the insertion of an amino acid at the stop codon (readthrough) or by alteration of the mRNA reading frame (frameshift). Here we report the effects of a host protein, large ribosomal protein 4 (RPL4), on the efficiency of recoding. Using a dual luciferase reporter assay, we found that transfection of cells with a plasmid encoding RPL4 cDNA increases recoding efficiency in a dose-dependent manner, with a maximal enhancement of nearly twofold. Expression of RPL4 increases recoding of reporters containing retroviral readthrough and frameshift sequences, as well as the Sindbis virus leaky termination signal. RPL4-induced enhancement of recoding is cell line specific and appears to be specific to RPL4 among ribosomal proteins. Cotransfection of RPL4 cDNA with Moloney murine leukemia proviral DNA results in Gag processing defects and a reduction of viral particle formation, presumably caused by the RPL4-dependent alteration of the Gag-to-Gag-Pol ratio required for virion assembly and release.
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36
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Revealing -1 programmed ribosomal frameshifting mechanisms by single-molecule techniques and computational methods. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:569870. [PMID: 22545064 PMCID: PMC3321566 DOI: 10.1155/2012/569870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 01/16/2012] [Indexed: 01/17/2023]
Abstract
Programmed ribosomal frameshifting (PRF) serves as an intrinsic translational regulation mechanism employed by some viruses to control the ratio between structural and enzymatic proteins. Most viral mRNAs which use PRF adapt an H-type pseudoknot to stimulate −1 PRF. The relationship between the thermodynamic stability and the frameshifting efficiency of pseudoknots has not been fully understood. Recently, single-molecule force spectroscopy has revealed that the frequency of −1 PRF correlates with the unwinding forces required for disrupting pseudoknots, and that some of the unwinding work dissipates irreversibly due to the torsional restraint of pseudoknots. Complementary to single-molecule techniques, computational modeling provides insights into global motions of the ribosome, whose structural transitions during frameshifting have not yet been elucidated in atomic detail. Taken together, recent advances in biophysical tools may help to develop antiviral therapies that target the ubiquitous −1 PRF mechanism among viruses.
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37
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Charbonneau J, Gendron K, Ferbeyre G, Brakier-Gingras L. The 5' UTR of HIV-1 full-length mRNA and the Tat viral protein modulate the programmed -1 ribosomal frameshift that generates HIV-1 enzymes. RNA (NEW YORK, N.Y.) 2012; 18:519-529. [PMID: 22286970 PMCID: PMC3285939 DOI: 10.1261/rna.030346.111] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 12/01/2011] [Indexed: 05/31/2023]
Abstract
Translation of the full-length messenger RNA (mRNA) of the human immunodeficiency virus type 1 (HIV-1) generates the precursor of the viral enzymes via a programmed -1 ribosomal frameshift. Here, using dual-luciferase reporters, we investigated whether the highly structured 5' untranslated region (UTR) of this mRNA, which interferes with translation initiation, can modulate HIV-1 frameshift efficiency. We showed that, when the 5' UTR of HIV-1 mRNA occupies the 5' end of the reporter mRNA, HIV-1 frameshift efficiency is increased about fourfold in Jurkat T-cells, compared with a control dual-luciferase reporter with a short unstructured 5' UTR. This increase was related to an interference with cap-dependent translation initiation by the TAR-Poly(A) region at the 5' end of the messenger. HIV-1 mRNA 5' UTR also contains an internal ribosome entry site (IRES), but we showed that, when the cap-dependent initiation mode is available, the IRES is not used or is weakly used. However, when the ribosomes have to use the IRES to translate the dual-luciferase reporter, the frameshift efficiency is comparable to that of the control dual-luciferase reporter. The decrease in cap-dependent initiation and the accompanying increase in frameshift efficiency caused by the 5' UTR of HIV-1 mRNA is antagonized, in a dose-dependent way, by the Tat viral protein. Tat also stimulates the IRES-dependent initiation and decreases the corresponding frameshift efficiency. A model is presented that accounts for the variations in frameshift efficiency depending on the 5' UTR and the presence of Tat, and it is proposed that a range of frameshift efficiencies is compatible with the virus replication.
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Affiliation(s)
- Johanie Charbonneau
- Département de biochimie, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
| | - Karine Gendron
- Département de biochimie, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
- Centre de recherche, Hôpital Ste-Justine, Montréal, Québec, Canada, H3T 1C5
| | - Gerardo Ferbeyre
- Département de biochimie, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
| | - Léa Brakier-Gingras
- Département de biochimie, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
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38
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Houck-Loomis B, Durney MA, Salguero C, Shankar N, Nagle JM, Goff SP, D'Souza VM. An equilibrium-dependent retroviral mRNA switch regulates translational recoding. Nature 2011; 480:561-4. [PMID: 22121021 DOI: 10.1038/nature10657] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 10/20/2011] [Indexed: 01/15/2023]
Abstract
Most retroviruses require translational recoding of a viral messenger RNA stop codon to maintain a precise ratio of structural (Gag) and enzymatic (Pol) proteins during virus assembly. Pol is expressed exclusively as a Gag-Pol fusion either by ribosomal frameshifting or by read-through of the gag stop codon. Both of these mechanisms occur infrequently and only affect 5-10% of translating ribosomes, allowing the virus to maintain the critical Gag to Gag-Pol ratio. Although it is understood that the frequency of the recoding event is regulated by cis RNA motifs, no mechanistic explanation is currently available for how the critical protein ratio is maintained. Here we present the NMR structure of the murine leukaemia virus recoding signal and show that a protonation-dependent switch occurs to induce the active conformation. The equilibrium is such that at physiological pH the active, read-through permissive conformation is populated at approximately 6%: a level that correlates with in vivo protein quantities. The RNA functions by a highly sensitive, chemo-mechanical coupling tuned to ensure an optimal read-through frequency. Similar observations for a frameshifting signal indicate that this novel equilibrium-based mechanism may have a general role in translational recoding.
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Affiliation(s)
- Brian Houck-Loomis
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, New York 10032, USA
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39
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Marcheschi RJ, Tonelli M, Kumar A, Butcher SE. Structure of the HIV-1 frameshift site RNA bound to a small molecule inhibitor of viral replication. ACS Chem Biol 2011; 6:857-64. [PMID: 21648432 DOI: 10.1021/cb200082d] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Programmed -1 translational frameshifting is an essential event in the replication cycle of HIV. Frameshifting is required for expression of the viral Pol proteins, and drug-like molecules that target this process may inhibit HIV replication. A small molecule stimulator of HIV-1 frameshifting and inhibitor of viral replication, DB213 (RG501), was previously discovered from a high-throughput screen. However, the mechanistic basis for this compound's effects was unknown, and to date no structural information exists for small molecule effectors of frameshifting. Here, we investigate the binding of DB213 to the frameshift site RNA and have determined the structure of this complex by NMR. Binding of DB213 stabilizes the RNA and increases its melting temperature by 10 °C. The ligand binds to a primary site on the RNA stem-loop, although nonspecific interactions are also detected. The compound binds in the major groove and spans a distance of 9 base pairs. DB213 hydrogen bonds to phosphate groups on opposite sides of the major groove and alters the conformation of a conserved GGA bulge in the RNA. This study may provide a starting point for structure-based optimization of compounds targeting the HIV-1 frameshift site RNA.
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Affiliation(s)
- Ryan J. Marcheschi
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Marco Tonelli
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Arvind Kumar
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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40
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Spano MN, Walter NG. Solution structure of an alternate conformation of helix27 from Escherichia coli16S rRNA. Biopolymers 2011; 95:653-68. [PMID: 21442607 DOI: 10.1002/bip.21626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 03/08/2011] [Accepted: 03/09/2011] [Indexed: 11/09/2022]
Abstract
Helix (H)27 of 16S ribosomal (r)RNA from Escherichia coli was dubbed the "switch helix" when mutagenesis suggested that two alternative base pair registers may have distinct functional roles in the bacterial ribosome. Although more recent genetic analyses suggest that H27 conformational switching is not required for translation, previous solution studies demonstrated that the isolated E. coli H27 can dynamically convert between the 885 and 888 conformations. Here, we have solved the nuclear magnetic resonance solution structure of a locked 888 conformation. NOE and residual dipolar coupling restraints reveal an architecture that markedly differs from that of the 885 conformation found in crystal structures of the bacterial ribosome. In place of the loop E motif that characterizes the 885 conformer and that the 888 conformer cannot adopt, we find evidence for an asymmetrical A-rich internal loop stabilized by stacking interactions among the unpaired A's. Comparison of the isolated H27 888 solution structure with the 885 crystal structure within the context of the ribosome suggests a difference in overall length of H27 that presents one plausible reason for the absence of H27 conformational switching within the sterically confining ribosome.
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41
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Abstract
Errors occur randomly and at low frequency during the translation of mRNA. However, such errors may also be programmed by the sequence and structure of the mRNA. These programmed events are called ‘recoding’ and are found mostly in viruses, in which they are usually essential for viral replication. Translational errors at a stop codon may also be induced by drugs, raising the possibility of developing new treatment protocols for genetic diseases on the basis of nonsense mutations. Many studies have been carried out, but the molecular mechanisms governing these events remain largely unknown. Studies on the yeast Saccharomyces cerevisiae have contributed to characterization of the HIV‐1 frameshifting site and have demonstrated that frameshifting is conserved from yeast to humans. Yeast has also proved a particularly useful model organism for deciphering the mechanisms of translation termination in eukaryotes and identifying the factors required to obtain a high level of natural suppression. These findings open up new possibilities for large‐scale screening in yeast to identify new drugs for blocking HIV replication by inhibiting frameshifting or restoring production of the full‐length protein from a gene inactivated by a premature termination codon. We explore these two aspects of the contribution of yeast studies to human medicine in this review.
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Affiliation(s)
- Laure Bidou
- Université Paris-Sud, IGM CNRS UMR 8621, Orsay, France
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42
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Miyazaki Y, Irobalieva RN, Tolbert BS, Smalls-Mantey A, Iyalla K, Loeliger K, D'Souza V, Khant H, Schmid MF, Garcia EL, Telesnitsky A, Chiu W, Summers MF. Structure of a conserved retroviral RNA packaging element by NMR spectroscopy and cryo-electron tomography. J Mol Biol 2010; 404:751-72. [PMID: 20933521 DOI: 10.1016/j.jmb.2010.09.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 09/07/2010] [Accepted: 09/07/2010] [Indexed: 01/11/2023]
Abstract
The 5'-untranslated regions of all gammaretroviruses contain a conserved "double-hairpin motif" (Ψ(CD)) that is required for genome packaging. Both hairpins (SL-C and SL-D) contain GACG tetraloops that, in isolated RNAs, are capable of forming "kissing" interactions stabilized by two intermolecular G-C base pairs. We have determined the three-dimensional structure of the double hairpin from the Moloney murine leukemia virus ([Ψ(CD)](2), 132 nt, 42.8 kDa) using a (2)H-edited NMR-spectroscopy-based approach. This approach enabled the detection of (1)H-(1)H dipolar interactions that were not observed in previous studies of isolated SL-C and SL-D hairpin RNAs using traditional (1)H-(1)H correlated and (1)H-(13)C-edited NMR methods. The hairpins participate in intermolecular cross-kissing interactions (SL-C to SL-D' and SLC' to SL-D) and stack in an end-to-end manner (SL-C to SL-D and SL-C' to SL-D') that gives rise to an elongated overall shape (ca 95 Å×45 Å×25 Å). The global structure was confirmed by cryo-electron tomography (cryo-ET), making [Ψ(CD)](2) simultaneously the smallest RNA to be structurally characterized to date by cryo-ET and among the largest to be determined by NMR. Our findings suggest that, in addition to promoting dimerization, [Ψ(CD)](2) functions as a scaffold that helps initiate virus assembly by exposing a cluster of conserved UCUG elements for binding to the cognate nucleocapsid domains of assembling viral Gag proteins.
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Affiliation(s)
- Yasuyuki Miyazaki
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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43
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Palde PB, Ofori LO, Gareiss PC, Lerea J, Miller BL. Strategies for recognition of stem-loop RNA structures by synthetic ligands: application to the HIV-1 frameshift stimulatory sequence. J Med Chem 2010; 53:6018-27. [PMID: 20672840 DOI: 10.1021/jm100231t] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Production of the Gag-Pol polyprotein in human immunodeficiency virus (HIV) requires a -1 ribosomal frameshift, which is directed by a highly conserved RNA stem-loop. Building on our discovery of a set of disulfide-containing peptides that bind this RNA, we describe medicinal chemistry efforts designed to begin to understand the structure-activity relationships and RNA sequence-selectivity relationships associated with these compounds. Additionally, we have prepared analogues incorporating an olefin or saturated hydrocarbon bioisostere of the disulfide moiety, as a first step toward enhancing biostability. The olefin-containing compounds exhibit affinity comparable to the lead disulfide and, importantly, have no discernible toxicity when incubated with human fibroblasts at concentrations up to 1 mM.
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Affiliation(s)
- Prakash B Palde
- Department of Dermatology, University of Rochester, Rochester, NY 14642, USA
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Tolbert BS, Miyazaki Y, Barton S, Kinde B, Starck P, Singh R, Bax A, Case DA, Summers MF. Major groove width variations in RNA structures determined by NMR and impact of 13C residual chemical shift anisotropy and 1H-13C residual dipolar coupling on refinement. JOURNAL OF BIOMOLECULAR NMR 2010; 47:205-19. [PMID: 20549304 PMCID: PMC2929647 DOI: 10.1007/s10858-010-9424-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 04/20/2010] [Indexed: 05/22/2023]
Abstract
Ribonucleic acid structure determination by NMR spectroscopy relies primarily on local structural restraints provided by (1)H- (1)H NOEs and J-couplings. When employed loosely, these restraints are broadly compatible with A- and B-like helical geometries and give rise to calculated structures that are highly sensitive to the force fields employed during refinement. A survey of recently reported NMR structures reveals significant variations in helical parameters, particularly the major groove width. Although helical parameters observed in high-resolution X-ray crystal structures of isolated A-form RNA helices are sensitive to crystal packing effects, variations among the published X-ray structures are significantly smaller than those observed in NMR structures. Here we show that restraints derived from aromatic (1)H- (13)C residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) can overcome NMR restraint and force field deficiencies and afford structures with helical properties similar to those observed in high-resolution X-ray structures.
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Affiliation(s)
- Blanton S Tolbert
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Yasuyuki Miyazaki
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Shawn Barton
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Benyam Kinde
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Patrice Starck
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Rashmi Singh
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250
| | - Ad Bax
- Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, MD 208992
| | - David A. Case
- Dept. of Chemistry & Chemical Biology and BioMaPS Institute, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Phone: (732)-445-5885; Fax: (732)-445-5958;
| | - Michael F Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, phone: (410)-455-2527; fax: (410)-455-1174;
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45
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Low JT, Weeks KM. SHAPE-directed RNA secondary structure prediction. Methods 2010; 52:150-8. [PMID: 20554050 DOI: 10.1016/j.ymeth.2010.06.007] [Citation(s) in RCA: 226] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Indexed: 12/25/2022] Open
Abstract
The diverse functional roles of RNA are determined by its underlying structure. Accurate and comprehensive knowledge of RNA structure would inform a broader understanding of RNA biology and facilitate exploiting RNA as a biotechnological tool and therapeutic target. Determining the pattern of base pairing, or secondary structure, of RNA is a first step in these endeavors. Advances in experimental, computational, and comparative analysis approaches for analyzing secondary structure have yielded accurate structures for many small RNAs, but only a few large (>500 nts) RNAs. In addition, most current methods for determining a secondary structure require considerable effort, analytical expertise, and technical ingenuity. In this review, we outline an efficient strategy for developing accurate secondary structure models for RNAs of arbitrary length. This approach melds structural information obtained using SHAPE chemistry with structure prediction using nearest-neighbor rules and the dynamic programming algorithm implemented in the RNAstructure program. Prediction accuracies reach >or=95% for RNAs on the kilobase scale. This approach facilitates both development of new models and refinement of existing RNA structure models, which we illustrate using the Gag-Pol frameshift element in an HIV-1 M-group genome. Most promisingly, integrated experimental and computational refinement brings closer the ultimate goal of efficiently and accurately establishing the secondary structure for any RNA sequence.
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Affiliation(s)
- Justin T Low
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-3290, USA
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Kobayashi Y, Zhuang J, Peltz S, Dougherty J. Identification of a cellular factor that modulates HIV-1 programmed ribosomal frameshifting. J Biol Chem 2010; 285:19776-84. [PMID: 20418372 DOI: 10.1074/jbc.m109.085621] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Programmed -1 ribosomal frameshifting (PRF) is a distinctive mode of gene expression utilized by some viruses, including human immunodeficiency virus type 1 (HIV-1), to produce multiple proteins from a single mRNA. -1 PRF induces a subset of elongating ribosomes to shift their translational reading frame by 1 base in the 5' direction. The appropriate ratio of Gag to Gag-Pol synthesis is tightly regulated by the PRF signal which promotes ribosomes to shift frame, and even small changes in PRF efficiency, either up or down, have significant inhibitory effects upon virus production, making PRF essential for HIV-1 replication. Although little has been reported about the cellular factors that modulate HIV-1 PRF, the cis-acting elements regulating PRF have been extensively investigated, and the PRF signal of HIV-1 was shown to include a slippery site and frameshift stimulatory signal. Recently, a genome-wide screen performed to identify cellular factors that affect HIV-1 replication demonstrated that down-regulation of eukaryotic release factor 1 (eRF1) inhibited HIV-1 replication. Because of the eRF1 role in translation, we hypothesized that eRF1 is important for HIV-1 PRF. Using a dual luciferase reporter system harboring a HIV-1 PRF signal, results showed that depletion or inhibition of eRF1 enhanced PRF in yeast, rabbit reticulocyte lysates, and mammalian cells. Consistent with the eRF1 role in modulating HIV PRF, depleting eRF1 increased the Gag-Pol to Gag ratio in cells infected with replication-competent virus. The increase in PRF was independent of a proximal termination codon and did not result from increased ribosomal pausing at the slippery site. This is the first time that a cellular factor has been identified which can promote HIV-1 PRF and highlights HIV-1 PRF as essential for replication and an important but under exploited antiviral drug target.
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Affiliation(s)
- Yoshifumi Kobayashi
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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47
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Hong HS, Kim YG, Hohng SC. Single-Molecule FRET Studies on Frameshifting RNA Structures of Human Immunodeficiency Virus. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.04.1021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Mazauric MH, Seol Y, Yoshizawa S, Visscher K, Fourmy D. Interaction of the HIV-1 frameshift signal with the ribosome. Nucleic Acids Res 2010; 37:7654-64. [PMID: 19812214 PMCID: PMC2794165 DOI: 10.1093/nar/gkp779] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ribosomal frameshifting on viral RNAs relies on the mechanical properties of structural elements, often pseudoknots and more rarely stem-loops, that are unfolded by the ribosome during translation. In human immunodeficiency virus (HIV)-1 type B a long hairpin containing a three-nucleotide bulge is responsible for efficient frameshifting. This three-nucleotide bulge separates the hairpin in two domains: an unstable lower stem followed by a GC-rich upper stem. Toeprinting and chemical probing assays suggest that a hairpin-like structure is retained when ribosomes, initially bound at the slippery sequence, were allowed multiple EF-G catalyzed translocation cycles. However, while the upper stem remains intact the lower stem readily melts. After the first, and single step of translocation of deacylated tRNA to the 30 S P site, movement of the mRNA stem-loop in the 5′ direction is halted, which is consistent with the notion that the downstream secondary structure resists unfolding. Mechanical stretching of the hairpin using optical tweezers only allows clear identification of unfolding of the upper stem at a force of 12.8 ± 1.0 pN. This suggests that the lower stem is unstable and may indeed readily unfold in the presence of a translocating ribosome.
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Affiliation(s)
- Marie-Hélène Mazauric
- Laboratoire de Chimie et Biologie Structurales, FRC 3115 ICSN-CNRS 1 ave de la terrasse, 91190 Gif-sur-Yvette, France
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Roberts LO, Jopling CL, Jackson RJ, Willis AE. Viral strategies to subvert the mammalian translation machinery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:313-67. [PMID: 20374746 PMCID: PMC7102724 DOI: 10.1016/s1877-1173(09)90009-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Viruses do not carry their own protein biosynthesis machinery and the translation of viral proteins therefore requires that the virus usurps the machinery of the host cell. To allow optimal translation of viral proteins at the expense of cellular proteins, virus families have evolved a variety of methods to repress the host translation machinery, while allowing effective viral protein synthesis. Many viruses use noncanonical mechanisms that permit translation of their own RNAs under these conditions. Viruses have also developed mechanisms to evade host innate immune responses that would repress translation under conditions of viral infection, in particular PKR activation in response to double-stranded RNA (dsRNA). Importantly, the study of viral translation mechanisms has enormously enhanced our understanding of many aspects of the cellular protein biosynthesis pathway and its components. A number of unusual mechanisms of translation initiation that were first discovered in viruses have since been observed in cellular mRNAs, and it has become apparent that a diverse range of translation mechanisms operates in eukaryotes, allowing subtle regulation of this essential process.
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Affiliation(s)
- Lisa O Roberts
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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50
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Marcheschi RJ, Mouzakis KD, Butcher SE. Selection and characterization of small molecules that bind the HIV-1 frameshift site RNA. ACS Chem Biol 2009; 4:844-54. [PMID: 19673541 DOI: 10.1021/cb900167m] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIV-1 requires a -1 translational frameshift to properly synthesize the viral enzymes required for replication. The frameshift mechanism is dependent upon two RNA elements, a seven-nucleotide slippery sequence (UUUUUUA) and a downstream RNA structure. Frameshifting occurs with a frequency of approximately 5%, and increasing or decreasing this frequency may result in a decrease in viral replication. Here, we report the results of a high-throughput screen designed to find small molecules that bind to the HIV-1 frameshift site RNA. Out of 34,500 compounds screened, 202 were identified as positive hits. We show that one of these compounds, doxorubicin, binds the HIV-1 RNA with low micromolar affinity (K(d) = 2.8 microM). This binding was confirmed and localized to the RNA using NMR. Further analysis revealed that this compound increased the RNA stability by approximately 5 degrees C and decreased translational frameshifting by 28% (+/-14%), as measured in vitro.
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Affiliation(s)
- Ryan J. Marcheschi
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Kathryn D. Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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