1
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Park SV, Kang B, Lee M, Yoo H, Jo H, Woo S, Oh SS. In vitro selection of a trans aptamer complex for target-responsive fluorescence activation. Anal Chim Acta 2024; 1301:342465. [PMID: 38553123 DOI: 10.1016/j.aca.2024.342465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/23/2024] [Accepted: 03/10/2024] [Indexed: 04/02/2024]
Abstract
BACKGROUND Most biological molecular complexes consist of multiple functional domains, yet rationally constructing such multifunctional complexes is challenging. Aptamers, the nucleic acid-based functional molecules, can perform multiple tasks including target recognition, conformational changes, and enzymatic activities, while being chemically synthesizable and tunable, and thus provide a basis for engineering enhanced functionalities through combination of multiple units. However, the conventional approach of simply combining aptamer units in a serial manner is susceptible to undesired crosstalk or interference between the aptamer units and to false interactions with non-target molecules; besides, the approach would require additional mechanisms to separate the units if they are desired to function independently. It is clearly a challenge to develop multi-aptamer complexes that preserve independent functions of each unit while avoiding undesired interference and non-specific interactions. RESULTS By directly in vitro selecting a 'trans' aptamer complex, we demonstrate that one aptamer unit ('utility module') can remain hidden or 'inactive' until a target analyte triggers the other unit ('sensing module') and separates the two aptamers. Since the operation of the utility module occurs free from the sensing module, unnecessary crosstalk between the two units can be avoided. Because the utility module is kept inactive until separated from the complex, non-specific interactions of the hidden module with noncognate targets can be naturally prevented. In our demonstration, the sensing module was selected to detect serotonin, a clinically important neurotransmitter, and the target-binding-induced structure-switching of the sensing module reveals and activates the utility module that turns on a fluorescence signal. The aptamer complex exhibited a moderately high affinity and an excellent specificity for serotonin with ∼16-fold discrimination against common neurotransmitter molecules, and displayed strong robustness to perturbations in the design, disallowing nonspecific reactions against various challenges. SIGNIFICANCE This work represents the first example of a trans aptamer complex that was in vitro selected de novo. The trans aptamer complex selected by our strategy does not require chemical modifications or immediate optimization processes to function, because the complex is directly selected to perform desired functions. This strategy should be applicable to a wide range of functional nucleic acid moieties, which will open up diverse applications in biosensing and molecular therapeutics.
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Affiliation(s)
- Soyeon V Park
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea
| | - Byunghwa Kang
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea
| | - Minjong Lee
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea
| | - Hyebin Yoo
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea
| | - Hyesung Jo
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea
| | - Sungwook Woo
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea.
| | - Seung Soo Oh
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 37673, South Korea.
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2
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Akatsu Y, Mutsuro-Aoki H, Tamura K. Development of Allosteric Ribozymes for ATP and l-Histidine Based on the R3C Ligase Ribozyme. Life (Basel) 2024; 14:520. [PMID: 38672790 PMCID: PMC11051094 DOI: 10.3390/life14040520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/02/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
During the evolution of the RNA, short RNAs are thought to have joined together to form long RNAs, enhancing their function as ribozymes. Previously, the artificial R3C ligase ribozyme (73 nucleotides) was successfully reduced to 46 nucleotides; however, its activity decreased significantly. Therefore, we aimed to develop allosteric ribozymes, whose activities could be regulated by effector compounds, based on the reduced R3C ligase ribozyme (R3C-A). Among the variants prepared by fusing an ATP-binding aptamer RNA with R3C-A, one mutant showed increased ligation activity in an ATP-dependent manner. Melting temperature measurements of the two RNA mutants suggested that the region around the aptamer site was stabilized by the addition of ATP. This resulted in a suitable conformation for the reaction at the ligation site. Another ribozyme was prepared by fusing R3C-A with a l-histidine-binding aptamer RNA, and the ligase activity increased with increasing l-histidine concentrations. Both ATP and l-histidine play prominent roles in current molecular biology and the interaction of RNAs and these molecules could be a key step in the evolution of the world of RNAs. Our results suggest promise in the development of general allosteric ribozymes that are independent of the type of effector molecule and provide important clues to the evolution of the RNA world.
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Affiliation(s)
- Yuna Akatsu
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan; (Y.A.); (H.M.-A.)
| | - Hiromi Mutsuro-Aoki
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan; (Y.A.); (H.M.-A.)
| | - Koji Tamura
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan; (Y.A.); (H.M.-A.)
- Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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3
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Kavita K, Breaker RR. Discovering riboswitches: the past and the future. Trends Biochem Sci 2023; 48:119-141. [PMID: 36150954 PMCID: PMC10043782 DOI: 10.1016/j.tibs.2022.08.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 01/25/2023]
Abstract
Riboswitches are structured noncoding RNA domains used by many bacteria to monitor the concentrations of target ligands and regulate gene expression accordingly. In the past 20 years over 55 distinct classes of natural riboswitches have been discovered that selectively sense small molecules or elemental ions, and thousands more are predicted to exist. Evidence suggests that some riboswitches might be direct descendants of the RNA-based sensors and switches that were likely present in ancient organisms before the evolutionary emergence of proteins. We provide an overview of the current state of riboswitch research, focusing primarily on the discovery of riboswitches, and speculate on the major challenges facing researchers in the field.
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Affiliation(s)
- Kumari Kavita
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA.
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4
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Qian S, Chang D, He S, Li Y. Aptamers from random sequence space: Accomplishments, gaps and future considerations. Anal Chim Acta 2022; 1196:339511. [DOI: 10.1016/j.aca.2022.339511] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/12/2022] [Accepted: 01/15/2022] [Indexed: 02/07/2023]
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5
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Czerniak T, Saenz JP. Lipid membranes modulate the activity of RNA through sequence-dependent interactions. Proc Natl Acad Sci U S A 2022; 119:e2119235119. [PMID: 35042820 PMCID: PMC8794826 DOI: 10.1073/pnas.2119235119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/02/2021] [Indexed: 12/11/2022] Open
Abstract
RNA is a ubiquitous biomolecule that can serve as both catalyst and information carrier. Understanding how RNA bioactivity is controlled is crucial for elucidating its physiological roles and potential applications in synthetic biology. Here, we show that lipid membranes can act as RNA organization platforms, introducing a mechanism for riboregulation. The activity of R3C ribozyme can be modified by the presence of lipid membranes, with direct RNA-lipid interactions dependent on RNA nucleotide content, base pairing, and length. In particular, the presence of guanine in short RNAs is crucial for RNA-lipid interactions, and G-quadruplex formation further promotes lipid binding. Lastly, by artificially modifying the R3C substrate sequence to enhance membrane binding, we generated a lipid-sensitive ribozyme reaction with riboswitch-like behavior. These findings introduce RNA-lipid interactions as a tool for developing synthetic riboswitches and RNA-based lipid biosensors and bear significant implications for RNA world scenarios for the origin of life.
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Affiliation(s)
- Tomasz Czerniak
- B CUBE Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
| | - James P Saenz
- B CUBE Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
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6
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Svehlova K, Lukšan O, Jakubec M, Curtis EA. Supernova: A Deoxyribozyme that Catalyzes a Chemiluminescent Reaction. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202109347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Katerina Svehlova
- Institute of Organic Chemistry and Biochemistry ASCR Prague Czech Republic
- Faculty of Science Charles University in Prague Prague Czech Republic
| | - Ondřej Lukšan
- Institute of Organic Chemistry and Biochemistry ASCR Prague Czech Republic
| | - Martin Jakubec
- Institute of Organic Chemistry and Biochemistry ASCR Prague Czech Republic
- Faculty of Science Charles University in Prague Prague Czech Republic
| | - Edward A. Curtis
- Institute of Organic Chemistry and Biochemistry ASCR Prague Czech Republic
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7
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Svehlova K, Lukšan O, Jakubec M, Curtis EA. Supernova: A Deoxyribozyme that Catalyzes a Chemiluminescent Reaction. Angew Chem Int Ed Engl 2021; 61:e202109347. [PMID: 34559935 PMCID: PMC9298802 DOI: 10.1002/anie.202109347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/17/2021] [Indexed: 11/10/2022]
Abstract
Functional DNA molecules are useful components in nanotechnology and synthetic biology. To expand the toolkit of functional DNA parts, in this study we used artificial evolution to identify a glowing deoxyribozyme called Supernova. This deoxyribozyme transfers a phosphate from a 1,2-dioxetane substrate to its 5' hydroxyl group, which triggers a chemiluminescent reaction and a flash of blue light. An engineered version of Supernova is only catalytically active in the presence of an oligonucleotide complementary to its 3' end, demonstrating that light production can be coupled to ligand binding. We anticipate that Supernova will be useful in a wide variety of applications, including as a signaling component in allosterically regulated sensors and in logic gates of molecular computers.
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Affiliation(s)
- Katerina Svehlova
- Institute of Organic Chemistry and Biochemistry ASCR, Prague, Czech Republic.,Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Ondřej Lukšan
- Institute of Organic Chemistry and Biochemistry ASCR, Prague, Czech Republic
| | - Martin Jakubec
- Institute of Organic Chemistry and Biochemistry ASCR, Prague, Czech Republic.,Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Edward A Curtis
- Institute of Organic Chemistry and Biochemistry ASCR, Prague, Czech Republic
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8
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Abstract
Biocatalysis is dominated by protein enzymes, and only a few classes of ribozymes are known to contribute to the task of promoting biochemical transformations. The RNA World theory encompasses the notion that earlier forms of life made use of a much greater diversity of ribozymes and other functional RNAs to guide complex metabolic states long before proteins had emerged in evolution. In recent years, the discoveries of various classes of ribozymes, riboswitches, and other noncoding RNAs in bacteria have provided additional support for the hypothesis that RNA molecules indeed have the catalytic competence to promote diverse chemical reactions without the aid of protein enzymes. Herein, some of the most striking observations made from examinations of natural riboswitches that bind small ligands are highlighted and used as a basis to imagine the characteristics and functions of long-extinct ribozymes from the RNA World.
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Affiliation(s)
- Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Department of Chemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520, United States
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9
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Wrist A, Sun W, Summers RM. The Theophylline Aptamer: 25 Years as an Important Tool in Cellular Engineering Research. ACS Synth Biol 2020; 9:682-697. [PMID: 32142605 DOI: 10.1021/acssynbio.9b00475] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The theophylline aptamer was isolated from an oligonucleotide library in 1994. Since that time, the aptamer has found wide utility, particularly in synthetic biology, cellular engineering, and diagnostic applications. The primary application of the theophylline aptamer is in the construction and characterization of synthetic riboswitches for regulation of gene expression. These riboswitches have been used to control cellular motility, regulate carbon metabolism, construct logic gates, screen for mutant enzymes, and control apoptosis. Other applications of the theophylline aptamer in cellular engineering include regulation of RNA interference and genome editing through CRISPR systems. Here we describe the uses of the theophylline aptamer for cellular engineering over the past 25 years. In so doing, we also highlight important synthetic biology applications to control gene expression in a ligand-dependent manner.
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Affiliation(s)
- Alexandra Wrist
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Wanqi Sun
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Ryan M. Summers
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
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10
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Wang J, Song Q, Guo X, Cui X, Tan L, Dong L. Precise Cross-Dimensional Regulation of the Structure of a Photoreversible DNA Nanoswitch. Anal Chem 2019; 91:14530-14537. [PMID: 31617350 DOI: 10.1021/acs.analchem.9b03547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study, an accurately and digitally regulated allosteric nanoswitch based on the conformational control of two DNA hairpins was developed. By switching between UV irradiation and blue light conditions, the second molecular beacon (H#2) would bind/separate with a repression sequence (RES) via the introduced PTG molecules (a photosensitive azobenzene derivative), resulting in the target aptamer sequence in the first molecular beacon (H#1) not being able/being able to hold the stem-loop configuration, hence losing/regaining the ability to bind with the target. Importantly, we successfully monitor conformation changes of the nanoswitch by an elegant mathematical model for connecting Ki (the dissociation constant between RES and H#2) with Kd (the overall equilibrium constant of the nanoswitch binding the target), hence realizing "observing" DNA structure across dimensions from "structural visualization" to digitization and, accurately, digitally regulating DNA structure from digitization to "structural visualization".
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Affiliation(s)
- Jing Wang
- College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , China.,School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 400044 , China.,Key Laboratory of Low-grade Energy Utilization Technologies & Systems of the Ministry of Education , Chongqing University , Chongqing 40004 , China
| | - Qitao Song
- College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , China.,Peking-Tsinghua Center for Life Sciences , Peking University , 100871 Beijing , China
| | - Xiaogang Guo
- College of Chemistry and Chemical Engineering , Yangtze Normal. University , Chongqing 408100 , China
| | - Xun Cui
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Luxi Tan
- School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 400044 , China.,Key Laboratory of Low-grade Energy Utilization Technologies & Systems of the Ministry of Education , Chongqing University , Chongqing 40004 , China
| | - Lichun Dong
- School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 400044 , China.,Key Laboratory of Low-grade Energy Utilization Technologies & Systems of the Ministry of Education , Chongqing University , Chongqing 40004 , China
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11
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Morse DP, Nevins CE, Aggrey-Fynn J, Bravo RJ, Pfaeffle HOI, Laney JE. Sensitive and specific detection of ligands using engineered riboswitches. J Biotechnol 2018. [PMID: 29518463 DOI: 10.1016/j.jbiotec.2018.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Riboswitches are RNA elements found in non-coding regions of messenger RNAs that regulate gene expression through a ligand-triggered conformational change. Riboswitches typically bind tightly and specifically to their ligands, so they have the potential to serve as highly effective sensors in vitro. In B. subtilis and other gram-positive bacteria, purine nucleotide synthesis is regulated by riboswitches that bind to guanine. We modified the xpt-pbuX guanine riboswitch for use in a fluorescence quenching assay that allowed us to specifically detect and quantify guanine in vitro. Using this assay, we reproducibly detected as little as 5 nM guanine. We then produced sensors for 2'-deoxyguanosine and cyclic diguanylate (c-diGMP) by appending the P1 stem of the guanine riboswitch to the ligand-binding domains of a 2'-deoxyguanosine riboswitch and a c-diGMP riboswitch. These hybrid sensors could detect 15 nM 2'-deoxyguanosine and 3 nM c-diGMP, respectively. Each sensor retained the ligand specificity of its corresponding natural riboswitch. In order to extend the utility of our approach, we developed a strategy for the in vitro selection of sensors with novel ligand specificity. Here we report a proof-of-principle experiment that demonstrated the feasibility of our selection strategy.
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Affiliation(s)
- Daniel P Morse
- Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA.
| | - Colin E Nevins
- Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA
| | - Joana Aggrey-Fynn
- Department of Biochemistry, Cell, and Molecular Biology, University of Ghana, Accra, Ghana
| | - Rick J Bravo
- Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA
| | - Herman O I Pfaeffle
- Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA
| | - Jess E Laney
- Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA
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12
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Felletti M, Hartig JS. Ligand-dependent ribozymes. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27687155 DOI: 10.1002/wrna.1395] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/12/2016] [Accepted: 08/23/2016] [Indexed: 12/20/2022]
Abstract
The discovery of catalytic RNA (ribozymes) more than 30 years ago significantly widened the horizon of RNA-based functions in natural systems. Similarly to the activity of protein enzymes that are often modulated by the presence of an interaction partner, some examples of naturally occurring ribozymes are influenced by ligands that can either act as cofactors or allosteric modulators. Recent discoveries of new and widespread ribozyme motifs in many different genetic contexts point toward the existence of further ligand-dependent RNA catalysts. In addition to the presence of ligand-dependent ribozymes in nature, researchers have engineered ligand dependency into natural and artificial ribozymes. Because RNA functions can often be assembled in a truly modular way, many different systems have been obtained utilizing different ligand-sensing domains and ribozyme activities in diverse applications. We summarize the occurrence of ligand-dependent ribozymes in nature and the many examples realized by researchers that engineered ligand-dependent catalytic RNA motifs. We will also highlight methods for obtaining ligand dependency as well as discuss the many interesting applications of ligand-controlled catalytic RNAs. WIREs RNA 2017, 8:e1395. doi: 10.1002/wrna.1395 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Michele Felletti
- Department of Chemistry and Konstanz Research School of Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Jörg S Hartig
- Department of Chemistry and Konstanz Research School of Chemical Biology, University of Konstanz, Konstanz, Germany
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13
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Menger M, Yarman A, Erdőssy J, Yildiz HB, Gyurcsányi RE, Scheller FW. MIPs and Aptamers for Recognition of Proteins in Biomimetic Sensing. BIOSENSORS 2016; 6:E35. [PMID: 27438862 PMCID: PMC5039654 DOI: 10.3390/bios6030035] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/04/2016] [Accepted: 07/11/2016] [Indexed: 12/12/2022]
Abstract
Biomimetic binders and catalysts have been generated in order to substitute the biological pendants in separation techniques and bioanalysis. The two major approaches use either "evolution in the test tube" of nucleotides for the preparation of aptamers or total chemical synthesis for molecularly imprinted polymers (MIPs). The reproducible production of aptamers is a clear advantage, whilst the preparation of MIPs typically leads to a population of polymers with different binding sites. The realization of binding sites in the total bulk of the MIPs results in a higher binding capacity, however, on the expense of the accessibility and exchange rate. Furthermore, the readout of the bound analyte is easier for aptamers since the integration of signal generating labels is well established. On the other hand, the overall negative charge of the nucleotides makes aptamers prone to non-specific adsorption of positively charged constituents of the sample and the "biological" degradation of non-modified aptamers and ionic strength-dependent changes of conformation may be challenging in some application.
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Affiliation(s)
- Marcus Menger
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, Potsdam D-14476, Germany.
| | - Aysu Yarman
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 25-26, Potsdam D-14476, Germany.
- Turkish-German University, Faculty of Science, Molecular Biotechnology, Sahinkaya Cad. No. 86, Bekoz, Istanbul 34820, Turkey.
| | - Júlia Erdőssy
- MTA-BME "Lendület" Chemical Nanosensors Research Group, Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, Budapest H-1111, Hungary.
| | - Huseyin Bekir Yildiz
- Department of Materials Science and Nanotechnology Engineering, KTO Karatay University, Konya 42020, Turkey.
| | - Róbert E Gyurcsányi
- MTA-BME "Lendület" Chemical Nanosensors Research Group, Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, Budapest H-1111, Hungary.
| | - Frieder W Scheller
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, Potsdam D-14476, Germany.
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 25-26, Potsdam D-14476, Germany.
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14
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Martini L, Meyer AJ, Ellefson JW, Milligan JN, Forlin M, Ellington AD, Mansy SS. In Vitro Selection for Small-Molecule-Triggered Strand Displacement and Riboswitch Activity. ACS Synth Biol 2015; 4:1144-50. [PMID: 25978303 DOI: 10.1021/acssynbio.5b00054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An in vitro selection method for ligand-responsive RNA sensors was developed that exploited strand displacement reactions. The RNA library was based on the thiamine pyrophosphate (TPP) riboswitch, and RNA sequences capable of hybridizing to a target duplex DNA in a TPP regulated manner were identified. After three rounds of selection, RNA molecules that mediated a strand exchange reaction upon TPP binding were enriched. The enriched sequences also showed riboswitch activity. Our results demonstrated that small-molecule-responsive nucleic acid sensors can be selected to control the activity of target nucleic acid circuitry.
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Affiliation(s)
- Laura Martini
- CIBIO, University of Trento, Via Sommarive 9, 38123 Povo, Italy
| | - Adam J. Meyer
- Department
of Chemistry and Biochemistry, Institute for Cellular and Molecular
Biology, Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jared W. Ellefson
- Department
of Chemistry and Biochemistry, Institute for Cellular and Molecular
Biology, Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - John N. Milligan
- Department
of Chemistry and Biochemistry, Institute for Cellular and Molecular
Biology, Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Michele Forlin
- CIBIO, University of Trento, Via Sommarive 9, 38123 Povo, Italy
| | - Andrew D. Ellington
- Department
of Chemistry and Biochemistry, Institute for Cellular and Molecular
Biology, Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Sheref S. Mansy
- CIBIO, University of Trento, Via Sommarive 9, 38123 Povo, Italy
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15
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Peselis A, Gao A, Serganov A. Cooperativity, allostery and synergism in ligand binding to riboswitches. Biochimie 2015; 117:100-9. [PMID: 26143008 DOI: 10.1016/j.biochi.2015.06.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 06/29/2015] [Indexed: 01/04/2023]
Abstract
Recent progress in identification and characterization of novel types of non-coding RNAs has proven that RNAs carry out a variety of cellular functions ranging from scaffolding to gene expression control. In both prokaryotic and eukaryotic cells, several classes of non-coding RNAs control expression of dozens of genes in response to specific cues. One of the most interesting and outstanding questions in the RNA field is whether regulatory RNAs are capable of employing basic biological concepts, such as allostery and cooperativity, previously attributed to the function of proteins. Aside from regulatory RNAs that form complementary base pairing with their nucleic acid targets, several RNA classes modulate gene expression via molecular mechanisms which can be paralleled to protein-mediated regulation. Among these RNAs are riboswitches, metabolite-sensing non-coding regulatory elements that adopt intrinsic three-dimensional structures and specifically bind various small molecule ligands. These characteristics of riboswitches make them well-suited for complex regulatory responses observed in allosteric and cooperative protein systems. Here we present an overview of the biochemical, genetic, and structural studies of riboswitches with a major focus on complex regulatory mechanisms and biological principles utilized by riboswitches for such genetic modulation.
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Affiliation(s)
- Alla Peselis
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ang Gao
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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Abstract
An RNA World that predated the modern world of polypeptide and polynucleotide is one of the most widely accepted models in origin of life research. In this model, the translation system shepherded the RNA World into the extant biology of DNA, RNA, and protein. Here, we examine the RNA World Hypothesis in the context of increasingly detailed information available about the origins, evolution, functions, and mechanisms of the translation system. We conclude that the translation system presents critical challenges to RNA World Hypotheses. Firstly, a timeline of the RNA World is problematic when the ribosome is incorporated. The mechanism of peptidyl transfer of the ribosome appears distinct from evolved enzymes, signaling origins in a chemical rather than biological milieu. Secondly, we have no evidence that the basic biochemical toolset of life is subject to substantive change by Darwinian evolution, as required for the transition from the RNA world to extant biology. Thirdly, we do not see specific evidence for biological takeover of ribozyme function by protein enzymes. Finally, we can find no basis for preservation of the ribosome as ribozyme or the universality of translation, if it were the case that other information transducing ribozymes, such as ribozyme polymerases, were replaced by protein analogs and erased from the phylogenetic record. We suggest that an updated model of the RNA World should address the current state of knowledge of the translation system.
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Sengupta A, Gavvala K, Koninti RK, Hazra P. Role of Mg²⁺ ions in flavin recognition by RNA aptamer. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 140:240-8. [PMID: 25173759 DOI: 10.1016/j.jphotobiol.2014.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 07/24/2014] [Accepted: 08/10/2014] [Indexed: 11/17/2022]
Abstract
The role of Mg(2+) ion in flavin (flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN)) recognition by RNA aptamer has been explored through steady state and time-resolved fluorescence, circular dichroism (CD), thermal melting (TM) and isothermal titration calorimetry (ITC) studies. A strong quenching of flavin emission is detected due to stacking interaction with the nucleobases in the mismatched region of aptamer, and it enhances manifold with increasing Mg(2+) concentrations. A comparatively lower binding affinity toward FAD compared to FMN is attributed to the presence of intramolecular 'stack' conformer of FAD, which cannot participate in the intermolecular stacking interactions with the nucleobases. CD and TM studies predict that flavin detection causes structural reformation of RNA aptamer. ITC results indicate that flavin detection is thermodynamically feasible and highly enthalpy driven.
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Affiliation(s)
- Abhigyan Sengupta
- Department of Chemistry, Mendeleev Block, Indian Institute of Science Education and Research (IISER)-Pune, Pune 411008, Maharashtra, India
| | - Krishna Gavvala
- Department of Chemistry, Mendeleev Block, Indian Institute of Science Education and Research (IISER)-Pune, Pune 411008, Maharashtra, India
| | - Raj Kumar Koninti
- Department of Chemistry, Mendeleev Block, Indian Institute of Science Education and Research (IISER)-Pune, Pune 411008, Maharashtra, India
| | - Partha Hazra
- Department of Chemistry, Mendeleev Block, Indian Institute of Science Education and Research (IISER)-Pune, Pune 411008, Maharashtra, India.
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Sett A, Das S, Bora U. Functional nucleic-acid-based sensors for environmental monitoring. Appl Biochem Biotechnol 2014; 174:1073-91. [PMID: 24903959 DOI: 10.1007/s12010-014-0990-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 05/19/2014] [Indexed: 01/16/2023]
Abstract
Efforts to replace conventional chromatographic methods for environmental monitoring with cheaper and easy to use biosensors for precise detection and estimation of hazardous environmental toxicants, water or air borne pathogens as well as various other chemicals and biologics are gaining momentum. Out of the various types of biosensors classified according to their bio-recognition principle, nucleic-acid-based sensors have shown high potential in terms of cost, sensitivity, and specificity. The discovery of catalytic activities of RNA (ribozymes) and DNA (DNAzymes) which could be triggered by divalent metallic ions paved the way for their extensive use in detection of heavy metal contaminants in environment. This was followed with the invention of small oligonucleotide sequences called aptamers which can fold into specific 3D conformation under suitable conditions after binding to target molecules. Due to their high affinity, specificity, reusability, stability, and non-immunogenicity to vast array of targets like small and macromolecules from organic, inorganic, and biological origin, they can often be exploited as sensors in industrial waste management, pollution control, and environmental toxicology. Further, rational combination of the catalytic activity of DNAzymes and RNAzymes along with the sequence-specific binding ability of aptamers have given rise to the most advanced form of functional nucleic-acid-based sensors called aptazymes. Functional nucleic-acid-based sensors (FNASs) can be conjugated with fluorescent molecules, metallic nanoparticles, or quantum dots to aid in rapid detection of a variety of target molecules by target-induced structure switch (TISS) mode. Although intensive research is being carried out for further improvements of FNAs as sensors, challenges remain in integrating such bio-recognition element with advanced transduction platform to enable its use as a networked analytical system for tailor made analysis of environmental monitoring.
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Affiliation(s)
- Arghya Sett
- Bioengineering Research Laboratory, Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
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Romero-López C, Díaz-González R, Berzal-Herranz A. RNA Selection and EvolutionIn Vitro:Powerful Techniques for the Analysis and Identification of new Molecular Tools. BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.2007.10817461] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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20
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Porchetta A, Vallée-Bélisle A, Plaxco KW, Ricci F. Using distal-site mutations and allosteric inhibition to tune, extend, and narrow the useful dynamic range of aptamer-based sensors. J Am Chem Soc 2012; 134:20601-4. [PMID: 23215257 PMCID: PMC3866043 DOI: 10.1021/ja310585e] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Here we demonstrate multiple, complementary approaches by which to tune, extend, or narrow the dynamic range of aptamer-based sensors. Specifically, we employ both distal-site mutations and allosteric control to tune the affinity and dynamic range of a fluorescent aptamer beacon. We show that allosteric control, achieved by using a set of easily designed oligonucleotide inhibitors that competes against the folding of the aptamer, allows rational fine-tuning of the affinity of our model aptamer across 3 orders of magnitude of target concentration with greater precision than that achieved using mutational approaches. Using these methods, we generate sets of aptamers varying significantly in target affinity and then combine them to recreate several of the mechanisms employed by nature to narrow or broaden the dynamic range of biological receptors. Such ability to finely control the affinity and dynamic range of aptamers may find many applications in synthetic biology, drug delivery, and targeted therapies, fields in which aptamers are of rapidly growing importance.
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Affiliation(s)
- Alessandro Porchetta
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
- Consorzio Interuniversitario Biostrutture e Biosistemi “INBB”, Rome, Italy
| | - Alexis Vallée-Bélisle
- Department of Chemistry and Biochemistry University of California, Santa Barbara, CA 93106 USA
- Center for Bioengineering, University of California, Santa Barbara, CA 93106 USA
- Laboratory of Biosensors & Nanomachines, Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California, Santa Barbara, CA 93106 USA
- Center for Bioengineering, University of California, Santa Barbara, CA 93106 USA
- Interdepartmental Program in Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106 USA
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
- Consorzio Interuniversitario Biostrutture e Biosistemi “INBB”, Rome, Italy
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Giambaşu GM, Lee TS, Scott WG, York DM. Mapping L1 ligase ribozyme conformational switch. J Mol Biol 2012; 423:106-22. [PMID: 22771572 DOI: 10.1016/j.jmb.2012.06.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 05/21/2012] [Accepted: 06/25/2012] [Indexed: 01/10/2023]
Abstract
L1 ligase (L1L) molecular switch is an in vitro optimized synthetic allosteric ribozyme that catalyzes the regioselective formation of a 5'-to-3' phosphodiester bond, a reaction for which there is no known naturally occurring RNA catalyst. L1L serves as a proof of principle that RNA can catalyze a critical reaction for prebiotic RNA self-replication according to the RNA world hypothesis. L1L crystal structure captures two distinct conformations that differ by a reorientation of one of the stems by around 80Å and are presumed to correspond to the active and inactive state, respectively. It is of great interest to understand the nature of these two states in solution and the pathway for their interconversion. In this study, we use explicit solvent molecular simulation together with a novel enhanced sampling method that utilizes concepts from network theory to map out the conformational transition between active and inactive states of L1L. We find that the overall switching mechanism can be described as a three-state/two-step process. The first step involves a large-amplitude swing that reorients stem C. The second step involves the allosteric activation of the catalytic site through distant contacts with stem C. Using a conformational space network representation of the L1L switch transition, it is shown that the connection between the three states follows different topographical patterns: the stem C swing step passes through a narrow region of the conformational space network, whereas the allosteric activation step covers a much wider region and a more diverse set of pathways through the network.
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Affiliation(s)
- George M Giambaşu
- BioMaPS Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
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22
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Abstract
Ribozymes are RNA molecules that act as chemical catalysts. In contemporary cells, most known ribozymes carry out phosphoryl transfer reactions. The nucleolytic ribozymes comprise a class of five structurally-distinct species that bring about site-specific cleavage by nucleophilic attack of the 2'-O on the adjacent 3'-P to form a cyclic 2',3'-phosphate. In general, they will also catalyse the reverse reaction. As a class, all these ribozymes appear to use general acid-base catalysis to accelerate these reactions by about a million-fold. In the Varkud satellite ribozyme, we have shown that the cleavage reaction is catalysed by guanine and adenine nucleobases acting as general base and acid, respectively. The hairpin ribozyme most probably uses a closely similar mechanism. Guanine nucleobases appear to be a common choice of general base, but the general acid is more variable. By contrast, the larger ribozymes such as the self-splicing introns and RNase P act as metalloenzymes.
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Affiliation(s)
- David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, MSI/WTB Complex, Dow Street, Dundee DD1 5EH, UK.
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23
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Nakano S, Mashima T, Matsugami A, Inoue M, Katahira M, Morii T. Structural aspects for the recognition of ATP by ribonucleopeptide receptors. J Am Chem Soc 2011; 133:4567-79. [PMID: 21370890 DOI: 10.1021/ja110725d] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A modular structure of ribonucleopeptide (RNP) affords a framework to construct macromolecular receptors and fluorescent sensors. We have isolated ATP-binding RNP with the minimum of nucleotides for ATP binding, in which the RNA consensus sequence is different from those reported for RNA aptamers against the ATP analogues. The three-dimensional structure of the substrate-binding complex of RNP was studied to understand the ATP-binding mechanism of RNP. A combination of NMR measurements, enzymatic and chemical mapping, and nucleotide mutation studies of the RNP-adenosine complex show that RNP interacts with the adenine ring of adenosine by forming a U:A:U triple with two invariant U nucleotides. The observed recognition mode for the adenine ring is different from those of RNA aptamers for ATP derivatives reported previously. The RNP-adenosine complex is folded into a particular structure by formation of the U:A:U triple and a Hoogsteen type A:U base pair. This recognition mechanism was successfully utilized to convert the substrate-binding specificity of RNP from ATP- to GTP-binding with a C(+):G:C triple recognition mode.
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Affiliation(s)
- Shun Nakano
- Institute of Advanced Energy, Kyoto University, Japan
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24
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Functional Nucleic Acids for Fluorescence-Based Biosensing Applications. ADVANCED FLUORESCENCE REPORTERS IN CHEMISTRY AND BIOLOGY III 2011. [DOI: 10.1007/978-3-642-18035-4_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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25
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Burke DH, Rhee SS. Assembly and activation of a kinase ribozyme. RNA (NEW YORK, N.Y.) 2010; 16:2349-2359. [PMID: 20935068 PMCID: PMC2995397 DOI: 10.1261/rna.2302810] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 08/30/2010] [Indexed: 05/30/2023]
Abstract
RNA activities can be regulated by modulating the relative energies of all conformations in a folding landscape; however, it is often unknown precisely how peripheral elements perturb the overall landscape in the absence of discrete alternative folds (inactive ensemble). This work explores the effects of sequence and secondary structure in governing kinase ribozyme activity. Kin.46 catalyzes thiophosphoryl transfer from ATPγS onto the 5' hydroxyl of polynucleotide substrates, and is regulated 10,000-fold by annealing an effector oligonucleotide to form activator helix P4. Transfer kinetics for an extensive series of ribozyme variants identified several dispensable internal single-stranded segments, in addition to a potential pseudoknot at the active site between segments J1/4 and J3/2 that is partially supported by compensatory rescue. Standard allosteric mechanisms were ruled out, such as formation of discrete repressive structures or docking P4 into the rest of the ribozyme via backbone 2' hydroxyls. Instead, P4 serves both to complete an important structural element (100-fold contribution to the reaction relative to a P4-deleted variant) and to mitigate nonspecific, inhibitory effects of the single-stranded tail (an additional 100-fold contribution to the apparent rate constant, k(obs)). Thermodynamic activation parameters ΔH(‡) and ΔS(‡), calculated from the temperature dependence of k(obs), varied with tail length and sequence. Inhibitory effects of the unpaired tail are largely enthalpic for short tails and are both enthalpic and entropic for longer tails. These results refine the structural view of this kinase ribozyme and highlight the importance of nonspecific ensemble effects in conformational regulation by peripheral elements.
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Affiliation(s)
- Donald H Burke
- Department of Molecular Microbiology & Immunology, University of Missouri, Columbia, Missouri 65211, USA.
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26
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Abstract
Aptamers are DNA or RNA oligonucleotides that can bind with high affinity and specificity to a wide range of targets such as proteins, metal ions or pathogenic microorganisms. Soluble aptamers and aptazymes have been used as sensing elements for developing homogeneous assays in a solution phase, the whole sensing process being carried out in a homogeneous solution. Contrary to most conventional heterogeneous assays that are time-consuming and labor-intensive, aptamer-based homogeneous assays are simple, easy-to-perform, rapid and do not require immobilization nor washing steps. To our knowledge, this review is the first entirely dedicated to aptamer-based homogeneous assays. Optical detection appears as the most developed technique. Colorimetry represents the simplest sensing mode that occupies a very important position among aptamer-based assays, involving gold nanoparticle aggregation (with unmodified or aptamer-modified gold NPs), the formation of HRP-mimicking DNAzyme with hemin, dye displacement or interactions with a cationic polymer. Fluorescence that is highly sensitive offers the most developed detection mode. Aptamers can be labeled or not, to give rise to turn-on or usually less sensitive turn-off fluorescent assays. Newly reported and thus less developed non-conventional magnetic resonance imaging (MRI) and electrochemistry also recently appeared in the literature, thrombin still remains the main detected target. Homogeneous assays based on aptazyme, an aptamer sequence connected to a known ribozyme motif, are also described in this review, involving optical detection, by colorimetry or fluorescence.
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Affiliation(s)
- Audrey Sassolas
- CNRS, UMR 5246, ICBMS, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Génie Enzymatique, Membranes Biomimétiques et Assemblages Supramoléculaires (GEMBAS), Université Lyon 1, Bât CPE, 43 boulevard du 11 novembre 1918, Villeurbanne, F-69622, France
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In vitro selection of structure-switching, self-reporting aptamers. Proc Natl Acad Sci U S A 2010; 107:14053-8. [PMID: 20660786 DOI: 10.1073/pnas.1009172107] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We describe an innovative selection approach to generate self-reporting aptamers (SRAs) capable of converting target-binding events into fluorescence readout without requiring additional modification, optimization, or the use of DNA helper strands. These aptamers contain a DNAzyme moiety that is initially maintained in an inactive conformation. Upon binding to their target, the aptamers undergo a structural switch that activates the DNAzyme, such that the binding event can be reported through significantly enhanced fluorescence produced by a specific stacking interaction between the active-conformation DNAzyme and a small molecule dye, N-methylmesoporphyrin IX. We demonstrate a purely in vitro selection-based approach for obtaining SRAs that function in both buffer and complex mixtures such as blood serum; after 15 rounds of selection with a structured DNA library, we were able to isolate SRAs that possess low nanomolar affinity and strong specificity for thrombin. Given ongoing progress in the engineering and characterization of functional DNA/RNA molecules, strategies such as ours have the potential to enable rapid, efficient, and economical isolation of nucleic acid molecules with diverse functionalities.
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Giambasu GM, Lee TS, Sosa CP, Robertson MP, Scott WG, York DM. Identification of dynamical hinge points of the L1 ligase molecular switch. RNA (NEW YORK, N.Y.) 2010; 16:769-780. [PMID: 20167653 PMCID: PMC2844624 DOI: 10.1261/rna.1897810] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 12/19/2009] [Indexed: 05/28/2023]
Abstract
The L1 ligase is an in vitro selected ribozyme that uses a noncanonically base-paired ligation site to catalyze regioselectively and regiospecifically the 5' to 3' phosphodiester bond ligation, a reaction relevant to origin of life hypotheses that invoke an RNA world scenario. The L1 ligase crystal structure revealed two different conformational states that were proposed to represent the active and inactive forms. It remains an open question as to what degree these two conformers persist as stable conformational intermediates in solution, and along what pathway are they able to interconvert. To explore these questions, we have performed a series of molecular dynamics simulations in explicit solvent of the inactive-active conformational switch in L1 ligase. Four simulations were performed departing from both conformers in both the reactant and product states, in addition to a simulation where local unfolding in the active state was induced. From these simulations, along with crystallographic data, a set of four virtual torsion angles that span two evolutionarily conserved and restricted regions were identified as dynamical hinge points in the conformational switch transition. The ligation site visits three distinct states characterized by hydrogen bond patterns that are correlated with the formation of specific contacts that may promote catalysis. The insights gained from these simulations contribute to a more detailed understanding of the coupled catalytic/conformational switch mechanism of L1 ligase that may facilitate the design and engineering of new catalytic riboswitches.
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Affiliation(s)
- George M Giambasu
- Biomedical Informatics and Computational Biology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Abel DL. The Universal Plausibility Metric (UPM) & Principle (UPP). Theor Biol Med Model 2009; 6:27. [PMID: 19958539 PMCID: PMC2796651 DOI: 10.1186/1742-4682-6-27] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 12/03/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mere possibility is not an adequate basis for asserting scientific plausibility. A precisely defined universal bound is needed beyond which the assertion of plausibility, particularly in life-origin models, can be considered operationally falsified. But can something so seemingly relative and subjective as plausibility ever be quantified? Amazingly, the answer is, "Yes." A method of objectively measuring the plausibility of any chance hypothesis (The Universal Plausibility Metric [UPM]) is presented. A numerical inequality is also provided whereby any chance hypothesis can be definitively falsified when its UPM metric of xi is < 1 (The Universal Plausibility Principle [UPP]). Both UPM and UPP pre-exist and are independent of any experimental design and data set. CONCLUSION No low-probability hypothetical plausibility assertion should survive peer-review without subjection to the UPP inequality standard of formal falsification (xi < 1).
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Affiliation(s)
- David L Abel
- Department of ProtoBioCybernetics/ProtoBioSemiotics, The Gene Emergence Project of The Origin of Life Science Foundation, Inc, 113-120 Hedgewood Dr, Greenbelt, MD 20770-1610, USA.
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31
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Affiliation(s)
- Juewen Liu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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Autocatalytic aptazymes enable ligand-dependent exponential amplification of RNA. Nat Biotechnol 2009; 27:288-92. [PMID: 19234448 PMCID: PMC2695811 DOI: 10.1038/nbt.1528] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 01/30/2009] [Indexed: 01/03/2023]
Abstract
RNA enzymes have been developed that undergo self-sustained replication at a constant temperature in the absence of proteins1. These RNA molecules amplify exponentially through a cross-replicative process, whereby two enzymes catalyze each other’s synthesis by joining component oligonucleotides. Other RNA enzymes have been made to operate in a ligand-dependent manner by combining a catalytic domain with a ligand-binding domain (aptamer) to provide an “aptazyme”2,3. The principle of ligand-dependent RNA catalysis now has been extended to the cross-replicating RNA enzymes so that exponential amplification occurs in the presence, but not the absence, of the cognate ligand. The exponential growth rate of the RNA depends on the concentration of the ligand, enabling one to determine the concentration of ligand in a sample. This process is analogous to quantitative PCR (qPCR), but can be generalized to a wide variety of targets, including proteins and small molecules that are relevant to medical diagnostics and environmental monitoring.
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Hayashi G, Hagihara M, Nakatani K. RNA aptamers that reversibly bind photoresponsive azobenzene-containing peptides. Chemistry 2009; 15:424-32. [PMID: 19035601 DOI: 10.1002/chem.200800936] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Modulation of biological networks assembled by diverse interactions among biologically active molecules has provided a platform for innovative biotechnologies. Here, we report RNA aptamers that bind to a photoresponsive peptide (KRAzR; Lys-Arg-azobenzene-Arg) containing azobenzene chromophore, which can change its structure by photoirradiation. Aptamers were identified after 10 cycles of an in vitro selection procedure starting with a DNA library containing a 70 nt random region. Surface plasmon resonance (SPR) analysis demonstrated that interactions between aptamers and KRAzR were fully controlled by appropriate photoirradiation to the SPR sensor chip. Upon irradiation of 360 nm on the KRAzR-immobilized surface, the binding of each aptamer to the surface was significantly decreased. Subsequent photoirradiation of the same surface with 430 nm restored the aptamer binding to the surface. We also observed that direct photoirradiation of the aptamer-peptide complex on a gold surface actively promoted dissociation of the complex. Furthermore, a doped reselection method was applied to acquire structural and sequence information of aptamer 66. From a data analysis of the conserved region and the mutation frequency, we were able to select a plausible secondary structure among three candidates predicted by computational folding simulation.
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Affiliation(s)
- Gosuke Hayashi
- Department of Regulatory Bioorganic Chemistry, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
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Ogawa A, Maeda M. A novel label-free biosensor using an aptazyme-suppressor-tRNA conjugate and an amber mutated reporter gene. Chembiochem 2009; 9:2204-8. [PMID: 18756550 DOI: 10.1002/cbic.200800294] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Atsushi Ogawa
- Bioengineering Laboratory, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Furchak JRW, Yang P, Jennings C, Walter NG, Kennedy RT. Assay for glucosamine 6-phosphate using a ligand-activated ribozyme with fluorescence resonance energy transfer or CE-laser-induced fluorescence detection. Anal Chem 2008; 80:8195-201. [PMID: 18842060 DOI: 10.1021/ac801410k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A naturally occurring aptazyme, the glmS ribozyme, is adapted to an assay for glucosamine 6-phosphate, an effector molecule for the aptazyme. In the assay, binding of analyte allosterically activates aptazyme to cleave a fluorescently labeled oligonucleotide substrate. The extent of reaction, and hence analyte concentration, is detected by either fluorescence resonance energy transfer (FRET) or capillary electrophoresis with laser-induced fluorescence (CE-LIF). With FRET, assay signal is the rate of increase in FRET in presence of analyte. With CE-LIF, the assay signal is the peak height of cleavage product formed after a fixed incubation time. The assay has a linear response up to 100 (CE-LIF) or 500 microM (FRET) and detection limit of approximately 500 nM for glucosamine 6-phosphate under single-turnover conditions. When substrate is present in excess of the aptazyme, it is possible to amplify the signal by multiple turnovers to achieve a 13-fold improvement in sensitivity and detection limit of 50 nM. Successful signal amplification requires a temperature cycle to alternately dissociate cleaved substrate and allow fresh substrate to bind aptazyme. The results show that aptazymes have potential utility as analytical reagents for quantification of effector molecules.
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Affiliation(s)
- Jennifer R W Furchak
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA
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Famulok M, Hartig JS, Mayer G. Functional aptamers and aptazymes in biotechnology, diagnostics, and therapy. Chem Rev 2007; 107:3715-43. [PMID: 17715981 DOI: 10.1021/cr0306743] [Citation(s) in RCA: 673] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Michael Famulok
- LIMES Institute, Program Unit Chemical Biology and Medicinal Chemistry, c/o Kekulé-Institut für Organische Chemie und Biochemie, Gerhard Domagk-Strasse 1, 53121 Bonn, Germany.
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Lee HW, Robinson SG, Bandyopadhyay S, Mitchell RH, Sen D. Reversible photo-regulation of a hammerhead ribozyme using a diffusible effector. J Mol Biol 2007; 371:1163-73. [PMID: 17619022 DOI: 10.1016/j.jmb.2007.06.042] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 06/07/2007] [Accepted: 06/12/2007] [Indexed: 11/19/2022]
Abstract
The potential utility of catalytic RNAs and DNAs (ribozymes and deoxyribozymes, respectively) as reagents in molecular biology as well as therapeutic agents for a variety of human diseases, has long been recognized. Although naturally occurring RNA-cleaving ribozymes are typically not subject to feedback control, rational methodologies for the creation of allosteric ribozymes, by functional combination of ribozyme and ligand-responsive aptamer RNA elements, have existed for some years. Here, we report the in vitro selection of RNA aptamers specific for binding one but not the other of two light-induced isomers of a dihydropyrene photo-switch compound, and the utilization of such an aptamer for the construction of the UG-dihydropyrene ribozyme, an allosteric hammerhead ribozyme whose catalysis is controllable by irradiation with visible versus ultraviolet light. In the presence of micromolar concentrations of the photo-switch compound, the ribozyme behaves as a two-state switch, exhibiting a >900-fold difference in catalytic rates between the two irradiation regimes. We anticipate that the UG-dihydropyrene, and other ribozymes like it, may find significant application in the developmental biology of model organisms such as Drosophila melanogaster and Caenorhabditis elegans, as well as in the biomedical sciences.
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Affiliation(s)
- Hyun-Wu Lee
- Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, B.C., Canada V5A 1S6
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Chen X, Wang Y, Liu Q, Zhang Z, Fan C, He L. Construction of molecular logic gates with a DNA-cleaving deoxyribozyme. Angew Chem Int Ed Engl 2007; 45:1759-62. [PMID: 16470893 DOI: 10.1002/anie.200502511] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xi Chen
- Bio-X Life Science Research Center, Shanghai Jiao Tong University, China
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40
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Abstract
Life originated, according to the RNA World hypothesis, from self-replicating ribozymes that catalyzed ligation of RNA fragments. We have solved the 2.6 angstrom crystal structure of a ligase ribozyme that catalyzes regiospecific formation of a 5' to 3' phosphodiester bond between the 5'-triphosphate and the 3'-hydroxyl termini of two RNA fragments. Invariant residues form tertiary contacts that stabilize a flexible stem of the ribozyme at the ligation site, where an essential magnesium ion coordinates three phosphates. The structure of the active site permits us to suggest how transition-state stabilization and a general base may catalyze the ligation reaction required for prebiotic RNA assembly.
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Affiliation(s)
- Michael P Robertson
- Center for the Molecular Biology of RNA and Department of Chemistry and Biochemistry, Robert L. Sinsheimer Laboratories, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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41
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Manrubia SC, Briones C. Modular evolution and increase of functional complexity in replicating RNA molecules. RNA (NEW YORK, N.Y.) 2007; 13:97-107. [PMID: 17105993 PMCID: PMC1705761 DOI: 10.1261/rna.203006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
At early stages of biochemical evolution, the complexity of replicating molecules was limited by unavoidably high mutation rates. In an RNA world, prior to the appearance of cellular life, an increase in molecular length, and thus in functional complexity, could have been mediated by modular evolution. We describe here a scenario in which short, replicating RNA sequences are selected to perform a simple function. Molecular function is represented through the secondary structure corresponding to each sequence, and a given target secondary structure yields the optimal function in the environment where the population evolves. The combination of independently evolved populations may have facilitated the emergence of larger molecules able to perform more complex functions (including RNA replication) that could arise as a combination of simpler ones. We quantitatively show that modular evolution has relevant advantages with respect to the direct evolution of large functional molecules, among them the allowance of higher mutation rates, the shortening of evolutionary times, and the very possibility of finding complex structures that could not be otherwise directly selected.
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42
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Link KH, Guo L, Ames TD, Yen L, Mulligan RC, Breaker RR. Engineering high-speed allosteric hammerhead ribozymes. Biol Chem 2007; 388:779-86. [PMID: 17655496 DOI: 10.1515/bc.2007.105] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Full-length hammerhead ribozymes were subjected to in vitro selection to identify variants that are allosterically regulated by theophylline in the presence of a physiologically relevant concentration of Mg(2+). The population of allosteric ribozymes resulting from 15 rounds of in vitro selection yielded variants with observed rate constants (k (obs)) as high as 8 min(-1) in the presence of theophylline and maximal k (obs) increases of up to 285-fold compared to rate constants measured in the absence of effector. The selected ribozymes have kinetic characteristics that are predicted to be sufficient for cellular gene control applications, but do not exhibit any activity in reporter gene assays. The inability of the engineered RNAs to control gene expression suggests that the in vitro and in vivo folding pathways of the RNAs are different. These results provide several key pieces of information that will aid in future efforts to engineer allosteric ribozymes for gene control applications.
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Affiliation(s)
- Kristian H Link
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8103, USA
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43
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Abstract
BACKGROUND Catalytic RNA molecules are called ribozymes. The aptamers are DNA or RNA molecules that have been selected from vast populations of random sequences, through a combinatorial approach known as SELEX. The selected oligo-nucleotide sequences (~200 bp in length) have the ability to recognize broad range of specific ligands by forming binding pockets. These novel aptamer sequences can bind to nucleic acids, proteins or small organic and inorganic chemical compounds and have many potential uses in medicine and technology. RESULTS The comprehensive sequence information on aptamers and ribozymes that have been generated by in vitro selection methods are included in this RiboaptDB database. Such types of unnatural data generated by in vitro methods are not available in the public 'natural' sequence databases such as GenBank and EMBL. The amount of sequence data generated by in vitro selection experiments has been accumulating exponentially. There are 370 artificial ribozyme sequences and 3842 aptamer sequences in the total 4212 sequences from 423 citations in this RiboaptDB. We included general search feature, and individual feature wise search, user submission form for new data through online and also local BLAST search. CONCLUSION This database, besides serving as a storehouse of sequences that may have diagnostic or therapeutic utility in medicine, provides valuable information for computational and theoretical biologists. The RiboaptDB is extremely useful for garnering information about in vitro selection experiments as a whole and for better understanding the distribution of functional nucleic acids in sequence space. The database is updated regularly and is publicly available at http://mfgn.usm.edu/ebl/riboapt/.
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Affiliation(s)
- Venkata Thodima
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA
| | - Mehdi Pirooznia
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA
| | - Youping Deng
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA
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44
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Hirabayashi M, Taira S, Kobayashi S, Konishi K, Katoh K, Hiratsuka Y, Kodaka M, Uyeda TQP, Yumoto N, Kubo T. Malachite green-conjugated microtubules as mobile bioprobes selective for malachite green aptamers with capturing/releasing ability. Biotechnol Bioeng 2006; 94:473-80. [PMID: 16572397 DOI: 10.1002/bit.20867] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have developed a novel mobile bioprobe using a conjugate of a kinesin-driven microtubule (MT) and malachite green (MG) as a platform for capturing MG RNA aptamers. The fluorescence of MG increases when it is bound to an MG aptamer, allowing MT-MG conjugates to work as sensors of RNA transcripts containing the MG aptamer sequence. Kinesin motor proteins provide an effective driving force to create mobile bioprobes without any manipulation. Although the fluorescence of a small number of MG-binding aptamers is low, the self-organization of tubulins into MTs enables the microscopic observation of the bound aptamers by collecting them on MTs. We demonstrate that MT-MG conjugates can select target aptamers from a transcription mixture and transport them without losing their inherent motility. Because the MG aptamer binds MG in a reversible manner, MT-MG conjugates can conditionally load and unload the target aptamers. This is one advantage of this system over the molecular probes developed previously in which reversible unloading is impossible due to high-affinity binding, such as between avidin and biotin. Furthermore, an MT-MG conjugate can be used as a platform for other MG aptameric sensors with recognition regions for various target analytes optimized by further selection procedures. This is the first step to applying living systems to in vitro devices. This technique could provide a new paradigm of mobile bioprobes establishing high-throughput in vitro selection systems using microfluidic devices operating in parallel.
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Affiliation(s)
- Miki Hirabayashi
- Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 6, Tsukuba, Ibaraki, Japan.
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45
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Narayanaswamy R, Ellington AD. Engineering RNA-based circuits. Handb Exp Pharmacol 2006:423-45. [PMID: 16594629 DOI: 10.1007/3-540-27262-3_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Nucleic acids can modulate gene function by base-pairing, via the molecular recognition of proteins and metabolites, and by catalysis. This diversity of functions can be combined with the ability to engineer nucleic acids based on Watson-Crick base-pairing rules to create a modular set of molecular "tools" for biotechnological and medical interventions in cellular metabolism. However, these individual RNA-based tools are most powerful when combined into rational logical or regulatory circuits, and the circuits can in turn be evolved for optimal function. Examples of genetic circuits that control translation and transcription are herein detailed, and more complex circuits with medical applications are anticipated.
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Affiliation(s)
- R Narayanaswamy
- Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A4800, Austin TX, 78712-0159, USA
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46
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Chen X, Wang Y, Liu Q, Zhang Z, Fan C, He L. Construction of Molecular Logic Gates with a DNA-Cleaving Deoxyribozyme. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200502511] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cho S, Kim JE, Lee BR, Kim JH, Kim BG. Bis-aptazyme sensors for hepatitis C virus replicase and helicase without blank signal. Nucleic Acids Res 2005; 33:e177. [PMID: 16314308 PMCID: PMC1292994 DOI: 10.1093/nar/gni174] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The fusion molecule (i.e. aptazyme) of aptamer and hammerhead ribozyme was developed as in situ sensor. Previously, the hammerhead ribozyme conjugated with aptamer through its stem II module showed a significant blank signal by self-cleavage. To reduce or remove its self-cleavage activity in the absence of target molecule, rational designs were attempted by reducing the binding affinity of the aptazyme to its RNA substrate, while maintaining the ribonuclease activity of the aptazyme. Interestingly, the bis-aptazymes which comprise the two aptamer-binding sites at both stem I and stem III of the hammerhead ribozyme showed very low blank signals, and their ratios of reaction rate constants, i.e. signal to noise ratios, were several tens to hundred times higher than those of the stem II-conjugated bis-aptazymes. The reduction in the blank signals seems to be caused by a higher dissociation constant between the main strand of the bis-aptazyme and its substrate arising from multi-point base-pairing of the bis-aptazymes. The bis-aptazymes for HCV replicase and helicase showed high selectivity against other proteins, and a linear relationship existed between their ribozyme activities and the target concentrations. In addition, a bis-aptazyme of dual functions was designed by inserting both aptamers for HCV replicase and helicase into the stem I and stem III of hammerhead ribozyme, respectively, and it also showed greater sensitivity and specificity for both proteins without blank signal.
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Affiliation(s)
- Suhyung Cho
- Interdisciplinary Program for Biochemical Engineering and Biotechnology, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
| | - Ji-Eun Kim
- School of Chemical and Biological Engineering, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
| | - Bo-Rahm Lee
- School of Chemical and Biological Engineering, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
| | - June-Hyung Kim
- School of Chemical and Biological Engineering, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
| | - Byung-Gee Kim
- Interdisciplinary Program for Biochemical Engineering and Biotechnology, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
- School of Chemical and Biological Engineering, Seoul National UniversityShinlim-dong, Kwanak-Gu, Seoul 151-744, Korea
- To whom correspondence should be addressed at Laboratory of Molecular Biotechnology and Biomaterials, School of Chemical and Biological Engineering, Seoul National University, Shinlim-dong, Kwanak-Gu, Seoul 151-744, Korea. Tel: +82 2 880 6774; Fax: +82 2 883 6020;
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48
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Abstract
Recombination is widespread among RNA viruses, but many molecular mechanisms of this phenomenon are still poorly understood. It was believed until recently that the only possible mechanism of RNA recombination is replicative template switching, with synthesis of a complementary strand starting on one viral RNA molecule and being completed on another. The newly synthesized RNA is a primary recombinant molecule in this case. Recent studies have revealed other mechanisms of replicative RNA recombination. In addition, recombination between the genomes of RNA viruses can be nonreplicative, resulting from a joining of preexisting parental molecules. Recombination is a potent tool providing for both the variation and conservation of the genome in RNA viruses. Replicative and nonreplicative mechanisms may contribute differently to each of these evolutionary processes. In the form of trans splicing, nonreplicative recombination of cell RNAs plays an important role in at least some organisms. It is conceivable that RNA recombination continues to contribute to the evolution of DNA genomes.
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Affiliation(s)
- A P Gmyl
- 1Chumakov Institute of Poliomyelitis and Viral Encephalites, Russian Academy of Medical Sciences, Moscow Region, 142782 Russia
| | - V I Agol
- 1Chumakov Institute of Poliomyelitis and Viral Encephalites, Russian Academy of Medical Sciences, Moscow Region, 142782 Russia.,2Moscow State University, Moscow, 119992 Russia
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49
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50
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Abstract
Just as Darwinian evolution in nature has led to the development of many sophisticated enzymes, Darwinian evolution in vitro has proven to be a powerful approach for obtaining similar results in the laboratory. This review focuses on the development of nucleic acid enzymes starting from a population of random-sequence RNA or DNA molecules. In order to illustrate the principles and practice of in vitro evolution, two especially well-studied categories of catalytic nucleic acid are considered: RNA enzymes that catalyze the template-directed ligation of RNA and DNA enzymes that catalyze the cleavage of RNA. The former reaction, which involves attack of a 2'- or 3'-hydroxyl on the alpha-phosphate of a 5'-triphosphate, is more difficult. It requires a comparatively larger catalytic motif, containing more nucleotides than can be sampled exhaustively within a starting population of random-sequence RNAs. The latter reaction involves deprotonation of the 2'-hydroxyl adjacent to the cleavage site, resulting in cleaved products that bear a 2',3'-cyclic phosphate and 5'-hydroxyl. The difficulty of this reaction, and therefore the complexity of the corresponding DNA enzyme, depends on whether a catalytic cofactor, such as a divalent metal cation or small molecule, is present in the reaction mixture.
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Affiliation(s)
- Gerald F Joyce
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
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