1
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Ito K, Tayama T, Uemura S, Iizuka R. Isolation of novel fluorogenic RNA aptamers via in vitro compartmentalization using microbead-display libraries. Talanta 2024; 278:126488. [PMID: 38955098 DOI: 10.1016/j.talanta.2024.126488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 06/12/2024] [Accepted: 06/28/2024] [Indexed: 07/04/2024]
Abstract
Fluorogenic RNA aptamers, which specifically bind to fluorogens and dramatically enhance their fluorescence, are valuable for imaging and detecting RNAs and metabolites in living cells. Most fluorogenic RNA aptamers have been identified and engineered through iterative rounds of in vitro selection based on their binding to target fluorogens. While such selection is an efficient approach for generating RNA aptamers, it is less efficient for isolating fluorogenic aptamers because it does not directly screen for fluorogenic properties. In this study, we combined a fluorescence-based in vitro selection technique using water-in-oil microdroplets with an affinity-based selection technique to obtain fluorogenic RNA aptamers. This approach allowed us to identify novel fluorogenic aptamers for a biotin-modified thiazole orange derivative. Our results demonstrate that our approach can expand the diversity of fluorogenic RNA aptamers, thus leading to new applications for the imaging and detection of biomolecules.
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Affiliation(s)
- Keisuke Ito
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tomotaka Tayama
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Sotaro Uemura
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Chiyoda-ku, Tokyo, 102-0075, Japan.
| | - Ryo Iizuka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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2
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Evans NM, Shivers LR, To AJ, Murphy GK, Dieckmann T. Biophysical characterization and design of a minimal version of the Hoechst RNA aptamer. Biochem Biophys Res Commun 2024; 711:149908. [PMID: 38613867 DOI: 10.1016/j.bbrc.2024.149908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/24/2024] [Accepted: 04/05/2024] [Indexed: 04/15/2024]
Abstract
RNA aptamers are oligonucleotides, selected through Systematic Evolution of Ligands by EXponential Enrichment (SELEX), that can bind to specific target molecules with high affinity. One such molecule is the RNA aptamer that binds to a blue-fluorescent Hoechst dye that was modified with bulky t-Bu groups to prevent non-specific binding to DNA. This aptamer has potential for biosensor applications; however, limited information is available regarding its conformation, molecular interactions with the ligand, and binding mechanism. The study presented here aims to biophysically characterize the Hoechst RNA aptamer when complexed with the t-Bu Hoechst dye and to further optimize the RNA sequence by designing and synthesizing new sequence variants. Each variant aptamer-t-Bu Hoechst complex was evaluated through a combination of fluorescence emission, native polyacrylamide gel electrophoresis, fluorescence titration, and isothermal titration calorimetry experiments. The results were used to design a minimal version of the aptamer consisting of only 21 nucleotides. The performed study also describes a more efficient method for synthesizing the t-Bu Hoechst dye derivative. Understanding the biophysical properties of the t-Bu Hoechst dye-RNA complex lays the foundation for nuclear magnetic resonance spectroscopy studies and its potential development as a building block for an aptamer-based biosensor that can be used in medical, environmental or laboratory settings.
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Affiliation(s)
- Natasha M Evans
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Lindsey R Shivers
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Avery J To
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Graham K Murphy
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
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3
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Abdolahzadeh A, Ang QR, Caine JR, Panchapakesan SSS, Thio S, Cojocaru R, Unrau PJ. Turn-on RNA Mango Beacons for trans-acting fluorogenic nucleic acid detection. RNA (NEW YORK, N.Y.) 2024; 30:392-403. [PMID: 38282417 PMCID: PMC10946430 DOI: 10.1261/rna.079833.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/03/2024] [Indexed: 01/30/2024]
Abstract
The Mango I and II RNA aptamers have been widely used in vivo and in vitro as genetically encodable fluorogenic markers that undergo large increases in fluorescence upon binding to their ligand, TO1-Biotin. However, while studying nucleic acid sequences, it is often desirable to have trans-acting probes that induce fluorescence upon binding to a target sequence. Here, we rationally design three types of light-up RNA Mango Beacons based on a minimized Mango core that induces fluorescence upon binding to a target RNA strand. Our first design is bimolecular in nature and uses a DNA inhibition strand to prevent folding of the Mango aptamer core until binding to a target RNA. Our second design is unimolecular in nature, and features hybridization arms flanking the core that inhibit G-quadruplex folding until refolding is triggered by binding to a target RNA strand. Our third design builds upon this structure, and incorporates a self-inhibiting domain into one of the flanking arms that deliberately binds to, and precludes folding of, the aptamer core until a target is bound. This design separates G-quadruplex folding inhibition and RNA target hybridization into separate modules, enabling a more universal unimolecular beacon design. All three Mango Beacons feature high contrasts and low costs when compared to conventional molecular beacons, with excellent potential for in vitro and in vivo applications.
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Affiliation(s)
- Amir Abdolahzadeh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Quiana R Ang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Jana R Caine
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
| | | | - Shinta Thio
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Razvan Cojocaru
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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4
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Nucleic acid-based fluorescent sensor systems: a review. Polym J 2022. [DOI: 10.1038/s41428-022-00623-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Krissanaprasit A, Key CM, Pontula S, LaBean TH. Self-Assembling Nucleic Acid Nanostructures Functionalized with Aptamers. Chem Rev 2021; 121:13797-13868. [PMID: 34157230 DOI: 10.1021/acs.chemrev.0c01332] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Researchers have worked for many decades to master the rules of biomolecular design that would allow artificial biopolymer complexes to self-assemble and function similarly to the diverse biochemical constructs displayed in natural biological systems. The rules of nucleic acid assembly (dominated by Watson-Crick base-pairing) have been less difficult to understand and manipulate than the more complicated rules of protein folding. Therefore, nucleic acid nanotechnology has advanced more quickly than de novo protein design, and recent years have seen amazing progress in DNA and RNA design. By combining structural motifs with aptamers that act as affinity handles and add powerful molecular recognition capabilities, nucleic acid-based self-assemblies represent a diverse toolbox for use by bioengineers to create molecules with potentially revolutionary biological activities. In this review, we focus on the development of self-assembling nucleic acid nanostructures that are functionalized with nucleic acid aptamers and their great potential in wide ranging application areas.
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Affiliation(s)
- Abhichart Krissanaprasit
- Department of Materials Science and Engineering, College of Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Carson M Key
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Sahil Pontula
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Thomas H LaBean
- Department of Materials Science and Engineering, College of Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
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6
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Huang K, Chen X, Li C, Song Q, Li H, Zhu L, Yang Y, Ren A. Structure-based investigation of fluorogenic Pepper aptamer. Nat Chem Biol 2021; 17:1289-1295. [PMID: 34725509 DOI: 10.1038/s41589-021-00884-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/20/2021] [Indexed: 11/09/2022]
Abstract
Pepper fluorescent RNAs are a recently reported bright, stable and multicolor fluorogenic aptamer tag that enable imaging of diverse RNAs in live cells. To investigate the molecular basis of the superior properties of Pepper, we determined the structures of complexes of Pepper aptamer bound with its cognate HBC or HBC-like fluorophores at high resolution by X-ray crystallography. The Pepper aptamer folds in a monomeric non-G-quadruplex tuning-fork-like architecture composed of a helix and one protruded junction region. The near-planar fluorophore molecule intercalates in the middle of the structure and is sandwiched between one non-G-quadruplex base quadruple and one noncanonical G·U wobble helical base pair. In addition, structure-based mutational analysis is evaluated by in vitro and live-cell fluorogenic detection. Taken together, our research provides a structural basis for demystifying the fluorescence activation mechanism of Pepper aptamer and for further improvement of its future application in RNA visualization.
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Affiliation(s)
- Kaiyi Huang
- Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Xianjun Chen
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Chunyan Li
- Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Qianqian Song
- Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Huiwen Li
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Linyong Zhu
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.
| | - Yi Yang
- Optogenetics & Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China.
| | - Aiming Ren
- Life Sciences Institute, Zhejiang University, Hangzhou, China.
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7
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Fluorescent functional nucleic acid: Principles, properties and applications in bioanalyzing. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116292] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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8
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Suss O, Motiei L, Margulies D. Broad Applications of Thiazole Orange in Fluorescent Sensing of Biomolecules and Ions. Molecules 2021; 26:2828. [PMID: 34068759 PMCID: PMC8126248 DOI: 10.3390/molecules26092828] [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: 04/05/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/13/2022] Open
Abstract
Fluorescent sensing of biomolecules has served as a revolutionary tool for studying and better understanding various biological systems. Therefore, it has become increasingly important to identify fluorescent building blocks that can be easily converted into sensing probes, which can detect specific targets with increasing sensitivity and accuracy. Over the past 30 years, thiazole orange (TO) has garnered great attention due to its low fluorescence background signal and remarkable 'turn-on' fluorescence response, being controlled only by its intramolecular torsional movement. These features have led to the development of numerous molecular probes that apply TO in order to sense a variety of biomolecules and metal ions. Here, we highlight the tremendous progress made in the field of TO-based sensors and demonstrate the different strategies that have enabled TO to evolve into a versatile dye for monitoring a collection of biomolecules.
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Affiliation(s)
| | | | - David Margulies
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel; (O.S.); (L.M.)
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9
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Ryckelynck M. Development and Applications of Fluorogen/Light-Up RNA Aptamer Pairs for RNA Detection and More. Methods Mol Biol 2021; 2166:73-102. [PMID: 32710404 DOI: 10.1007/978-1-0716-0712-1_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The central role of RNA in living systems made it highly desirable to have noninvasive and sensitive technologies allowing for imaging the synthesis and the location of these molecules in living cells. This need motivated the development of small pro-fluorescent molecules called "fluorogens" that become fluorescent upon binding to genetically encodable RNAs called "light-up aptamers." Yet, the development of these fluorogen/light-up RNA pairs is a long and thorough process starting with the careful design of the fluorogen and pursued by the selection of a specific and efficient synthetic aptamer. This chapter summarizes the main design and the selection strategies used up to now prior to introducing the main pairs. Then, the vast application potential of these molecules for live-cell RNA imaging and other applications is presented and discussed.
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Affiliation(s)
- Michael Ryckelynck
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, Strasbourg, France.
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10
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Kolpashchikov DM, Spelkov AA. Binary (Split) Light‐up Aptameric Sensors. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.201914919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Dmitry M. Kolpashchikov
- Chemistry Department University of Central Florida Orlando FL 32816-2366 USA
- Burnett School of Biomedical Sciences University of Central Florida Orlando FL 32816 USA
| | - Alexander A. Spelkov
- Laboratory of Solution Chemistry of Advanced Materials and Technologies ITMO University 9 Lomonosova Str. St. Petersburg 191002 Russian Federation
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11
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Al Mazid MF, Shkel O, Kharkivska Y, Lee JS. Application of fluorescent turn-on aptamers in RNA studies. Mol Omics 2021; 17:483-491. [PMID: 34137415 DOI: 10.1039/d1mo00085c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
RNA is an intermediate player between DNA transcription and protein translation. RNAs also interact with other macromolecules and metabolites and regulate their fate. The emerging number of RNA identifications expanded new areas of study to determine their applicability and functional analysis. Recently, extensive research has been focused on visualizing RNA in living biological samples and a method has been developed by the evolution of specific fluorophore-binding aptamers through the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method. Several promising fluorescent turn-on aptamers are currently available, and they can detect RNA-RNA, RNA-protein, ligand binding, small molecule, and metabolite interactions in vitro and under live-cell conditions. Here we review the currently available fluorescent turn-on aptamers and discuss their applicability for analyzing the fate of targeted RNAs in in vitro and in vivo systems.
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Affiliation(s)
| | - Olha Shkel
- Bio-Med Program KIST-School UST, Seoul, 02792, Republic of Korea
| | | | - Jun-Seok Lee
- Department of Pharmacology, Korea University College of Medicine, Seoul, 02841, Republic of Korea.
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12
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Fujimoto K, Watanabe N. Fluorescence In Situ Hybridization of 16S rRNA in
Escherichia coli
Using Multiple Photo‐Cross‐Linkable Probes. ChemistrySelect 2020. [DOI: 10.1002/slct.202003343] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Kenzo Fujimoto
- School of Advanced Science and Technology Japan Advanced Institute of Science and Technology Asahidai 1–1, Nomi Ishikawa 923-1292 Japan
| | - Nanami Watanabe
- School of Advanced Science and Technology Japan Advanced Institute of Science and Technology Asahidai 1–1, Nomi Ishikawa 923-1292 Japan
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13
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Kolpashchikov DM, Spelkov AA. Binary (Split) Light-up Aptameric Sensors. Angew Chem Int Ed Engl 2020; 60:4988-4999. [PMID: 32208549 DOI: 10.1002/anie.201914919] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Indexed: 12/12/2022]
Abstract
This Minireview discusses the design and applications of binary (also known as split) light-up aptameric sensors (BLAS). BLAS consist of two RNA or DNA strands and a fluorogenic organic dye added as a buffer component. When associated, the two strands form a dye-binding site, followed by an increase in fluorescence of the aptamer-bound dye. The design is cost-efficient because it uses short oligonucleotides and does not require conjugation of organic dyes with nucleic acids. In some applications, BLAS design is preferable over monolithic sensors because of simpler assay optimization and improved selectivity. RNA-based BLAS can be expressed in cells and used for the intracellular monitoring of biological molecules. BLAS have been used as reporters of nucleic acid association events in RNA nanotechnology and nucleic-acid-based molecular computation. Other applications of BLAS include the detection of nucleic acids, proteins, and cancer cells, and potentially they can be tailored to report a broad range of biological analytes.
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Affiliation(s)
- Dmitry M Kolpashchikov
- Chemistry Department, University of Central Florida, Orlando, FL, 32816-2366, USA.,Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, 32816, USA
| | - Alexander A Spelkov
- Laboratory of Solution Chemistry of Advanced Materials and Technologies, ITMO University, 9 Lomonosova Str., St. Petersburg, 191002, Russian Federation
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14
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Debiais M, Lelievre A, Smietana M, Müller S. Splitting aptamers and nucleic acid enzymes for the development of advanced biosensors. Nucleic Acids Res 2020; 48:3400-3422. [PMID: 32112111 PMCID: PMC7144939 DOI: 10.1093/nar/gkaa132] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 12/16/2022] Open
Abstract
In analogy to split-protein systems, which rely on the appropriate fragmentation of protein domains, split aptamers made of two or more short nucleic acid strands have emerged as novel tools in biosensor set-ups. The concept relies on dissecting an aptamer into a series of two or more independent fragments, able to assemble in the presence of a specific target. The stability of the assembled structure can further be enhanced by functionalities that upon folding would lead to covalent end-joining of the fragments. To date, only a few aptamers have been split successfully, and application of split aptamers in biosensing approaches remains as promising as it is challenging. Further improving the stability of split aptamer target complexes and with that the sensitivity as well as efficient working modes are important tasks. Here we review functional nucleic acid assemblies that are derived from aptamers and ribozymes/DNAzymes. We focus on the thrombin, the adenosine/ATP and the cocaine split aptamers as the three most studied DNA split systems and on split DNAzyme assemblies. Furthermore, we extend the subject into split light up RNA aptamers used as mimics of the green fluorescent protein (GFP), and split ribozymes.
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Affiliation(s)
- Mégane Debiais
- Institut des Biomolécules Max Mousseron, University of Montpellier, CNRS, ENCSM, Montpellier, France
| | - Amandine Lelievre
- University Greifswald, Institute for Biochemistry, Greifswald, Germany
| | - Michael Smietana
- Institut des Biomolécules Max Mousseron, University of Montpellier, CNRS, ENCSM, Montpellier, France
| | - Sabine Müller
- University Greifswald, Institute for Biochemistry, Greifswald, Germany
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15
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Gao T, Luo Y, Li W, Cao Y, Pei R. Progress in the isolation of aptamers to light-up the dyes and the applications. Analyst 2020; 145:701-718. [DOI: 10.1039/c9an01825e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The progress in the selection of aptamers to light-up the dyes and the related applications are reviewed.
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Affiliation(s)
- Tian Gao
- CAS Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Yu Luo
- CAS Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Wenjing Li
- CAS Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Yanwei Cao
- CAS Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Renjun Pei
- CAS Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
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16
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Abdolahzadeh A, Dolgosheina EV, Unrau PJ. RNA detection with high specificity and sensitivity using nested fluorogenic Mango NASBA. RNA (NEW YORK, N.Y.) 2019; 25:1806-1813. [PMID: 31551299 PMCID: PMC6859864 DOI: 10.1261/rna.072629.119] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/16/2019] [Indexed: 05/30/2023]
Abstract
There is a pressing need for nucleic acid-based assays that are capable of rapidly and reliably detecting pathogenic organisms. Many of the techniques available for the detection of pathogenic RNA possess one or more limiting factors that make the detection of low-copy RNA challenging. Although RT-PCR is the most commonly used method for detecting pathogen-related RNA, it requires expensive thermocycling equipment and is comparatively slow. Isothermal methods promise procedural simplicity but have traditionally suffered from amplification artifacts that tend to preclude easy identification of target nucleic acids. Recently, the isothermal SHERLOCK system overcame this problem by using CRISPR to distinguish amplified target sequences from artifactual background signal. However, this system comes at the cost of introducing considerable enzymatic complexity and a corresponding increase in total assay time. Therefore, simpler and less expensive strategies are highly desirable. Here, we demonstrate that by nesting NASBA primers and modifying the NASBA inner primers to encode an RNA Mango aptamer sequence we can dramatically increase the sensitivity of NASBA to 1.5 RNA molecules per microliter. As this isothermal nucleic acid detection scheme directly produces a fluorescent reporter, real-time detection is intrinsic to the assay. Nested Mango NASBA is highly specific and, in contrast to existing RNA detection systems, offers a cheap, simple, and specific way to rapidly detect single-molecule amounts of pathogenic RNA.
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Affiliation(s)
- Amir Abdolahzadeh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Elena V Dolgosheina
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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17
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Panigaj M, Johnson MB, Ke W, McMillan J, Goncharova EA, Chandler M, Afonin KA. Aptamers as Modular Components of Therapeutic Nucleic Acid Nanotechnology. ACS NANO 2019; 13:12301-12321. [PMID: 31664817 PMCID: PMC7382785 DOI: 10.1021/acsnano.9b06522] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Nucleic acids play a central role in all domains of life, either as genetic blueprints or as regulators of various biochemical pathways. The chemical makeup of ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), generally represented by a sequence of four monomers, also provides precise instructions for folding and higher-order assembly of these biopolymers that, in turn, dictate biological functions. The sequence-based specific 3D structures of nucleic acids led to the development of the directed evolution of oligonucleotides, SELEX (systematic evolution of ligands by exponential enrichment), against a chosen target molecule. Among the variety of functions, selected oligonucleotides named aptamers also allow targeting of cell-specific receptors with antibody-like precision and can deliver functional RNAs without a transfection agent. The advancements in the field of customizable nucleic acid nanoparticles (NANPs) opened avenues for the design of nanoassemblies utilizing aptamers for triggering or blocking cell signaling pathways or using aptamer-receptor combinations to activate therapeutic functionalities. A recent selection of fluorescent aptamers enables real-time tracking of NANP formation and interactions. The aptamers are anticipated to contribute to the future development of technologies, enabling an efficient assembly of functional NANPs in mammalian cells or in vivo. These research topics are of top importance for the field of therapeutic nucleic acid nanotechnology with the promises to scale up mass production of NANPs suitable for biomedical applications, to control the intracellular organization of biological materials to enhance the efficiency of biochemical pathways, and to enhance the therapeutic potential of NANP-based therapeutics while minimizing undesired side effects and toxicities.
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Affiliation(s)
- Martin Panigaj
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
- Institute of Biology and Ecology, Faculty of Science, Pavol Jozef Safarik University in Kosice, Kosice 04154, Slovak Republic
| | - M. Brittany Johnson
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Weina Ke
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Jessica McMillan
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Ekaterina A. Goncharova
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
- Laboratory of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 191002, Russian Federation
| | - Morgan Chandler
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
| | - Kirill A. Afonin
- Nanoscale Science Program, Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States
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18
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Chen X, Zhang D, Su N, Bao B, Xie X, Zuo F, Yang L, Wang H, Jiang L, Lin Q, Fang M, Li N, Hua X, Chen Z, Bao C, Xu J, Du W, Zhang L, Zhao Y, Zhu L, Loscalzo J, Yang Y. Visualizing RNA dynamics in live cells with bright and stable fluorescent RNAs. Nat Biotechnol 2019; 37:1287-1293. [PMID: 31548726 DOI: 10.1038/s41587-019-0249-1] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 08/02/2019] [Indexed: 12/15/2022]
Abstract
Fluorescent RNAs (FRs), aptamers that bind and activate fluorescent dyes, have been used to image abundant cellular RNA species. However, limitations such as low brightness and limited availability of dye/aptamer combinations with different spectral characteristics have limited use of these tools in live mammalian cells and in vivo. Here, we develop Peppers, a series of monomeric, bright and stable FRs with a broad range of emission maxima spanning from cyan to red. Peppers allow simple and robust imaging of diverse RNA species in live cells with minimal perturbation of the target RNA's transcription, localization and translation. Quantification of the levels of proteins and their messenger RNAs in single cells suggests that translation is governed by normal enzyme kinetics but with marked heterogeneity. We further show that Peppers can be used for imaging genomic loci with CRISPR display, for real-time tracking of protein-RNA tethering, and for super-resolution imaging. We believe these FRs will be useful tools for live imaging of cellular RNAs.
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Affiliation(s)
- Xianjun Chen
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Dasheng Zhang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Ni Su
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Bingkun Bao
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Xin Xie
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Fangting Zuo
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Lipeng Yang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Hui Wang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Li Jiang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Qiuning Lin
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Mengyue Fang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Ningfeng Li
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Xin Hua
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Zhengda Chen
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Chunyan Bao
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Jinjin Xu
- Key Laboratory of Advanced Control and Optimization for Chemical Processed of Ministry of Education, School of information Science and Engineering, East China University of Science and Technology, Shanghai, China
| | - Wenli Du
- Key Laboratory of Advanced Control and Optimization for Chemical Processed of Ministry of Education, School of information Science and Engineering, East China University of Science and Technology, Shanghai, China
| | - Lixin Zhang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China
| | - Yuzheng Zhao
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China.,School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Linyong Zhu
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China. .,School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China.
| | - Joseph Loscalzo
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Yi Yang
- Optogenetics and Synthetic Biology Interdisciplinary Research Center, State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, East China University of Science and Technology, Shanghai, China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China. .,School of Pharmacy, East China University of Science and Technology, Shanghai, China.
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19
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Cox KJ, Subramanian HKK, Samaniego CC, Franco E, Choudhary A. A universal method for sensitive and cell-free detection of CRISPR-associated nucleases. Chem Sci 2019; 10:2653-2662. [PMID: 30996981 PMCID: PMC6419926 DOI: 10.1039/c8sc03426e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/28/2018] [Indexed: 12/18/2022] Open
Abstract
A multitude of biological applications for CRISPR-associated (Cas) nucleases have propelled the development of robust cell-based methods for quantitation of on- and off-target activities of these nucleases. However, emerging applications of these nucleases require cell-free methods that are simple, sensitive, cost effective, high throughput, multiplexable, and generalizable to all classes of Cas nucleases. Current methods for cell-free detection are cumbersome, expensive, or require sophisticated sequencing technologies, hindering their widespread application beyond the field of life sciences. Developing such cell-free assays is challenging for multiple reasons, including that Cas nucleases are single-turnover enzymes that must be present in large excess over their substrate and that different classes of Cas nucleases exhibit wildly different operating mechanisms. Here, we report the development of a cell-free method wherein Cas nuclease activity is amplified via an in vitro transcription reaction that produces a fluorescent RNA:small-molecule adduct. We demonstrate that our method is sensitive, detecting activity from low nanomolar concentrations of several families of Cas nucleases, and can be conducted in a high-throughput microplate fashion with a simple fluorescent-based readout. We provide a mathematical framework for quantifying the activities of these nucleases and demonstrate two applications of our method, namely the development of a logic circuit and the characterization of an anti-CRISPR protein. We anticipate our method will be valuable to those studying Cas nucleases and will allow the application of Cas nuclease beyond the field of life sciences.
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Affiliation(s)
- Kurt J Cox
- Chemical Biology and Therapeutics Science , Broad Institute of MIT and Harvard , 415 Main Street, Rm 3012 , Cambridge , MA 02142 , USA . ; ; Tel: +1 617 714 7445
- Department of Medicine , Harvard Medical School , Boston , MA 02115 , USA
- Divisions of Renal Medicine and Engineering , Brigham and Women's Hospital , Boston , MA 02115 , USA
| | - Hari K K Subramanian
- Department of Mechanical Engineering , University of California - Riverside , Riverside , CA - 92521 , USA . ; Tel: +1 951 827 2442
| | - Christian Cuba Samaniego
- Department of Mechanical Engineering , University of California - Riverside , Riverside , CA - 92521 , USA . ; Tel: +1 951 827 2442
| | - Elisa Franco
- Department of Mechanical Engineering , University of California - Riverside , Riverside , CA - 92521 , USA . ; Tel: +1 951 827 2442
| | - Amit Choudhary
- Chemical Biology and Therapeutics Science , Broad Institute of MIT and Harvard , 415 Main Street, Rm 3012 , Cambridge , MA 02142 , USA . ; ; Tel: +1 617 714 7445
- Department of Medicine , Harvard Medical School , Boston , MA 02115 , USA
- Divisions of Renal Medicine and Engineering , Brigham and Women's Hospital , Boston , MA 02115 , USA
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20
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Abstract
Diverse mechanisms and functions of posttranscriptional regulation by small regulatory RNAs and RNA-binding proteins have been described in bacteria. In contrast, little is known about the spatial organization of RNAs in bacterial cells. In eukaryotes, subcellular localization and transport of RNAs play important roles in diverse physiological processes, such as embryonic patterning, asymmetric cell division, epithelial polarity, and neuronal plasticity. It is now clear that bacterial RNAs also can accumulate at distinct sites in the cell. However, due to the small size of bacterial cells, RNA localization and localization-associated functions are more challenging to study in bacterial cells, and the underlying molecular mechanisms of transcript localization are less understood. Here, we review the emerging examples of RNAs localized to specific subcellular locations in bacteria, with indications that subcellular localization of transcripts might be important for gene expression and regulatory processes. Diverse mechanisms for bacterial RNA localization have been suggested, including close association to their genomic site of transcription, or to the localizations of their protein products in translation-dependent or -independent processes. We also provide an overview of the state of the art of technologies to visualize and track bacterial RNAs, ranging from hybridization-based approaches in fixed cells to in vivo imaging approaches using fluorescent protein reporters and/or RNA aptamers in single living bacterial cells. We conclude with a discussion of open questions in the field and ongoing technological developments regarding RNA imaging in eukaryotic systems that might likewise provide novel insights into RNA localization in bacteria.
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21
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Fluorogenic RNA Aptamers: A Nano-platform for Fabrication of Simple and Combinatorial Logic Gates. NANOMATERIALS 2018; 8:nano8120984. [PMID: 30486495 PMCID: PMC6315349 DOI: 10.3390/nano8120984] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/16/2018] [Accepted: 11/20/2018] [Indexed: 12/14/2022]
Abstract
RNA aptamers that bind non-fluorescent dyes and activate their fluorescence are highly sensitive, nonperturbing, and convenient probes in the field of synthetic biology. These RNA molecules, referred to as light-up aptamers, operate as molecular nanoswitches that alter folding and fluorescence function in response to ligand binding, which is important in biosensing and molecular computing. Herein, we demonstrate a conceptually new generation of smart RNA nano-devices based on malachite green (MG)-binding RNA aptamer, which fluorescence output controlled by addition of short DNA oligonucleotides inputs. Four types of RNA switches possessing AND, OR, NAND, and NOR Boolean logic functions were created in modular form, allowing MG dye binding affinity to be changed by altering 3D conformation of the RNA aptamer. It is essential to develop higher-level logic circuits for the production of multi-task nanodevices for data processing, typically requiring combinatorial logic gates. Therefore, we further designed and synthetized higher-level half adder logic circuit by “in parallel” integration of two logic gates XOR and AND within a single RNA nanoparticle. The design utilizes fluorescence emissions from two different RNA aptamers: MG-binding RNA aptamer (AND gate) and Broccoli RNA aptamer that binds DFHBI dye (XOR gate). All computationally designed RNA devices were synthesized and experimentally tested in vitro. The ability to design smart nanodevices based on RNA binding aptamers offers a new route to engineer “label-free” ligand-sensing regulatory circuits, nucleic acid detection systems, and gene control elements.
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22
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Shelke SA, Shao Y, Laski A, Koirala D, Weissman BP, Fuller JR, Tan X, Constantin TP, Waggoner AS, Bruchez MP, Armitage BA, Piccirilli JA. Structural basis for activation of fluorogenic dyes by an RNA aptamer lacking a G-quadruplex motif. Nat Commun 2018; 9:4542. [PMID: 30382099 PMCID: PMC6208384 DOI: 10.1038/s41467-018-06942-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 09/26/2018] [Indexed: 12/24/2022] Open
Abstract
The DIR2s RNA aptamer, a second-generation, in-vitro selected binder to dimethylindole red (DIR), activates the fluorescence of cyanine dyes, DIR and oxazole thiazole blue (OTB), allowing detection of two well-resolved emission colors. Using Fab BL3-6 and its cognate hairpin as a crystallization module, we solved the crystal structures of both the apo and OTB-SO3 bound forms of DIR2s at 2.0 Å and 1.8 Å resolution, respectively. DIR2s adopts a compact, tuning fork-like architecture comprised of a helix and two short stem-loops oriented in parallel to create the ligand binding site through tertiary interactions. The OTB-SO3 fluorophore binds in a planar conformation to a claw-like structure formed by a purine base-triple, which provides a stacking platform for OTB-SO3, and an unpaired nucleotide, which partially caps the binding site from the top. The absence of a G-quartet or base tetrad makes the DIR2s aptamer unique among fluorogenic RNAs with known 3D structure. The DIR2s RNA aptamer activates the fluorescence of cyanine dyes allowing detection of two well-resolved emission colors. Here authors solve the crystal structures of the apo and OTB-SO3 fluorophore-bound DIR2s and show how the fluorophore ligand is bound.
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Affiliation(s)
- Sandip A Shelke
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Yaming Shao
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Artur Laski
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Deepak Koirala
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | | | - James R Fuller
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Xiaohong Tan
- Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.,Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Tudor P Constantin
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Alan S Waggoner
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.,Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Marcel P Bruchez
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.,Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.,Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Bruce A Armitage
- Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.,Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Joseph A Piccirilli
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA. .,Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA.
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23
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Lloyd J, Tran CH, Wadhwani K, Cuba Samaniego C, Subramanian HKK, Franco E. Dynamic Control of Aptamer-Ligand Activity Using Strand Displacement Reactions. ACS Synth Biol 2018; 7:30-37. [PMID: 29028334 DOI: 10.1021/acssynbio.7b00277] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nucleic acid aptamers are an expandable toolkit of sensors and regulators. To employ aptamer regulators within nonequilibrium molecular networks, the aptamer-ligand interactions should be tunable over time, so that functions within a given system can be activated or suppressed on demand. This is accomplished through complementary sequences to aptamers, which achieve programmable aptamer-ligand dissociation by displacing the aptamer from the ligand. We demonstrate the effectiveness of our simple approach on light-up aptamers as well as on aptamers inhibiting viral RNA polymerases, dynamically controlling the functionality of the aptamer-ligand complex. Mathematical models allow us to obtain estimates for the aptamer displacement kinetics. Our results suggest that aptamers, paired with their complement, could be used to build dynamic nucleic acid networks with direct control over a variety of aptamer-controllable enzymes and their downstream pathways.
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Affiliation(s)
- Jonathan Lloyd
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Claire H. Tran
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Krishen Wadhwani
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Christian Cuba Samaniego
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Hari K. K. Subramanian
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Elisa Franco
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
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24
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Bouhedda F, Autour A, Ryckelynck M. Light-Up RNA Aptamers and Their Cognate Fluorogens: From Their Development to Their Applications. Int J Mol Sci 2017; 19:ijms19010044. [PMID: 29295531 PMCID: PMC5795994 DOI: 10.3390/ijms19010044] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022] Open
Abstract
An RNA-based fluorogenic module consists of a light-up RNA aptamer able to specifically interact with a fluorogen to form a fluorescent complex. Over the past decade, significant efforts have been devoted to the development of such modules, which now cover the whole visible spectrum, as well as to their engineering to serve in a wide range of applications. In this review, we summarize the different strategies used to develop each partner (the fluorogen and the light-up RNA aptamer) prior to giving an overview of their applications that range from live-cell RNA imaging to the set-up of high-throughput drug screening pipelines. We then conclude with a critical discussion on the current limitations of these modules and how combining in vitro selection with screening approaches may help develop even better molecules.
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Affiliation(s)
- Farah Bouhedda
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
| | - Alexis Autour
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
| | - Michael Ryckelynck
- Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, UPR 9002, F-67000 Strasbourg, France.
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25
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Li C, Tebo AG, Gautier A. Fluorogenic Labeling Strategies for Biological Imaging. Int J Mol Sci 2017; 18:ijms18071473. [PMID: 28698494 PMCID: PMC5535964 DOI: 10.3390/ijms18071473] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 12/27/2022] Open
Abstract
The spatiotemporal fluorescence imaging of biological processes requires effective tools to label intracellular biomolecules in living systems. This review presents a brief overview of recent labeling strategies that permits one to make protein and RNA strongly fluorescent using synthetic fluorogenic probes. Genetically encoded tags selectively binding the exogenously applied molecules ensure high labeling selectivity, while high imaging contrast is achieved using fluorogenic chromophores that are fluorescent only when bound to their cognate tag, and are otherwise dark. Beyond avoiding the need for removal of unbound synthetic dyes, these approaches allow the development of sophisticated imaging assays, and open exciting prospects for advanced imaging, particularly for multiplexed imaging and super-resolution microscopy.
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Affiliation(s)
- Chenge Li
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
| | - Alison G Tebo
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
| | - Arnaud Gautier
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
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26
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Tan X, Constantin TP, Sloane KL, Waggoner AS, Bruchez MP, Armitage BA. Fluoromodules Consisting of a Promiscuous RNA Aptamer and Red or Blue Fluorogenic Cyanine Dyes: Selection, Characterization, and Bioimaging. J Am Chem Soc 2017. [PMID: 28644615 DOI: 10.1021/jacs.7b04211] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
An RNA aptamer selected for binding to the fluorogenic cyanine dye, dimethylindole red (DIR), also binds and activates another cyanine, oxazole thiazole blue (OTB), giving two well-resolved emission colors. The aptamer binds to each dye with submicromolar KD values, and the resulting fluoromodules exhibit fluorescence quantum yields ranging from 0.17 to 0.51 and excellent photostability. The aptamer was fused to a second aptamer previously selected for binding to the epidermal growth factor receptor (EGFR) to create a bifunctional aptamer that labels cell-surface EGFR on mammalian cells. The fluorescent color of the aptamer-labeled EGFR can be switched between blue and red in situ simply by exchanging the dye in the medium. The promiscuity of the aptamer can also be used to distinguish between cell-surface and internalized EGFR on the basis of the addition of red or blue fluorogen at different times.
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Affiliation(s)
- Xiaohong Tan
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
| | - Tudor P Constantin
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
| | - Kelly L Sloane
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
| | - Alan S Waggoner
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
| | - Marcel P Bruchez
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
| | - Bruce A Armitage
- Departments of Chemistry and Biological Sciences, Molecular Biosensor and Imaging Center, and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, United States
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27
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Selection and characterization of dimethylindole red DNA aptamers for the development of light-up fluorescent probes. Talanta 2017; 168:217-221. [PMID: 28391845 DOI: 10.1016/j.talanta.2017.03.041] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 03/16/2017] [Indexed: 01/12/2023]
Abstract
To develop novel label-free light-up probes with improved performance characteristics and low background, we selected DNA aptamers for dimethylindole red (DIR) by a modified affinity chromatography based SELEX method. DIR is an anionic propylsulfonate substituted red-emitting dye derivative of thiazole orange and exhibited weak fluorescence in fluid solution and in the presence of dsDNA. After 14 rounds of selection, a shortened 42-mer DNA aptamer with sub-micromolar dissociation constant (Kd=0.65±0.17μM) was selected. The fluorescent intensity of DIR was dramatically enhanced in the presence of the specific aptamer. The aptamer gave a 140-fold fluorescence enhancement in a saturated concentration. The DIR-aptamer pair could be potentially used as novel light-up fluorescent probe to construct sensors for various applications.
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28
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Kato T, Shimada I, Kimura R, Hyuga M. Light-up fluorophore--DNA aptamer pair for label-free turn-on aptamer sensors. Chem Commun (Camb) 2016; 52:4041-4. [PMID: 26891088 DOI: 10.1039/c5cc08816j] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We developed a light-up fluorophore-DNA aptamer pair for label-free aptamer sensors that fluoresce upon binding to the analyte. A 42mer DNA aptamer binding to the environment-sensitive fluorophore, dapoxyl, which increased the fluorescence by more than 700-fold upon binding, was successfully used to construct aptamer sensors by fusion with analyte-binding DNA aptamers.
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Affiliation(s)
- Teru Kato
- Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
| | - Ippei Shimada
- Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
| | - Ryota Kimura
- Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
| | - Masumi Hyuga
- Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
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29
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Dolgosheina EV, Unrau PJ. Fluorophore-binding RNA aptamers and their applications. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:843-851. [PMID: 27501452 DOI: 10.1002/wrna.1383] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/20/2016] [Accepted: 07/07/2016] [Indexed: 12/21/2022]
Abstract
Why image RNA? Of all the biological molecules, RNA exhibits the most diverse range of functions. Evidence suggests that transcription produces a wide range of noncoding RNAs (ncRNAs), both short (e.g., siRNAs, miRNAs) and long (e.g., telomeric RNAs) that regulate many aspects of gene expression, including the epigenetic processes that underlie cell fate determination, polarization, and morphogenesis. All these functions are realized through the exquisite temporal and spatial control of RNA expression levels and the stability of specific RNAs within well-defined sub-cellular compartments. Given the central importance of RNA in dictating cell behavior via gene-related functions, there is a great demand for RNA imaging methods so as to determine the composition of the cellular 'transcriptome' and to acquire a complete spatial-temporal profile of RNA localization. Recent advances in fluorophore-binding RNA aptamers promise to provide exactly this knowledge, which can ultimately advance our understanding of cell function and behavior in conditions of health and disease, and in response to external stimuli. WIREs RNA 2016, 7:843-851. doi: 10.1002/wrna.1383 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Elena V Dolgosheina
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
| | - Peter J Unrau
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
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30
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Abstract
Seeing is not only believing; it also includes understanding. Cellular imaging with GFP in live cells has been transformative in many research fields. Modulation of cellular regulation is tightly regulated and innovative imaging technologies contribute to further understand cellular signaling and physiology. New types of genetically encoded biosensors have been developed over the last decade. They are RNA aptamers that bind with their cognate fluorogen ligands and activate their fluorescence. The emergence and the evolution of these RNA aptamers as well as their conversion into a wide spectrum of applications are examined in a global way.
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Affiliation(s)
- Jonathan Ouellet
- Department of Chemistry and Physics, Monmouth UniversityWest Long Branch, NJ, USA
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31
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Pfeiffer F, Mayer G. Selection and Biosensor Application of Aptamers for Small Molecules. Front Chem 2016; 4:25. [PMID: 27379229 PMCID: PMC4908669 DOI: 10.3389/fchem.2016.00025] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/30/2016] [Indexed: 12/12/2022] Open
Abstract
Small molecules play a major role in the human body and as drugs, toxins, and chemicals. Tools to detect and quantify them are therefore in high demand. This review will give an overview about aptamers interacting with small molecules and their selection. We discuss the current state of the field, including advantages as well as problems associated with their use and possible solutions to tackle these. We then discuss different kinds of small molecule aptamer-based sensors described in literature and their applications, ranging from detecting drinking water contaminations to RNA imaging.
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Affiliation(s)
- Franziska Pfeiffer
- Department of Chemical Biology, Life and Medical Sciences Institute, University of Bonn Bonn, Germany
| | - Günter Mayer
- Department of Chemical Biology, Life and Medical Sciences Institute, University of Bonn Bonn, Germany
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32
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Abstract
Intracellular trafficking and asymmetric localization of RNA molecules within cells are a prevalent process across phyla involved in developmental control and signaling and thus in the determination of cell fate. In addition to intracellular localization, plants support the trafficking of RNA molecules also between cells through plasmodesmata (PD), which has important roles in the cell-to-cell and systemic communication during plant growth and development. Viruses have developed strategies to exploit the underlying plant RNA transport mechanisms for the cell-to-cell and systemic dissemination of infection. In vivo RNA visualization methods have revolutionized the study of RNA dynamics in living cells. However, their application in plants is still in its infancy. To gain insights into the RNA transport mechanisms in plants, we study the localization and transport of Tobacco mosaic virus RNA using MS2 tagging. This technique involves the tagging of the RNA of interest with repeats of an RNA stem-loop (SL) that is derived from the origin of assembly of the bacteriophage MS2 and recruits the MS2 coat protein (MCP). Thus, expression of MCP fused to a fluorescent marker allows the specific visualization of the SL-carrying RNA. Here we describe a detailed protocol for Agrobacterium tumefaciens-mediated transient expression and in vivo visualization of MS2-tagged mRNAs in Nicotiana benthamiana leaves.
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Affiliation(s)
- E J Peña
- Instituto de Biotecnología y Biología Molecular, CCT-La Plata CONICET, Fac. Cs. Exactas, U.N.L.P., La Plata, Argentina
| | - M Heinlein
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France.
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33
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Autour A, Westhof E, Ryckelynck M. iSpinach: a fluorogenic RNA aptamer optimized for in vitro applications. Nucleic Acids Res 2016; 44:2491-500. [PMID: 26932363 PMCID: PMC4824111 DOI: 10.1093/nar/gkw083] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/01/2016] [Indexed: 01/03/2023] Open
Abstract
Using random mutagenesis and high throughput screening by microfluidic-assisted In Vitro Compartmentalization, we report the isolation of an order of magnitude times brighter mutants of the light-up RNA aptamers Spinach that are far less salt-sensitive and with a much higher thermal stability than the parent molecule. Further engineering gave iSpinach, a molecule with folding and fluorescence properties surpassing those of all currently known aptamer based on the fluorogenic co-factor 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI). We illustrate the potential of iSpinach in a new sensitive and high throughput-compatible fluorogenic assay that measures co-transcriptionally the catalytic constant (kcat) of a model ribozyme.
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Affiliation(s)
- Alexis Autour
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, 15 rue René Descartes, 67084, Strasbourg, France
| | - Eric Westhof
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, 15 rue René Descartes, 67084, Strasbourg, France
| | - Michael Ryckelynck
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de biologie moléculaire et cellulaire du CNRS, 15 rue René Descartes, 67084, Strasbourg, France
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34
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Abstract
RNAs have highly complex and dynamic cellular localization patterns. Technologies for imaging RNA in living cells are important for uncovering their function and regulatory pathways. One approach for imaging RNA involves genetically encoding fluorescent RNAs using RNA mimics of green fluorescent protein (GFP). These mimics are RNA aptamers that bind fluorophores resembling those naturally found in GFP and activate their fluorescence. These RNA-fluorophore complexes, including Spinach, Spinach2, and Broccoli, can be used to tag RNAs and to image their localization in living cells. In this article, we describe the generation and optimization of these aptamers, along with strategies for expanding the spectral properties of their associated RNA-fluorophore complexes. We also discuss the structural basis for the fluorescence and photophysical properties of Spinach, and we describe future prospects for designing enhanced RNA-fluorophore complexes with enhanced photostability and increased sensitivity.
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Affiliation(s)
- Mingxu You
- Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10065; ,
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35
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Wang J, Zhang Y, Wang H, Chen Y, Xu L, Gao T, Pei R. Selection and analysis of DNA aptamers to berberine to develop a label-free light-up fluorescent probe. NEW J CHEM 2016. [DOI: 10.1039/c6nj02290a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three DNA aptamers for berberine were successfully selected and the final shortened 21-mer aptamer showed higher fluorescence enhancement than G-quadruplexes.
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Affiliation(s)
- Jine Wang
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Yajie Zhang
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Hongyan Wang
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Yang Chen
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Lijun Xu
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Tian Gao
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
| | - Renjun Pei
- Key Laboratory of Nano-Bio Interface
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Suzhou
- China
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36
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Ilgu M, Ray J, Bendickson L, Wang T, Geraskin IM, Kraus GA, Nilsen-Hamilton M. Light-up and FRET aptamer reporters; evaluating their applications for imaging transcription in eukaryotic cells. Methods 2015; 98:26-33. [PMID: 26707205 DOI: 10.1016/j.ymeth.2015.12.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 11/19/2022] Open
Abstract
The regulation of RNA transcription is central to cellular function. Changes in gene expression drive differentiation and cellular responses to events such as injury. RNA trafficking can also have a large impact on protein expression and its localization. Thus, the ability to image RNA transcription and trafficking in real time and in living cells is a worthwhile goal that has been difficult to achieve. The availability of "light-up" aptamers that cause an increase in fluorescence of their ligands when bound by the aptamer have shown promise for reporting on RNA production and localization in vivo. Here we have investigated two light-up aptamers (the malachite green aptamer and the Spinach aptamers) for their suitabilities as reporters of RNA expression in vivo using two eukaryotic cell types, yeast and mammalian. Our analysis focused on the aptamer ligands, their contributions to background noise, and the impact of tandem aptamer strings on signal strength and ligand affinity. Whereas the background fluorescence is very low in vitro, this is not always true for cell imaging. Our results suggest the need for caution in using light-up aptamers as reporters for imaging RNA. In particular, images should be collected and analyzed by operators blinded to the sample identities. The appropriate control condition of ligand with the cells in the absence of aptamer expression must be included in each experiment. This control condition establishes that the specific interaction of ligand with aptamer, rather than nonspecific interactions with unknown cell elements, is responsible for the observed fluorescent signals. High background signals due to nonspecific interactions of aptamer ligands with cell components can be minimized by using IMAGEtags (Intracellular Multiaptamer GEnetic tags), which signal by FRET and are promising RNA reporters for imaging transcription.
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Affiliation(s)
- Muslum Ilgu
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, United States
| | - Judhajeet Ray
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, United States
| | - Lee Bendickson
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, United States; Ames Laboratory, US DOE, United States
| | | | | | - George A Kraus
- Department of Chemistry, Ames, IA, United States; Ames Laboratory, US DOE, United States
| | - Marit Nilsen-Hamilton
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, United States; Ames Laboratory, US DOE, United States.
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37
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Jullien L, Gautier A. Fluorogen-based reporters for fluorescence imaging: a review. Methods Appl Fluoresc 2015; 3:042007. [PMID: 29148509 DOI: 10.1088/2050-6120/3/4/042007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fluorescence bioimaging has recently jumped into a new area of spatiotemporal resolution and sensitivity thanks to synergistic advances in both optical physics and probe/biosensor design. This review focuses on the recent development of genetically encodable fluorescent reporters that bind endogenously present or exogenously applied fluorogenic chromophores (so-called fluorogens) and activate their fluorescence. We highlight the innovative engineering and design that gave rise to these new natural and synthetic fluorescent reporters, and describe some of the emerging applications in imaging and biosensing.
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Affiliation(s)
- Ludovic Jullien
- École Normale Supérieure-PSL Research University, Department of Chemistry, 24 rue Lhomond, F-75005 Paris, France. Sorbonne Universités, UPMC Univ Paris 06, UMR 8640 PASTEUR, F-75005 Paris, France. CNRS, UMR 8640 PASTEUR, F-75005 Paris, France
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38
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Hatano A, Shiraishi M, Terado N, Tanabe A, Fukuda K. Enzymatic synthesis and RNA interference of nucleosides incorporating stable isotopes into a base moiety. Bioorg Med Chem 2015; 23:6683-8. [PMID: 26404411 DOI: 10.1016/j.bmc.2015.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/03/2015] [Accepted: 09/04/2015] [Indexed: 11/25/2022]
Abstract
Thymidine phosphorylase was used to catalyze the conversion of thymidine (or methyluridine) and uracil incorporating stable isotopes to deoxyuridine (or uridine) with the uracil base incorporating the stable isotope. These base-exchange reactions proceeded with high conversion rates (75-96%), and the isolated yields were also good (64-87%). The masses of all synthetic compounds incorporating stable isotopes were identical to the theoretical molecular weights via EIMS. (13)C NMR spectra showed spin-spin coupling between (13)C and (15)N in the synthetic compounds, and the signals were split, further proving incorporation of the isotopes into the compounds. The RNA interference effects of this siRNA with uridine incorporating stable isotopes were also investigated. A 25mer siRNA had a strong knockdown effect on the MARCKS protein. The insertion position and number of uridine moieties incorporating stable isotopes introduced into the siRNA had no influence on the silencing of the target protein. This incorporation of stable isotopes into RNA and DNA has the potential to function as a chemically benign tracer in cells.
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Affiliation(s)
- Akihiko Hatano
- Department of Chemistry, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama 337-8570, Japan.
| | - Mitsuya Shiraishi
- Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
| | - Nanae Terado
- Department of Chemistry, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama 337-8570, Japan
| | - Atsuhiro Tanabe
- Department of Chemistry, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama 337-8570, Japan
| | - Kenji Fukuda
- Taiyo Nippon Sanso Corp., 10 Okubo, Tsukuba-shi, Ibaragi 300-2611, Japan
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39
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Arora A, Sunbul M, Jäschke A. Dual-colour imaging of RNAs using quencher- and fluorophore-binding aptamers. Nucleic Acids Res 2015; 43:e144. [PMID: 26175046 PMCID: PMC4666381 DOI: 10.1093/nar/gkv718] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 07/02/2015] [Indexed: 01/12/2023] Open
Abstract
In order to gain deeper insight into the functions and dynamics of RNA in cells, the development of methods for imaging multiple RNAs simultaneously is of paramount importance. Here, we describe a modular approach to image RNA in living cells using an RNA aptamer that binds to dinitroaniline, an efficient general contact quencher. Dinitroaniline quenches the fluorescence of different fluorophores when directly conjugated to them via ethylene glycol linkers by forming a non-fluorescent intramolecular complex. Since the binding of the RNA aptamer to the quencher destroys the fluorophore-quencher complex, fluorescence increases dramatically upon binding. Using this principle, a series of fluorophores were turned into fluorescent turn-on probes by conjugating them to dinitroaniline. These probes ranged from fluorescein-dinitroaniline (green) to TexasRed-dinitroaniline (red) spanning across the visible spectrum. The dinitroaniline-binding aptamer (DNB) was generated by in vitro selection, and was found to bind all probes, leading to fluorescence increase in vitro and in living cells. When expressed in E. coli, the DNB aptamer could be labelled and visualized with different-coloured fluorophores and therefore it can be used as a genetically encoded tag to image target RNAs. Furthermore, combining contact-quenched fluorogenic probes with orthogonal DNB (the quencher-binding RNA aptamer) and SRB-2 aptamers (a fluorophore-binding RNA aptamer) allowed dual-colour imaging of two different fluorescence-enhancing RNA tags in living cells, opening new avenues for studying RNA co-localization and trafficking.
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Affiliation(s)
- Ankita Arora
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
| | - Murat Sunbul
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
| | - Andres Jäschke
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, Heidelberg 69120, Germany
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40
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Sunbul M, Nacheva L, Jäschke A. Proximity-Induced Covalent Labeling of Proteins with a Reactive Fluorophore-Binding Peptide Tag. Bioconjug Chem 2015; 26:1466-9. [PMID: 26086394 DOI: 10.1021/acs.bioconjchem.5b00304] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Labeling of proteins with fluorescent dyes in live cells enables the investigation of their roles in biological systems by fluorescence microscopy. Because the labeling procedure should not disturb the native function of the protein of interest, it is of high importance to find the optimum labeling method for the problem to be studied. Here, we developed a rapid one-step method to covalently and site-specifically label proteins with a TexasRed fluorophore in vitro and in live bacteria. To this end, a genetically encodable TexasRed fluorophore-binding peptide (TR512) was converted into a reactive tag (ReacTR) by adjoining a cysteine residue which rapidly reacts with N-α-chloroacetamide-conjugated TexasRed fluorophore owing to the proximity effect; ReacTR tag first binds to the TexasRed fluorophore and this interaction brings the nucleophilic cysteine and the electrophilic N-α-chloroacetamide groups in close proximity. Our method has several advantages over existing methods: (i) it utilizes a peptide tag much smaller than fluorescent proteins, the SNAP, CLIP, or HaLo tags; (ii) it allows for labeling of proteins with a small, photostable, red-emitting TexasRed fluorophore; (iii) the probe used is very easy to synthesize; (iv) no enzyme is required to transfer the fluorophore to the peptide tag; and (v) labeling yields a stable covalent product in a very fast reaction.
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Affiliation(s)
- Murat Sunbul
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Lora Nacheva
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
| | - Andres Jäschke
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, 69120 Heidelberg, Germany
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41
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Zhang L, Liu H, Shao Y, Lin C, Jia H, Chen G, Yang D, Wang Y. Selective lighting up of epiberberine alkaloid fluorescence by fluorophore-switching aptamer and stoichiometric targeting of human telomeric DNA G-quadruplex multimer. Anal Chem 2015; 87:730-7. [PMID: 25429435 PMCID: PMC5515279 DOI: 10.1021/ac503730j] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Aptamers, that exist naturally in living cells as functional elements and can switch nonfluorescent natural targets to fluorophores, are very useful in developing highly sensitive and selective biosensors and screening functional agents. This work demonstrates that human telomeric G-quadruplex (HTG) can serve as a potential fluorophore-switching aptamer (FSA) to target a natural isoquinoline alkaloid. We found that, among the G-quadruplexes studied here and the various structurally similar alkaloids including epiberberine (EPI), berberine (BER), palmatine (PAL), jatrorrhizine (JAT), coptisine (COP), worenine (WOR), sanguinarine (SAN), chelerythrine (CHE), and nitidine (NIT), only the HTG DNA, especially with a 5'-TA-3' residue at the 5' end of the G-quadruplex tetrad (5'-TAG3(TTAG3)3-3', TA[Q]) as the minimal sequence, is the most efficient FSA to selectively light up the EPI fluorescence. Compared to the 5' end flanking sequences, the 3' end flanking sequences of the tetrad contribute significantly less to the recognition of EPI. The binding affinity of EPI to TA[Q] (K(d) = 37 nM) is at least 20 times tighter than those of the other alkaloids. The steady-state absorption, steady-state/time-resolved fluorescence, and NMR studies demonstrate that EPI most likely interact with the 5' end flanking sequence substructure beyond the core [Q] and the G-quadruplex tetrad in a much more specific manner than the other alkaloids. The highly selective and tight binding of EPI with the FSA and significantly enhanced fluorescence suggest the potential development of a selective EPI sensor (detection limit of 10 nM). More importantly, EPI, as the brightest FSA emitter among the alkaloids, can also serve as an efficient conformation probe for HTG DNA and discriminate the DNA G-quadruplex from the RNA counterpart. Furthermore, EPI can bind stoichiometrically to each G-quadruplex unit of long HTG DNA multimer with the most significant fluorescence enhancement, which has not been achieved by the previously reported probes. Our work suggests the potential use of EPI as a bioimaging probe and a therapeutic DNA binder.
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Affiliation(s)
- Lihua Zhang
- Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Hua Liu
- Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Yong Shao
- Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Clement Lin
- College of Pharmacy, BIO5 Institute, Arizona Cancer Center, Department of Chemistry, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Huan Jia
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Danzhou Yang
- College of Pharmacy, BIO5 Institute, Arizona Cancer Center, Department of Chemistry, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Ying Wang
- Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
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42
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Abstract
We describe design parameters for the synthesis and analytical application of a label-free RNA molecular beacon, termed Spinach.ST. The RNA aptamer Spinach fluoresces upon binding the small-molecule fluorophore DFHBI ((Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one). Spinach has been reengineered by extending its 5'- and 3'-ends to create Spinach.ST, which is predicted to fold into an inactive conformation that fails to bind DHFBI. Hybridization of a trigger oligonucleotide to a designed toehold on Spinach.ST initiates toehold-mediated strand displacement and restores the DFHBI-binding, fluorescence-enhancing conformation of Spinach. The versatile Spinach.ST sensor can detect DNA or RNA trigger sequences and can readily distinguish single-nucleotide mismatches in the trigger toehold. Primer design techniques are described that augment amplicons produced by enzymatic amplification with Spinach.ST triggers. Interaction between these triggers and Spinach.ST molecular beacons leads to the real-time, sequence-specific quantitation of these amplicons. The use of Spinach.ST with isothermal amplification reactions such as nucleic acid sequence-based amplification (NASBA) may enable point-of-care applications. The same design principles could also be used to adapt Spinach reporters to the assay of nonnucleic acid analytes in trans.
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43
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Filonov GS, Moon JD, Svensen N, Jaffrey SR. Broccoli: rapid selection of an RNA mimic of green fluorescent protein by fluorescence-based selection and directed evolution. J Am Chem Soc 2014; 136:16299-308. [PMID: 25337688 PMCID: PMC4244833 DOI: 10.1021/ja508478x] [Citation(s) in RCA: 479] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Genetically
encoded fluorescent ribonucleic acids (RNAs) have diverse
applications, including imaging RNA trafficking and as a component
of RNA-based sensors that exhibit fluorescence upon binding small
molecules in live cells. These RNAs include the Spinach and Spinach2
aptamers, which bind and activate the fluorescence of fluorophores
similar to that found in green fluorescent protein. Although additional
highly fluorescent RNA–fluorophore complexes would extend the
utility of this technology, the identification of novel RNA–fluorophore
complexes is difficult. Current approaches select aptamers on the
basis of their ability to bind fluorophores, even though fluorophore
binding alone is not sufficient to activate fluorescence. Additionally,
aptamers require extensive mutagenesis to efficiently fold and exhibit
fluorescence in living cells. Here we describe a platform for rapid
generation of highly fluorescent RNA–fluorophore complexes
that are optimized for function in cells. This procedure involves
selection of aptamers on the basis of their binding to fluorophores,
coupled with fluorescence-activated cell sorting (FACS) of millions
of aptamers expressed in Escherichia coli. Promising
aptamers are then further optimized using a FACS-based directed evolution
approach. Using this approach, we identified several novel aptamers,
including a 49-nt aptamer, Broccoli. Broccoli binds and activates
the fluorescence of (Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one. Broccoli shows
robust folding and green fluorescence in cells, and increased fluorescence
relative to Spinach2. This reflects, in part, improved folding in
the presence of low cytosolic magnesium concentrations. Thus, this
novel fluorescence-based selection approach simplifies the generation
of aptamers that are optimized for expression and performance in living
cells.
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Affiliation(s)
- Grigory S Filonov
- Department of Pharmacology, Weill Cornell Medical College , New York, New York 10065, United States
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44
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Song W, Strack RL, Svensen N, Jaffrey SR. Plug-and-play fluorophores extend the spectral properties of Spinach. J Am Chem Soc 2014; 136:1198-201. [PMID: 24393009 PMCID: PMC3929357 DOI: 10.1021/ja410819x] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Spinach
and Spinach2 are RNA aptamers that can be used for the
genetic encoding of fluorescent RNA. Spinach2 binds and activates
the fluorescence of (Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (DFHBI), allowing
the dynamic localizations of Spinach2-tagged RNAs to be imaged in
live cells. The spectral properties of Spinach2 are limited by DFHBI,
which produces fluorescence that is bluish-green and is not optimized
for filters commonly used in fluorescence microscopes. Here we characterize
the structural features that are required for fluorophore binding
to Spinach2 and describe novel fluorophores that bind and are switched
to a fluorescent state by Spinach2. These diverse Spinach2–fluorophore
complexes exhibit fluorescence that is more compatible with existing
microscopy filter sets and allows Spinach2-tagged constructs to be
imaged with either GFP or YFP filter cubes. Thus, these “plug-and-play”
fluorophores allow the spectral properties of Spinach2 to be altered
on the basis of the specific spectral needs of the experiment.
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Affiliation(s)
- Wenjiao Song
- Department of Pharmacology, Weill Medical College, Cornell University , New York, New York 10065, United States
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Han KY, Leslie BJ, Fei J, Zhang J, Ha T. Understanding the photophysics of the spinach-DFHBI RNA aptamer-fluorogen complex to improve live-cell RNA imaging. J Am Chem Soc 2013; 135:19033-8. [PMID: 24286188 DOI: 10.1021/ja411060p] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The use of aptamer-fluorogen complexes is an emerging strategy for RNA imaging. Despite its promise for cellular imaging and sensing, the low fluorescence intensity of the Spinach-DFHBI RNA aptamer-fluorogen complex hampers its utility in quantitative live-cell and high-resolution imaging applications. Here we report that illumination of the Spinach-fluorogen complex induces photoconversion and subsequently fluorogen dissociation, leading to fast fluorescence decay and fluorogen-concentration-dependent recovery. The fluorescence lifetime of Spinach-DFHBI is 4.0 ± 0.1 ns irrespective of the extent of photoconversion. We detail a low-repetition-rate illumination scheme that enables us to maximize the potential of the Spinach-DFHBI RNA imaging tag in living cells.
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Affiliation(s)
- Kyu Young Han
- Howard Hughes Medical Institute , Urbana, Illinois 61801, United States
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Sunbul M, Jäschke A. Contact-mediated quenching for RNA imaging in bacteria with a fluorophore-binding aptamer. Angew Chem Int Ed Engl 2013; 52:13401-4. [PMID: 24133044 DOI: 10.1002/anie.201306622] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/05/2013] [Indexed: 01/22/2023]
Affiliation(s)
- Murat Sunbul
- Institut für Pharmazie und Molekulare Biotechnologie, Universität Heidelberg, 69120 Heidelberg (Germany) http://www.jaeschke.uni-hd.de
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Sunbul M, Jäschke A. Contact-Mediated Quenching for RNA Imaging in Bacteria with a Fluorophore-Binding Aptamer. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201306622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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van Nies P, Nourian Z, Kok M, van Wijk R, Moeskops J, Westerlaken I, Poolman JM, Eelkema R, van Esch JH, Kuruma Y, Ueda T, Danelon C. Unbiased Tracking of the Progression of mRNA and Protein Synthesis in Bulk and in Liposome-Confined Reactions. Chembiochem 2013; 14:1963-6. [DOI: 10.1002/cbic.201300449] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Indexed: 12/18/2022]
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Höfer K, Langejürgen LV, Jäschke A. Universal aptamer-based real-time monitoring of enzymatic RNA synthesis. J Am Chem Soc 2013; 135:13692-4. [PMID: 23991672 DOI: 10.1021/ja407142f] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In vitro transcription is an essential laboratory technique for enzymatic RNA synthesis. Unfortunately, no methods exist for analyzing quality and quantity of the synthesized RNA while the transcription proceeds. Here we describe a simple, robust, and universal system for monitoring and quantifying the synthesis of any RNA in real time without interference from abortive transcription byproducts. The distinguishing feature is a universal fluorescence module (UFM), consisting of the eGFP-like Spinach aptamer and a highly active hammerhead ribozyme, which is appended to the RNA of interest (ROI). In the transcription mixture, the primary transcript is cleaved rapidly behind the ROI, thereby releasing always the same UFM, independent of the ROI sequence, polymerase, or promoter used. The UFM binds to the target of the Spinach aptamer, the fluorogenic dye DFHBI, and thereby induces a strong fluorescence signal. This design allows real-time quantification, standardization, parallelization, and high-throughput screening.
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Affiliation(s)
- Katharina Höfer
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University , 69120 Heidelberg, Germany
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Hayashi G, Okamoto A. Probe design for the effective fluorescence imaging of intracellular RNA. CHEM REC 2013; 13:209-17. [PMID: 23495145 DOI: 10.1002/tcr.201200026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Indexed: 01/18/2023]
Abstract
Over the past two decades, the spatiotemporal analysis of fluorescently labeled single RNA species has provided a broad insight into the synthesis, localization, degradation, and transport of RNA. To elucidate the dynamic behavior of functional RNAs in living cells, researchers throughout the world have proposed numerous fluorometric strategies for intracellular RNA imaging. Because, like most other biological molecules, RNA is intrinsically nonfluorescent, the development of methods for the labeling of RNAs of interest with fluorescent molecules is essential. Several artificial tag sequences have been attached onto the 3' end of target RNAs and used as scaffolds for interacting with their fluorescent counterparts. In this Personal Account, we focus on the methods that have been developed to show how RNAs expressed in cells can be labeled and visualized by fluorescent proteins, small molecules, or nucleic acids. Each of these methods is designed to increase the sensitivity and specificity for imaging or to decrease the background fluorescence.
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Affiliation(s)
- Gosuke Hayashi
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Tokyo 153-8904, Japan
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