1
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Levintov L, Vashisth H. Structural and computational studies of HIV-1 RNA. RNA Biol 2024; 21:1-32. [PMID: 38100535 PMCID: PMC10730233 DOI: 10.1080/15476286.2023.2289709] [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] [Accepted: 11/21/2023] [Indexed: 12/17/2023] Open
Abstract
Viruses remain a global threat to animals, plants, and humans. The type 1 human immunodeficiency virus (HIV-1) is a member of the retrovirus family and carries an RNA genome, which is reverse transcribed into viral DNA and further integrated into the host-cell DNA for viral replication and proliferation. The RNA structures from the HIV-1 genome provide valuable insights into the mechanisms underlying the viral replication cycle. Moreover, these structures serve as models for designing novel therapeutic approaches. Here, we review structural data on RNA from the HIV-1 genome as well as computational studies based on these structural data. The review is organized according to the type of structured RNA element which contributes to different steps in the viral replication cycle. This is followed by an overview of the HIV-1 transactivation response element (TAR) RNA as a model system for understanding dynamics and interactions in the viral RNA systems. The review concludes with a description of computational studies, highlighting the impact of biomolecular simulations in elucidating the mechanistic details of various steps in the HIV-1's replication cycle.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering & Bioengineering, University of New Hampshire, Durham, USA
| | - Harish Vashisth
- Department of Chemical Engineering & Bioengineering, University of New Hampshire, Durham, USA
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2
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Abstract
Although fragment-based drug discovery (FBDD) has been successfully implemented and well-explored for protein targets, its feasibility for RNA targets is emerging. Despite the challenges associated with the selective targeting of RNA, efforts to integrate known methods of RNA binder discovery with fragment-based approaches have been fruitful, as a few bioactive ligands have been identified. Here, we review various fragment-based approaches implemented for RNA targets and provide insights into experimental design and outcomes to guide future work in the area. Indeed, investigations surrounding the molecular recognition of RNA by fragments address rather important questions such as the limits of molecular weight that confer selective binding and the physicochemical properties favorable for RNA binding and bioactivity.
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Affiliation(s)
- Blessy M. Suresh
- UF Scripps Biomedical Research & The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Amirhossein Taghavi
- UF Scripps Biomedical Research & The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L. Childs-Disney
- UF Scripps Biomedical Research & The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D. Disney
- UF Scripps Biomedical Research & The Scripps Research Institute, Department of Chemistry, 130 Scripps Way, Jupiter, Florida 33458, United States
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3
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Shin YH, Kim DE, Yu KL, Park CM, Kim HG, Kim KC, Bae S, Yoon CH. A Novel Time-Resolved Fluorescence Resonance Energy Transfer Assay for the Discovery of Small-Molecule Inhibitors of HIV-1 Tat-Regulated Transcription. Int J Mol Sci 2023; 24:ijms24119139. [PMID: 37298089 DOI: 10.3390/ijms24119139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/17/2023] [Accepted: 05/18/2023] [Indexed: 06/12/2023] Open
Abstract
Human immunodeficiency virus-1 (HIV-1) transactivator (Tat)-mediated transcription is essential for HIV-1 replication. It is determined by the interaction between Tat and transactivation response (TAR) RNA, a highly conserved process representing a prominent therapeutic target against HIV-1 replication. However, owing to the limitations of current high-throughput screening (HTS) assays, no drug that disrupts the Tat-TAR RNA interaction has been uncovered yet. We designed a homogenous (mix-and-read) time-resolved fluorescence resonance energy transfer (TR-FRET) assay using europium cryptate as a fluorescence donor. It was optimized by evaluating different probing systems for Tat-derived peptides or TAR RNA. The specificity of the optimal assay was validated by mutants of the Tat-derived peptides and TAR RNA fragment, individually and by competitive inhibition with known TAR RNA-binding peptides. The assay generated a constant Tat-TAR RNA interaction signal, discriminating the compounds that disrupted the interaction. Combined with a functional assay, the TR-FRET assay identified two small molecules (460-G06 and 463-H08) capable of inhibiting Tat activity and HIV-1 infection from a large-scale compound library. The simplicity, ease of operation, and rapidity of our assay render it suitable for HTS to identify Tat-TAR RNA interaction inhibitors. The identified compounds may also act as potent molecular scaffolds for developing a new HIV-1 drug class.
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Affiliation(s)
- Young Hyun Shin
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
| | - Dong-Eun Kim
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
| | - Kyung Lee Yu
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
| | - Chul Min Park
- Department for Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Daejeon 34114, Republic of Korea
| | - Hong Gi Kim
- Department for Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Daejeon 34114, Republic of Korea
| | - Kyung-Chang Kim
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
| | - Songmee Bae
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
| | - Cheol-Hee Yoon
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, Korea National Institute of Health, 187 Osongsaengmyeong 2-ro, Cheongju 363951, Republic of Korea
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4
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Childs-Disney JL, Yang X, Gibaut QMR, Tong Y, Batey RT, Disney MD. Targeting RNA structures with small molecules. Nat Rev Drug Discov 2022; 21:736-762. [PMID: 35941229 PMCID: PMC9360655 DOI: 10.1038/s41573-022-00521-4] [Citation(s) in RCA: 141] [Impact Index Per Article: 70.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2022] [Indexed: 01/07/2023]
Abstract
RNA adopts 3D structures that confer varied functional roles in human biology and dysfunction in disease. Approaches to therapeutically target RNA structures with small molecules are being actively pursued, aided by key advances in the field including the development of computational tools that predict evolutionarily conserved RNA structures, as well as strategies that expand mode of action and facilitate interactions with cellular machinery. Existing RNA-targeted small molecules use a range of mechanisms including directing splicing - by acting as molecular glues with cellular proteins (such as branaplam and the FDA-approved risdiplam), inhibition of translation of undruggable proteins and deactivation of functional structures in noncoding RNAs. Here, we describe strategies to identify, validate and optimize small molecules that target the functional transcriptome, laying out a roadmap to advance these agents into the next decade.
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Affiliation(s)
| | - Xueyi Yang
- Department of Chemistry, Scripps Research, Jupiter, FL, USA
| | | | - Yuquan Tong
- Department of Chemistry, Scripps Research, Jupiter, FL, USA
| | - Robert T Batey
- Department of Biochemistry, University of Colorado, Boulder, CO, USA.
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5
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Kognole AA, Hazel A, MacKerell AD. SILCS-RNA: Toward a Structure-Based Drug Design Approach for Targeting RNAs with Small Molecules. J Chem Theory Comput 2022; 18:5672-5691. [PMID: 35913731 PMCID: PMC9474704 DOI: 10.1021/acs.jctc.2c00381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RNA molecules can act as potential drug targets in different diseases, as their dysregulated expression or misfolding can alter various cellular processes. Noncoding RNAs account for ∼70% of the human genome, and these molecules can have complex tertiary structures that present a great opportunity for targeting by small molecules. In the present study, the site identification by ligand competitive saturation (SILCS) computational approach is extended to target RNA, termed SILCS-RNA. Extensions to the method include an enhanced oscillating excess chemical potential protocol for the grand canonical Monte Carlo calculations and individual simulations of the neutral and charged solutes from which the SILCS functional group affinity maps (FragMaps) are calculated for subsequent binding site identification and docking calculations. The method is developed and evaluated against seven RNA targets and their reported small molecule ligands. SILCS-RNA provides a detailed characterization of the functional group affinity pattern in the small molecule binding sites, recapitulating the types of functional groups present in the ligands. The developed method is also shown to be useful for identification of new potential binding sites and identifying ligand moieties that contribute to binding, granular information that can facilitate ligand design. However, limitations in the method are evident including the ability to map the regions of binding sites occupied by ligand phosphate moieties and to fully account for the wide range of conformational heterogeneity in RNA associated with binding of different small molecules, emphasizing inherent challenges associated with applying computer-aided drug design methods to RNA. While limitations are present, the current study indicates how the SILCS-RNA approach may enhance drug discovery efforts targeting RNAs with small molecules.
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Affiliation(s)
- Abhishek A Kognole
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
| | - Anthony Hazel
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
| | - Alexander D MacKerell
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
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6
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Mediouni S, Lyu S, Schader SM, Valente ST. Forging a Functional Cure for HIV: Transcription Regulators and Inhibitors. Viruses 2022; 14:1980. [PMID: 36146786 PMCID: PMC9502519 DOI: 10.3390/v14091980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/28/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
Current antiretroviral therapy (ART) increases the survival of HIV-infected individuals, yet it is not curative. The major barrier to finding a definitive cure for HIV is our inability to identify and eliminate long-lived cells containing the dormant provirus, termed viral reservoir. When ART is interrupted, the viral reservoir ensures heterogenous and stochastic HIV viral gene expression, which can reseed infection back to pre-ART levels. While strategies to permanently eradicate the virus have not yet provided significant success, recent work has focused on the management of this residual viral reservoir to effectively limit comorbidities associated with the ongoing viral transcription still observed during suppressive ART, as well as limit the need for daily ART. Our group has been at the forefront of exploring the viability of the block-and-lock remission approach, focused on the long-lasting epigenetic block of viral transcription such that without daily ART, there is no risk of viral rebound, transmission, or progression to AIDS. Numerous studies have reported inhibitors of both viral and host factors required for HIV transcriptional activation. Here, we highlight and review some of the latest HIV transcriptional inhibitor discoveries that may be leveraged for the clinical exploration of block-and-lock and revolutionize the way we treat HIV infections.
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Affiliation(s)
- Sonia Mediouni
- Department of Immunology and Microbiology, UF Scripps Biomedical Research, 130 Scripps Way, 3C1, Jupiter, FL 33458, USA
| | - Shuang Lyu
- Department of Immunology and Microbiology, UF Scripps Biomedical Research, 130 Scripps Way, 3C1, Jupiter, FL 33458, USA
| | - Susan M. Schader
- Department of Infectious Disease Research, Drug Development Division, Southern Research, 431 Aviation Way, Frederick, MD 21701, USA
| | - Susana T. Valente
- Department of Immunology and Microbiology, UF Scripps Biomedical Research, 130 Scripps Way, 3C1, Jupiter, FL 33458, USA
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7
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Martin C, Bonnet M, Patino N, Azoulay S, Di Giorgio A, Duca M. Design, synthesis and evaluation of neomycin‐imidazole conjugates for RNA cleavage. Chempluschem 2022; 87:e202200250. [DOI: 10.1002/cplu.202200250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/30/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Céline Martin
- Université Côte d'Azur Faculté des Sciences: Universite Cote d'Azur Faculte des Sciences Institut de Chimie de Nice 28 Avenue Valrose 06100 Nice FRANCE
| | - Maurinne Bonnet
- Université Côte d'Azur Faculté des Sciences: Universite Cote d'Azur Faculte des Sciences Institut de Chimie de Nice 28 Avenue Valrose 06100 Nice FRANCE
| | - Nadia Patino
- Université Côte d'Azur Faculté des Sciences: Universite Cote d'Azur Faculte des Sciences Institut de Chimie de Nice 28 Avenue Valrose 06100 Nice FRANCE
| | - Stéphane Azoulay
- Université Côte d'Azur Faculté des Sciences: Universite Cote d'Azur Faculte des Sciences Institut de Chimie de Nice 28 Avenue Valrose 06100 Nice FRANCE
| | - Audrey Di Giorgio
- Université Côte d'Azur Faculté des Sciences: Universite Cote d'Azur Faculte des Sciences Institut de Chimie de Nice 28 Avenue Valrose 06100 Nice FRANCE
| | - Maria Duca
- Institut de Chimie de Nice Université Côte d'Azur Parc Valrose 06100 Nice FRANCE
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8
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Kallert E, Fischer TR, Schneider S, Grimm M, Helm M, Kersten C. Protein-Based Virtual Screening Tools Applied for RNA-Ligand Docking Identify New Binders of the preQ 1-Riboswitch. J Chem Inf Model 2022; 62:4134-4148. [PMID: 35994617 DOI: 10.1021/acs.jcim.2c00751] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Targeting RNA with small molecules is an emerging field. While several ligands for different RNA targets are reported, structure-based virtual screenings (VSs) against RNAs are still rare. Here, we elucidated the general capabilities of protein-based docking programs to reproduce native binding modes of small-molecule RNA ligands and to discriminate known binders from decoys by the scoring function. The programs were found to perform similar compared to the RNA-based docking tool rDOCK, and the challenges faced during docking, namely, protomer and tautomer selection, target dynamics, and explicit solvent, do not largely differ from challenges in conventional protein-ligand docking. A prospective VS with the Bacillus subtilis preQ1-riboswitch aptamer domain performed with FRED, HYBRID, and FlexX followed by microscale thermophoresis assays identified six active compounds out of 23 tested VS hits with potencies between 29.5 nM and 11.0 μM. The hits were selected not solely based on their docking score but for resembling key interactions of the native ligand. Therefore, this study demonstrates the general feasibility to perform structure-based VSs against RNA targets, while at the same time it highlights pitfalls and their potential solutions when executing RNA-ligand docking.
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Affiliation(s)
- Elisabeth Kallert
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
| | - Tim R Fischer
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
| | - Simon Schneider
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
| | - Maike Grimm
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
| | - Mark Helm
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
| | - Christian Kersten
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, Mainz 55128, Germany
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9
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Martín-Villamil M, Sanmartín I, Moreno Á, Gallego J. Pharmacophore-Based Discovery of Viral RNA Conformational Modulators. Pharmaceuticals (Basel) 2022; 15:ph15060748. [PMID: 35745667 PMCID: PMC9229403 DOI: 10.3390/ph15060748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/09/2022] [Accepted: 06/11/2022] [Indexed: 02/05/2023] Open
Abstract
New RNA-binding small-molecule scaffolds are needed to unleash the pharmacological potential of RNA targets. Here we have applied a pharmacophore-based virtual screening approach, seldom used in the RNA recognition field, to identify novel conformational inhibitors of the hepatitis C virus internal ribosome entry site. The conformational effect of the screening hits was assessed with a fluorescence resonance energy transfer assay, and the affinity, specificity, and binding site of the ligands were determined using a combination of fluorescence intensity and NMR spectroscopy experiments. The results indicate that this strategy can be successfully applied to discover RNA conformational inhibitors bearing substantially less positive charge than the reference ligands. This methodology can potentially be accommodated to other RNA motifs of pharmacological interest, facilitating the discovery of novel RNA-targeted molecules.
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10
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fingeRNAt—A novel tool for high-throughput analysis of nucleic acid-ligand interactions. PLoS Comput Biol 2022; 18:e1009783. [PMID: 35653385 PMCID: PMC9197077 DOI: 10.1371/journal.pcbi.1009783] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/14/2022] [Accepted: 05/06/2022] [Indexed: 11/19/2022] Open
Abstract
Computational methods play a pivotal role in drug discovery and are widely applied in virtual screening, structure optimization, and compound activity profiling. Over the last decades, almost all the attention in medicinal chemistry has been directed to protein-ligand binding, and computational tools have been created with this target in mind. With novel discoveries of functional RNAs and their possible applications, RNAs have gained considerable attention as potential drug targets. However, the availability of bioinformatics tools for nucleic acids is limited. Here, we introduce fingeRNAt—a software tool for detecting non-covalent interactions formed in complexes of nucleic acids with ligands. The program detects nine types of interactions: (i) hydrogen and (ii) halogen bonds, (iii) cation-anion, (iv) pi-cation, (v) pi-anion, (vi) pi-stacking, (vii) inorganic ion-mediated, (viii) water-mediated, and (ix) lipophilic interactions. However, the scope of detected interactions can be easily expanded using a simple plugin system. In addition, detected interactions can be visualized using the associated PyMOL plugin, which facilitates the analysis of medium-throughput molecular complexes. Interactions are also encoded and stored as a bioinformatics-friendly Structural Interaction Fingerprint (SIFt)—a binary string where the respective bit in the fingerprint is set to 1 if a particular interaction is present and to 0 otherwise. This output format, in turn, enables high-throughput analysis of interaction data using data analysis techniques. We present applications of fingeRNAt-generated interaction fingerprints for visual and computational analysis of RNA-ligand complexes, including analysis of interactions formed in experimentally determined RNA-small molecule ligand complexes deposited in the Protein Data Bank. We propose interaction fingerprint-based similarity as an alternative measure to RMSD to recapitulate complexes with similar interactions but different folding. We present an application of interaction fingerprints for the clustering of molecular complexes. This approach can be used to group ligands that form similar binding networks and thus have similar biological properties. The fingeRNAt software is freely available at https://github.com/n-szulc/fingeRNAt.
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11
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Chen Q, Li Y, Lin C, Chen L, Luo H, Xia S, Liu C, Cheng X, Liu C, Li J, Dou D. OUP accepted manuscript. Nucleic Acids Res 2022; 50:e67. [PMID: 35288754 PMCID: PMC9262588 DOI: 10.1093/nar/gkac173] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 02/02/2022] [Accepted: 03/04/2022] [Indexed: 11/21/2022] Open
Abstract
DNA-encoded library (DEL) technology is a powerful tool for small molecule identification in drug discovery, yet the reported DEL selection strategies were applied primarily on protein targets in either purified form or in cellular context. To expand the application of this technology, we employed DEL selection on an RNA target HIV-1 TAR (trans-acting responsive region), but found that the majority of signals were resulted from false positive DNA–RNA binding. We thus developed an optimized selection strategy utilizing RNA patches and competitive elution to minimize unwanted DNA binding, followed by k-mer analysis and motif search to differentiate false positive signal. This optimized strategy resulted in a very clean background in a DEL selection against Escherichia coli FMN Riboswitch, and the enriched compounds were determined with double digit nanomolar binding affinity, as well as similar potency in functional FMN competition assay. These results demonstrated the feasibility of small molecule identification against RNA targets using DEL selection. The developed experimental and computational strategy provided a promising opportunity for RNA ligand screening and expanded the application of DEL selection to a much wider context in drug discovery.
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Affiliation(s)
| | | | | | - Liu Chen
- HitGen Inc., Shuangliu District, Chengdu, China
| | - Hao Luo
- HitGen Inc., Shuangliu District, Chengdu, China
| | - Shuai Xia
- HitGen Inc., Shuangliu District, Chengdu, China
| | - Chuan Liu
- HitGen Inc., Shuangliu District, Chengdu, China
| | | | | | - Jin Li
- HitGen Inc., Shuangliu District, Chengdu, China
| | - Dengfeng Dou
- To whom correspondence should be addressed. Tel: +86 28 85197385 8700;
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12
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Kozlovskii I, Popov P. Structure-based deep learning for binding site detection in nucleic acid macromolecules. NAR Genom Bioinform 2021; 3:lqab111. [PMID: 34859211 PMCID: PMC8633674 DOI: 10.1093/nargab/lqab111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/14/2021] [Accepted: 11/09/2021] [Indexed: 12/30/2022] Open
Abstract
Structure-based drug design (SBDD) targeting nucleic acid macromolecules, particularly RNA, is a gaining momentum research direction that already resulted in several FDA-approved compounds. Similar to proteins, one of the critical components in SBDD for RNA is the correct identification of the binding sites for putative drug candidates. RNAs share a common structural organization that, together with the dynamic nature of these molecules, makes it challenging to recognize binding sites for small molecules. Moreover, there is a need for structure-based approaches, as sequence information only does not consider conformation plasticity of nucleic acid macromolecules. Deep learning holds a great promise to resolve binding site detection problem, but requires a large amount of structural data, which is very limited for nucleic acids, compared to proteins. In this study we composed a set of ∼2000 nucleic acid-small molecule structures comprising ∼2500 binding sites, which is ∼40-times larger than previously used one, and demonstrated the first structure-based deep learning approach, BiteNetN, to detect binding sites in nucleic acid structures. BiteNetN operates with arbitrary nucleic acid complexes, shows the state-of-the-art performance, and can be helpful in the analysis of different conformations and mutant variants, as we demonstrated for HIV-1 TAR RNA and ATP-aptamer case studies.
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Affiliation(s)
- Igor Kozlovskii
- iMolecule, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
| | - Petr Popov
- iMolecule, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
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13
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Kumar A, Vashisth H. Conformational dynamics and energetics of viral RNA recognition by lab-evolved proteins. Phys Chem Chem Phys 2021; 23:24773-24779. [PMID: 34714308 PMCID: PMC8579469 DOI: 10.1039/d1cp03822b] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 10/14/2021] [Indexed: 12/01/2022]
Abstract
The conserved and structured elements in viral RNA genomes interact with proteins to regulate various events in the viral life cycle and have become key targets for developing novel therapeutic approaches. We probe physical interactions between lab-evolved proteins and a viral RNA element from the HIV-1 genome. Specifically, we study the role of an arginine-rich loop in recognition of designed proteins by the viral RNA element. We report free energy calculations to quantitatively estimate the protein/RNA binding energetics, focusing on the mutations of arginine residues involved in recognition of the major groove of RNA by proteins.
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Affiliation(s)
- Amit Kumar
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
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14
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Chavali SS, Mali SM, Bonn R, Saseendran A, Bennett RP, Smith HC, Fasan R, Wedekind JE. Cyclic peptides with a distinct arginine-fork motif recognize the HIV trans-activation response RNA in vitro and in cells. J Biol Chem 2021; 297:101390. [PMID: 34767799 DOI: 10.1016/j.jbc.2021.101390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 12/21/2022] Open
Abstract
RNA represents a potential target for new antiviral therapies, which are urgently needed to address public health threats such as the human immunodeficiency virus (HIV). We showed previously that the interaction between the viral Tat protein and the HIV-1 trans-activation response (TAR) RNA was blocked by the cyclic peptide TB-CP-6.9a. This peptide was derived from a TAR-binding loop that emerged during lab-evolution of a TAR-binding protein (TBP) family. Here we synthesized and characterized a next-generation, cyclic-peptide library based on the TBP scaffold. We sought to identify conserved RNA-binding interactions, and the influence of cyclization linkers on RNA binding and antiviral activity. A diverse group of cyclization linkers, encompassing disulfide bonds to bicyclic aromatic staples, was used to restrain the cyclic peptide geometry. Thermodynamic profiling revealed specific arginine-rich sequences with low to sub-micromolar affinity driven by enthalpic and entropic contributions. The best compounds exhibited no appreciable off-target binding to related molecules, such as BIV TAR and human 7SK RNAs. A specific arginine-to-lysine change in the highest affinity cyclic peptide reduced TAR binding by 10-fold, suggesting that TBP-derived cyclic peptides use an arginine-fork motif to recognize the TAR major-groove while differentiating the mode of binding from other TAR-targeting molecules. Finally, we showed that HIV infectivity in cell culture was reduced in the presence of cyclic peptides constrained by methylene or naphthalene-based linkers. Our findings provide insight into the molecular determinants required for HIV-1 TAR recognition and antiviral activity. These findings are broadly relevant to the development of antivirals that target RNA molecules.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA
| | - Sachitanand M Mali
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA
| | - Rachel Bonn
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA
| | | | | | - Harold C Smith
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA; OyaGen, Inc., Rochester NY 14623, USA
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA
| | - Joseph E Wedekind
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA.
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15
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Levintov L, Vashisth H. Role of conformational heterogeneity in ligand recognition by viral RNA molecules. Phys Chem Chem Phys 2021; 23:11211-11223. [PMID: 34010381 DOI: 10.1039/d1cp00679g] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ribonucleic acid (RNA) molecules are known to undergo conformational changes in response to various environmental stimuli including temperature, pH, and ligands. In particular, viral RNA molecules are a key example of conformationally adapting molecules that have evolved to switch between many functional conformations. The transactivation response element (TAR) RNA from the type-1 human immunodeficiency virus (HIV-1) is a viral RNA molecule that is being increasingly explored as a potential therapeutic target due to its role in the viral replication process. In this work, we have studied the dynamics in TAR RNA in apo and liganded states by performing explicit-solvent molecular dynamics (MD) simulations initiated with 27 distinct structures. We determined that the TAR RNA structure is significantly stabilized on ligand binding with especially decreased fluctuations in its two helices. This rigidity is further coupled with the decreased flipping of bulge nucleotides, which were observed to flip more frequently in the absence of ligands. We found that initially-distinct structures of TAR RNA converged to similar conformations on removing ligands. We also report that conformational dynamics in unliganded TAR structures leads to the formation of binding pockets capable of accommodating ligands of various sizes.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
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16
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Role and Perspective of Molecular Simulation-Based Investigation of RNA-Ligand Interaction: From Small Molecules and Peptides to Photoswitchable RNA Binding. Molecules 2021; 26:molecules26113384. [PMID: 34205049 PMCID: PMC8199858 DOI: 10.3390/molecules26113384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 12/15/2022] Open
Abstract
Aberrant RNA–protein complexes are formed in a variety of diseases. Identifying the ligands that interfere with their formation is a valuable therapeutic strategy. Molecular simulation, validated against experimental data, has recently emerged as a powerful tool to predict both the pose and energetics of such ligands. Thus, the use of molecular simulation may provide insight into aberrant molecular interactions in diseases and, from a drug design perspective, may allow for the employment of less wet lab resources than traditional in vitro compound screening approaches. With regard to basic research questions, molecular simulation can support the understanding of the exact molecular interaction and binding mode. Here, we focus on examples targeting RNA–protein complexes in neurodegenerative diseases and viral infections. These examples illustrate that the strategy is rather general and could be applied to different pharmacologically relevant approaches. We close this study by outlining one of these approaches, namely the light-controllable association of small molecules with RNA, as an emerging approach in RNA-targeting therapy.
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17
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Abdelsattar AS, Mansour Y, Aboul-Ela F. The Perturbed Free-Energy Landscape: Linking Ligand Binding to Biomolecular Folding. Chembiochem 2021; 22:1499-1516. [PMID: 33351206 DOI: 10.1002/cbic.202000695] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/19/2020] [Indexed: 12/24/2022]
Abstract
The effects of ligand binding on biomolecular conformation are crucial in drug design, enzyme mechanisms, the regulation of gene expression, and other biological processes. Descriptive models such as "lock and key", "induced fit", and "conformation selection" are common ways to interpret such interactions. Another historical model, linked equilibria, proposes that the free-energy landscape (FEL) is perturbed by the addition of ligand binding energy for the bound population of biomolecules. This principle leads to a unified, quantitative theory of ligand-induced conformation change, building upon the FEL concept. We call the map of binding free energy over biomolecular conformational space the "binding affinity landscape" (BAL). The perturbed FEL predicts/explains ligand-induced conformational changes conforming to all common descriptive models. We review recent experimental and computational studies that exemplify the perturbed FEL, with emphasis on RNA. This way of understanding ligand-induced conformation dynamics motivates new experimental and theoretical approaches to ligand design, structural biology and systems biology.
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Affiliation(s)
- Abdallah S Abdelsattar
- Center for X-Ray Determination of the Structure of Matter, Zewail City of Science and Technology, Ahmed Zewail Road, October Gardens, 12578, Giza, Egypt
| | - Youssef Mansour
- Center for X-Ray Determination of the Structure of Matter, Zewail City of Science and Technology, Ahmed Zewail Road, October Gardens, 12578, Giza, Egypt
| | - Fareed Aboul-Ela
- Center for X-Ray Determination of the Structure of Matter, Zewail City of Science and Technology, Ahmed Zewail Road, October Gardens, 12578, Giza, Egypt
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18
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Kelly ML, Chu CC, Shi H, Ganser LR, Bogerd HP, Huynh K, Hou Y, Cullen BR, Al-Hashimi HM. Understanding the characteristics of nonspecific binding of drug-like compounds to canonical stem-loop RNAs and their implications for functional cellular assays. RNA (NEW YORK, N.Y.) 2021; 27:12-26. [PMID: 33028652 PMCID: PMC7749633 DOI: 10.1261/rna.076257.120] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 09/26/2020] [Indexed: 05/30/2023]
Abstract
Identifying small molecules that selectively bind an RNA target while discriminating against all other cellular RNAs is an important challenge in RNA-targeted drug discovery. Much effort has been directed toward identifying drug-like small molecules that minimize electrostatic and stacking interactions that lead to nonspecific binding of aminoglycosides and intercalators to many stem-loop RNAs. Many such compounds have been reported to bind RNAs and inhibit their cellular activities. However, target engagement and cellular selectivity assays are not routinely performed, and it is often unclear whether functional activity directly results from specific binding to the target RNA. Here, we examined the propensities of three drug-like compounds, previously shown to bind and inhibit the cellular activities of distinct stem-loop RNAs, to bind and inhibit the cellular activities of two unrelated HIV-1 stem-loop RNAs: the transactivation response element (TAR) and the rev response element stem IIB (RREIIB). All compounds bound TAR and RREIIB in vitro, and two inhibited TAR-dependent transactivation and RRE-dependent viral export in cell-based assays while also exhibiting off-target interactions consistent with nonspecific activity. A survey of X-ray and NMR structures of RNA-small molecule complexes revealed that aminoglycosides and drug-like molecules form hydrogen bonds with functional groups commonly accessible in canonical stem-loop RNA motifs, in contrast to ligands that specifically bind riboswitches. Our results demonstrate that drug-like molecules can nonspecifically bind stem-loop RNAs most likely through hydrogen bonding and electrostatic interactions and reinforce the importance of assaying for off-target interactions and RNA selectivity in vitro and in cells when assessing novel RNA-binders.
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Affiliation(s)
- Megan L Kelly
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Chia-Chieh Chu
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Honglue Shi
- Department of Chemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Laura R Ganser
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Hal P Bogerd
- Department of Molecular Genetics and Microbiology, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Kelly Huynh
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Yuze Hou
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Bryan R Cullen
- Department of Molecular Genetics and Microbiology, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
- Department of Chemistry, Center for Virology, Duke University Medical Center, Durham, North Carolina 27710, USA
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19
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Chavali SS, Mali SM, Jenkins JL, Fasan R, Wedekind JE. Co-crystal structures of HIV TAR RNA bound to lab-evolved proteins show key roles for arginine relevant to the design of cyclic peptide TAR inhibitors. J Biol Chem 2020; 295:16470-16486. [PMID: 33051202 PMCID: PMC7864049 DOI: 10.1074/jbc.ra120.015444] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/24/2020] [Indexed: 01/28/2023] Open
Abstract
RNA-protein interfaces control key replication events during the HIV-1 life cycle. The viral trans-activator of transcription (Tat) protein uses an archetypal arginine-rich motif (ARM) to recruit the host positive transcription elongation factor b (pTEFb) complex onto the viral trans-activation response (TAR) RNA, leading to activation of HIV transcription. Efforts to block this interaction have stimulated production of biologics designed to disrupt this essential RNA-protein interface. Here, we present four co-crystal structures of lab-evolved TAR-binding proteins (TBPs) in complex with HIV-1 TAR. Our results reveal that high-affinity binding requires a distinct sequence and spacing of arginines within a specific β2-β3 hairpin loop that arose during selection. Although loops with as many as five arginines were analyzed, only three arginines could bind simultaneously with major-groove guanines. Amino acids that promote backbone interactions within the β2-β3 loop were also observed to be important for high-affinity interactions. Based on structural and affinity analyses, we designed two cyclic peptide mimics of the TAR-binding β2-β3 loop sequences present in two high-affinity TBPs (KD values of 4.2 ± 0.3 and 3.0 ± 0.3 nm). Our efforts yielded low-molecular weight compounds that bind TAR with low micromolar affinity (KD values ranging from 3.6 to 22 μm). Significantly, one cyclic compound within this series blocked binding of the Tat-ARM peptide to TAR in solution assays, whereas its linear counterpart did not. Overall, this work provides insight into protein-mediated TAR recognition and lays the ground for the development of cyclic peptide inhibitors of a vital HIV-1 RNA-protein interaction.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Sachitanand M Mali
- Department of Chemistry, University of Rochester, Rochester, New York, USA
| | - Jermaine L Jenkins
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, Rochester, New York, USA
| | - Joseph E Wedekind
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
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20
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Martin C, De Piccoli S, Gaysinski M, Becquart C, Azoulay S, Di Giorgio A, Duca M. Unveiling RNA‐Binding Properties of Verapamil and Preparation of New Derivatives as Inhibitors of HIV‐1 Tat‐TAR Interaction. Chempluschem 2020. [DOI: 10.1002/cplu.201900650] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Céline Martin
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Serena De Piccoli
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Marc Gaysinski
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Cécile Becquart
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Stéphane Azoulay
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Audrey Di Giorgio
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
| | - Maria Duca
- Université Côte d'Azur Institute of Chemistry of Nice (ICN) 28 avenue Valrose 06100 Nice France
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21
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Abstract
RNA recognition frequently results in conformational changes that optimize intermolecular binding. As a consequence, the overall binding affinity of RNA to its binding partners depends not only on the intermolecular interactions formed in the bound state but also on the energy cost associated with changing the RNA conformational distribution. Measuring these "conformational penalties" is, however, challenging because bound RNA conformations tend to have equilibrium populations in the absence of the binding partner that fall outside detection by conventional biophysical methods. In this study we employ as a model system HIV-1 TAR RNA and its interaction with the ligand argininamide (ARG), a mimic of TAR's cognate protein binding partner, the transactivator Tat. We use NMR chemical shift perturbations and relaxation dispersion in combination with Bayesian inference to develop a detailed thermodynamic model of coupled conformational change and ligand binding. Starting from a comprehensive 12-state model of the equilibrium, we estimate the energies of six distinct detectable thermodynamic states that are not accessible by currently available methods. Our approach identifies a minimum of four RNA intermediates that differ in terms of the TAR conformation and ARG occupancy. The dominant bound TAR conformation features two bound ARG ligands and has an equilibrium population in the absence of ARG that is below detection limit. Consequently, even though ARG binds to TAR with an apparent overall weak affinity (Kdapp ≈ 0.2 mM), it binds the prefolded conformation with a Kd in the nM range. Our results show that conformational penalties can be major determinants of RNA-ligand binding affinity as well as a source of binding cooperativity, with important implications for a predictive understanding of how RNA is recognized and for RNA-targeted drug discovery.
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Affiliation(s)
- Nicole I. Orlovsky
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Terrence G. Oas
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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22
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Zhang BG, Qiu HH, Jiang J, Liu J, Shi YZ. 3D structure stability of the HIV-1 TAR RNA in ion solutions: A coarse-grained model study. J Chem Phys 2019; 151:165101. [PMID: 31675878 DOI: 10.1063/1.5126128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
As an extremely common structural motif, RNA hairpins with bulge loops [e.g., the human immunodeficiency virus type 1 (HIV-1) transactivation response (TAR) RNA] can play essential roles in normal cellular processes by binding to proteins and small ligands, which could be very dependent on their three-dimensional (3D) structures and stability. Although the structures and conformational dynamics of the HIV-1 TAR RNA have been extensively studied, there are few investigations on the thermodynamic stability of the TAR RNA, especially in ion solutions, and the existing studies also have some divergence on the unfolding process of the RNA. Here, we employed our previously developed coarse-grained model with implicit salt to predict the 3D structure, stability, and unfolding pathway for the HIV-1 TAR RNA over a wide range of ion concentrations. As compared with the extensive experimental/theoretical results, the present model can give reliable predictions on the 3D structure stability of the TAR RNA from the sequence. Based on the predictions, our further comprehensive analyses on the stability of the TAR RNA as well as its variants revealed that the unfolding pathway of an RNA hairpin with a bulge loop is mainly determined by the relative stability between different states (folded state, intermediate state, and unfolded state) and the strength of the coaxial stacking between two stems in folded structures, both of which can be apparently modulated by the ion concentrations as well as the sequences.
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Affiliation(s)
- Ben-Gong Zhang
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Hua-Hai Qiu
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Jian Jiang
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Jie Liu
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Ya-Zhou Shi
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
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23
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Sadowski I, Hashemi FB. Strategies to eradicate HIV from infected patients: elimination of latent provirus reservoirs. Cell Mol Life Sci 2019; 76:3583-3600. [PMID: 31129856 PMCID: PMC6697715 DOI: 10.1007/s00018-019-03156-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/29/2019] [Accepted: 05/20/2019] [Indexed: 02/06/2023]
Abstract
35 years since identification of HIV as the causative agent of AIDS, and 35 million deaths associated with this disease, significant effort is now directed towards the development of potential cures. Current anti-retroviral (ART) therapies for HIV/AIDS can suppress virus replication to undetectable levels, and infected individuals can live symptom free so long as treatment is maintained. However, removal of therapy allows rapid re-emergence of virus from a highly stable reservoir of latently infected cells that exist as a barrier to elimination of the infection with current ART. Prospects of a cure for HIV infection are significantly encouraged by two serendipitous cases where individuals have entered remission following stem cell transplantation from compatible HIV-resistant donors. However, development of a routine cure that could become available to millions of infected individuals will require a means of specifically purging cells harboring latent HIV, preventing replication of latent provirus, or destruction of provirus genomes by gene editing. Elimination of latently infected cells will require a means of exposing this population, which may involve identification of a natural specific biomarker or therapeutic intervention to force their exposure by reactivation of virus expression. Accordingly, the proposed "Shock and Kill" strategy involves treatment with latency-reversing agents (LRA) to induce HIV provirus expression thus exposing these cells to killing by cellular immunity or apoptosis. Current efforts to enable this strategy are directed at developing improved combinations of LRA to produce broad and robust induction of HIV provirus and enhancing the elimination of cells where replication has been reactivated by targeted immune modulation. Alternative strategies may involve preventing re-emergence virus from latently infected cells by "Lock and Block" intervention, where transcription of provirus is inhibited to prevent virus spread or disruption of the HIV provirus genome by genome editing.
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Affiliation(s)
- Ivan Sadowski
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
| | - Farhad B Hashemi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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24
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Shortridge MD, Wille PT, Jones AN, Davidson A, Bogdanovic J, Arts E, Karn J, Robinson JA, Varani G. An ultra-high affinity ligand of HIV-1 TAR reveals the RNA structure recognized by P-TEFb. Nucleic Acids Res 2019; 47:1523-1531. [PMID: 30481318 PMCID: PMC6379670 DOI: 10.1093/nar/gky1197] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/09/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
The HIV-1 trans-activator protein Tat binds the trans-activation response element (TAR) to facilitate recruitment of the super elongation complex (SEC) to enhance transcription of the integrated pro-viral genome. The Tat–TAR interaction is critical for viral replication and the emergence of the virus from the latent state, therefore, inhibiting this interaction has long been pursued to discover new anti-viral or latency reversal agents. However, discovering active compounds that directly target RNA with high affinity and selectivity remains a significant challenge; limiting pre-clinical development. Here, we report the rational design of a macrocyclic peptide mimic of the arginine rich motif of Tat, which binds to TAR with low pM affinity and 100-fold selectivity against closely homologous RNAs. Despite these unprecedented binding properties, the new ligand (JB181) only moderately inhibits Tat-dependent reactivation in cells and recruitment of positive transcription elongation factor (P-TEFb) to TAR. The NMR structure of the JB181–TAR complex revealed that the ligand induces a structure in the TAR loop that closely mimics the P-TEFb/Tat1:57/AFF4/TAR complex. These results strongly suggest that high-affinity ligands which bind the UCU bulge are not likely to inhibit recruitment of the SEC and suggest that targeting of the TAR loop will be an essential feature of effective Tat inhibitors.
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Affiliation(s)
- Matthew D Shortridge
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Paul T Wille
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106-4960
| | - Alisha N Jones
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Amy Davidson
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Jasmina Bogdanovic
- Department of Chemistry, University of Zurich, Zurich, Switzerland CH-8057
| | - Eric Arts
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106-4960
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106-4960
| | - John A Robinson
- Department of Chemistry, University of Zurich, Zurich, Switzerland CH-8057
| | - Gabriele Varani
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
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25
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Abstract
RNA structures play a pivotal role in many biological processes and the progression of human disease, making them an attractive target for therapeutic development. Often RNA structures operate through the formation of complexes with RNA-binding proteins, however, much like protein-protein interactions, RNA-protein interactions span large surface areas and often lack traditional druggable properties, making it challenging to target them with small molecules. Peptides provide much greater surface areas and therefore greater potential for forming specific and high affinity interactions with RNA. In this chapter, we discuss our approach for engineering peptides that bind to structured RNAs by highlighting methods and design strategies from previous successful projects aimed at inhibiting the HIV Tat-TAR interaction and the biogenesis of oncogenic microRNAs.
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Affiliation(s)
- Matthew J Walker
- Department of Chemistry, University of Washington, Seattle, WA, United States
| | - Gabriele Varani
- Department of Chemistry, University of Washington, Seattle, WA, United States.
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26
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Thompson RD, Baisden JT, Zhang Q. NMR characterization of RNA small molecule interactions. Methods 2019; 167:66-77. [PMID: 31128236 DOI: 10.1016/j.ymeth.2019.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 01/25/2023] Open
Abstract
Exciting discoveries of naturally occurring ligand-sensing and disease-linked noncoding RNAs have promoted significant interests in understanding RNA-small molecule interactions. NMR spectroscopy is a powerful tool for characterizing intermolecular interactions. In this review, we describe protocols and approaches for applying NMR spectroscopy to investigate interactions between RNA and small molecules. We review protocols for RNA sample preparation, methods for identifying RNA-binding small molecules, approaches for mapping RNA-small molecule interactions, determining complex structures, and characterizing binding kinetics. We hope this review will provide a guideline to streamline NMR applications in studying RNA-small molecule interactions, facilitating both basic mechanistic understandings of RNA functions and translational efforts in developing RNA-targeted therapeutics.
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Affiliation(s)
- Rhese D Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jared T Baisden
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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27
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Chavali SS, Bonn-Breach R, Wedekind JE. Face-time with TAR: Portraits of an HIV-1 RNA with diverse modes of effector recognition relevant for drug discovery. J Biol Chem 2019; 294:9326-9341. [PMID: 31080171 DOI: 10.1074/jbc.rev119.006860] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Small molecules and short peptides that potently and selectively bind RNA are rare, making the molecular structures of these complexes highly exceptional. Accordingly, several recent investigations have provided unprecedented structural insights into how peptides and proteins recognize the HIV-1 transactivation response (TAR) element, a 59-nucleotide-long, noncoding RNA segment in the 5' long terminal repeat region of viral transcripts. Here, we offer an integrated perspective on these advances by describing earlier progress on TAR binding to small molecules, and by drawing parallels to recent successes in the identification of compounds that target the hepatitis C virus internal ribosome entry site (IRES) and the flavin-mononucleotide riboswitch. We relate this work to recent progress that pinpoints specific determinants of TAR recognition by: (i) viral Tat proteins, (ii) an innovative lab-evolved TAR-binding protein, and (iii) an ultrahigh-affinity cyclic peptide. New structural details are used to model the TAR-Tat-super-elongation complex (SEC) that is essential for efficient viral transcription and represents a focal point for antiviral drug design. A key prediction is that the Tat transactivation domain makes modest contacts with the TAR apical loop, whereas its arginine-rich motif spans the entire length of the TAR major groove. This expansive interface has significant implications for drug discovery and design, and it further suggests that future lab-evolved proteins could be deployed to discover steric restriction points that block Tat-mediated recruitment of the host SEC to HIV-1 TAR.
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Affiliation(s)
- Sai Shashank Chavali
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Rachel Bonn-Breach
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Joseph E Wedekind
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
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28
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Merriman DK, Yuan J, Shi H, Majumdar A, Herschlag D, Al-Hashimi HM. Increasing the length of poly-pyrimidine bulges broadens RNA conformational ensembles with minimal impact on stacking energetics. RNA (NEW YORK, N.Y.) 2018; 24:1363-1376. [PMID: 30012568 PMCID: PMC6140463 DOI: 10.1261/rna.066258.118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/05/2018] [Indexed: 05/03/2023]
Abstract
Helical elements separated by bulges frequently undergo transitions between unstacked and coaxially stacked conformations during the folding and function of noncoding RNAs. Here, we examine the dynamic properties of poly-pyrimidine bulges of varying length (n = 1-4, 7) across a range of Mg2+ concentrations using HIV-1 TAR RNA as a model system and solution NMR spectroscopy. In the absence of Mg2+, helices linked by bulges with n ≥ 3 residues adopt predominantly unstacked conformations (stacked population <15%), whereas one-bulge and two-bulge motifs adopt predominantly stacked conformations (stacked population >74%). In the presence of 3 mM Mg2+, the helices predominantly coaxially stack (stacked population >84%), regardless of bulge length, and the midpoint for the Mg2+-dependent stacking transition is within threefold regardless of bulge length. In the absence of Mg2+, the difference between free energy of interhelical coaxial stacking across the bulge variants is estimated to be ∼2.9 kcal/mol, based on an NMR chemical shift mapping with stacking being more energetically disfavored for the longer bulges. This difference decreases to ∼0.4 kcal/mol in the presence of Mg2+ NMR RDCs and resonance intensity data show increased dynamics in the stacked state with increasing bulge length in the presence of Mg2+ We propose that Mg2+ helps to neutralize the growing electrostatic repulsion in the stacked state with increasing bulge length thereby increasing the number of coaxial conformations that are sampled. Energetically compensated interhelical stacking dynamics may help to maximize the conformational adaptability of RNA and allow a wide range of conformations to be optimally stabilized by proteins and ligands.
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Affiliation(s)
- Dawn K Merriman
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Jiayi Yuan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Biology, Duke University, Durham, North Carolina 27708, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Ananya Majumdar
- Biomolecular NMR Facility, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Hashim M Al-Hashimi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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A Massively Parallel Selection of Small Molecule-RNA Motif Binding Partners Informs Design of an Antiviral from Sequence. Chem 2018; 4:2384-2404. [PMID: 30719503 DOI: 10.1016/j.chempr.2018.08.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many RNAs cause disease; however, RNA is rarely exploited as a small-molecule drug target. Our programmatic focus is to define privileged RNA motif small-molecule interactions to enable the rational design of compounds that modulate RNA biology starting from only sequence. We completed a massive, library-versus-library screen that probed over 50 million binding events between RNA motifs and small molecules. The resulting data provide a rich encyclopedia of small-molecule RNA recognition patterns, defining chemotypes and RNA motifs that confer selective, avid binding. The resulting interaction maps were mined against the entire viral genome of hepatitis C virus (HCV). A small molecule was identified that avidly bound RNA motifs present in the HCV 30 UTR and inhibited viral replication while having no effect on host cells. Collectively, this study represents the first whole-genome pattern recognition between small molecules and RNA folds.
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30
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Identification of small-molecule ligands that bind to MiR-21 as potential therapeutics for endometriosis by screening ZINC database and in-vitro assays. Gene 2018; 662:46-53. [DOI: 10.1016/j.gene.2018.03.094] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/17/2018] [Accepted: 03/28/2018] [Indexed: 12/20/2022]
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31
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Ganser LR, Lee J, Rangadurai A, Merriman DK, Kelly ML, Kansal AD, Sathyamoorthy B, Al-Hashimi HM. High-performance virtual screening by targeting a high-resolution RNA dynamic ensemble. Nat Struct Mol Biol 2018; 25:425-434. [PMID: 29728655 PMCID: PMC5942591 DOI: 10.1038/s41594-018-0062-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/27/2018] [Indexed: 12/22/2022]
Abstract
Dynamic ensembles hold great promise in advancing RNA-targeted drug discovery. Here we subjected the transactivation response element (TAR) RNA from human immunodeficiency virus type-1 to experimental high-throughput screening against ~100,000 drug-like small molecules. Results were augmented with 170 known TAR-binding molecules and used to generate sublibraries optimized for evaluating enrichment when virtually screening a dynamic ensemble of TAR determined by combining NMR spectroscopy data and molecular dynamics simulations. Ensemble-based virtual screening scores molecules with an area under the receiver operator characteristic curve of ~0.85-0.94 and with ~40-75% of all hits falling within the top 2% of scored molecules. The enrichment decreased significantly for ensembles generated from the same molecular dynamics simulations without input NMR data and for other control ensembles. The results demonstrate that experimentally determined RNA ensembles can significantly enrich libraries with true hits and that the degree of enrichment is dependent on the accuracy of the ensemble.
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Affiliation(s)
- Laura R Ganser
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Janghyun Lee
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | | | - Megan L Kelly
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Aman D Kansal
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | | | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
- Department of Chemistry, Duke University, Durham, NC, USA.
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32
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Shin Y, Choi BS, Kim KC, Kang C, Kim K, Yoon CH. Development of a dual reporter screening assay for distinguishing the inhibition of HIV Tat-mediated transcription from off-target effects. J Virol Methods 2017; 249:1-9. [PMID: 28807730 DOI: 10.1016/j.jviromet.2017.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 12/29/2022]
Abstract
Human immunodeficiency virus (HIV) encodes a transcription trans-activator (Tat) with an essential role in the transcriptional elongation of viral RNA based on the viral promoter long terminal repeat (LTR). Tat-mediated transcription is conserved and can be distinguished from host transcription, so it is a therapeutic target for combating HIV replication. Traditional screening assays for Tat-mediated transcriptional inhibitors are based on the biochemical properties of Tat and transactivation-responsive RNA. We developed an inducible system based on two lentiviral expression cassettes for doxycycline (Dox)-inducible Tat and Renilla luciferase (R-Luc) using TZM-bl cells harboring LTR-driven firefly luciferase (F-Luc). The cells simultaneously expressed both Tat-induced F-Luc and R-Luc, so it was possible to recognize off-target effects in the presence of Dox. The system was validated with known inhibitors: CYC202 obtained high sensitivity and specificity, whereas 6Bio and DRB had off-target effects. The MTT-based cytotoxicity test indicated the resistance of the system even at concentrations with off-target effects. The specificity of the system was confirmed using antiretroviral drugs. Our dual reporter system can simply detect Tat inhibitory effects, as well as precisely discriminate between the inhibitory and off-target effects of inhibitors, and may be useful for the development of a therapeutic anti-HIV drug.
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Affiliation(s)
- YoungHyun Shin
- Division of AIDS, Korea National Institute of Health, Chungbuk, Republic of Korea; Division of Viral Disease Research, Korea National Institute of Health, Chungbuk, Republic of Korea.
| | - Byeong-Sun Choi
- Division of AIDS, Korea National Institute of Health, Chungbuk, Republic of Korea; Division of Viral Disease Research, Korea National Institute of Health, Chungbuk, Republic of Korea.
| | - Kyung-Chang Kim
- Division of AIDS, Korea National Institute of Health, Chungbuk, Republic of Korea; Division of Viral Disease Research, Korea National Institute of Health, Chungbuk, Republic of Korea.
| | - Chun Kang
- Division of AIDS, Korea National Institute of Health, Chungbuk, Republic of Korea; Division of Viral Diseases, Korea National Institute of Health, Chungbuk, Republic of Korea.
| | - Kisoon Kim
- Division of Viral Disease Research, Korea National Institute of Health, Chungbuk, Republic of Korea.
| | - Cheol-Hee Yoon
- Division of AIDS, Korea National Institute of Health, Chungbuk, Republic of Korea; Division of Viral Disease Research, Korea National Institute of Health, Chungbuk, Republic of Korea.
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Abstract
In addition to continuous rapid progress in RNA structure determination, probing, and biophysical studies, the past decade has seen remarkable advances in the development of a new generation of RNA folding theories and models. In this article, we review RNA structure prediction models and models for ion-RNA and ligand-RNA interactions. These new models are becoming increasingly important for a mechanistic understanding of RNA function and quantitative design of RNA nanotechnology. We focus on new methods for physics-based, knowledge-based, and experimental data-directed modeling for RNA structures and explore the new theories for the predictions of metal ion and ligand binding sites and metal ion-dependent RNA stabilities. The integration of these new methods with theories about the cellular environment effects in RNA folding, such as molecular crowding and cotranscriptional kinetic effects, may ultimately lead to an all-encompassing RNA folding model.
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Affiliation(s)
- Li-Zhen Sun
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
| | - Dong Zhang
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and MU Informatics Institute, University of Missouri, Columbia, Missouri 65211;
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34
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Patwardhan NN, Ganser LR, Kapral GJ, Eubanks CS, Lee J, Sathyamoorthy B, Al-Hashimi HM, Hargrove AE. Amiloride as a new RNA-binding scaffold with activity against HIV-1 TAR. MEDCHEMCOMM 2017; 8:1022-1036. [PMID: 28798862 PMCID: PMC5546750 DOI: 10.1039/c6md00729e] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 03/14/2017] [Indexed: 12/23/2022]
Abstract
Diversification of RNA-targeted scaffolds offers great promise in the search for selective ligands of therapeutically relevant RNA such as HIV-1 TAR. We herein report the establishment of amiloride as a novel RNA-binding scaffold along with synthetic routes for combinatorial C(5)- and C(6)-diversification. Iterative modifications at the C(5)- and C(6)- positions yielded derivative 24, which demonstrated a 100-fold increase in activity over the parent dimethylamiloride in peptide displacement assays. NMR chemical shift mapping was performed using the 2D SOFAST- [1H-13C] HMQC NMR method, which allowed for facile and rapid evaluation of binding modes for all library members. Cheminformatic analysis revealed distinct differences between selective and non-selective ligands. In this study, we evolved dimethylamiloride from a weak TAR ligand to one of the tightest binding selective TAR ligands reported to date through a novel combination of synthetic methods and analytical techniques. We expect these methods to allow for rapid library expansion and tuning of the amiloride scaffold for a range of RNA targets and for SOFAST NMR to allow unprecedented evaluation of small molecule:RNA interactions.
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Affiliation(s)
- Neeraj N. Patwardhan
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Laura R. Ganser
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Gary J. Kapral
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Christopher S. Eubanks
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Janghyun Lee
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Bharathwaj Sathyamoorthy
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Hashim M. Al-Hashimi
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Amanda E. Hargrove
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
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35
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Merriman DK, Xue Y, Yang S, Kimsey IJ, Shakya A, Clay M, Al-Hashimi HM. Shortening the HIV-1 TAR RNA Bulge by a Single Nucleotide Preserves Motional Modes over a Broad Range of Time Scales. Biochemistry 2016; 55:4445-56. [PMID: 27232530 DOI: 10.1021/acs.biochem.6b00285] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Helix-junction-helix (HJH) motifs are flexible building blocks of RNA architecture that help define the orientation and dynamics of helical domains. They are also frequently involved in adaptive recognition of proteins and small molecules and in the formation of tertiary contacts. Here, we use a battery of nuclear magnetic resonance techniques to examine how deleting a single bulge residue (C24) from the human immunodeficiency virus type 1 (HIV-1) transactivation response element (TAR) trinucleotide bulge (U23-C24-U25) affects dynamics over a broad range of time scales. Shortening the bulge has an effect on picosecond-to-nanosecond interhelical and local bulge dynamics similar to that casued by increasing the Mg(2+) and Na(+) concentration, whereby a preexisting two-state equilibrium in TAR is shifted away from a bent flexible conformation toward a coaxial conformation, in which all three bulge residues are flipped out and flexible. Surprisingly, the point deletion minimally affects microsecond-to-millisecond conformational exchange directed toward two low-populated and short-lived excited conformational states that form through reshuffling of bases pairs throughout TAR. The mutant does, however, adopt a slightly different excited conformational state on the millisecond time scale, in which U23 is intrahelical, mimicking the expected conformation of residue C24 in the excited conformational state of wild-type TAR. Thus, minor changes in HJH topology preserve motional modes in RNA occurring over the picosecond-to-millisecond time scales but alter the relative populations of the sampled states or cause subtle changes in their conformational features.
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Affiliation(s)
- Dawn K Merriman
- Department of Chemistry, Duke University , Durham, North Carolina 27708, United States
| | - Yi Xue
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Shan Yang
- Baxter Health Care (Suzhou) Company, Ltd. , Suzhou, Jiang Su 215028, China
| | - Isaac J Kimsey
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Anisha Shakya
- Department of Chemistry and Biophysics, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Mary Clay
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Hashim M Al-Hashimi
- Department of Chemistry, Duke University , Durham, North Carolina 27708, United States.,Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
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36
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Iron(II) supramolecular helicates interfere with the HIV-1 Tat-TAR RNA interaction critical for viral replication. Sci Rep 2016; 6:29674. [PMID: 27405089 PMCID: PMC4940744 DOI: 10.1038/srep29674] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 06/21/2016] [Indexed: 01/15/2023] Open
Abstract
The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates.
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37
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Le Douce V, Ait-Amar A, Forouzan Far F, Fahmi F, Quiel J, El Mekdad H, Daouad F, Marban C, Rohr O, Schwartz C. Improving combination antiretroviral therapy by targeting HIV-1 gene transcription. Expert Opin Ther Targets 2016; 20:1311-1324. [PMID: 27266557 DOI: 10.1080/14728222.2016.1198777] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Combination Antiretroviral Therapy (cART) has not allowed the cure of HIV. The main obstacle to HIV eradication is the existence of quiescent reservoirs. Several other limitations of cART have been described, such as strict life-long treatment and high costs, restricting it to Western countries, as well as the development of multidrug resistance. Given these limitations and the impetus to find a cure, the development of new treatments is necessary. Areas covered: In this review, we discuss the current status of several efficient molecules able to suppress HIV gene transcription, including NF-kB and Tat inhibitors. We also assess the potential of new proteins belonging to the intriguing DING family, which have been reported to have potential anti-HIV-1 activity by inhibiting HIV gene transcription. Expert opinion: Targeting HIV-1 gene transcription is an alternative approach, which could overcome cART-related issues, such as the emergence of multidrug resistance. Improving cART will rely on the identification and characterization of new actors inhibiting HIV-1 transcription. Combining such efforts with the use of new technologies, the development of new models for preclinical studies, and improvement in drug delivery will considerably reduce drug toxicity and thus increase patient adherence.
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Affiliation(s)
- Valentin Le Douce
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France.,c UCD Centre for Research in Infectious Diseases (CRID) School of Medicine and Medical Science , University College Dublin , Dublin 4 , Ireland
| | - Amina Ait-Amar
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Faezeh Forouzan Far
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Faiza Fahmi
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Jose Quiel
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Hala El Mekdad
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Fadoua Daouad
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Céline Marban
- d Faculté de Chirurgie Dentaire , Inserm UMR 1121 , Strasbourg , France
| | - Olivier Rohr
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France.,e Institut Universitaire de France , Paris , France
| | - Christian Schwartz
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France
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38
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Recent advances in the identification of Tat-mediated transactivation inhibitors: progressing toward a functional cure of HIV. Future Med Chem 2016; 8:421-42. [PMID: 26933891 DOI: 10.4155/fmc.16.3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The current anti-HIV combination therapy does not eradicate the virus that persists mainly in quiescent infected CD4(+) T cells as a latent integrated provirus that resumes after therapy interruption. The Tat-mediated transactivation (TMT) is a critical step in the HIV replication cycle that could give the opportunity to reduce the size of latent reservoirs. More than two decades of research led to the identification of various TMT inhibitors. While none of them met the criteria to reach the market, the search for a suitable TMT inhibitor is still actively pursued. Really promising compounds, including one in a Phase III clinical trial, have been recently identified, thus warranting an update.
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39
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Pascale L, González AL, Di Giorgio A, Gaysinski M, Teixido Closa J, Tejedor RE, Azoulay S, Patino N. Deciphering structure-activity relationships in a series of Tat/TAR inhibitors. J Biomol Struct Dyn 2016; 34:2327-38. [PMID: 26524629 DOI: 10.1080/07391102.2015.1114971] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A series of pentameric "Polyamide Amino Acids" (PAAs) compounds derived from the same trimeric precursor have been synthesized and investigated as HIV TAR RNA ligands, in the absence and in the presence of a Tat fragment. All PAAs bind TAR with similar sub-micromolar affinities but their ability to compete efficiently with the Tat fragment strongly differs, IC50 ranging from 35 nM to >2 μM. While NMR and CD studies reveal that all PAA interact with TAR at the same site and induce globally the same RNA conformational change upon binding, a comparative thermodynamic study of PAA/TAR equilibria highlights distinct TAR binding modes for Tat competitor and non-competitor PAAs. This led us to suggest two distinct interaction modes that have been further validated by molecular modeling studies. While the binding of Tat competitor PAAs induces a contraction at the TAR bulge region, the binding of non-competitor ones widens it. This could account for the distinct PAA ability to compete with Tat fragment. Our work illustrates how comparative thermodynamic studies of a series of RNA ligands of same chemical family are of value for understanding their binding modes and for rationalizing structure-activity relationships.
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Affiliation(s)
- Lise Pascale
- a Institut de Chimie de Nice UMR7272, Université Nice Sophia Antipolis , 06108 Nice Cedex , France
| | - Alejandro López González
- b Molecular Design Lab, IQS School of Engineering , Universitat Ramon Llull , 08017 Barcelona , Spain
| | - Audrey Di Giorgio
- a Institut de Chimie de Nice UMR7272, Université Nice Sophia Antipolis , 06108 Nice Cedex , France
| | - Marc Gaysinski
- a Institut de Chimie de Nice UMR7272, Université Nice Sophia Antipolis , 06108 Nice Cedex , France
| | - Jordi Teixido Closa
- b Molecular Design Lab, IQS School of Engineering , Universitat Ramon Llull , 08017 Barcelona , Spain
| | - Roger Estrada Tejedor
- b Molecular Design Lab, IQS School of Engineering , Universitat Ramon Llull , 08017 Barcelona , Spain
| | - Stéphane Azoulay
- a Institut de Chimie de Nice UMR7272, Université Nice Sophia Antipolis , 06108 Nice Cedex , France
| | - Nadia Patino
- a Institut de Chimie de Nice UMR7272, Université Nice Sophia Antipolis , 06108 Nice Cedex , France
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40
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Stefaniak F, Chudyk EI, Bodkin M, Dawson WK, Bujnicki JM. Modeling of ribonucleic acid-ligand interactions. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2015. [DOI: 10.1002/wcms.1226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Filip Stefaniak
- Laboratory of Bioinformatics and Protein Engineering; International Institute of Molecular and Cell Biology; Warsaw Poland
| | - Ewa I. Chudyk
- Research Informatics; Evotec (UK) Ltd; Milton Park UK
| | | | - Wayne K. Dawson
- Laboratory of Bioinformatics and Protein Engineering; International Institute of Molecular and Cell Biology; Warsaw Poland
| | - Janusz M. Bujnicki
- Laboratory of Bioinformatics and Protein Engineering; International Institute of Molecular and Cell Biology; Warsaw Poland
- Laboratory of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology; Adam Mickiewicz University; Poznan Poland
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41
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Wynn JE, Santos WL. HIV-1 drug discovery: targeting folded RNA structures with branched peptides. Org Biomol Chem 2015; 13:5848-58. [PMID: 25958855 PMCID: PMC4511164 DOI: 10.1039/c5ob00589b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) is an RNA virus that is prone to high rates of mutation. While the disease is managed with current antiretroviral therapies, drugs with a new mode of action are needed. A strategy towards this goal is aimed at targeting the native three-dimensional fold of conserved RNA structures. This perspective highlights medium-sized peptides and peptidomimetics used to target two conserved RNA structures of HIV-1. In particular, branched peptides have the capacity to bind in a multivalent fashion, utilizing a large surface area to achieve the necessary affinity and selectivity toward the target RNA.
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Affiliation(s)
- Jessica E Wynn
- Department of Chemistry and Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, USA.
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42
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Yin S, Jiang H, Chen D, Murchie AIH. Substrate recognition and modification by the nosiheptide resistance methyltransferase. PLoS One 2015; 10:e0122972. [PMID: 25910005 PMCID: PMC4409310 DOI: 10.1371/journal.pone.0122972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 02/11/2015] [Indexed: 11/29/2022] Open
Abstract
Background The proliferation of antibiotic resistant pathogens is an increasing threat to the general public. Resistance may be conferred by a number of mechanisms including covalent or mutational modification of the antibiotic binding site, covalent modification of the drug, or the over-expression of efflux pumps. The nosiheptide resistance methyltransferase (NHR) confers resistance to the thiazole antibiotic nosiheptide in the nosiheptide producer organism Streptomyces actuosus through 2ʹO-methylation of 23S rRNA at the nucleotide A1067. Although the crystal structures of NHR and the closely related thiostrepton-resistance methyltransferase (TSR) in complex with the cofactor S-Adenosyl-L-methionine (SAM) are available, the principles behind NHR substrate recognition and catalysis remain unclear. Methodology/Principal Findings We have analyzed the binding interactions between NHR and model 58 and 29 nucleotide substrate RNAs by gel electrophoresis mobility shift assays (EMSA) and fluorescence anisotropy. We show that the enzyme binds to RNA as a dimer. By constructing a hetero-dimer complex composed of one wild-type subunit and one inactive mutant NHR-R135A subunit, we show that only one functional subunit of the NHR homodimer is required for its enzymatic activity. Mutational analysis suggests that the interactions between neighbouring bases (G1068 and U1066) and A1067 have an important role in methyltransfer activity, such that the substitution of a deoxy sugar spacer (5ʹ) to the target nucleotide achieved near wild-type levels of methylation. A series of atomic substitutions at specific positions on the substrate adenine show that local base-base interactions between neighbouring bases are important for methylation. Conclusion/Significance Taken together these data suggest that local base-base interactions play an important role in aligning the substrate 2’ hydroxyl group of A1067 for methyl group transfer. Methylation of nucleic acids is playing an increasingly important role in fundamental biological processes and we anticipate that the approach outlined in this manuscript may be useful for investigating other classes of nucleic acid methyltransferases.
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Affiliation(s)
- Sitao Yin
- Key Laboratory of Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- Institutes of Biomedical Sciences, Fudan University Shanghai Medical College, Shanghai 200032, PR China
| | - Hengyi Jiang
- Key Laboratory of Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- Institutes of Biomedical Sciences, Fudan University Shanghai Medical College, Shanghai 200032, PR China
| | - Dongrong Chen
- Key Laboratory of Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- Institutes of Biomedical Sciences, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- * E-mail: (AM); (DC)
| | - Alastair I. H. Murchie
- Key Laboratory of Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- Institutes of Biomedical Sciences, Fudan University Shanghai Medical College, Shanghai 200032, PR China
- * E-mail: (AM); (DC)
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43
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Shortridge MD, Varani G. Structure based approaches for targeting non-coding RNAs with small molecules. Curr Opin Struct Biol 2015; 30:79-88. [PMID: 25687935 PMCID: PMC4416997 DOI: 10.1016/j.sbi.2015.01.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 01/19/2015] [Accepted: 01/28/2015] [Indexed: 12/22/2022]
Abstract
The increasing appreciation of the central role of non-coding RNAs (miRNAs and long non-coding RNAs) in chronic and degenerative human disease makes them attractive therapeutic targets. This would not be unprecedented: the bacterial ribosomal RNA is a mainstay for antibacterial treatment, while the conservation and functional importance of viral RNA regulatory elements has long suggested they would constitute attractive targets for new antivirals. Oligonucleotide-based chemistry has obvious appeals but also considerable pharmacological limitations that are yet to be addressed satisfactorily. Recent studies identifying small molecules targeting non-coding RNAs may provide an alternative approach to oligonucleotide methods. Here we review recent work investigating new structural and chemical principles for targeting RNA with small molecules.
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Affiliation(s)
- Matthew D Shortridge
- Department of Chemistry, University of Washington, Seattle, Box 351700, Seattle 98195, USA
| | - Gabriele Varani
- Department of Chemistry, University of Washington, Seattle, Box 351700, Seattle 98195, USA.
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Musiani F, Rossetti G, Capece L, Gerger TM, Micheletti C, Varani G, Carloni P. Molecular dynamics simulations identify time scale of conformational changes responsible for conformational selection in molecular recognition of HIV-1 transactivation responsive RNA. J Am Chem Soc 2014; 136:15631-7. [PMID: 25313638 PMCID: PMC5521259 DOI: 10.1021/ja507812v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The HIV-1 Tat protein and several small molecules bind to HIV-1 transactivation responsive RNA (TAR) by selecting sparsely populated but pre-existing conformations. Thus, a complete characterization of TAR conformational ensemble and dynamics is crucial to understand this paradigmatic system and could facilitate the discovery of new antivirals targeting this essential regulatory element. We show here that molecular dynamics simulations can be effectively used toward this goal by bridging the gap between functionally relevant time scales that are inaccessible to current experimental techniques. Specifically, we have performed several independent microsecond long molecular simulations of TAR based on one of the most advanced force fields available for RNA, the parmbsc0 AMBER. Our simulations are first validated against available experimental data, yielding an excellent agreement with measured residual dipolar couplings and order parameter S(2). This contrast with previous molecular dynamics simulations (Salmon et al., J. Am. Chem. Soc. 2013 135, 5457-5466) based on the CHARMM36 force field, which could achieve only modest accord with the experimental RDC values. Next, we direct the computation toward characterizing the internal dynamics of TAR over the microsecond time scale. We show that the conformational fluctuations observed over this previously elusive time scale have a strong functionally oriented character in that they are primed to sustain and assist ligand binding.
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Affiliation(s)
- Francesco Musiani
- Scuola Internazionale Superiore di Studi Avanzati (SISSA/ISAS), via Bonomea 265, 34136 Trieste, Italy
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, 40127 Bologna, Italy
- Institute of Neuroscience and Medicine INM-9 and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Computational Biophysics, German Research School for Simulation Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Giulia Rossetti
- Institute of Neuroscience and Medicine INM-9 and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Computational Biophysics, German Research School for Simulation Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Luciana Capece
- International Centre for Genetic Engineering and Biotechnology, AREA Science Park, Padriciano 99, 34149 Trieste, Italy
| | - Thomas Martin Gerger
- Institute of Neuroscience and Medicine INM-9 and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Computational Biophysics, German Research School for Simulation Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Cristian Micheletti
- Scuola Internazionale Superiore di Studi Avanzati (SISSA/ISAS), via Bonomea 265, 34136 Trieste, Italy
| | - Gabriele Varani
- Department of Chemistry and Department of Biochemistry, University of Washington, Seattle, 98195 WA, USA
| | - Paolo Carloni
- Institute of Neuroscience and Medicine INM-9 and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Computational Biophysics, German Research School for Simulation Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
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Dickson A, Mustoe AM, Salmon L, Brooks CL. Efficient in silico exploration of RNA interhelical conformations using Euler angles and WExplore. Nucleic Acids Res 2014; 42:12126-37. [PMID: 25294827 PMCID: PMC4231733 DOI: 10.1093/nar/gku799] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/04/2014] [Accepted: 08/25/2014] [Indexed: 12/20/2022] Open
Abstract
HIV-1 TAR RNA is a two-helix bulge motif that plays a critical role in HIV viral replication and is an important drug target. However, efforts at designing TAR inhibitors have been challenged by its high degree of structural flexibility, which includes slow large-amplitude reorientations of its helices with respect to one another. Here, we use the recently introduced algorithm WExplore in combination with Euler angles to achieve unprecedented sampling of the TAR conformational ensemble. Our ensemble achieves similar agreement with experimental NMR data when compared with previous TAR computational studies, and is generated at a fraction of the computational cost. It clearly emerges from configuration space network analysis that the intermittent formation of the A22-U40 base pair acts as a reversible switch that enables sampling of interhelical conformations that would otherwise be topologically disallowed. We find that most previously determined ligand-bound structures are found in similar location in the network, and we use a sample-and-select approach to guide the construction of a set of novel conformations which can serve as the basis for future drug development efforts. Collectively, our findings demonstrate the utility of WExplore in combination with suitable order parameters as a method for exploring RNA conformational space.
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Affiliation(s)
- Alex Dickson
- Department of Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109, USA
| | - Anthony M Mustoe
- Department of Biophysics, University of Michigan, 930 N University, Ann Arbor, MI 48109, USA
| | - Loïc Salmon
- Department of Biophysics, University of Michigan, 930 N University, Ann Arbor, MI 48109, USA
| | - Charles L Brooks
- Department of Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109, USA Department of Biophysics, University of Michigan, 930 N University, Ann Arbor, MI 48109, USA
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Wan Z, Chen X. Triptolide inhibits human immunodeficiency virus type 1 replication by promoting proteasomal degradation of Tat protein. Retrovirology 2014; 11:88. [PMID: 25323821 PMCID: PMC4205289 DOI: 10.1186/s12977-014-0088-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 09/23/2014] [Indexed: 11/30/2022] Open
Abstract
Background Plants remain an important source of new drugs, new leads and new chemical entities. Triptolide is a diterpenoid epoxide isolated from Tripterygium wilfordii Hook F that possesses a broad range of bioactivities, including anti-inflammatory, immunosuppressive and anti-tumor properties. The antiviral activity of triptolide against human immunodeficiency virus type 1 (HIV-1) has not been reported. Results In this study, nanomolar concentrations of triptolide were shown to potently inhibit HIV-1 replication in vitro. To identify the step(s) of the HIV-1 replication cycle affected by triptolide, time-of-addition studies, PCR analysis and direct transfection of viral genomic DNA were performed. The results of these experiments indicated that triptolide acts at the stage of viral gene transcription. In addition, a luciferase-based reporter assay that allows quantitative analysis of long terminal repeat (LTR)-driven transcription showed that Tat-induced LTR activation was impaired in the presence of triptolide. Moreover, Western blot analysis of exogenous gene expression (driven by the human elongation factor 1 α subunit promoter) in transiently transfected cells revealed that triptolide specifically reduces the steady-state level of Tat protein, without suppressing global gene expression. Further studies showed that triptolide accelerates Tat protein degradation, which can be rescued by administration of the proteasome inhibitor MG132. Mutation analysis revealed that N-terminal domains of Tat protein and nuclear localization are required for triptolide to reduce steady-state level of Tat. Conclusion This study suggests for the first time that triptolide exerts its anti-HIV-1 activity by specifically prompting the degradation of the virally encoded Tat protein, which is a novel mechanism of action for an anti-HIV-1 compound. This compound may serve as a starting point for developing a novel HIV-1 therapeutic approach or as a basic research tool for interrogating events during viral replication.
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Affiliation(s)
- Zhitao Wan
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China. .,Current address: China Novartis Institutes for BioMedical Research, Shanghai, People's Republic of China.
| | - Xulin Chen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China.
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Blond A, Ennifar E, Tisné C, Micouin L. The design of RNA binders: targeting the HIV replication cycle as a case study. ChemMedChem 2014; 9:1982-96. [PMID: 25100137 DOI: 10.1002/cmdc.201402259] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Indexed: 01/08/2023]
Abstract
The human immunodeficiency virus 1 (HIV-1) replication cycle is finely tuned with many important steps involving RNA-RNA or protein-RNA interactions, all of them being potential targets for the development of new antiviral compounds. This cycle can also be considered as a good benchmark for the evaluation of early-stage strategies aiming at designing drugs that bind to RNA, with the possibility to correlate in vitro activities with antiviral properties. In this review, we highlight different approaches developed to interfere with four important steps of the HIV-1 replication cycle: the early stage of reverse transcription, the transactivation of viral transcription, the nuclear export of partially spliced transcripts and the dimerization step.
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Affiliation(s)
- Aurélie Blond
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601, CNRS, Université Paris Descartes, Sorbonne Paris Cité, Faculté des Sciences Fondamentales et Biomédicales, 45 Rue des Saints Pères, 75006 Paris (France)
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Kellish PC, Kumar S, Mack TS, Spano MN, Hennig M, Arya DP. Multivalent Amino Sugars to Recognize Different TAR RNA Conformations. MEDCHEMCOMM 2014; 5:1235-1246. [PMID: 27076899 PMCID: PMC4828046 DOI: 10.1039/c4md00165f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neomycin dimers synthesized using "click chemistry" with varying functionality and length in the linker region have been shown to be effective in targeting the HIV-1 TAR RNA region of the HIV virus. TAR (Transactivation Response) RNA region, a 59 base pair stem loop structure located at the 5'-end of all nascent viral transcripts interacts with its target, a key regulatory protein, Tat, and necessitates the replication of HIV-1 virus. Ethidium bromide displacement and FRET competition assays have revealed nanomolar binding affinity between neomycin dimers and wildtype TAR RNA while in case of neomycin, only a weak binding was detected. Here, NMR and FID-based comparisons reveal an extended binding interface for neomycin dimers involving the upper stem of the TAR RNA thereby offering an explanation for increased affinities. To further explore the potential of these modified aminosugars we have extended binding studies to include four TAR RNA mutants that display conformational differences with minimal sequence variation. The differences in binding between neomycin and neomycin dimers is characterized with TAR RNA mutants that include mutations to the bulge region, hairpin region, and both the bulge and hairpin regions. Our results demonstrate the effect of these mutations on neomycin binding and our results show that linker functionalities between dimeric units of neomycin can distinguish between the conformational differences of mutant TAR RNA structures.
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Affiliation(s)
- Patrick C. Kellish
- Laboratory of Medicinal Chemistry, Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Sunil Kumar
- Laboratory of Medicinal Chemistry, Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Todd S. Mack
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 70 President St., Charleston, SC 29425
| | | | - Mirko Hennig
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 70 President St., Charleston, SC 29425
| | - Dev P. Arya
- Laboratory of Medicinal Chemistry, Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
- NUBAD, LLC, 900B West Faris Rd., Greenville, SC 29605
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Mustoe AM, Al-Hashimi HM, Brooks CL. Coarse grained models reveal essential contributions of topological constraints to the conformational free energy of RNA bulges. J Phys Chem B 2014; 118:2615-27. [PMID: 24547945 PMCID: PMC3983386 DOI: 10.1021/jp411478x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
![]()
Recent studies have shown that simple
stereochemical constraints
encoded at the RNA secondary structure level significantly restrict
the orientation of RNA helices across two-way junctions and yield
physically reasonable distributions of RNA 3D conformations. Here
we develop a new coarse-grain model, TOPRNA, that is optimized for
exploring detailed aspects of these topological constraints in complex
RNA systems. Unlike prior models, TOPRNA effectively treats RNAs as
collections of semirigid helices linked by freely rotatable single
strands, allowing us to isolate the effects of secondary structure
connectivity and sterics on 3D structure. Simulations of bulge junctions
show that TOPRNA captures new aspects of topological constraints,
including variations arising from deviations in local A-form structure,
translational displacements of the helices, and stereochemical constraints
imposed by bulge-linker nucleotides. Notably, these aspects of topological
constraints define free energy landscapes that coincide with the distribution
of bulge conformations in the PDB. Our simulations also quantitatively
reproduce NMR RDC measurements made on HIV-1 TAR at low salt concentrations,
although not for different TAR mutants or at high salt concentrations.
Our results confirm that topological constraints are an important
determinant of bulge conformation and dynamics and demonstrate the
utility of TOPRNA for studying the topological constraints of complex
RNAs.
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Affiliation(s)
- Anthony M Mustoe
- Departments of Biophysics and ‡Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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Borkar AN, De Simone A, Montalvao RW, Vendruscolo M. A method of determining RNA conformational ensembles using structure-based calculations of residual dipolar couplings. J Chem Phys 2014; 138:215103. [PMID: 23758399 DOI: 10.1063/1.4804301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We describe a method of determining the conformational fluctuations of RNA based on the incorporation of nuclear magnetic resonance (NMR) residual dipolar couplings (RDCs) as replica-averaged structural restraints in molecular dynamics simulations. In this approach, the alignment tensor required to calculate the RDCs corresponding to a given conformation is estimated from its shape, and multiple replicas of the RNA molecule are simulated simultaneously to reproduce in silico the ensemble-averaging procedure performed in the NMR measurements. We provide initial evidence that with this approach it is possible to determine accurately structural ensembles representing the conformational fluctuations of RNA by applying the reference ensemble test to the trans-activation response element of the human immunodeficiency virus type 1.
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Affiliation(s)
- Aditi N Borkar
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
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