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Kimoto M, Hirao I. Genetic alphabet expansion technology by creating unnatural base pairs. Chem Soc Rev 2020; 49:7602-7626. [PMID: 33015699 DOI: 10.1039/d0cs00457j] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent advancements in the creation of artificial extra base pairs (unnatural base pairs, UBPs) are opening the door to a new research area, xenobiology, and genetic alphabet expansion technologies. UBPs that function as third base pairs in replication, transcription, and/or translation enable the site-specific incorporation of novel components into DNA, RNA, and proteins. Here, we describe the UBPs developed by three research teams and their application in PCR-based diagnostics, high-affinity DNA aptamer generation, site-specific labeling of RNAs, semi-synthetic organism creation, and unnatural-amino-acid-containing protein synthesis.
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Affiliation(s)
- Michiko Kimoto
- Institute of Bioengineering and Nanotechnology, A*STAR, Singapore.
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2
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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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3
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Hamashima K, Kimoto M, Hirao I. Creation of unnatural base pairs for genetic alphabet expansion toward synthetic xenobiology. Curr Opin Chem Biol 2018; 46:108-114. [PMID: 30059833 DOI: 10.1016/j.cbpa.2018.07.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/02/2018] [Accepted: 07/13/2018] [Indexed: 01/10/2023]
Abstract
Artificial extra base pairs (unnatural base pairs, UBPs) expand the genetic alphabet of DNA, thus broadening entire biological systems in the central dogma. UBPs function as third base pairs in replication, transcription, and/or translation, and have created a new research area, synthetic xenobiology, providing genetic engineering tools to generate novel DNAs, RNAs, and proteins with increased functionalities. Several UBPs have been developed and applied to PCR technology, DNA aptamer generation, and semi-synthetic organism creation. Among them, we developed a series of UBPs and demonstrated unique quantitative PCR and high-affinity DNA aptamer generation methods.
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Affiliation(s)
- Kiyofumi Hamashima
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, #07-01, Singapore 138669, Singapore
| | - Michiko Kimoto
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, #07-01, Singapore 138669, Singapore
| | - Ichiro Hirao
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, #07-01, Singapore 138669, Singapore.
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Domnick C, Eggert F, Kath-Schorr S. Site-specific enzymatic introduction of a norbornene modified unnatural base into RNA and application in post-transcriptional labeling. Chem Commun (Camb) 2016; 51:8253-6. [PMID: 25874847 DOI: 10.1039/c5cc01765c] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Inverse electron demand Diels-Alder cycloadditions have proven to be extremely useful for mild and additive-free orthogonal labeling of biomolecules, amongst others, for RNA labeling in vitro and in a cellular context. Here we present a method for site-specific introduction of an alkene modification into RNA via T7 in vitro transcription. For this, an unnatural, hydrophobic base pairing system developed by Romesberg and coworkers was modified introducing one or two norbornene moieties at predefined positions into RNA oligonucleotides in an in vitro transcription reaction. This allows post-transcriptional functionalization of these RNA molecules with tetrazine derivatives containing for instance fluorophores or biotin.
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Affiliation(s)
- Christof Domnick
- Life and Medical Sciences Institute, University of Bonn, Bonn, Germany.
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Kath-Schorr S. Cycloadditions for Studying Nucleic Acids. Top Curr Chem (Cham) 2015; 374:4. [PMID: 27572987 DOI: 10.1007/s41061-015-0004-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 11/30/2015] [Indexed: 12/13/2022]
Abstract
Cycloaddition reactions for site-specific or global modification of nucleic acids have enabled the preparation of a plethora of previously inaccessible DNA and RNA constructs for structural and functional studies on naturally occurring nucleic acids, the assembly of nucleic acid nanostructures, therapeutic applications, and recently, the development of novel aptamers. In this chapter, recent progress in nucleic acid functionalization via a range of different cycloaddition (click) chemistries is presented. At first, cycloaddition/click chemistries already used for modifying nucleic acids are summarized, ranging from the well-established copper(I)-catalyzed alkyne-azide cycloaddition reaction to copper free methods, such as the strain-promoted azide-alkyne cycloaddition, tetrazole-based photoclick chemistry and the inverse electron demand Diels-Alder cycloaddition reaction between strained alkenes and tetrazine derivatives. The subsequent sections contain selected applications of nucleic acid functionalization via click chemistry; in particular, site-specific enzymatic labeling in vitro, either via DNA and RNA recognizing enzymes or by introducing unnatural base pairs modified for click reactions. Further sections report recent progress in metabolic labeling and fluorescent detection of DNA and RNA synthesis in vivo, click nucleic acid ligation, click chemistry in nanostructure assembly and click-SELEX as a novel method for the selection of aptamers.
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Affiliation(s)
- Stephanie Kath-Schorr
- LIMES Institute, Chemical Biology and Medicinal Chemistry Unit, University of Bonn, Bonn, Germany.
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Loakes D, Holliger P. Polymerase engineering: towards the encoded synthesis of unnatural biopolymers. Chem Commun (Camb) 2009:4619-31. [PMID: 19641798 DOI: 10.1039/b903307f] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
DNA is not only a repository of genetic information for life, it is also a unique polymer with remarkable properties: it associates according to well-defined rules, it can be assembled into diverse nanostructures of defined geometry, it can be evolved to bind ligands and catalyse chemical reactions and it can serve as a supramolecular scaffold to arrange chemical groups in space. However, its chemical makeup is rather uniform and the physicochemical properties of the four canonical bases only span a narrow range. Much wider chemical diversity is accessible through solid-phase synthesis but oligomers are limited to <100 nucleotides and variations in chemistry can usually not be replicated and thus are not amenable to evolution. Recent advances in nucleic acid chemistry and polymerase engineering promise to bring the synthesis, replication and ultimately evolution of nucleic acid polymers with greatly expanded chemical diversity within our reach.
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Affiliation(s)
- David Loakes
- Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge, Cambridgeshire, UKCB2 0QH
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Srivatsan SG, Tor Y. Fluorescent pyrimidine ribonucleotide: synthesis, enzymatic incorporation, and utilization. J Am Chem Soc 2007; 129:2044-53. [PMID: 17256858 PMCID: PMC2517582 DOI: 10.1021/ja066455r] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Fluorescent nucleobase analogues that respond to changes in their microenvironment are valuable for studying RNA structure, dynamics, and recognition. The most commonly used fluorescent ribonucleoside is 2-aminopurine, a highly responsive purine analogue. Responsive isosteric fluorescent pyrimidine analogues are, however, rare. Appending five-membered aromatic heterocycles at the 5-position on a pyrimidine core has recently been found to provide a family of responsive fluorescent nucleoside analogues with emission in the visible range. To explore the potential utility of this chromophore for studying RNA-ligand interactions, an efficient incorporation method is necessary. Here we describe the synthesis of the furan-containing ribonucleoside and its triphosphate, as well as their basic photophysical characteristics. We demonstrate that T7 RNA polymerase accepts this fluorescent ribonucleoside triphosphate as a substrate in in vitro transcription reactions and very efficiently incorporates it into RNA oligonucleotides, generating fluorescent constructs. Furthermore, we utilize this triphosphate for the enzymatic preparation of a fluorescent bacterial A-site, an RNA construct of potential therapeutic utility. We show that the binding of this RNA target to aminoglycoside antibiotics, its cognate ligands, can be effectively monitored by fluorescence spectroscopy. These observations are significant since isosteric emissive U derivatives are scarce and the trivial synthesis and effective enzymatic incorporation of the furan-containing U triphosphate make it accessible to the biophysical community.
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Affiliation(s)
- Seergazhi G. Srivatsan
- Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093-0358, E-mail:
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California, San Diego La Jolla, CA 92093-0358, E-mail:
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Hirao I. Placing extra components into RNA by specific transcription using unnatural base pair systems. Biotechniques 2006; 40:711, 713, 715 passim. [PMID: 16774113 DOI: 10.2144/000112187] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Ichiro Hirao
- Protein Research Group, RIKEN Genomic Sciences Center, Kanagawa, Japan
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Kawai R, Kimoto M, Ikeda S, Mitsui T, Endo M, Yokoyama S, Hirao I. Site-specific fluorescent labeling of RNA molecules by specific transcription using unnatural base pairs. J Am Chem Soc 2006; 127:17286-95. [PMID: 16332078 DOI: 10.1021/ja0542946] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Site-specific fluorescent labeling of RNA molecules was achieved by specific transcription using an unnatural base pair system. The unnatural base pairs between 2-amino-6-(2-thienyl)purine (s) and 2-oxo(1H)pyridine (y), and 2-amino-6-(2-thiazolyl)purine (v) and y function in transcription, and the substrates of y and 5-modified y bases can be site-specifically incorporated into RNA, opposite s or v in DNA templates, by T7 RNA polymerase. Ribonucleoside 5'-triphosphates of 5-fluorophore-linked y bases were chemically synthesized from the nucleoside of y. These fluorescent substrates were site-specifically incorporated into RNA by transcription mediated by the s-y and v-y pairs. By using this fluorescent labeling method, specific positions of Raf-binding and theophylline-binding RNA aptamers were fluorescently labeled, and the specific binding to their target molecules was detected by their fluorescent intensities. This site-specific labeling method using an unnatural base pair system will be useful for analyzing conformational changes of RNA molecules and for detecting interactions between RNA and its binding species.
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Affiliation(s)
- Rie Kawai
- Protein Research Group, RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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Moriyama K, Kimoto M, Mitsui T, Yokoyama S, Hirao I. Site-specific biotinylation of RNA molecules by transcription using unnatural base pairs. Nucleic Acids Res 2005; 33:e129. [PMID: 16113238 PMCID: PMC1188086 DOI: 10.1093/nar/gni128] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Direct site-specific biotinylation of RNA molecules was achieved by specific transcription mediated by unnatural base pairs. Unnatural base pairs between 2-amino-6-(2-thienyl)purine (denoted by s) and 2-oxo(1H)pyridine (denoted by y), or 2-amino-6-(2-thiazolyl)purine (denoted as v) and y specifically function in T7 transcription. Using these unnatural base pairs, the substrate of biotinylated-y (Bio-yTP) was selectively incorporated into RNA, opposite s or v in the DNA templates, by T7 RNA polymerase. This method was applied to the immobilization of an RNA aptamer on sensor chips, and the aptamer accurately recognized its target protein. This direct site-specific biotinylation will provide a tool for RNA-based biotechnologies.
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Affiliation(s)
- Kei Moriyama
- Research Center for Advanced Science and Technology, The University of Tokyo4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Michiko Kimoto
- Protein Research Group, RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Tsuneo Mitsui
- Research Center for Advanced Science and Technology, The University of Tokyo4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Shigeyuki Yokoyama
- Protein Research Group, RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- RIKEN Harima Institute at SPring-81-1-1 Kohto, Mikazuki-cho, Sayo, Hyogo 679-5148, Japan
| | - Ichiro Hirao
- Research Center for Advanced Science and Technology, The University of Tokyo4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
- Protein Research Group, RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- To whom correspondence should be addressed at Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. Tel: +81 3 5452 5442; Fax: +81 3 5452 5442;
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Mitsui T, Kimoto M, Harada Y, Yokoyama S, Hirao I. An efficient unnatural base pair for a base-pair-expanded transcription system. J Am Chem Soc 2005; 127:8652-8. [PMID: 15954770 DOI: 10.1021/ja0425280] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For the site-specific incorporation of artificial components into RNA by transcription, an efficient, unnatural base pair between 2-amino-6-(2-thiazolyl)purine (denoted as v) and 2-oxo(1H)pyridine (denoted as y) was developed. The substrates of y and 5-substituted y were site-specifically incorporated into RNA by T7 RNA polymerase opposite v in templates. The efficiency and fidelity of the v-y pairing in transcription were as high as those of the natural A-T(U) and G-C pairings. Furthermore, RNAs containing two adjacent y bases were also transcribed from DNA templates containing two v bases. This specific transcription allows the large-scale preparation of artificial RNAs and can be combined with other systems to simultaneously incorporate several different components into a transcript.
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Affiliation(s)
- Tsuneo Mitsui
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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Hirao I, Fujiwara T, Kimoto M, Yokoyama S. Unnatural base pairs between 2- and 6-substituted purines and 2-oxo(1H)pyridine for expansion of the genetic alphabet. Bioorg Med Chem Lett 2004; 14:4887-90. [PMID: 15341945 DOI: 10.1016/j.bmcl.2004.07.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 07/15/2004] [Accepted: 07/17/2004] [Indexed: 10/26/2022]
Abstract
An unnatural base pair between 2-amino-6-(2-thienyl)purine (denoted by s) and 2-oxo(1H)pyridine (denoted by y) shows high selectivity in transcription and translation. Toward the further development of unnatural base pairs that also have exclusive selectivity in replication, we examined the roles of the 2-amino and 6-thienyl groups of s using base pairs between y and purine-analogs, 6-thienylpurine and 2-amino-6-furanylpurine, as well as s. The results obtained from the thermal stability and DNA polymerase single-nucleotide insertion experiments suggest that the 2-amino group of s contributes toward the shape complementarity of the pairing with y, rather than the hydrogen bonding with the 2-keto group of y. In addition, the bulkiness of positions 2 and 6 of the unnatural purines cooperatively determines the selectivity of the noncanonical pairing with y or the natural pyrimidines in replication. This information is useful not only for the development of unnatural, orthogonal base pairs, but also for understanding the mechanisms of base pair formation in replication.
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Affiliation(s)
- Ichiro Hirao
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
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