1
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Heel SV, Juen F, Bartosik K, Micura R, Kreutz C, Breuker K. Resolving the intricate binding of neomycin B to multiple binding motifs of a neomycin-sensing riboswitch aptamer by native top-down mass spectrometry and NMR spectroscopy. Nucleic Acids Res 2024; 52:4691-4701. [PMID: 38567725 PMCID: PMC11077050 DOI: 10.1093/nar/gkae224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 03/05/2024] [Accepted: 03/25/2024] [Indexed: 05/09/2024] Open
Abstract
Understanding small molecule binding to RNA can be complicated by an intricate interplay between binding stoichiometry, multiple binding motifs, different occupancies of different binding motifs, and changes in the structure of the RNA under study. Here, we use native top-down mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy to experimentally resolve these factors and gain a better understanding of the interactions between neomycin B and the 40 nt aptamer domain of a neomycin-sensing riboswitch engineered in yeast. Data from collisionally activated dissociation of the 1:1, 1:2 and 1:3 RNA-neomycin B complexes identified a third binding motif C of the riboswitch in addition to the two motifs A and B found in our previous study, and provided occupancies of the different binding motifs for each complex stoichiometry. Binding of a fourth neomycin B molecule was unspecific according to both MS and NMR data. Intriguingly, all major changes in the aptamer structure can be induced by the binding of the first neomycin B molecule regardless of whether it binds to motif A or B as evidenced by stoichiometry-resolved MS data together with titration data from 1H NMR spectroscopy in the imino proton region. Specific binding of the second and third neomycin B molecules further stabilizes the riboswitch aptamer, thereby allowing for a gradual response to increasing concentrations of neomycin B, which likely leads to a fine-tuning of the cellular regulatory mechanism.
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Affiliation(s)
- Sarah Viola Heel
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Fabian Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Karolina Bartosik
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
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2
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Shino A, Otsu M, Imai K, Fukuzawa K, Morishita EC. Probing RNA-Small Molecule Interactions Using Biophysical and Computational Approaches. ACS Chem Biol 2023; 18:2368-2376. [PMID: 37856793 PMCID: PMC10662358 DOI: 10.1021/acschembio.3c00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 08/30/2023] [Indexed: 10/21/2023]
Abstract
Interest in small molecules that target RNA is flourishing, and the expectation set on them to treat diseases with unmet medical needs is high. However, several challenges remain, including difficulties in selecting suitable tools and establishing workflows for their discovery. In this context, we optimized experimental and computational approaches that were previously employed for the protein targets. Here, we demonstrate that a fluorescence-based assay can be effectively used to screen small molecule libraries for their ability to bind and stabilize an RNA stem-loop. Our screen identified several fluoroquinolones that bind to the target stem-loop. We further probed their interactions with the target using biolayer interferometry, isothermal titration calorimetry (ITC), and nuclear magnetic resonance spectroscopy. The results of these biophysical assays suggest that the fluoroquinolones bind the target in a similar manner. Armed with this knowledge, we built models for the complexes of the fluoroquinolones and the RNA target. Then, we performed fragment molecular orbital (FMO) calculations to dissect the interactions between the fluoroquinolones and the RNA. We found that the binding free energies obtained from the ITC experiments correlated strongly with the interaction energies calculated by FMO. Finally, we designed fluoroquinolone analogues and performed FMO calculations to predict their binding free energies. Taken together, the results of this study support the importance of conducting orthogonal assays in binding confirmation and compound selection and demonstrate the usefulness of FMO calculations in the rational design of RNA-targeted small molecules.
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Affiliation(s)
- Amiu Shino
- Basic
Research Division, Veritas In Silico Inc., Shinagawa, Tokyo 141-0031, Japan
| | - Maina Otsu
- Basic
Research Division, Veritas In Silico Inc., Shinagawa, Tokyo 141-0031, Japan
| | - Koji Imai
- Basic
Research Division, Veritas In Silico Inc., Shinagawa, Tokyo 141-0031, Japan
| | - Kaori Fukuzawa
- Graduate
School of Pharmaceutical Sciences, Osaka
University, Suita, Osaka 565-0871, Japan
- School
of Pharmacy and Pharmaceutical Sciences, Hoshi University, Shinagawa, Tokyo 142-8501, Japan
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3
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Chan KH, Wang Y, Zheng BX, Long W, Feng X, Wong WL. RNA-Selective Small-Molecule Ligands: Recent Advances in Live-Cell Imaging and Drug Discovery. ChemMedChem 2023; 18:e202300271. [PMID: 37649155 DOI: 10.1002/cmdc.202300271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 08/13/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023]
Abstract
RNA structures, including those formed from coding and noncoding RNAs, alternative to protein-based drug targets, could be a promising target of small molecules for drug discovery against various human diseases, particularly in anticancer, antibacterial and antivirus development. The normal cellular activity of cells is critically dependent on the function of various RNA molecules generated from DNA transcription. Moreover, many studies support that mRNA-targeting small molecules may regulate the synthesis of disease-related proteins via the non-covalent mRNA-ligand interactions that do not involve gene modification. RNA-ligand interaction is thus an attractive approach to address the challenge of "undruggable" proteins in drug discovery because the intracellular activity of these proteins is hard to be suppressed with small molecule ligands. We selectively surveyed a specific area of RNA structure-selective small molecule ligands in fluorescence live cell imaging and drug discovery because the area was currently underexplored. This state-of-the-art review thus mainly focuses on the research published within the past three years and aims to provide the most recent information on this research area; hopefully, it could be complementary to the previously reported reviews and give new insights into the future development on RNA-specific small molecule ligands for live cell imaging and drug discovery.
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Affiliation(s)
- Ka Hin Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Yakun Wang
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
| | - Bo-Xin Zheng
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Wei Long
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
| | - Xinxin Feng
- State Key Laboratory of Chem-/Bio-Sensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology and School of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
| | - Wing-Leung Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR 999077, P. R. China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, P. R. China
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4
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Li Q, Kang C. Targeting RNA-binding proteins with small molecules: Perspectives, pitfalls and bifunctional molecules. FEBS Lett 2023; 597:2031-2047. [PMID: 37519019 DOI: 10.1002/1873-3468.14710] [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: 03/01/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 08/01/2023]
Abstract
RNA-binding proteins (RBPs) play vital roles in organisms through binding with RNAs to regulate their functions. Small molecules affecting the function of RBPs have been developed, providing new avenues for drug discovery. Herein, we describe the perspectives on developing small molecule regulators of RBPs. The following types of small molecule modulators are of great interest in drug discovery: small molecules binding to RBPs to affect interactions with RNA molecules, bifunctional molecules binding to RNA or RBP to influence their interactions, and other types of molecules that affect the stability of RNA or RBPs. Moreover, we emphasize that the bifunctional molecules may play important roles in small molecule development to overcome the challenges encountered in the process of drug discovery.
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Affiliation(s)
- Qingxin Li
- Guangdong Provincial Engineering Laboratory of Biomass High Value Utilization, Institute of Biological and Medical Engineering, Guangdong Academy of Sciences, Guangzhou, China
| | - Congbao Kang
- Experimental Drug Development Centre, Agency for Science, Technology and Research, Singapore, Singapore
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5
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Marušič M, Toplishek M, Plavec J. NMR of RNA - Structure and interactions. Curr Opin Struct Biol 2023; 79:102532. [PMID: 36746110 DOI: 10.1016/j.sbi.2023.102532] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/11/2022] [Accepted: 12/19/2022] [Indexed: 02/07/2023]
Abstract
RNA was shown to have a more substantial role in the regulation of diverse cellular processes than anticipated until recently. Answers to questions what is the structure of specific RNAs, how structure changes to accommodate different functional roles, and how RNA senses other biomolecules and changes its fold upon interaction create a complete representation of RNA involved in cellular processes. Nuclear magnetic resonance (NMR) spectroscopy encompasses a collection of methods and approaches that offer insight into several structural aspects of RNAs. We review the most recent advances in the field of viral, long non-coding, regulatory, and four-stranded RNAs, with an emphasis on the detection of dynamic sub-states and in view of chemical modifications that expand RNA's function.
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Affiliation(s)
- Maja Marušič
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Maria Toplishek
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia; University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia; EN-FIST Centre of Excellence, Cesta OF 13, Ljubljana, Slovenia.
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6
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Morishita EC. Discovery of RNA-targeted small molecules through the merging of experimental and computational technologies. Expert Opin Drug Discov 2023; 18:207-226. [PMID: 36322542 DOI: 10.1080/17460441.2022.2134852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The field of RNA-targeted small molecules is rapidly evolving, owing to the advances in experimental and computational technologies. With the identification of several bioactive small molecules that target RNA, including the FDA-approved risdiplam, the biopharmaceutical industry is gaining confidence in the field. This review, based on the literature obtained from PubMed, aims to disseminate information about the various technologies developed for targeting RNA with small molecules and propose areas for improvement to develop drugs more efficiently, particularly those linked to diseases with unmet medical needs. AREAS COVERED The technologies for the identification of RNA targets, screening of chemical libraries against RNA, assessing the bioactivity and target engagement of the hit compounds, structure determination, and hit-to-lead optimization are reviewed. Along with the description of the technologies, their strengths, limitations, and examples of how they can impact drug discovery are provided. EXPERT OPINION Many existing technologies employed for protein targets have been repurposed for use in the discovery of RNA-targeted small molecules. In addition, technologies tailored for RNA targets have been developed. Nevertheless, more improvements are necessary, such as artificial intelligence to dissect important RNA structures and RNA-small-molecule interactions and more powerful chemical probing and structure prediction techniques.
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7
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Mollica L, Cupaioli FA, Rossetti G, Chiappori F. An overview of structural approaches to study therapeutic RNAs. Front Mol Biosci 2022; 9:1044126. [PMID: 36387283 PMCID: PMC9649582 DOI: 10.3389/fmolb.2022.1044126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 10/18/2022] [Indexed: 11/07/2023] Open
Abstract
RNAs provide considerable opportunities as therapeutic agent to expand the plethora of classical therapeutic targets, from extracellular and surface proteins to intracellular nucleic acids and its regulators, in a wide range of diseases. RNA versatility can be exploited to recognize cell types, perform cell therapy, and develop new vaccine classes. Therapeutic RNAs (aptamers, antisense nucleotides, siRNA, miRNA, mRNA and CRISPR-Cas9) can modulate or induce protein expression, inhibit molecular interactions, achieve genome editing as well as exon-skipping. A common RNA thread, which makes it very promising for therapeutic applications, is its structure, flexibility, and binding specificity. Moreover, RNA displays peculiar structural plasticity compared to proteins as well as to DNA. Here we summarize the recent advances and applications of therapeutic RNAs, and the experimental and computational methods to analyze their structure, by biophysical techniques (liquid-state NMR, scattering, reactivity, and computational simulations), with a focus on dynamic and flexibility aspects and to binding analysis. This will provide insights on the currently available RNA therapeutic applications and on the best techniques to evaluate its dynamics and reactivity.
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Affiliation(s)
- Luca Mollica
- Department of Medical Biotechnologies and Translational Medicine, L.I.T.A/University of Milan, Milan, Italy
| | | | | | - Federica Chiappori
- National Research Council—Institute for Biomedical Technologies, Milan, Italy
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8
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El-shobaky A, Elshafey R, Radi AE. Electrochemical studies on the binding of the sulfonated reactive dye Levafix Royal Blue E-FR with DNA. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2022; 19:4253-4260. [DOI: 10.1007/s13738-022-02598-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/26/2022] [Indexed: 09/02/2023]
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9
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Falco N, Garfio CM, Spitalny L, Spitale RC. A Fluorescent Reverse-Transcription Assay to Detect Chemical Adducts on RNA. Biochemistry 2022; 61:1665-1668. [PMID: 35876726 PMCID: PMC10010264 DOI: 10.1021/acs.biochem.2c00270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Herein, we detail a novel reverse-transcription (RT) assay to directly detect chemical adducts on RNA. We optimize a fluorescence quenching assay to detect RT polymerization and employ our approach to detect N1-alkylation of inosine, an important post-transcriptional modification, using a phenylacrylamide as a model compound. We anticipate our approach can be expanded to identify novel reagents that form adducts with RNA and further explored to understand the relationship between RT processivity and natural post-transcriptional modifications in RNA.
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10
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Dayie TK, Olenginski LT, Taiwo KM. Isotope Labels Combined with Solution NMR Spectroscopy Make Visible the Invisible Conformations of Small-to-Large RNAs. Chem Rev 2022; 122:9357-9394. [PMID: 35442658 PMCID: PMC9136934 DOI: 10.1021/acs.chemrev.1c00845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Indexed: 02/07/2023]
Abstract
RNA is central to the proper function of cellular processes important for life on earth and implicated in various medical dysfunctions. Yet, RNA structural biology lags significantly behind that of proteins, limiting mechanistic understanding of RNA chemical biology. Fortunately, solution NMR spectroscopy can probe the structural dynamics of RNA in solution at atomic resolution, opening the door to their functional understanding. However, NMR analysis of RNA, with only four unique ribonucleotide building blocks, suffers from spectral crowding and broad linewidths, especially as RNAs grow in size. One effective strategy to overcome these challenges is to introduce NMR-active stable isotopes into RNA. However, traditional uniform labeling methods introduce scalar and dipolar couplings that complicate the implementation and analysis of NMR measurements. This challenge can be circumvented with selective isotope labeling. In this review, we outline the development of labeling technologies and their application to study biologically relevant RNAs and their complexes ranging in size from 5 to 300 kDa by NMR spectroscopy.
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Affiliation(s)
- Theodore K. Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Lukasz T. Olenginski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Kehinde M. Taiwo
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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11
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Synthesis of atom-specific nucleobase and ribose labeled uridine phosphoramidite for NMR analysis of large RNAs. MONATSHEFTE FUR CHEMIE 2021. [DOI: 10.1007/s00706-021-02851-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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12
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Falese JP, Donlic A, Hargrove AE. Targeting RNA with small molecules: from fundamental principles towards the clinic. Chem Soc Rev 2021; 50:2224-2243. [PMID: 33458725 PMCID: PMC8018613 DOI: 10.1039/d0cs01261k] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent advances in our understanding of RNA biology have uncovered crucial roles for RNA in multiple disease states, ranging from viral and bacterial infections to cancer and neurological disorders. As a result, multiple laboratories have become interested in developing drug-like small molecules to target RNA. However, this development comes with multiple unique challenges. For example, RNA is inherently dynamic and has limited chemical diversity. In addition, promiscuous RNA-binding ligands are often identified during screening campaigns. This Tutorial Review overviews important considerations and advancements for generating RNA-targeted small molecules, ranging from fundamental chemistry to promising small molecule examples with demonstrated clinical efficacy. Specifically, we begin by exploring RNA functional classes, structural hierarchy, and dynamics. We then discuss fundamental RNA recognition principles along with methods for small molecule screening and RNA structure determination. Finally, we review unique challenges and emerging solutions from both the RNA and small molecule perspectives for generating RNA-targeted ligands before highlighting a selection of the "Greatest Hits" to date. These molecules target RNA in a variety of diseases, including cancer, neurodegeneration, and viral infection, in cellular and animal model systems. Additionally, we explore the recently FDA-approved small molecule regulator of RNA splicing, risdiplam, for treatment of spinal muscular atrophy. Together, this Tutorial Review showcases the fundamental role of chemical and molecular recognition principles in enhancing our understanding of RNA biology and contributing to the rapidly growing number of RNA-targeted probes and therapeutics. In particular, we hope this widely accessible review will serve as inspiration for aspiring small molecule and/or RNA researchers.
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Affiliation(s)
- James P Falese
- Duke University School of Medicine, Department of Biochemistry, Durham, North Carolina, USA.
| | - Anita Donlic
- Princeton University, Department of Chemical and Biological Engineering, Princeton, New Jersey, USA
| | - Amanda E Hargrove
- Duke University School of Medicine, Department of Biochemistry, Durham, North Carolina, USA. and Duke University, Department of Chemistry, Durham, North Carolina, USA
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13
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Hagler LD, Bonson SE, Kocheril PA, Zimmerman SC. Assessing the feasibility and stability of uracil base flipping in RNA–small molecule complexes using molecular dynamics simulations. CAN J CHEM 2020. [DOI: 10.1139/cjc-2019-0421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Small molecules can be used to target RNAs that mediate disease. A fundamental understanding of binding interactions between RNA and small molecules and the structure of their complexes will further inform the design of new targeting agents. Two small molecule ligands were investigated for their ability to recognize the expanded CUG repeat sequence in RNA, the causative agent of myotonic dystrophy type 1. We report the use of molecular dynamics simulations to explore small molecule–RNA complexes and the finding of a stabilized base flipped conformation at UU mismatches. The results of this computational study support experimental observations and suggest that base flipping is feasible for CUG-repeat RNA.
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Affiliation(s)
- Lauren D. Hagler
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sarah E. Bonson
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Philip A. Kocheril
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Steven C. Zimmerman
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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14
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Wuebben C, Blume S, Abdullin D, Brajtenbach D, Haege F, Kath-Schorr S, Schiemann O. Site-Directed Spin Labeling of RNA with a Gem-Diethylisoindoline Spin Label: PELDOR, Relaxation, and Reduction Stability. Molecules 2019; 24:E4482. [PMID: 31817785 PMCID: PMC6943706 DOI: 10.3390/molecules24244482] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 01/08/2023] Open
Abstract
Ribonucleic acid function is governed by its structure, dynamics, and interaction with other biomolecules and influenced by the local environment. Thus, methods are needed that enable one to study RNA under conditions as natural as possible, possibly within cells. Site-directed spin-labeling of RNA with nitroxides in combination with, for example, pulsed electron-electron double resonance (PELDOR or DEER) spectroscopy has been shown to provide such information. However, for in-cell measurements, the usually used gem-dimethyl nitroxides are less suited, because they are quickly reduced under in-cell conditions. In contrast, gem-diethyl nitroxides turned out to be more stable, but labeling protocols for binding these to RNA have been sparsely reported. Therefore, we describe here the bioconjugation of an azide functionalized gem-diethyl isoindoline nitroxide to RNA using a copper (I)-catalyzed azide-alkyne cycloaddition ("click"-chemistry). The labeling protocol provides high yields and site selectivity. The analysis of the orientation selective PELDOR data show that the gem-diethyl and gem-dimethyl labels adopt similar conformations. Interestingly, in deuterated buffer, both labels attached to RNA yield TM relaxation times that are considerably longer than observed for the same type of label attached to proteins, enabling PELDOR time windows of up to 20 microseconds. Together with the increased stability in reducing environments, this label is very promising for in-cell Electron Paramagnetic Resonance (EPR) studies.
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Affiliation(s)
- Christine Wuebben
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
| | - Simon Blume
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
| | - Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
| | - Dominik Brajtenbach
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
| | - Florian Haege
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
| | - Stephanie Kath-Schorr
- Life & Medical Sciences Institute Chemical Biology & Medicinal Chemistry Unit, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany;
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany; (C.W.); (S.B.); (D.A.); (D.B.); (F.H.)
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15
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Ursu A, Vézina-Dawod S, Disney MD. Methods to identify and optimize small molecules interacting with RNA (SMIRNAs). Drug Discov Today 2019; 24:2002-2016. [PMID: 31356880 PMCID: PMC6842402 DOI: 10.1016/j.drudis.2019.06.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/11/2019] [Accepted: 06/27/2019] [Indexed: 01/14/2023]
Abstract
RNAs, particularly noncoding RNAs (ncRNAs), are becoming increasingly important therapeutic targets, because they are causative and antagonists of human disease. Indeed, aberrant RNA structural elements and expression deregulate biological processes. In this review, we describe methodologies to discover and optimize small molecules interacting with RNA (SMIRNAs), including the evaluation of direct target engagement and the rescue of RNA-mediated phenotypes in vitro and in vivo. Such studies are essential to fully characterize the mode of action of SMIRNAs and advance our understanding of rationally and efficiently drugging RNAs for therapeutic benefit.
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Affiliation(s)
- Andrei Ursu
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Simon Vézina-Dawod
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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16
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Methods to identify and characterize RNA-targeting small molecules. Methods 2019; 167:1-2. [PMID: 31381979 DOI: 10.1016/j.ymeth.2019.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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