1
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Yeboah SK, Zigli A, Sintim HO. 2',4'-LNA-Functionalized 5'-S-Phosphorothioester CDNs as STING Agonists. Chembiochem 2024; 25:e202400321. [PMID: 38720428 DOI: 10.1002/cbic.202400321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 05/07/2024] [Indexed: 07/03/2024]
Abstract
Cyclic dinucleotides (CDNs) have garnered popularity over the last decade as immunotherapeutic agents, which activate the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway to trigger an immune response. Many analogs of 2'3'-cGAMP, c-di-GMP, and c-di-AMP have been developed and shown as effective cancer vaccines and immunomodulators for the induction of both the adaptive and innate immune systems. Unfortunately, the effectiveness of these CDNs is limited by their chemical and enzymatic instability. We recently introduced 5'-endo-phosphorothoiate 2'3'-cGAMP analogs as potent STING agonist with improved resistance to cleavage by clinically relevant phosphodiesterases. We herein report the synthesis of locked nucleic acid-functionalized (LNA) endo-S-CDNs and evaluate their ability to activate STING in THP1 monocytes. Interestingly, some of our synthesized LNA 3'3'-endo-S-CDNs can moderately activate hSTING REF haplotype (R232H), which exhibit diminished response to both 2'3'-cGAMP and ADU-S100. Also, we show that one of our most potent endo-S-CDNs has remarkable chemical (oxidants I2 and H2O2) and phosphodiesterase stability.
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Affiliation(s)
- Simpa K Yeboah
- Department of Chemistry, 560 Oval Drive, West Lafayette, Indiana, 47907-2084
- Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907, USA
| | - Abdulai Zigli
- Department of Chemistry, 560 Oval Drive, West Lafayette, Indiana, 47907-2084
- Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907, USA
| | - Herman O Sintim
- Department of Chemistry, 560 Oval Drive, West Lafayette, Indiana, 47907-2084
- Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology, and Infectious Disease, West Lafayette, IN 47907, USA
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2
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Burra VLSP, Sahoo PS, Dhankhar A, Jhajj J, Kasamuthu PS, K SSVK, Macha SKR. Understanding the structural basis of the binding specificity of c-di-AMP to M. smegmatis RecA using computational biology approach. J Biomol Struct Dyn 2024; 42:2043-2057. [PMID: 38093709 DOI: 10.1080/07391102.2023.2227709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/09/2023] [Indexed: 02/21/2024]
Abstract
Mycobacterium tuberculosis RecA (MtRecA), a protein involved in DNA repair, homologous recombination and SOS pathway, contributes to the development of multidrug resistance. ATP binding-site in RecA has been a drug target to disable RecA dependent DNA repair. For the first time, experiments have shown the existence and binding of c-di-AMP to a novel allosteric site in the C-terminal-Domain (CTD) of Mycobacterium smegmatis RecA (MsRecA), a close homolog of MtRecA. In addition, it was observed that the c-di-AMP was not binding to Escherichia coli RecA (EcRecA). This article analyses the possible interactions of the three RecA homologs with the various c-di-AMP conformations to gain insights into the structural basis of the natural preference of c-di-AMP to MsRecA and not to EcRecA, using the structural biology tools. The comparative analysis, based on amino acid composition, homology, motifs, residue types, docking, molecular dynamics simulations and binding free energy calculations, indeed, conclusively indicates strong binding of c-di-AMP to MsRecA. Having very similar results as MsRecA, it is highly plausible for c-di-AMP to strongly bind MtRecA as well. These insights from the in-silico studies adds a new therapeutic approach against TB through design and development of novel allosteric inhibitors for the first time against MtRecA.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- V L S Prasad Burra
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - Partha Sarathi Sahoo
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - Amit Dhankhar
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - Jatinder Jhajj
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - Prasanna Sudharson Kasamuthu
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - S S V Kiran K
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
| | - Samuel Krupa Rakshan Macha
- Centre for Advanced Research and Innovation in Structural Biology of Diseases, K L E F (Deemed to be) University, Vaddeswaram, Andhra Pradesh, India
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3
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Chen Y, Zhai W, Zhang K, Liu H, Zhu T, Su L, Bermudez L, Chen H, Guo A. Small RNA Profiling in Mycobacterium Provides Insights Into Stress Adaptability. Front Microbiol 2021; 12:752537. [PMID: 34803973 PMCID: PMC8600241 DOI: 10.3389/fmicb.2021.752537] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/01/2021] [Indexed: 11/29/2022] Open
Abstract
Mycobacteria encounter a number of environmental changes during infection and respond using different mechanisms. Small RNA (sRNA) is a post-transcriptionally regulatory system for gene functions and has been investigated in many other bacteria. This study used Mycobacterium tuberculosis and Mycobacterium bovis Bacillus Calmette-Guérin (BCG) infection models and sequenced whole bacterial RNAs before and after host cell infection. A comparison of differentially expressed sRNAs using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) and target prediction was carried out. Six pathogenically relevant stress conditions, growth rate, and morphology were used to screen and identify sRNAs. From these data, a subset of sRNAs was differentially expressed in multiple infection groups and stress conditions. Many were found associated with lipid metabolism. Among them, ncBCG427 was significantly downregulated when BCG entered into macrophages and was associated with increased biofilm formation. The reduction of virulence possibility depends on regulating lipid metabolism.
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Affiliation(s)
- Yingyu Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Wenjun Zhai
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Kailun Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Han Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Tingting Zhu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Li Su
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Luiz Bermudez
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Aizhen Guo
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,National Animal Tuberculosis Para-Reference Laboratory (Wuhan) of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
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4
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He J, Yin W, Galperin MY, Chou SH. Cyclic di-AMP, a second messenger of primary importance: tertiary structures and binding mechanisms. Nucleic Acids Res 2020; 48:2807-2829. [PMID: 32095817 DOI: 10.1093/nar/gkaa112] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/09/2020] [Accepted: 02/21/2020] [Indexed: 12/12/2022] Open
Abstract
Cyclic diadenylate (c-di-AMP) is a widespread second messenger in bacteria and archaea that is involved in the maintenance of osmotic pressure, response to DNA damage, and control of central metabolism, biofilm formation, acid stress resistance, and other functions. The primary importance of c-di AMP stems from its essentiality for many bacteria under standard growth conditions and the ability of several eukaryotic proteins to sense its presence in the cell cytoplasm and trigger an immune response by the host cells. We review here the tertiary structures of the domains that regulate c-di-AMP synthesis and signaling, and the mechanisms of c-di-AMP binding, including the principal conformations of c-di-AMP, observed in various crystal structures. We discuss how these c-di-AMP molecules are bound to the protein and riboswitch receptors and what kinds of interactions account for the specific high-affinity binding of the c-di-AMP ligand. We describe seven kinds of non-covalent-π interactions between c-di-AMP and its receptor proteins, including π-π, C-H-π, cation-π, polar-π, hydrophobic-π, anion-π and the lone pair-π interactions. We also compare the mechanisms of c-di-AMP and c-di-GMP binding by the respective receptors that allow these two cyclic dinucleotides to control very different biological functions.
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Affiliation(s)
- Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China.,Institute of Biochemistry and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
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5
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He J, Yin W, Galperin MY, Chou SH. Cyclic di-AMP, a second messenger of primary importance: tertiary structures and binding mechanisms. Nucleic Acids Res 2020. [PMID: 32095817 DOI: 10.1093/nar/gkaa112"] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cyclic diadenylate (c-di-AMP) is a widespread second messenger in bacteria and archaea that is involved in the maintenance of osmotic pressure, response to DNA damage, and control of central metabolism, biofilm formation, acid stress resistance, and other functions. The primary importance of c-di AMP stems from its essentiality for many bacteria under standard growth conditions and the ability of several eukaryotic proteins to sense its presence in the cell cytoplasm and trigger an immune response by the host cells. We review here the tertiary structures of the domains that regulate c-di-AMP synthesis and signaling, and the mechanisms of c-di-AMP binding, including the principal conformations of c-di-AMP, observed in various crystal structures. We discuss how these c-di-AMP molecules are bound to the protein and riboswitch receptors and what kinds of interactions account for the specific high-affinity binding of the c-di-AMP ligand. We describe seven kinds of non-covalent-π interactions between c-di-AMP and its receptor proteins, including π-π, C-H-π, cation-π, polar-π, hydrophobic-π, anion-π and the lone pair-π interactions. We also compare the mechanisms of c-di-AMP and c-di-GMP binding by the respective receptors that allow these two cyclic dinucleotides to control very different biological functions.
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Affiliation(s)
- Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P. R. China.,Institute of Biochemistry and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China
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6
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Launer-Felty KD, Strobel SA. Enzymatic synthesis of cyclic dinucleotide analogs by a promiscuous cyclic-AMP-GMP synthetase and analysis of cyclic dinucleotide responsive riboswitches. Nucleic Acids Res 2019. [PMID: 29514227 PMCID: PMC5888326 DOI: 10.1093/nar/gky137] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cyclic dinucleotides are second messenger molecules produced by both prokaryotes and eukaryotes in response to external stimuli. In bacteria, these molecules bind to RNA riboswitches and several protein receptors ultimately leading to phenotypic changes such as biofilm formation, ion transport and secretion of virulence factors. Some cyclic dinucleotide analogs bind differentially to biological receptors and can therefore be used to better understand cyclic dinucleotide mechanisms in vitro and in vivo. However, production of some of these analogs involves lengthy, multistep syntheses. Here, we describe a new, simple method for enzymatic synthesis of several 3′, 5′ linked cyclic dinucleotide analogs of c-di-GMP, c-di-AMP and c-AMP-GMP using the cyclic-AMP-GMP synthetase, DncV. The enzymatic reaction efficiently produced most cyclic dinucleotide analogs, such as 2′-amino sugar substitutions and phosphorothioate backbone modifications, for all three types of cyclic dinucleotides without the use of protecting groups or organic solvents. We used these novel analogs to explore differences in phosphate backbone and 2′-hydroxyl recognition between GEMM-I and GEMM-Ib riboswitches.
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Affiliation(s)
- Katherine D Launer-Felty
- Department of Molecular Biophysics and Biochemistry and Department of Chemistry, Chemical Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry and Department of Chemistry, Chemical Biology Institute, Yale University, West Haven, CT 06516, USA
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7
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Torgerson CD, Hiller DA, Stav S, Strobel SA. Gene regulation by a glycine riboswitch singlet uses a finely tuned energetic landscape for helical switching. RNA (NEW YORK, N.Y.) 2018; 24:1813-1827. [PMID: 30237163 PMCID: PMC6239177 DOI: 10.1261/rna.067884.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/18/2018] [Indexed: 05/09/2023]
Abstract
Riboswitches contain structured aptamer domains that, upon ligand binding, facilitate helical switching in their downstream expression platforms to alter gene expression. To fully dissect how riboswitches function requires a better understanding of the energetic landscape for helical switching. Here, we report a sequencing-based high-throughput assay for monitoring in vitro transcription termination and use it to simultaneously characterize the functional effects of all 522 single point mutants of a glycine riboswitch type-1 singlet. Mutations throughout the riboswitch cause ligand-dependent defects, but only mutations within the terminator hairpin alter readthrough efficiencies in the absence of ligand. A comprehensive analysis of the expression platform reveals that ligand binding stabilizes the antiterminator by just 2-3 kcal/mol, indicating that the competing expression platform helices must be extremely close in energy to elicit a significant ligand-dependent response. These results demonstrate that gene regulation by this riboswitch is highly constrained by the energetics of ligand binding and conformational switching. These findings exemplify the energetic parameters of RNA conformational rearrangements driven by binding events.
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Affiliation(s)
- Chad D Torgerson
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - David A Hiller
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Shira Stav
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
| | - Scott A Strobel
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, USA
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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8
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Warminski M, Kowalska J, Jemielity J. Synthesis of RNA 5'-Azides from 2'-O-Pivaloyloxymethyl-Protected RNAs and Their Reactivity in Azide-Alkyne Cycloaddition Reactions. Org Lett 2017. [PMID: 28636394 DOI: 10.1021/acs.orglett.7b01591] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Commercially available 2'-O-pivaloyloxymethyl (PivOM) phosphoramidites were employed in an SPS protocol for RNA 5' azides. The utility of the N3-RNAs in CuAAC and SPAAC was demonstrated by RNA 5' labeling, chemical ligation including fragment joining and cyclization, and bioconjugation. As a result, several new RNA conjugates that may be valuable tools for studies on biological events such as innate immune response (cyclic dinucleotides), post-transcriptional gene regulation (circular RNAs), or mRNA turnover (m7G capped RNAs) were obtained.
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Affiliation(s)
- Marcin Warminski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw , Pasteura 5, 02-093 Warsaw, Poland
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw , Pasteura 5, 02-093 Warsaw, Poland
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw , Banacha 2c, 02-097 Warsaw, Poland
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9
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Shiraishi K, Saito-Tarashima N, Igata Y, Murakami K, Okamoto Y, Miyake Y, Furukawa K, Minakawa N. Synthesis and evaluation of c-di-4'-thioAMP as an artificial ligand for c-di-AMP riboswitch. Bioorg Med Chem 2017; 25:3883-3889. [PMID: 28559057 DOI: 10.1016/j.bmc.2017.05.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 11/26/2022]
Abstract
Cyclic-di-adenosine monophosphate (c-di-AMP) is a bacterial second messenger that binds to an RNA receptor called riboswitch and regulates its downstream genes involving cell wall metabolism, ion transport, and spore germination. Therefore, the c-di-AMP riboswitch can be a novel target of antibiotics. In this study, we synthesized c-di-4'-thioAMP (1), which possesses a sulfur atom instead of an oxygen atom in the furanose ring, as a candidate of a bioisoster for natural c-di-AMP. The resulting 1 bound to the c-di-AMP riboswitch with a micromolar affinity (34.8μM), and the phosphodiesterase resistance of 1 was >12-times higher than that of c-di-AMP. Thus, 1 can be considered to be a stable ligand against a c-di-AMP riboswitch.
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Affiliation(s)
- Kazuto Shiraishi
- Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Noriko Saito-Tarashima
- Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Yosuke Igata
- Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Keiji Murakami
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan
| | - Yasuko Okamoto
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Yamashiro-cho, Tokushima 770-8514, Japan
| | - Yoichiro Miyake
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan; Department of Oral Health Sciences, Faculty of Health and Welfare, Tokushima Bunri University, 180 Yamashiro-cho, Tokushima 770-8514, Japan
| | - Kazuhiro Furukawa
- Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Noriaki Minakawa
- Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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10
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Jones CP, Ferré-D'Amaré AR. Long-Range Interactions in Riboswitch Control of Gene Expression. Annu Rev Biophys 2017; 46:455-481. [PMID: 28375729 DOI: 10.1146/annurev-biophys-070816-034042] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Riboswitches are widespread RNA motifs that regulate gene expression in response to fluctuating metabolite concentrations. Known primarily from bacteria, riboswitches couple specific ligand binding and changes in RNA structure to mRNA expression in cis. Crystal structures of the ligand binding domains of most of the phylogenetically widespread classes of riboswitches, each specific to a particular metabolite or ion, are now available. Thus, the bound states-one end point-have been thoroughly characterized, but the unbound states have been more elusive. Consequently, it is less clear how the unbound, sensing riboswitch refolds into the ligand binding-induced output state. The ligand recognition mechanisms of riboswitches are diverse, but we find that they share a common structural strategy in positioning their binding sites at the point of the RNA three-dimensional fold where the residues farthest from one another in sequence meet. We review how riboswitch folds adhere to this fundamental strategy and propose future research directions for understanding and harnessing their ability to specifically control gene expression.
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Affiliation(s)
- Christopher P Jones
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20824;
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11
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Ruff KM, Muhammad A, McCown PJ, Breaker RR, Strobel SA. Singlet glycine riboswitches bind ligand as well as tandem riboswitches. RNA (NEW YORK, N.Y.) 2016; 22:1728-1738. [PMID: 27659053 PMCID: PMC5066625 DOI: 10.1261/rna.057935.116] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/23/2016] [Indexed: 05/21/2023]
Abstract
The glycine riboswitch often occurs in a tandem architecture, with two ligand-binding domains (aptamers) followed by a single expression platform. Based on previous observations, we hypothesized that "singlet" versions of the glycine riboswitch, which contain only one aptamer domain, are able to bind glycine if appropriate structural contacts are maintained. An initial alignment of 17 putative singlet riboswitches indicated that the single consensus aptamer domain is flanked by a conserved peripheral stem-loop structure. These singlets were sorted into two subtypes based on whether the active aptamer domain precedes or follows the peripheral stem-loop, and an example of each subtype of singlet riboswitch was characterized biochemically. The singlets possess glycine-binding affinities comparable to those of previously published tandem examples, and the conserved peripheral domains form A-minor interactions with the single aptamer domain that are necessary for ligand-binding activity. Analysis of sequenced genomes identified a significant number of singlet glycine riboswitches. Based on these observations, we propose an expanded model for glycine riboswitch gene control that includes singlet and tandem architectures.
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Affiliation(s)
- Karen M Ruff
- Department of Molecular Biophysics and Biochemistry
| | | | - Phillip J McCown
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8114, USA
| | - Ronald R Breaker
- Department of Molecular Biophysics and Biochemistry
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8114, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8114, USA
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12
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Opoku-Temeng C, Zhou J, Zheng Y, Su J, Sintim HO. Cyclic dinucleotide (c-di-GMP, c-di-AMP, and cGAMP) signalings have come of age to be inhibited by small molecules. Chem Commun (Camb) 2016; 52:9327-42. [PMID: 27339003 DOI: 10.1039/c6cc03439j] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bacteria utilize nucleotide-based second messengers to regulate a myriad of physiological processes. Cyclic dinucleotides have emerged as central regulators of bacterial physiology, controlling processes ranging from cell wall homeostasis to virulence production, and so far over thousands of manuscripts have provided biological insights into c-di-NMP signaling. The development of small molecule inhibitors of c-di-NMP signaling has significantly lagged behind. Recent developments in assays that allow for high-throughput screening of inhibitors suggest that the time is right for a concerted effort to identify inhibitors of these fascinating second messengers. Herein, we review c-di-NMP signaling and small molecules that have been developed to inhibit cyclic dinucleotide-related enzymes.
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Affiliation(s)
- Clement Opoku-Temeng
- Department of Chemistry, Center for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA.
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13
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Chemical synthesis of RNA with site-specific methylphosphonate modifications. Methods 2016; 107:79-88. [PMID: 27037236 PMCID: PMC5405801 DOI: 10.1016/j.ymeth.2016.03.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/25/2016] [Accepted: 03/26/2016] [Indexed: 11/21/2022] Open
Abstract
Methylphosphonate(mP)-modified RNA serves as valuable probe to evaluate biomolecular interactions between the nucleic acid backbone and binding partners, such as proteins or small molecules. Here, we describe an efficient workflow for the synthesis of RNA with a single mP modification in diastereomerically pure form. While the automated assembly of mP-modified RNA is straightforward, its deprotection under basic conditions is challenging; a carefully optimized step-by-step procedure is provided. In addition, we demonstrate purification and separation strategies for the RP and SP-configurated RNA diastereomers using a combination of anion-exchange and reversed-phase HPLC, and comment on troubleshooting if their separation appears difficult. Furthermore, we demonstrate the stereochemical assignment of short RP and SP mP-modified RNA diastereomers based on 2D ROESY NMR spectroscopy and we report on the impact of the mP modification on thermal and thermodynamic stabilities of RNA-DNA hybrid and RNA-RNA duplexes.
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