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Chandankar SS, Kondhare D, Leonard P, Seela F. Purine DNA Constructs Designed to Expand the Genetic Code: Functionalization, Impact of Ionic Forms, and Molecular Recognition of 7-Deazaxanthine-7-Deazapurine-2,6-diamine Base Pairs and Their Purine Counterparts. J Org Chem 2023; 88:13149-13168. [PMID: 37669119 DOI: 10.1021/acs.joc.3c01370] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Purine DNA represents an alternative pairing system formed by two purines in the base pair with the recognition elements of Watson-Crick DNA. Base functionalization of 7-deaza-2'-deoxyxanthosine with ethynyl and octadiynyl residues led to clickable side chain derivatives with short and long linker arms. As complementary bases, purine-2,6-diamine or 7-deazapurine-2,6-diamine 2'-deoxyribonucleosides were used. 7-Deaza-7-iodo-2'-deoxyxanthosine served as a starting material for Sonogashira cross-coupling and the p-nitrophenylethyl group for base protection. Phosphoramidite building blocks for DNA synthesis were prepared. Oligonucleotides containing single modifications or runs of three purine base pairs embedded in 12-mer Watson-Crick DNA were synthesized and hybridized with complementary strands with purine- or 7-deazapurine-2,6-diamine located opposite to the xanthine derivatives. The stability of base pairs was evaluated in a comparative study on the basis of DNA melting experiments and Tm values. As 7-deazaxanthine and xanthine nucleosides form anionic forms at neutral pH, duplex stability became pK-dependent, and the system with 7-deazapurine displayed a significant higher stability as that containing xanthine. Alkynyl side chains are well accommodated in the purine-purine helix. Click adducts with pyrene showed that short linker arms destabilize duplexes, whereas long linkers increase duplex stability. CD and fluorescence measurements provide further insights into purine-purine base pairing.
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Affiliation(s)
- Somnath Shivaji Chandankar
- Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany
| | - Dasharath Kondhare
- Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany
| | - Peter Leonard
- Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany
| | - Frank Seela
- Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany
- Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie neuer Materialien, Universität Osnabrück, Barbarastrasse 7, 49069 Osnabrück, Germany
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Mair S, Erharter K, Renard E, Brillet K, Brunner M, Lusser A, Kreutz C, Ennifar E, Micura R. Towards a comprehensive understanding of RNA deamination: synthesis and properties of xanthosine-modified RNA. Nucleic Acids Res 2022; 50:6038-6051. [PMID: 35687141 PMCID: PMC9226506 DOI: 10.1093/nar/gkac477] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/28/2022] [Accepted: 05/20/2022] [Indexed: 12/25/2022] Open
Abstract
Nucleobase deamination, such as A-to-I editing, represents an important posttranscriptional modification of RNA. When deamination affects guanosines, a xanthosine (X) containing RNA is generated. However, the biological significance and chemical consequences on RNA are poorly understood. We present a comprehensive study on the preparation and biophysical properties of X-modified RNA. Thermodynamic analyses revealed that base pairing strength is reduced to a level similar to that observed for a G•U replacement. Applying NMR spectroscopy and X-ray crystallography, we demonstrate that X can form distinct wobble geometries with uridine depending on the sequence context. In contrast, X pairing with cytidine occurs either through wobble geometry involving protonated C or in Watson–Crick-like arrangement. This indicates that the different pairing modes are of comparable stability separated by low energetic barriers for switching. Furthermore, we demonstrate that the flexible pairing properties directly affect the recognition of X-modified RNA by reverse transcription enzymes. Primer extension assays and PCR-based sequencing analysis reveal that X is preferentially read as G or A and that the ratio depends on the type of reverse transcriptase. Taken together, our results elucidate important properties of X-modified RNA paving the way for future studies on its biological significance.
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Affiliation(s)
- Stefan Mair
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Kevin Erharter
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Eva Renard
- Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 67000 Strasbourg, France
| | - Karl Brillet
- Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 67000 Strasbourg, France
| | - Melanie Brunner
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Alexandra Lusser
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Eric Ennifar
- Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 67000 Strasbourg, France
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
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Blümler A, Schwalbe H, Heckel A. Solid‐Phase‐Supported Chemoenzymatic Synthesis of a Light‐Activatable tRNA Derivative. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202111613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Anja Blümler
- Institute for Organic Chemistry and Chemical Biology Goethe University Frankfurt am Main Max-von-Laue-Strasse 7 60438 Frankfurt/Main Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology Goethe University Frankfurt am Main Max-von-Laue-Strasse 7 60438 Frankfurt/Main Germany
- Institute for Organic Chemistry and Chemical Biology Center for Biomolecular Magnetic Resonance BMRZ Goethe University Frankfurt am Main Max-von-Laue-Strasse 7 60438 Frankfurt/Main Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology Goethe University Frankfurt am Main Max-von-Laue-Strasse 7 60438 Frankfurt/Main Germany
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Blümler A, Schwalbe H, Heckel A. Solid-Phase-Supported Chemoenzymatic Synthesis of a Light-Activatable tRNA Derivative. Angew Chem Int Ed Engl 2021; 61:e202111613. [PMID: 34738704 PMCID: PMC9299214 DOI: 10.1002/anie.202111613] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Indexed: 12/14/2022]
Abstract
Herein, we present a multi‐cycle chemoenzymatic synthesis of modified RNA with simplified solid‐phase handling to overcome size limitations of RNA synthesis. It combines the advantages of classical chemical solid‐phase synthesis and enzymatic synthesis using magnetic streptavidin beads and biotinylated RNA. Successful introduction of light‐controllable RNA nucleotides into the tRNAMet sequence was confirmed by gel electrophoresis and mass spectrometry. The methods tolerate modifications in the RNA phosphodiester backbone and allow introductions of photocaged and photoswitchable nucleotides as well as photocleavable strand breaks and fluorophores.
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Affiliation(s)
- Anja Blümler
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438, Frankfurt/Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438, Frankfurt/Main, Germany.,Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance BMRZ, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438, Frankfurt/Main, Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438, Frankfurt/Main, Germany
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Depmeier H, Hoffmann E, Bornewasser L, Kath‐Schorr S. Strategies for Covalent Labeling of Long RNAs. Chembiochem 2021; 22:2826-2847. [PMID: 34043861 PMCID: PMC8518768 DOI: 10.1002/cbic.202100161] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/26/2021] [Indexed: 12/17/2022]
Abstract
The introduction of chemical modifications into long RNA molecules at specific positions for visualization, biophysical investigations, diagnostic and therapeutic applications still remains challenging. In this review, we present recent approaches for covalent internal labeling of long RNAs. Topics included are the assembly of large modified RNAs via enzymatic ligation of short synthetic oligonucleotides and synthetic biology approaches preparing site-specifically modified RNAs via in vitro transcription using an expanded genetic alphabet. Moreover, recent approaches to employ deoxyribozymes (DNAzymes) and ribozymes for RNA labeling and RNA methyltransferase based labeling strategies are presented. We discuss the potentials and limits of the individual methods, their applicability for RNAs with several hundred to thousands of nucleotides in length and indicate future directions in the field.
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Affiliation(s)
- Hannah Depmeier
- University of CologneDepartment of ChemistryGreinstr. 450939CologneGermany
| | - Eva Hoffmann
- University of CologneDepartment of ChemistryGreinstr. 450939CologneGermany
| | - Lisa Bornewasser
- University of CologneDepartment of ChemistryGreinstr. 450939CologneGermany
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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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Müller D, Trucks S, Schwalbe H, Hengesbach M. Genetic Code Expansion Facilitates Position-Selective Modification of Nucleic Acids and Proteins. Chempluschem 2020; 85:1233-1243. [PMID: 32515171 DOI: 10.1002/cplu.202000150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/11/2020] [Indexed: 12/12/2022]
Abstract
Transcription and translation obey to the genetic code of four nucleobases and 21 amino acids evolved over billions of years. Both these processes have been engineered to facilitate the use of non-natural building blocks in both nucleic acids and proteins, enabling researchers with a decent toolbox for structural and functional analyses. Here, we review the most common approaches for how labeling of both nucleic acids as well as proteins in a site-selective fashion with either modifiable building blocks or spectroscopic probes can be facilitated by genetic code expansion. We emphasize methodological approaches and how these can be adapted for specific modifications, both during as well as after biomolecule synthesis. These modifications can facilitate, for example, a number of different spectroscopic analysis techniques and can under specific circumstances even be used in combination.
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Affiliation(s)
- Diana Müller
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Sven Trucks
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Martin Hengesbach
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
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Hegelein A, Müller D, Größl S, Göbel M, Hengesbach M, Schwalbe H. Genetic Code Expansion Facilitates Position-Selective Labeling of RNA for Biophysical Studies. Chemistry 2020; 26:1800-1810. [PMID: 31692134 PMCID: PMC7027469 DOI: 10.1002/chem.201904623] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/04/2019] [Indexed: 12/13/2022]
Abstract
Nature relies on reading and synthesizing the genetic code with high fidelity. Nucleic acid building blocks that are orthogonal to the canonical A-T and G-C base-pairs are therefore uniquely suitable to facilitate position-specific labeling of nucleic acids. Here, we employ the orthogonal kappa-xanthosine-base-pair for in vitro transcription of labeled RNA. We devised an improved synthetic route to obtain the phosphoramidite of the deoxy-version of the kappa nucleoside in solid phase synthesis. From this DNA template, we demonstrate the reliable incorporation of xanthosine during in vitro transcription. Using NMR spectroscopy, we show that xanthosine introduces only minor structural changes in an RNA helix. We furthermore synthesized a clickable 7-deaza-xanthosine, which allows to site-specifically modify transcribed RNA molecules with fluorophores or other labels.
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Affiliation(s)
- Andreas Hegelein
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic ResonanceGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Diana Müller
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic ResonanceGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Sylvester Größl
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Michael Göbel
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Martin Hengesbach
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic ResonanceGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic ResonanceGoethe University FrankfurtMax-von-Laue-Strasse 760438Frankfurt am MainGermany
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