1
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Wang YP, Eriksson LA, Zhang RB. Mechanism of Dual-Site Recognition in a Classic DNA Aptamer. J Chem Inf Model 2024; 64:7698-7708. [PMID: 39327929 DOI: 10.1021/acs.jcim.4c01389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
Nucleic acid aptamers possess unique advantages in specific recognition. However, the lack of in-depth investigation into their dynamic recognition mechanisms has restricted their rational design and potential applications in fields such as biosensing and targeted therapy. We herein utilized enhanced sampling molecular dynamics to address affinities of adenosine monophosphate (AMP) to the dual binding sites in the DNA aptamer, focusing on the dynamic recognition mechanism and pathways. The present results indicate that in addition to the widely known intermolecular interactions, inequivalence of chemical environments of the two binding sites leads to slightly higher stability of AMP binding to the site proximal to the aptamer terminus. In the presence of two AMPs captured by the two sites, each binding free energy is enhanced. In particular, an additional hydrogen bond of AMP to A10 is introduced in the dual-site binding complex, which increases the binding energy from -4.25 ± 0.47 to -9.48 ± 0.33 kcal mol-1 in the site close to the loop. For the dual-site recognition process, the free energy landscape and minimum free energy pathway calculations elucidate the crucial role of electrostatic interactions between the AMP phosphate groups and Na+ ions in positively cooperative binding mechanisms.
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Affiliation(s)
- Yun-Peng Wang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, South Street No. 5, Zhongguancun, Haidian District, Beijing 100081, China
| | - Leif A Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 7b, Göteborg 405 30, Sweden
| | - Ru-Bo Zhang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, South Street No. 5, Zhongguancun, Haidian District, Beijing 100081, China
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2
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Zhang S, Wang Z, Qiao J, Yu T, Zhang W. The effect of the loop on the thermodynamic and kinetic of single base pair in pseudoknot. J Chem Phys 2024; 161:085105. [PMID: 39212209 DOI: 10.1063/5.0216593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 08/11/2024] [Indexed: 09/04/2024] Open
Abstract
RNA pseudoknots are RNA molecules with specialized three-dimensional structures that play important roles in various biological processes. To understand the functions and mechanisms of pseudoknots, it is essential to elucidate their structures and folding pathways. The most fundamental step in RNA folding is the opening and closing of a base pair. The effect of flexible loops on the base pair in pseudoknots remains unclear. In this work, we use molecular dynamics simulations and Markov state model to study the configurations, thermodynamic and kinetic of single base pair in pseudoknots. We find that the presence of the loop leads to a trap state. In addition, the rate-limiting step for the formation of base pair is the disruption of the trap state, rather than the open state to the closed state, which is quite different from the previous studies on non-pseudoknot RNA. For the thermodynamic parameters in pseudoknots, we find that the entropy difference upon opening the base pair between this simulation and the nearest-neighbor model results from the different entropy of different lengths of loop in solution. The thermodynamic parameters of the stack in pseudoknot are close to the nearest-neighbor parameters. The bases on the loop have different distribution patterns in different states, and the slow transition states of the loop are determined by the orientation of the bases.
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Affiliation(s)
- Shuhao Zhang
- Department of Physics, Wuhan University, Wuhan, Hubei, People's Republic of China
| | - Zhen Wang
- Department of Physics, Wuhan University, Wuhan, Hubei, People's Republic of China
| | - Jie Qiao
- Department of Physics, Wuhan University, Wuhan, Hubei, People's Republic of China
| | - Ting Yu
- Department of Physics, Wuhan University, Wuhan, Hubei, People's Republic of China
| | - Wenbing Zhang
- Department of Physics, Wuhan University, Wuhan, Hubei, People's Republic of China
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3
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Hoeher JE, Sande NE, Widom JR. Probing and perturbing riboswitch folding using a fluorescent base analogue. Photochem Photobiol 2024; 100:419-433. [PMID: 38098287 PMCID: PMC10950518 DOI: 10.1111/php.13896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 03/20/2024]
Abstract
Riboswitches are mRNA segments that regulate gene expression in response to ligand binding. The Class I preQ1 riboswitch consists of a stem-loop and an adenine-rich single-stranded tail ("L3"), which adopt a pseudoknot structure upon binding of the ligand preQ1 . We inserted 2-aminopurine (2-AP), a fluorescent analogue of adenine (A), into the riboswitch at six different positions within L3. Here, 2-AP functions both as a spectroscopic probe and as a "mutation" that reveals how alteration of specific A residues impacts the riboswitch. Using fluorescence and circular dichroism spectroscopy, we found that 2-AP decreases the affinity of the riboswitch for preQ1 at all labeling positions tested, although modified and unmodified variants undergo the same global conformational changes at sufficiently high preQ1 concentration. 2-AP substitution is most detrimental to ligand binding at sites proximal to the ligand-binding pocket, while distal labeling sites exhibit the largest impacts on the stability of the L3 domain in the absence of ligand. Insertion of multiple 2-AP residues does not induce significant additional disruptions. Our results show that interactions involving the A residues in L3 play a critical role in ligand recognition by the preQ1 riboswitch and that 2-AP substitution exerts complex and varied impacts on this riboswitch.
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Affiliation(s)
- Janson E. Hoeher
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR
| | - Natalie E. Sande
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR
| | - Julia R. Widom
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR
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4
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Eichler C, Himmelstoß M, Plangger R, Weber LI, Hartl M, Kreutz C, Micura R. Advances in RNA Labeling with Trifluoromethyl Groups. Chemistry 2023; 29:e202302220. [PMID: 37534701 PMCID: PMC10947337 DOI: 10.1002/chem.202302220] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/04/2023]
Abstract
Fluorine labeling of ribonucleic acids (RNA) in conjunction with 19 F NMR spectroscopy has emerged as a powerful strategy for spectroscopic analysis of RNA structure and dynamics, and RNA-ligand interactions. This study presents the first syntheses of 2'-OCF3 guanosine and uridine phosphoramidites, their incorporation into oligoribonucleotides by solid-phase synthesis and a comprehensive study of their properties. NMR spectroscopic analysis showed that the 2'-OCF3 modification is associated with preferential C2'-endo conformation of the U and G ribose in single-stranded RNA. When paired to the complementary strand, slight destabilization of the duplex caused by the modification was revealed by UV melting curve analysis. Moreover, the power of the 2'-OCF3 label for NMR spectroscopy is demonstrated by dissecting RNA pseudoknot folding and its binding to a small molecule. Furthermore, the 2'-OCF3 modification has potential for applications in therapeutic oligonucleotides. To this end, three 2'-OCF3 modified siRNAs were tested in silencing of the BASP1 gene which indicated enhanced performance for one of them. Importantly, together with earlier work, the present study completes the set of 2'-OCF3 nucleoside phosphoramidites to all four standard nucleobases (A, U, C, G) and hence enables applications that utilize the favorable properties of the 2'-OCF3 group without any restrictions in placing the modification into the RNA target sequence.
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Affiliation(s)
- Clemens Eichler
- Institute of Organic ChemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Maximilian Himmelstoß
- Institute of Organic ChemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Raphael Plangger
- Institute of Organic ChemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Leonie I. Weber
- Institute of BiochemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Markus Hartl
- Institute of BiochemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Christoph Kreutz
- Institute of Organic ChemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Ronald Micura
- Institute of Organic ChemistryCenter for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
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5
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Silkenath B, Kläge D, Altwein H, Schmidhäuser N, Mayer G, Hartig JS, Wittmann V. Phosphonate and Thiasugar Analogues of Glucosamine-6-phosphate: Activation of the glmS Riboswitch and Antibiotic Activity. ACS Chem Biol 2023; 18:2324-2334. [PMID: 37793187 PMCID: PMC10594590 DOI: 10.1021/acschembio.3c00452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023]
Abstract
The glmS riboswitch is a motif found in 5'-untranslated regions of bacterial mRNA that controls the synthesis of glucosamine-6-phosphate (GlcN6P), an essential building block for the bacterial cell wall, by a feedback mechanism. Activation of the glmS riboswitch by GlcN6P mimics interferes with the ability of bacteria to synthesize its cell wall. Accordingly, GlcN6P mimics acting as glmS activators are promising candidates for future antibiotic drugs that may overcome emerging bacterial resistance against established antibiotics. We describe the synthesis of a series of phosphonate mimics of GlcN6P as well as the thiasugar analogue of GlcN6P. The phosphonate mimics differ in their pKa value to answer the question of whether derivatives with a pKa matching that of GlcN6P would be efficient glmS activators. We found that all derivatives activate the riboswitch, however, less efficiently than GlcN6P. This observation can be explained by the missing hydrogen bonds in the case of phosphonates and is valuable information for the design of future GlcN6P mimics. The thiasugar analogue of GlcN6P on the other hand turned out to be a glmS riboswitch activator with the same activity as the natural metabolite GlcN6P. The nonphosphorylated thiasugar displayed antimicrobial activity against certain bacilli. Therefore, the compound is a promising lead structure for the development of future antibiotics with a potentially novel mode of action.
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Affiliation(s)
- Bjarne Silkenath
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Dennis Kläge
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Hanna Altwein
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Nina Schmidhäuser
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Günter Mayer
- LIMES
Institute, Center for Aptamer Research & Development, University of Bonn, 53121 Bonn, Germany
| | - Jörg S. Hartig
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Valentin Wittmann
- Department
of Chemistry, University of Konstanz, 78457 Konstanz, Germany
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6
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Kaiser C, Vogel M, Appel B, Weigand J, Müller S, Suess B, Wachtveitl J. Magnesium Ion-Driven Folding and Conformational Switching Kinetics of Tetracycline Binding Aptamer: Implications for in vivo Riboswitch Engineering. J Mol Biol 2023; 435:168253. [PMID: 37640152 DOI: 10.1016/j.jmb.2023.168253] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023]
Abstract
Engineering in vitro selected RNA aptamers into in vivo functional riboswitches represents a long-standing challenge in molecular biology. The highly specific aptamer domain of the riboswitch undergoes a conformational adjustment in response to ligand sensing, which in turn exerts the regulatory function. Besides essential factors like structural complexity and ligand binding kinetics, the active role of magnesium ions in stabilizing RNA tertiary structures and assisting in ligand binding can be a vital criterion. We present spectroscopic studies on the magnesium ion-driven folding of the Tetracycline binding aptamer. Using fluorescent labels, the aptamer pre-folding and subsequent ligand binding is monitored by magnesium titration experiments and time-resolved stopped-flow measurements. A minimum concentration of 0.5 mM magnesium is required to fold into a magnesium ion-stabilized binding-competent state with a preformed binding pocket. Tetracycline binding causes a pronounced conformational change that results in the establishment of the triple helix core motif, and that further propagates towards the closing stem. By a dynamic acquisition of magnesium ions, a kink motif is formed at the intersection of the triple helix and closing stem regions. This ultimately entails a stabilization of the closing stem which is discussed as a key element in the regulatory function of the Tetracycline aptamer.
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Affiliation(s)
- Christoph Kaiser
- Institute for Physical and Theoretical Chemistry, Goethe University, Frankfurt/Main, Max-von-Laue Str. 9, D-60438, Germany.
| | - Marc Vogel
- Department of Biology, Technical University Darmstadt, Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany
| | - Bettina Appel
- Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17489 Greifswald, Germany
| | - Julia Weigand
- Department of Biology, Technical University Darmstadt, Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany; Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Marbacher Weg 6, D-35037, Germany. https://twitter.com/WachtveitlLab
| | - Sabine Müller
- Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17489 Greifswald, Germany
| | - Beatrix Suess
- Department of Biology, Technical University Darmstadt, Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany; Centre for Synthetic Biology, Technical University Darmstadt, Darmstadt, Germany.
| | - Josef Wachtveitl
- Institute for Physical and Theoretical Chemistry, Goethe University, Frankfurt/Main, Max-von-Laue Str. 9, D-60438, Germany.
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7
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Dohno C, Kimura M, Fujiwara Y, Nakatani K. Photoswitchable molecular glue for RNA: reversible photocontrol of structure and function of the ribozyme. Nucleic Acids Res 2023; 51:9533-9541. [PMID: 37615580 PMCID: PMC10570050 DOI: 10.1093/nar/gkad690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 07/31/2023] [Accepted: 08/10/2023] [Indexed: 08/25/2023] Open
Abstract
Single-stranded RNA folds into a variety of secondary and higher-order structures. Distributions and dynamics of multiple RNA conformations are responsible for the biological function of RNA. We here developed a photoswitchable molecular glue for RNA, which could reversibly control the association of two unpaired RNA regions in response to light stimuli. The photoswitchable molecular glue, NCTA, is an RNA-binding ligand possessing a photoisomerizable azobenzene moiety. Z-NCTA is an active ligand for the target RNA containing 5'-WGG-3'/5'-WGG-3' (W = U or A) site and stabilizes its hybridized state, while its isomer E-NCTA is not. Photoreversible isomerization of NCTA enabled control of the secondary and tertiary structure of the target RNA. The RNA-cleaving activity of hammerhead ribozyme, where appropriate RNA folding is necessary, could be reversibly regulated by photoirradiation in cells treated with NCTA, demonstrating precise photocontrol of RNA structure and function by the photoswitchable molecular glue.
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Affiliation(s)
- Chikara Dohno
- Department of Regulatory Bioorganic Chemistry, SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Maki Kimura
- Department of Regulatory Bioorganic Chemistry, SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Yusuke Fujiwara
- Department of Regulatory Bioorganic Chemistry, SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Kazuhiko Nakatani
- Department of Regulatory Bioorganic Chemistry, SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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8
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Wang J, Koduru T, Harish B, McCallum SA, Larsen KP, Patel KS, Peters EV, Gillilan RE, Puglisi EV, Puglisi JD, Makhatadze G, Royer CA. Pressure pushes tRNA Lys3 into excited conformational states. Proc Natl Acad Sci U S A 2023; 120:e2215556120. [PMID: 37339210 PMCID: PMC10293818 DOI: 10.1073/pnas.2215556120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 05/16/2023] [Indexed: 06/22/2023] Open
Abstract
Conformational dynamics play essential roles in RNA function. However, detailed structural characterization of excited states of RNA remains challenging. Here, we apply high hydrostatic pressure (HP) to populate excited conformational states of tRNALys3, and structurally characterize them using a combination of HP 2D-NMR, HP-SAXS (HP-small-angle X-ray scattering), and computational modeling. HP-NMR revealed that pressure disrupts the interactions of the imino protons of the uridine and guanosine U-A and G-C base pairs of tRNALys3. HP-SAXS profiles showed a change in shape, but no change in overall extension of the transfer RNA (tRNA) at HP. Configurations extracted from computational ensemble modeling of HP-SAXS profiles were consistent with the NMR results, exhibiting significant disruptions to the acceptor stem, the anticodon stem, and the D-stem regions at HP. We propose that initiation of reverse transcription of HIV RNA could make use of one or more of these excited states.
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Affiliation(s)
- Jinqiu Wang
- Graduate Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Tejaswi Koduru
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
| | | | - Scott A. McCallum
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Kevin P. Larsen
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Karishma S. Patel
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Edgar V. Peters
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY12180
| | | | - Elisabetta V. Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - Joseph D. Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA94305
| | - George Makhatadze
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
| | - Catherine A. Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY12180
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9
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RPflex: A Coarse-Grained Network Model for RNA Pocket Flexibility Study. Int J Mol Sci 2023; 24:ijms24065497. [PMID: 36982570 PMCID: PMC10058308 DOI: 10.3390/ijms24065497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/09/2023] [Accepted: 03/11/2023] [Indexed: 03/18/2023] Open
Abstract
RNA regulates various biological processes, such as gene regulation, RNA splicing, and intracellular signal transduction. RNA’s conformational dynamics play crucial roles in performing its diverse functions. Thus, it is essential to explore the flexibility characteristics of RNA, especially pocket flexibility. Here, we propose a computational approach, RPflex, to analyze pocket flexibility using the coarse-grained network model. We first clustered 3154 pockets into 297 groups by similarity calculation based on the coarse-grained lattice model. Then, we introduced the flexibility score to quantify the flexibility by global pocket features. The results show strong correlations between the flexibility scores and root-mean-square fluctuation (RMSF) values, with Pearson correlation coefficients of 0.60, 0.76, and 0.53 in Testing Sets I–III. Considering both flexibility score and network calculations, the Pearson correlation coefficient was increased to 0.71 in flexible pockets on Testing Set IV. The network calculations reveal that the long-range interaction changes contributed most to flexibility. In addition, the hydrogen bonds in the base–base interactions greatly stabilize the RNA structure, while backbone interactions determine RNA folding. The computational analysis of pocket flexibility could facilitate RNA engineering for biological or medical applications.
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10
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Yu T, Liu T, Wang Y, Zhang S, Zhang W. Thermodynamics and kinetics of an A-U RNA base pair under force studied by molecular dynamics simulations. Phys Rev E 2023; 107:024404. [PMID: 36932572 DOI: 10.1103/physreve.107.024404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 01/04/2023] [Indexed: 06/18/2023]
Abstract
Mechanical force has been widely used to study RNA folding and unfolding. Understanding how the force affects the opening and closing of a single base pair, which is a basic step for RNA folding and unfolding and a fundamental behavior in some important biological activities, is crucial to understanding the mechanism of RNA folding and unfolding under mechanical force. In this work, we investigated the opening and closing process of an RNA base pair under mechanical force with constant-force stretching molecular dynamics simulations. It was found that high mechanical force results in overstretching, and the open state is a high-energy state. The enthalpy and entropy change of the base-pair opening-closing transition were obtained and the results at low forces were in good agreement with the nearest-neighbor model. The temperature and force dependence of the opening and closing rates were also obtained. The position of the transition state for the base-pair opening-closing transition under mechanical force was determined. The free energy barrier of opening a base pair without force is the enthalpy increase, and the work done by the force from the closed state to the transition state decreases the barrier and increases the opening rate. The free energy barrier of closing the base pair without force results from the entropy loss, and the work done by the force from the open state to the transition state increases the barrier and decreases the closing rate. The transition rates are strongly dependent on the temperature and force, while the transition path times are weakly dependent on force and temperature.
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Affiliation(s)
- Ting Yu
- Department of Physics, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
| | - Taigang Liu
- Department of Physics, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
- School of Medical Engineering, Xinxiang Medical University, Xinxiang, Henan 453003, People's Republic of China
| | - Yujie Wang
- Department of Physics, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
- Department of Physics and Telecommunication Engineering, Zhoukou Normal University, Zhoukou, Henan 466000, People's Republic of China
| | - Shuhao Zhang
- Department of Physics, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
| | - Wenbing Zhang
- Department of Physics, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
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11
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Xu X, Egger M, Li C, Chen H, Micura R, Ren A. Structure-based investigations of the NAD+-II riboswitch. Nucleic Acids Res 2023; 51:54-67. [PMID: 36610789 PMCID: PMC9841397 DOI: 10.1093/nar/gkac1227] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/07/2022] [Accepted: 12/10/2022] [Indexed: 01/09/2023] Open
Abstract
Riboswitches are conserved non-coding domains in bacterial mRNA with gene regulation function that are essential for maintaining enzyme co-factor metabolism. Recently, the pnuC RNA motif was reported to selectively bind nicotinamide adenine dinucleotide (NAD+), defining a novel class of NAD+ riboswitches (NAD+-II) according to phylogenetic analysis. To reveal the three-dimensional architecture and the ligand-binding mode of this riboswitch, we solved the crystal structure of NAD+-II riboswitch in complex with NAD+. Strikingly and in contrast to class-I riboswitches that form a tight recognition pocket for the adenosine diphosphate (ADP) moiety of NAD+, the class-II riboswitches form a binding pocket for the nicotinamide mononucleotide (NMN) portion of NAD+ and display only unspecific interactions with the adenosine. We support this finding by an additional structure of the class-II RNA in complex with NMN alone. The structures define a novel RNA tertiary fold that was further confirmed by mutational analysis in combination with isothermal titration calorimetry (ITC), and 2-aminopurine-based fluorescence spectroscopic folding studies. Furthermore, we truncated the pnuC RNA motif to a short RNA helical scaffold with binding affinity comparable to the wild-type motif to allude to the potential of engineering the NAD+-II motif for biotechnological applications.
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Affiliation(s)
| | | | | | - Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ronald Micura
- Correspondence may also be addressed to Ronald Micura.
| | - Aiming Ren
- To whom correspondence should be addressed. Tel: +86 571 88981228; Fax: +86 571 88981227;
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12
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Zheng L, Song Q, Xu X, Shen X, Li C, Li H, Chen H, Ren A. Structure-based insights into recognition and regulation of SAM-sensing riboswitches. SCIENCE CHINA. LIFE SCIENCES 2023; 66:31-50. [PMID: 36459353 DOI: 10.1007/s11427-022-2188-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/17/2022] [Indexed: 12/03/2022]
Abstract
Riboswitches are highly conserved RNA elements that located in the 5'-UTR of mRNAs, which undergo real-time structure conformational change to achieve the regulation of downstream gene expression by sensing their cognate ligands. S-adenosylmethionine (SAM) is a ubiquitous methyl donor for transmethylation reactions in all living organisms. SAM riboswitch is one of the most abundant riboswitches that bind to SAM with high affinity and selectivity, serving as regulatory modules in multiple metabolic pathways. To date, seven SAM-specific riboswitch classes that belong to four families, one SAM/SAH riboswitch and one SAH riboswitch have been identified. Each SAM riboswitch family has a well-organized tertiary core scaffold to support their unique ligand-specific binding pocket. In this review, we summarize the current research progress on the distribution, structure, ligand recognition and gene regulation mechanism of these SAM-related riboswitch families, and further discuss their evolutionary prospects and potential applications.
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Affiliation(s)
- Luqian Zheng
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.,The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518033, China
| | - Qianqian Song
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xiaochen Xu
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xin Shen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Chunyan Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hongcheng Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Aiming Ren
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China. .,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.
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13
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Steinmetzger C, Höbartner C. Probing of Fluorogenic RNA Aptamers via Supramolecular Förster Resonance Energy Transfer with a Universal Fluorescent Nucleobase Analog. Methods Mol Biol 2023; 2570:155-173. [PMID: 36156781 DOI: 10.1007/978-1-0716-2695-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Fluorogenic RNA aptamers are synthetic RNAs that have been evolved by in vitro selection methods to bind and light up conditionally fluorescent organic ligands. Compared with other probes for RNA detection, they are less invasive than hybridization-based methods (FISH, molecular beacons) and are considerably smaller than fluorescent protein-recruiting systems (MS2, Pumilio variants). Fluorogenic aptamers have therefore found widespread use as genetically encodable tags for RNA detection in live cells and have also been used in combination with riboswitches to construct versatile metabolite sensors for in vitro use. Their success builds on a fundamental understanding of their three-dimensional structure to explain the mechanisms of ligand interaction and to rationally design functional aptamer devices. In this protocol, we describe a supramolecular FRET-based structure probing method for fluorogenic aptamers that exploits distance- and orientation-dependent energy transfer efficiencies between site-specifically incorporated fluorescent nucleoside analogs and non-covalently bound ligands, exemplified by 4-cyanoindol riboside (4CI) and the DMHBI+-binding RNA aptamer Chili. This method yields structural restraints that bridge the gap between traditional low-resolution secondary structure probing methods and more elaborate high-resolution methods such as X-ray crystallography and NMR spectroscopy.
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Affiliation(s)
- Christian Steinmetzger
- Institute of Organic Chemistry, Julius Maximilians University Würzburg, Würzburg, Germany
| | - Claudia Höbartner
- Institute of Organic Chemistry, Julius Maximilians University Würzburg, Würzburg, Germany. .,Center for Nanosystems Chemistry (CNC), Julius Maximilians University Würzburg, Würzburg, Germany.
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14
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Binet T, Avalle B, Dávila Felipe M, Maffucci I. AptaMat: a matrix-based algorithm to compare single-stranded oligonucleotides secondary structures. Bioinformatics 2022; 39:6849515. [PMID: 36440922 PMCID: PMC9805580 DOI: 10.1093/bioinformatics/btac752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 11/14/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022] Open
Abstract
MOTIVATION Comparing single-stranded nucleic acids (ssNAs) secondary structures is fundamental when investigating their function and evolution and predicting the effect of mutations on their structures. Many comparison metrics exist, although they are either too elaborate or not sensitive enough to distinguish close ssNAs structures. RESULTS In this context, we developed AptaMat, a simple and sensitive algorithm for ssNAs secondary structures comparison based on matrices representing the ssNAs secondary structures and a metric built upon the Manhattan distance in the plane. We applied AptaMat to several examples and compared the results to those obtained by the most frequently used metrics, namely the Hamming distance and the RNAdistance, and by a recently developed image-based approach. We showed that AptaMat is able to discriminate between similar sequences, outperforming all the other here considered metrics. In addition, we showed that AptaMat was able to correctly classify 14 RFAM families within a clustering procedure. AVAILABILITY AND IMPLEMENTATION The python code for AptaMat is available at https://github.com/GEC-git/AptaMat.git. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Thomas Binet
- Université de technologie de Compiègne, UPJV, CNRS, Enzyme and Cell Engineering, Centre de recherche Royallieu, CS 60 319 - 60 203, Compiègne Cedex, France
| | - Bérangère Avalle
- Université de technologie de Compiègne, UPJV, CNRS, Enzyme and Cell Engineering, Centre de recherche Royallieu, CS 60 319 - 60 203, Compiègne Cedex, France
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15
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Li J, Zhang X, Hong L, Liu Y. Entropy Driving the Mg 2+-Induced Folding of TPP Riboswitch RNA. J Phys Chem B 2022; 126:9457-9464. [PMID: 36379020 DOI: 10.1021/acs.jpcb.2c03688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mg2+ is well known to facilitate the structural folding of RNA. However, the thermodynamic and dynamic roles of Mg2+ in RNA folding remain elusive. Here, we exploit single-molecule fluorescence resonance energy transfer (smFRET) and isothermal titration calorimetry (ITC) to study the mechanism of Mg2+ in facilitating the folding of thiamine pyrophosphate (TPP) riboswitch RNA. The results of smFRET identify that the presence of Mg2+ compacts the RNA and enlarges the conformational dispersity among individual RNA molecules, resulting in a large gain of entropy. The compact yet flexible conformations triggered by Mg2+ may help the riboswitch recognize its specific ligand and further fold. This is supported by the ITC experiments, in which the Mg2+-induced RNA folding is driven by entropy (ΔS) instead of enthalpy (ΔH). Our results complement the understanding of the Mg2+-induced RNA folding. The strategy developed in this work can be used to model other RNAs' folding under different conditions.
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Affiliation(s)
- Jun Li
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaoyu Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Liang Hong
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Liu
- State Key Laboratory of Microbial Metabolism, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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16
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Bonilla SL, Kieft JS. The promise of cryo-EM to explore RNA structural dynamics. J Mol Biol 2022; 434:167802. [PMID: 36049551 PMCID: PMC10084733 DOI: 10.1016/j.jmb.2022.167802] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/24/2022] [Accepted: 08/24/2022] [Indexed: 01/13/2023]
Abstract
Conformational dynamics are essential to macromolecular function. This is certainly true of RNA, whose ability to undergo programmed conformational dynamics is essential to create and regulate complex biological processes. However, methods to easily and simultaneously interrogate both the structure and conformational dynamics of fully functional RNAs in isolation and in complex with proteins have not historically been available. Due to its ability to image and classify single particles, cryogenic electron microscopy (cryo-EM) has the potential to address this gap and may be particularly amenable to exploring structural dynamics within the three-dimensional folds of biologically active RNAs. We discuss the possibilities and current limitations of applying cryo-EM to simultaneously study RNA structure and conformational dynamics, and present one example that illustrates this (as of yet) not fully realized potential.
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Affiliation(s)
- Steve L Bonilla
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA. https://twitter.com/Steve_Bonilla
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, Aurora, CO 80045, USA; RNA BioScience Initiative, University of Colorado Anschutz Medical Campus, School of Medicine, Aurora, CO 80045, USA.
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17
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Zhou Y, Jiang Y, Chen SJ. RNA-ligand molecular docking: advances and challenges. WILEY INTERDISCIPLINARY REVIEWS. COMPUTATIONAL MOLECULAR SCIENCE 2022; 12:e1571. [PMID: 37293430 PMCID: PMC10250017 DOI: 10.1002/wcms.1571] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/20/2021] [Indexed: 12/16/2022]
Abstract
With rapid advances in computer algorithms and hardware, fast and accurate virtual screening has led to a drastic acceleration in selecting potent small molecules as drug candidates. Computational modeling of RNA-small molecule interactions has become an indispensable tool for RNA-targeted drug discovery. The current models for RNA-ligand binding have mainly focused on the docking-and-scoring method. Accurate docking and scoring should tackle four crucial problems: (1) conformational flexibility of ligand, (2) conformational flexibility of RNA, (3) efficient sampling of binding sites and binding poses, and (4) accurate scoring of different binding modes. Moreover, compared with the problem of protein-ligand docking, predicting ligand binding to RNA, a negatively charged polymer, is further complicated by additional effects such as metal ion effects. Thermodynamic models based on physics-based and knowledge-based scoring functions have shown highly encouraging success in predicting ligand binding poses and binding affinities. Recently, kinetic models for ligand binding have further suggested that including dissociation kinetics (residence time) in ligand docking would result in improved performance in estimating in vivo drug efficacy. More recently, the rise of deep-learning approaches has led to new tools for predicting RNA-small molecule binding. In this review, we present an overview of the recently developed computational methods for RNA-ligand docking and their advantages and disadvantages.
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Affiliation(s)
- Yuanzhe Zhou
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
| | - Yangwei Jiang
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
| | - Shi-Jie Chen
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
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18
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Sharma S, Singh V, Biswas P. Analysis of the Passage Times for Unfolding/Folding of the Adenine Riboswitch Aptamer. ACS PHYSICAL CHEMISTRY AU 2022; 2:353-363. [PMID: 36855421 PMCID: PMC9955275 DOI: 10.1021/acsphyschemau.1c00056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational transitions of the adenosine deaminase A-riboswitch aptamer both with and without ligand binding are investigated within the tenets of the generalized Langevin equation in a complex viscoelastic cellular environment. Steered molecular dynamics (SMD) simulations are performed to evaluate and compare the results of the first passage times (FPTs) with those obtained from the theory for the unfold and fold transitions of the aptamer. The results of the distribution of Kramers's FPT reveal that the unfold-fold transitions are faster and hence more probable as compared to the fold-unfold transitions of the riboswitch aptamer for both ligand-bound and -unbound states. The transition path time is lower than Kramers's FPT for the riboswitch aptamer as the transition path times for the unfold-fold transition of both without and with ligand binding are insensitive to the details of the exact mechanism of the transition events. However, Kramers's FPTs show varied distributions which correspond to different transition pathways, unlike the transition path times. The mean FPT increases with an increase in the complexity of the cellular environment. The results of Kramers's FPT, transition path time distribution, and mean FPT obtained from our calculations qualitatively match with those obtained from the SMD simulations. Analytically derived values of the mean transition path time show good quantitative agreement with those estimated from the single-molecule force spectroscopy experiments for higher barrier heights.
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19
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Kumar S, Reddy G. TPP Riboswitch Populates Holo-Form-like Structure Even in the Absence of Cognate Ligand at High Mg 2+ Concentration. J Phys Chem B 2022; 126:2369-2381. [PMID: 35298161 DOI: 10.1021/acs.jpcb.1c10794] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Riboswitches are noncoding RNA that regulate gene expression by folding into specific three-dimensional structures (holo-form) upon binding by their cognate ligand in the presence of Mg2+. Riboswitch functioning is also hypothesized to be under kinetic control requiring large cognate ligand concentrations. We ask the question under thermodynamic conditions, can the riboswitches populate structures similar to the holo-form only in the presence of Mg2+ and absence of cognate ligand binding. We addressed this question using thiamine pyrophosphate (TPP) riboswitch as a model system and computer simulations using a coarse-grained model for RNA. The folding free energy surface (FES) shows that with the initial increase in Mg2+ concentration ([Mg2+]), the aptamer domain (AD) of TPP riboswitch undergoes a barrierless collapse in its dimensions. On further increase in [Mg2+], intermediates separated by barriers appear on the FES, and one of the intermediates has a TPP ligand-binding competent structure. We show that site-specific binding of the Mg2+ aids in the formation of tertiary contacts. For [Mg2+] greater than physiological concentration, AD folds into a structure similar to the crystal structure of the TPP holo-form even in the absence of the TPP ligand. The folding kinetics shows that TPP AD populates an intermediate due to the misalignment of two arms present in the structure, which acts as a kinetic trap, leading to larger folding timescales. The predictions of the intermediate structures from the simulations are amenable for experimental verification.
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Affiliation(s)
- Sunil Kumar
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Govardhan Reddy
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
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20
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Tabuchi T, Yokobayashi Y. High-throughput screening of cell-free riboswitches by fluorescence-activated droplet sorting. Nucleic Acids Res 2022; 50:3535-3550. [PMID: 35253887 PMCID: PMC8989549 DOI: 10.1093/nar/gkac152] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/20/2022] [Indexed: 11/14/2022] Open
Abstract
Cell-free systems that display complex functions without using living cells are emerging as new platforms to test our understanding of biological systems as well as for practical applications such as biosensors and biomanufacturing. Those that use cell-free protein synthesis (CFPS) systems to enable genetically programmed protein synthesis have relied on genetic regulatory components found or engineered in living cells. However, biological constraints such as cell permeability, metabolic stability, and toxicity of signaling molecules prevent development of cell-free devices using living cells even if cell-free systems are not subject to such constraints. Efforts to engineer regulatory components directly in CFPS systems thus far have been based on low-throughput experimental approaches, limiting the availability of basic components to build cell-free systems with diverse functions. Here, we report a high-throughput screening method to engineer cell-free riboswitches that respond to small molecules. Droplet-sorting of riboswitch variants in a CFPS system rapidly identified cell-free riboswitches that respond to compounds that are not amenable to bacterial screening methods. Finally, we used a histamine riboswitch to demonstrate chemical communication between cell-sized droplets.
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Affiliation(s)
- Takeshi Tabuchi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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21
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Yadav R, Widom JR, Chauvier A, Walter NG. An anionic ligand snap-locks a long-range interaction in a magnesium-folded riboswitch. Nat Commun 2022; 13:207. [PMID: 35017489 PMCID: PMC8752731 DOI: 10.1038/s41467-021-27827-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 12/02/2021] [Indexed: 01/22/2023] Open
Abstract
The archetypical transcriptional crcB fluoride riboswitch from Bacillus cereus is an intricately structured non-coding RNA element enhancing gene expression in response to toxic levels of fluoride. Here, we used single molecule FRET to uncover three dynamically interconverting conformations appearing along the transcription process: two distinct undocked states and one pseudoknotted docked state. We find that the fluoride anion specifically snap-locks the magnesium-induced, dynamically docked state. The long-range, nesting, single base pair A40-U48 acts as the main linchpin, rather than the multiple base pairs comprising the pseudoknot. We observe that the proximally paused RNA polymerase further fine-tunes the free energy to promote riboswitch docking. Finally, we show that fluoride binding at short transcript lengths is an early step toward partitioning folding into the docked conformation. These results reveal how the anionic fluoride ion cooperates with the magnesium-associated RNA to govern regulation of downstream genes needed for fluoride detoxification of the cell.
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Affiliation(s)
- Rajeev Yadav
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, 97403, USA
| | - Adrien Chauvier
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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22
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Dagenais P, Desjardins G, Legault P. An integrative NMR-SAXS approach for structural determination of large RNAs defines the substrate-free state of a trans-cleaving Neurospora Varkud Satellite ribozyme. Nucleic Acids Res 2021; 49:11959-11973. [PMID: 34718697 PMCID: PMC8599749 DOI: 10.1093/nar/gkab963] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 09/01/2021] [Accepted: 10/26/2021] [Indexed: 11/26/2022] Open
Abstract
The divide-and-conquer strategy is commonly used for protein structure determination, but its applications to high-resolution structure determination of RNAs have been limited. Here, we introduce an integrative approach based on the divide-and-conquer strategy that was undertaken to determine the solution structure of an RNA model system, the Neurospora VS ribozyme. NMR and SAXS studies were conducted on a minimal trans VS ribozyme as well as several isolated subdomains. A multi-step procedure was used for structure determination that first involved pairing refined NMR structures with SAXS data to obtain structural subensembles of the various subdomains. These subdomain structures were then assembled to build a large set of structural models of the ribozyme, which was subsequently filtered using SAXS data. The resulting NMR-SAXS structural ensemble shares several similarities with the reported crystal structures of the VS ribozyme. However, a local structural difference is observed that affects the global fold by shifting the relative orientation of the two three-way junctions. Thus, this finding highlights a global conformational change associated with substrate binding in the VS ribozyme that is likely critical for its enzymatic activity. Structural studies of other large RNAs should benefit from similar integrative approaches that allow conformational sampling of assembled fragments.
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Affiliation(s)
- Pierre Dagenais
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Box 6128, Downtown Station, Montreal, QC H3C 3J7, Quebec, Canada
| | - Geneviève Desjardins
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Box 6128, Downtown Station, Montreal, QC H3C 3J7, Quebec, Canada
| | - Pascale Legault
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Box 6128, Downtown Station, Montreal, QC H3C 3J7, Quebec, Canada
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23
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Xu X, Egger M, Chen H, Bartosik K, Micura R, Ren A. Insights into xanthine riboswitch structure and metal ion-mediated ligand recognition. Nucleic Acids Res 2021; 49:7139-7153. [PMID: 34125892 PMCID: PMC8266621 DOI: 10.1093/nar/gkab486] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/29/2021] [Accepted: 05/27/2021] [Indexed: 12/26/2022] Open
Abstract
Riboswitches are conserved functional domains in mRNA that mostly exist in bacteria. They regulate gene expression in response to varying concentrations of metabolites or metal ions. Recently, the NMT1 RNA motif has been identified to selectively bind xanthine and uric acid, respectively, both are involved in the metabolic pathway of purine degradation. Here, we report a crystal structure of this RNA bound to xanthine. Overall, the riboswitch exhibits a rod-like, continuously stacked fold composed of three stems and two internal junctions. The binding-pocket is determined by the highly conserved junctional sequence J1 between stem P1 and P2a, and engages a long-distance Watson–Crick base pair to junction J2. Xanthine inserts between a G–U pair from the major groove side and is sandwiched between base triples. Strikingly, a Mg2+ ion is inner-sphere coordinated to O6 of xanthine and a non-bridging oxygen of a backbone phosphate. Two further hydrated Mg2+ ions participate in extensive interactions between xanthine and the pocket. Our structure model is verified by ligand binding analysis to selected riboswitch mutants using isothermal titration calorimetry, and by fluorescence spectroscopic analysis of RNA folding using 2-aminopurine-modified variants. Together, our study highlights the principles of metal ion-mediated ligand recognition by the xanthine riboswitch.
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Affiliation(s)
- Xiaochen Xu
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Michaela Egger
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Karolina Bartosik
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
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24
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Sarkar B, Ishii K, Tahara T. Microsecond Folding of preQ 1 Riboswitch and Its Biological Significance Revealed by Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy. J Am Chem Soc 2021; 143:7968-7978. [PMID: 34013733 DOI: 10.1021/jacs.1c01077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Riboswitches are regulatory elements of bacterial mRNA which function with conformational switching upon binding of specific cellular metabolites. In particular, transcriptional riboswitches regulate gene expression kinetically through the conformational change of the aptamer domain. In this study, we investigate the conformational dynamics and ligand binding mechanisms of the aptamer domain of a transcriptional prequeuosine (preQ1) riboswitch from Bacillus subtilis using two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS) with microsecond time resolution. The obtained time-resolved single-molecule data indicate that the aptamer domain undergoes folding/unfolding including three forms, which are attributed to hairpin (O), pseudoknot-like (pF), and H-type pseudoknot (fF) structures. It is found that a cofactor, Mg2+, binds only to the fF form with the conformational selection mechanism. In contrast, it is indicated that the ligand, preQ1, binds to the O form with the induced-fit mechanism and significantly accelerates the microsecond O → pF folding process. It is also shown that the binding with preQ1 substantially stabilizes the fF form that is generated from the pF form with a long time constant (>10 ms). Combining these results with the results of a former smFRET study on the slower time scale, we obtain an overall picture of the folding/unfolding dynamics of the aptamer domain as well as its energy landscape. On the basis of the picture obtained, we discuss the significance of the microsecond folding/unfolding of the aptamer domain for biological function of the riboswitch and propose the molecular mechanism of the gene expression controlled by the structural dynamics of the aptamer domain.
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Affiliation(s)
- Bidyut Sarkar
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Kunihiko Ishii
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
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25
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Kaiser C, Schneider J, Groher F, Suess B, Wachtveitl J. What defines a synthetic riboswitch? - Conformational dynamics of ciprofloxacin aptamers with similar binding affinities but varying regulatory potentials. Nucleic Acids Res 2021; 49:3661-3671. [PMID: 33772594 PMCID: PMC8053125 DOI: 10.1093/nar/gkab166] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/25/2021] [Accepted: 03/23/2021] [Indexed: 11/16/2022] Open
Abstract
Among the many in vitro-selected aptamers derived from SELEX protocols, only a small fraction has the potential to be applied for synthetic riboswitch engineering. Here, we present a comparative study of the binding properties of three different aptamers that bind to ciprofloxacin with similar KD values, yet only two of them can be applied as riboswitches. We used the inherent ligand fluorescence that is quenched upon binding as the reporter signal in fluorescence titration and in time-resolved stopped-flow experiments. Thus, we were able to demonstrate differences in the binding kinetics of regulating and non-regulating aptamers. All aptamers studied underwent a two-step binding mechanism that suggests an initial association step followed by a reorganization of the aptamer to accommodate the ligand. We show that increasing regulatory potential is correlated with a decreasing back-reaction rate of the second binding step, thus resulting in a virtually irreversible last binding step of regulating aptamers. We suggest that a highly favoured structural adaption of the RNA to the ligand during the final binding step is essential for turning an aptamer into a riboswitch. In addition, our results provide an explanation for the fact that so few aptamers with regulating capacity have been found to date. Based on our data, we propose an adjustment of the selection protocol for efficient riboswitch detection.
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Affiliation(s)
- Christoph Kaiser
- Institute for Physical and Theoretical Chemistry, Goethe-Universität Frankfurt, Max-von-Laue-Straße 8, D-60438 Frankfurt am Main, Germany
| | - Jeannine Schneider
- Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany
| | - Florian Groher
- Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany
| | - Beatrix Suess
- Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, D-64287 Darmstadt, Germany.,Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Josef Wachtveitl
- Institute for Physical and Theoretical Chemistry, Goethe-Universität Frankfurt, Max-von-Laue-Straße 8, D-60438 Frankfurt am Main, Germany
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26
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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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27
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Broft P, Dzatko S, Krafcikova M, Wacker A, Hänsel‐Hertsch R, Dötsch V, Trantirek L, Schwalbe H. In-Cell NMR Spectroscopy of Functional Riboswitch Aptamers in Eukaryotic Cells. Angew Chem Int Ed Engl 2021; 60:865-872. [PMID: 32975353 PMCID: PMC7839747 DOI: 10.1002/anie.202007184] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/22/2020] [Indexed: 12/14/2022]
Abstract
We report here the in-cell NMR-spectroscopic observation of the binding of the cognate ligand 2'-deoxyguanosine to the aptamer domain of the bacterial 2'-deoxyguanosine-sensing riboswitch in eukaryotic cells, namely Xenopus laevis oocytes and in human HeLa cells. The riboswitch is sufficiently stable in both cell types to allow for detection of binding of the ligand to the riboswitch. Most importantly, we show that the binding mode established by in vitro characterization of this prokaryotic riboswitch is maintained in eukaryotic cellular environment. Our data also bring important methodological insights: Thus far, in-cell NMR studies on RNA in mammalian cells have been limited to investigations of short (<15 nt) RNA fragments that were extensively modified by protecting groups to limit their degradation in the intracellular space. Here, we show that the in-cell NMR setup can be adjusted for characterization of much larger (≈70 nt) functional and chemically non-modified RNA.
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Affiliation(s)
- P. Broft
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
| | - S. Dzatko
- National Centre for Biomolecular ResearchMasaryk UniversityKamenice 5625 00BrnoCzech Republic
- Central European Institute of Technology (CEITEC)Masaryk UniversityKamenice 753/5625 00BrnoCzech Republic
| | - M. Krafcikova
- National Centre for Biomolecular ResearchMasaryk UniversityKamenice 5625 00BrnoCzech Republic
- Institute of BiophysicsCzech Academy of SciencesKralovopolska 135612 65BrnoCzech Republic
| | - A. Wacker
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
| | - Robert Hänsel‐Hertsch
- Present address: Center for Molecular Medicine CologneRobert-Koch-Str. 2150931CologneGermany
| | - Volker Dötsch
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute of Biophysical ChemistryGoethe UniversityMax-von-Laue-Str. 960438Frankfurt/M.Germany
| | - L. Trantirek
- Central European Institute of Technology (CEITEC)Masaryk UniversityKamenice 753/5625 00BrnoCzech Republic
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ)Institute for Organic Chemistry and Chemical BiologyGoethe UniversityMax-von-Laue-Str. 760438Frankfurt/M.Germany
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28
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Panchapakesan SSS, Corey L, Malkowski SN, Higgs G, Breaker RR. A second riboswitch class for the enzyme cofactor NAD . RNA (NEW YORK, N.Y.) 2021; 27:99-105. [PMID: 33087526 PMCID: PMC7749635 DOI: 10.1261/rna.077891.120] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 10/19/2020] [Indexed: 06/01/2023]
Abstract
A bacterial noncoding RNA motif almost exclusively associated with pnuC genes was uncovered using comparative sequence analysis. Some PnuC proteins are known to transport nicotinamide riboside (NR), which is a component of the ubiquitous and abundant enzyme cofactor nicotinamide adenine dinucleotide (NAD+). Thus, we speculated that the newly found "pnuC motif" RNAs might function as aptamers for a novel class of NAD+-sensing riboswitches. RNA constructs that encompass the conserved nucleotides and secondary structure features that define the motif indeed selectively bind NAD+, nicotinamide mononucleotide (NMN), and NR. Mutations that disrupt strictly conserved nucleotides of the aptamer also disrupt ligand binding. These bioinformatic and biochemical findings indicate that pnuC motif RNAs are likely members of a second riboswitch class that regulates gene expression in response to NAD+ binding.
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Affiliation(s)
- Shanker S S Panchapakesan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Lukas Corey
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Sarah N Malkowski
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Gadareth Higgs
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA
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29
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Chen H, Egger M, Xu X, Flemmich L, Krasheninina O, Sun A, Micura R, Ren A. Structural distinctions between NAD+ riboswitch domains 1 and 2 determine differential folding and ligand binding. Nucleic Acids Res 2020; 48:12394-12406. [PMID: 33170270 PMCID: PMC7708056 DOI: 10.1093/nar/gkaa1029] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 11/13/2022] Open
Abstract
Riboswitches are important gene regulatory elements frequently encountered in bacterial mRNAs. The recently discovered nadA riboswitch contains two similar, tandemly arrayed aptamer domains, with the first domain possessing high affinity for nicotinamide adenine dinucleotide (NAD+). The second domain which comprises the ribosomal binding site in a putative regulatory helix, however, has withdrawn from detection of ligand-induced structural modulation thus far, and therefore, the identity of the cognate ligand and the regulation mechanism have remained unclear. Here, we report crystal structures of both riboswitch domains, each bound to NAD+. Furthermore, we demonstrate that ligand binding to domain 2 requires significantly higher concentrations of NAD+ (or ADP retaining analogs) compared to domain 1. Using a fluorescence spectroscopic approach, we further shed light on the structural features which are responsible for the different ligand affinities, and describe the Mg2+-dependent, distinct folding and pre-organization of their binding pockets. Finally, we speculate about possible scenarios for nadA RNA gene regulation as a putative two-concentration sensor module for a time-controlled signal that is primed and stalled by the gene regulation machinery at low ligand concentrations (domain 1), and finally triggers repression of translation as soon as high ligand concentrations are reached in the cell (domain 2).
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Affiliation(s)
- Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Michaela Egger
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, 6020, Austria
| | - Xiaochen Xu
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Laurin Flemmich
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, 6020, Austria
| | - Olga Krasheninina
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, 6020, Austria
| | - Aiai Sun
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub-lane Xiangshan, Hangzhou 310024, China
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, 6020, Austria
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
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30
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Cooperativity and Allostery in RNA Systems. Methods Mol Biol 2020; 2253:255-271. [PMID: 33315228 DOI: 10.1007/978-1-0716-1154-8_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
Allostery is among the most basic biological principles employed by biological macromolecules to achieve a biologically active state in response to chemical cues. Although initially used to describe the impact of small molecules on the conformation and activity of protein enzymes, the definition of this term has been significantly broadened to describe long-range conformational change of macromolecules in response to small or large effectors. Such a broad definition could be applied to RNA molecules, which do not typically serve as protein-free cellular enzymes but fold and form macromolecular assemblies with the help of various ligand molecules, including ions and proteins. Ligand-induced allosteric changes in RNA molecules are often accompanied by cooperative interactions between RNA and its ligand, thus streamlining the folding and assembly pathways. This chapter provides an overview of the interplay between cooperativity and allostery in RNA systems and outlines methods to study these two biological principles.
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Broft P, Dzatko S, Krafcikova M, Wacker A, Hänsel‐Hertsch R, Dötsch V, Trantirek L, Schwalbe H. In‐Cell NMR Spectroscopy of Functional Riboswitch Aptamers in Eukaryotic Cells. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- P. Broft
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
| | - S. Dzatko
- National Centre for Biomolecular Research Masaryk University Kamenice 5 625 00 Brno Czech Republic
- Central European Institute of Technology (CEITEC) Masaryk University Kamenice 753/5 625 00 Brno Czech Republic
| | - M. Krafcikova
- National Centre for Biomolecular Research Masaryk University Kamenice 5 625 00 Brno Czech Republic
- Institute of Biophysics Czech Academy of Sciences Kralovopolska 135 612 65 Brno Czech Republic
| | - A. Wacker
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
| | - Robert Hänsel‐Hertsch
- Present address: Center for Molecular Medicine Cologne Robert-Koch-Str. 21 50931 Cologne Germany
| | - Volker Dötsch
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute of Biophysical Chemistry Goethe University Max-von-Laue-Str. 9 60438 Frankfurt/M. Germany
| | - L. Trantirek
- Central European Institute of Technology (CEITEC) Masaryk University Kamenice 753/5 625 00 Brno Czech Republic
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ) Institute for Organic Chemistry and Chemical Biology Goethe University Max-von-Laue-Str. 7 60438 Frankfurt/M. Germany
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32
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Nußbaumer F, Plangger R, Roeck M, Kreutz C. Aromatic
19
F–
13
C TROSY—[
19
F,
13
C]‐Pyrimidine Labeling for NMR Spectroscopy of RNA. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) University of Innsbruck Innrain 80/82 6020 Innsbruck Austria
| | - Raphael Plangger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) University of Innsbruck Innrain 80/82 6020 Innsbruck Austria
| | - Manuel Roeck
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) University of Innsbruck Innrain 80/82 6020 Innsbruck Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) University of Innsbruck Innrain 80/82 6020 Innsbruck Austria
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33
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Nußbaumer F, Plangger R, Roeck M, Kreutz C. Aromatic 19 F- 13 C TROSY-[ 19 F, 13 C]-Pyrimidine Labeling for NMR Spectroscopy of RNA. Angew Chem Int Ed Engl 2020; 59:17062-17069. [PMID: 32558232 PMCID: PMC7540360 DOI: 10.1002/anie.202006577] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Indexed: 12/22/2022]
Abstract
We present the access to [5-19 F, 5-13 C]-uridine and -cytidine phosphoramidites for the production of site-specifically modified RNAs up to 65 nucleotides (nts). The amidites were used to introduce [5-19 F, 5-13 C]-pyrimidine labels into five RNAs-the 30 nt human immunodeficiency virus trans activation response (HIV TAR) 2 RNA, the 61 nt human hepatitis B virus ϵ (hHBV ϵ) RNA, the 49 nt SAM VI riboswitch aptamer domain from B. angulatum, the 29 nt apical stem loop of the pre-microRNA (miRNA) 21 and the 59 nt full length pre-miRNA 21. The main stimulus to introduce the aromatic 19 F-13 C-spin topology into RNA comes from a work of Boeszoermenyi et al., in which the dipole-dipole interaction and the chemical shift anisotropy relaxation mechanisms cancel each other leading to advantageous TROSY properties shown for aromatic protein sidechains. This aromatic 13 C-19 F labeling scheme is now transferred to RNA. We provide a protocol for the resonance assignment by solid phase synthesis based on diluted [5-19 F, 5-13 C]/[5-19 F] pyrimidine labeling. For the 61 nt hHBV ϵ we find a beneficial 19 F-13 C TROSY enhancement, which should be even more pronounced in larger RNAs and will facilitate the NMR studies of larger RNAs. The [19 F, 13 C]-labeling of the SAM VI aptamer domain and the pre-miRNA 21 further opens the possibility to use the biorthogonal stable isotope reporter nuclei in in vivo NMR to observe ligand binding and microRNA processing in a biological relevant setting.
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Affiliation(s)
- Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80/826020InnsbruckAustria
| | - Raphael Plangger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80/826020InnsbruckAustria
| | - Manuel Roeck
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80/826020InnsbruckAustria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80/826020InnsbruckAustria
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34
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Bartosik K, Debiec K, Czarnecka A, Sochacka E, Leszczynska G. Synthesis of Nucleobase-Modified RNA Oligonucleotides by Post-Synthetic Approach. Molecules 2020; 25:E3344. [PMID: 32717917 PMCID: PMC7436257 DOI: 10.3390/molecules25153344] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/15/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
The chemical synthesis of modified oligoribonucleotides represents a powerful approach to study the structure, stability, and biological activity of RNAs. Selected RNA modifications have been proven to enhance the drug-like properties of RNA oligomers providing the oligonucleotide-based therapeutic agents in the antisense and siRNA technologies. The important sites of RNA modification/functionalization are the nucleobase residues. Standard phosphoramidite RNA chemistry allows the site-specific incorporation of a large number of functional groups to the nucleobase structure if the building blocks are synthetically obtainable and stable under the conditions of oligonucleotide chemistry and work-up. Otherwise, the chemically modified RNAs are produced by post-synthetic oligoribonucleotide functionalization. This review highlights the post-synthetic RNA modification approach as a convenient and valuable method to introduce a wide variety of nucleobase modifications, including recently discovered native hypermodified functional groups, fluorescent dyes, photoreactive groups, disulfide crosslinks, and nitroxide spin labels.
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Affiliation(s)
| | | | | | | | - Grazyna Leszczynska
- Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland; (K.B.); (K.D.); (A.C.); (E.S.)
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35
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Steinmetzger C, Bäuerlein C, Höbartner C. Supramolecular Fluorescence Resonance Energy Transfer in Nucleobase‐Modified Fluorogenic RNA Aptamers. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201916707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Carmen Bäuerlein
- Institute of Organic ChemistryUniversity of Würzburg Am Hubland 97074 Würzburg Germany
| | - Claudia Höbartner
- Institute of Organic ChemistryUniversity of Würzburg Am Hubland 97074 Würzburg Germany
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36
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Steinmetzger C, Bäuerlein C, Höbartner C. Supramolecular Fluorescence Resonance Energy Transfer in Nucleobase-Modified Fluorogenic RNA Aptamers. Angew Chem Int Ed Engl 2020; 59:6760-6764. [PMID: 32052536 PMCID: PMC7187157 DOI: 10.1002/anie.201916707] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/11/2020] [Indexed: 12/14/2022]
Abstract
RNA aptamers form compact tertiary structures and bind their ligands in specific binding sites. Fluorescence-based strategies reveal information on structure and dynamics of RNA aptamers. Herein, we report the incorporation of the universal emissive nucleobase analog 4-cyanoindole into the fluorogenic RNA aptamer Chili, and its application as a donor for supramolecular FRET to the bound ligands DMHBI+ or DMHBO+ . The photophysical properties of the new nucleobase-ligand-FRET pair revealed structural restraints for the overall RNA aptamer organization and identified nucleotide positions suitable for FRET-based readout of ligand binding. This strategy is generally suitable for binding-site mapping and may also be applied for responsive aptamer devices.
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Affiliation(s)
| | - Carmen Bäuerlein
- Institute of Organic ChemistryUniversity of WürzburgAm Hubland97074WürzburgGermany
| | - Claudia Höbartner
- Institute of Organic ChemistryUniversity of WürzburgAm Hubland97074WürzburgGermany
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37
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Li J, Fang X, Ming X. Visibly Emitting Thiazolyl-Uridine Analogues as Promising Fluorescent Probes. J Org Chem 2020; 85:4602-4610. [DOI: 10.1021/acs.joc.9b03208] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Jinsi Li
- Department of Pharmacy, Chengdu Medical College, No. 783 Xindu Avenue, Chengdu, Sichuan 610500, P. R. China
| | - Xuerong Fang
- Department of Pharmacy, Chengdu Medical College, No. 783 Xindu Avenue, Chengdu, Sichuan 610500, P. R. China
| | - Xin Ming
- Department of Pharmacy, Chengdu Medical College, No. 783 Xindu Avenue, Chengdu, Sichuan 610500, P. R. China
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38
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Li H, Tang Y, Li B. Homogeneous and Universal Detection of Various Targets with a Dual-Step Transduced Toehold Switch Sensor. Chembiochem 2020; 21:1418-1422. [PMID: 31913537 DOI: 10.1002/cbic.201900749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Indexed: 12/13/2022]
Abstract
Toehold switch sensors represent a class of new advances that allow specific targets to trigger in situ expression of a protein reporter. Although they offer unique advantages of a label-free nature and high portability, they generally require repeated sequence design, high expenditure, and laborious optimization of toehold switch sequences according to different targets. To simplify the sensing process further and to improve its practicability, we innovatively introduce a dual-step pre-transduction upon traditional toehold switch sensor. Through two successive toehold-mediated strand-displacement reactions that are initiated, respectively, by a linear and an associative trigger, different DNAs, RNAs, or ligands of functional nucleic acids can be generally transduced into the input of one high-performance toehold switch sensor. This advance greatly increases the target range. Furthermore, the whole process is signal-on, homogeneous, and free of any requirements for complicated operations such as probe labeling, separation, and reconstruction of the toehold switch, being promising and practical even in portable or point-of-care assays.
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Affiliation(s)
- Huan Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China.,University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Yidan Tang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
| | - Bingling Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China.,University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
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39
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Abstract
RNA molecules fold into complex three-dimensional structures that sample alternate conformations ranging from minor differences in tertiary structure dynamics to major differences in secondary structure. This allows them to form entirely different substructures with each population potentially giving rise to a distinct biological outcome. The substructures can be partitioned along an existing energy landscape given a particular static cellular cue or can be shifted in response to dynamic cues such as ligand binding. We review a few key examples of RNA molecules that sample alternate conformations and how these are capitalized on for control of critical regulatory functions.
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Affiliation(s)
- Marie Teng-Pei Wu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Victoria D'Souza
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
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40
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Sun A, Gasser C, Li F, Chen H, Mair S, Krasheninina O, Micura R, Ren A. SAM-VI riboswitch structure and signature for ligand discrimination. Nat Commun 2019; 10:5728. [PMID: 31844059 PMCID: PMC6914780 DOI: 10.1038/s41467-019-13600-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/13/2019] [Indexed: 12/16/2022] Open
Abstract
Riboswitches are metabolite-sensing, conserved domains located in non-coding regions of mRNA that are central to regulation of gene expression. Here we report the first three-dimensional structure of the recently discovered S-adenosyl-L-methionine responsive SAM-VI riboswitch. SAM-VI adopts a unique fold and ligand pocket that are distinct from all other known SAM riboswitch classes. The ligand binds to the junctional region with its adenine tightly intercalated and Hoogsteen base-paired. Furthermore, we reveal the ligand discrimination mode of SAM-VI by additional X-ray structures of this riboswitch bound to S-adenosyl-L-homocysteine and a synthetic ligand mimic, in combination with isothermal titration calorimetry and fluorescence spectroscopy to explore binding thermodynamics and kinetics. The structure is further evaluated by analysis of ligand binding to SAM-VI mutants. It thus provides a thorough basis for developing synthetic SAM cofactors for applications in chemical and synthetic RNA biology.
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Affiliation(s)
- Aiai Sun
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China
| | - Catherina Gasser
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Fudong Li
- National Science Center for Physical Sciences at Microscale Division of Molecular & Cell Biophysics and School of Life Sciences, University of Science and Technology of China, 230026, Hefei, China
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China
| | - Stefan Mair
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Olga Krasheninina
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, Leopold Franzens University, Innsbruck, A6020, Austria.
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China.
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41
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Malkowski SN, Spencer TCJ, Breaker RR. Evidence that the nadA motif is a bacterial riboswitch for the ubiquitous enzyme cofactor NAD . RNA (NEW YORK, N.Y.) 2019; 25:1616-1627. [PMID: 31467147 PMCID: PMC6859854 DOI: 10.1261/rna.072538.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 07/29/2019] [Indexed: 05/04/2023]
Abstract
The nadA motif is a riboswitch candidate present in various Acidobacteria species that was previously identified by bioinformatic analysis of bacterial DNA data sets. More than 100 unique representatives have been identified exclusively upstream of nadA genes, which code for an enzyme in the biosynthetic pathway of the ubiquitous coenzyme NAD+ The architecture of nadA motif RNAs suggests they use structurally similar tandem ligand-binding aptamer domains to control translation initiation. Biochemical analyses reveal that the first domain selectively binds ligands carrying an adenosine 5'-diphosphate (5' ADP) moiety, including NAD+ and its reduced form, NADH. Genetic analyses indicate that a tandem nadA motif RNA suppresses gene expression when NAD+ is abundant, and that both aptamer domains are required for maximal gene regulation. However, we have not observed selective binding of the nicotinamide moiety of NAD+ or binding by the second putative aptamer in vitro, despite sequence and structural similarities between the tandem domains.
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Affiliation(s)
- Sarah N Malkowski
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Tara C J Spencer
- Department of Biology, Howard University, Washington, D.C. 20059, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103, USA
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Neuner E, Micura R. Practical synthesis of N-(di- n-butylamino)methylene-protected 2-aminopurine riboside phosphoramidite for RNA solid-phase synthesis. MONATSHEFTE FUR CHEMIE 2019; 150:1941-1946. [PMID: 31929656 PMCID: PMC6936340 DOI: 10.1007/s00706-019-02502-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/09/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Eva Neuner
- Institute of Organic Chemistry, Leopold-Franzens University, Innrain 80-82, Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry, Leopold-Franzens University, Innrain 80-82, Innsbruck, Austria
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Sakata Y, Tamiya M, Okada M, Akine S. Switching of Recognition First and Reaction First Mechanisms in Host–Guest Binding Associated with Chemical Reactions. J Am Chem Soc 2019; 141:15597-15604. [DOI: 10.1021/jacs.9b06926] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yoko Sakata
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University Kakuma-machi, Kanazawa 920-1192, Japan
| | - Munehiro Tamiya
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Masahiro Okada
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Shigehisa Akine
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University Kakuma-machi, Kanazawa 920-1192, Japan
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Dwidar M, Seike Y, Kobori S, Whitaker C, Matsuura T, Yokobayashi Y. Programmable Artificial Cells Using Histamine-Responsive Synthetic Riboswitch. J Am Chem Soc 2019; 141:11103-11114. [PMID: 31241330 DOI: 10.1021/jacs.9b03300] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Artificial cells that encapsulate DNA-programmable protein expression machinery are emerging as an attractive platform for studying fundamental cellular properties and applications in synthetic biology. However, interfacing these artificial cells with the complex and dynamic chemical environment remains a major and urgent challenge. We demonstrate that the repertoire of molecules that artificial cells respond to can be expanded by synthetic RNA-based gene switches, or riboswitches. We isolated an RNA aptamer that binds histamine with high affinity and specificity and used it to design robust riboswitches that activate protein expression in the presence of histamine. Finally, the riboswitches were incorporated in artificial cells to achieve controlled release of an encapsulated small molecule and to implement a self-destructive kill-switch. Synthetic riboswitches should serve as modular and versatile interfaces to link artificial cell phenotypes with the complex chemical environment.
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Affiliation(s)
- Mohammed Dwidar
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University , Onna , Okinawa 904-0495 , Japan
| | - Yusuke Seike
- Department of Biotechnology, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Shungo Kobori
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University , Onna , Okinawa 904-0495 , Japan
| | - Charles Whitaker
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University , Onna , Okinawa 904-0495 , Japan
| | - Tomoaki Matsuura
- Department of Biotechnology, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University , Onna , Okinawa 904-0495 , Japan
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Sung HL, Nesbitt DJ. Novel Heat-Promoted Folding Dynamics of the yybP-ykoY Manganese Riboswitch: Kinetic and Thermodynamic Studies at the Single-Molecule Level. J Phys Chem B 2019; 123:5412-5422. [DOI: 10.1021/acs.jpcb.9b02852] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
| | - David J. Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
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Umuhire Juru A, Patwardhan NN, Hargrove AE. Understanding the Contributions of Conformational Changes, Thermodynamics, and Kinetics of RNA-Small Molecule Interactions. ACS Chem Biol 2019; 14:824-838. [PMID: 31042354 DOI: 10.1021/acschembio.8b00945] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The implication of RNA in multiple cellular processes beyond protein coding has revitalized interest in the development of small molecules for therapeutically targeting RNA and for further probing its cellular biology. However, the process of rationally designing such small molecule probes is hampered by the paucity of information about fundamental molecular recognition principles of RNA. In this Review, we summarize two important and often underappreciated aspects of RNA-small molecule recognition: RNA conformational dynamics and the biophysical properties of interactions of small molecules with RNA, specifically thermodynamics and kinetics. While conformational flexibility is often said to impede RNA ligand development, the ability of small molecules to influence the RNA conformational landscape can have a significant effect on the cellular functions of RNA. An analysis of the conformational landscape of RNA and the interactions of individual conformations with ligands can thus guide the development of new small molecule probes, which needs to be investigated further. Additionally, while it is common practice to quantify the binding affinities ( Ka or Kd) of small molecules for biomacromolecules as a measure of their activity, further biophysical characterization of their interaction can provide a deeper understanding. Studies that focus on the thermodynamic and kinetic parameters for interaction between RNA and ligands are next discussed. Finally, this Review provides the reader with a perspective on how such in-depth analysis of biophysical characteristics of the interaction of RNA and small molecules can impact our understanding of these interactions and how they will benefit the future design of small molecule probes.
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Affiliation(s)
- Aline Umuhire Juru
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Neeraj N. Patwardhan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Amanda E. Hargrove
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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Milisavljevič N, Perlíková P, Pohl R, Hocek M. Enzymatic synthesis of base-modified RNA by T7 RNA polymerase. A systematic study and comparison of 5-substituted pyrimidine and 7-substituted 7-deazapurine nucleoside triphosphates as substrates. Org Biomol Chem 2019; 16:5800-5807. [PMID: 30063056 DOI: 10.1039/c8ob01498a] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We synthesized a small library of eighteen 5-substituted pyrimidine or 7-substituted 7-deazapurine nucleoside triphosphates bearing methyl, ethynyl, phenyl, benzofuryl or dibenzofuryl groups through cross-coupling reactions of nucleosides followed by triphosphorylation or through direct cross-coupling reactions of halogenated nucleoside triphosphates. We systematically studied the influence of the modification on the efficiency of T7 RNA polymerase catalyzed synthesis of modified RNA and found that modified ATP, UTP and CTP analogues bearing smaller modifications were good substrates and building blocks for the RNA synthesis even in difficult sequences incorporating multiple modified nucleotides. Bulky dibenzofuryl derivatives of ATP and GTP were not substrates for the RNA polymerase. In the case of modified GTP analogues, a modified procedure using a special promoter and GMP as initiator needed to be used to obtain efficient RNA synthesis. The T7 RNA polymerase synthesis of modified RNA can be very efficiently used for synthesis of modified RNA but the method has constraints in the sequence of the first three nucleotides of the transcript, which must contain a non-modified G in the +1 position.
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Affiliation(s)
- Nemanja Milisavljevič
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, CZ-16610, Prague 6, Czech Republic.
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Sung HL, Nesbitt DJ. Single-Molecule FRET Kinetics of the Mn 2+ Riboswitch: Evidence for Allosteric Mg 2+ Control of "Induced-Fit" vs "Conformational Selection" Folding Pathways. J Phys Chem B 2019; 123:2005-2015. [PMID: 30739441 DOI: 10.1021/acs.jpcb.8b11841] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gene expression in bacteria is often regulated dynamically by conformational changes in a riboswitch upon ligand binding, a detailed understanding of which is very much in its infancy. For example, the manganese riboswitch is a widespread RNA motif that conformationally responds in regulating bacterial gene expression to micromolar levels of its eponymous ligand, Mn2+, but the mechanistic pathways are poorly understood. In this work, we quantitatively explore the dynamic folding behavior of the manganese riboswitch by single-molecule fluorescence resonance energy transfer spectroscopy as a function of cation/ligand conditions. From the detailed analysis of the kinetics, the Mn2+ is shown to fold the riboswitch by a "bind-then-fold" (i.e., "induced-fit", IF) mechanism, whereby the ligand binds first and then promotes folding. On the other hand, the data also clearly reveal the presence of a folded yet ligand-free structure predominating due to the addition of physiological Mg2+ to a nonselective metal ion binding site. Of particular kinetic interest, such a Mg2+ "prefolded" conformation of the riboswitch is shown to exhibit a significantly increased affinity for Mn2+ and further stabilization by subsequent binding of the ligand, thereby promoting efficient riboswitch folding by a "fold-then-bind" (i.e., "conformational selection", CS) mechanism. Our results not only demonstrate Mg2+-controlled switching between IF and CS riboswitch folding pathways but also suggest a novel heterotropic allosteric control in the manganese riboswitch activity co-regulated by Mg2+ binding.
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Abstract
RNA is a versatile biomolecule capable of transferring information, taking on distinct three-dimensional shapes, and reacting to ambient conditions. RNA molecules utilize a wide range of mechanisms to control gene expression. An example of such regulation is riboswitches. Consisting exclusively of RNA, they are able to control important metabolic processes, thus providing an elegant and efficient RNA-only regulation system. Existing across all domains of life, riboswitches appear to represent one of the most highly conserved mechanisms for the regulation of a broad range of biochemical pathways. Through binding of a wide range of small-molecule ligands to their so-called aptamer domain, riboswitches undergo a conformational change in their downstream "expression platform." In consequence, the pattern of gene expression changes, which in turn results in increased or decreased protein production. Riboswitches unite the sensing and transduction of a signal that can directly be coupled to the metabolism of the cell; thus they constitute a very potent regulatory mechanism for many organisms. Highly specific RNA-binding domains not only occur in vivo but can also be evolved by means of the SELEX (systematic evolution of ligands by exponential enrichment) method, which allows in vitro selection of aptamers against almost any ligand. Coupling of these aptamers with an expression platform has led to the development of synthetic riboswitches, a highly active research field of great relevance and immense potential. The aim of this review is to summarize developments in the riboswitch field over the last decade and address key questions of recent research.
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Wales DJ, Disney MD, Yildirim I. Computational Investigation of RNA A-Bulges Related to the Microtubule-Associated Protein Tau Causing Frontotemporal Dementia and Parkinsonism. J Phys Chem B 2019; 123:57-65. [PMID: 30517788 PMCID: PMC6465094 DOI: 10.1021/acs.jpcb.8b09139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mutations in the human tau gene result in alternative splicing of the tau protein, which causes frontotemporal dementia and Parkinsonism. One disease mechanism is linked to the stability of a hairpin within the microtubule-associated protein tau (MAPT) mRNA, which contains an A-bulge. Here we employ computational methods to investigate the structural and thermodynamic properties of several A-bulge RNAs with different closing base-pairs. We find that the current amber RNA force field has a preference to overstabilize base-triple over stacked states, even though some of the A-bulges are known to prefer stacked states according to NMR studies. We further determined that if the neighboring base-pairs of A-bulges are AU, this situation can lead to base slippage. However, when the 3'-side of the A-bulge has an UA base-pair, the stacked state is stabilized by an extra interaction that is not observed in the other sequences. We suggest that these A-bulge RNA systems could be used as benchmarks to improve the current RNA force fields.
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Affiliation(s)
- David J. Wales
- Department of Chemistry, University of Cambridge, Cambridge, Cambridgeshire CB2 1EW, U.K
| | - Matthew D. Disney
- Department of Chemistry, Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Ilyas Yildirim
- Department of Chemistry, Scripps Research Institute, Jupiter, Florida 33458, United States
- Department of Chemistry and Biochemistry, Florida Atlantic University, Jupiter, Florida 33458, United States
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