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Lee Y, Gu S, Al-Hashimi HM. Insights into the A-C Mismatch Conformational Ensemble in Duplex DNA and its Role in Genetic Processes through a Structure-based Review. J Mol Biol 2024; 436:168710. [PMID: 39009073 DOI: 10.1016/j.jmb.2024.168710] [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: 05/15/2024] [Revised: 07/10/2024] [Accepted: 07/10/2024] [Indexed: 07/17/2024]
Abstract
Knowing the conformational ensembles formed by mismatches is crucial for understanding how they are generated and repaired and how they contribute to genomic instability. Here, we review structural and energetic studies of the A-C mismatch in duplex DNA and use the information to identify critical conformational states in its ensemble and their significance in genetic processes. In the 1970s, Topal and Fresco proposed the A-C wobble stabilized by two hydrogen bonds, one requiring protonation of adenine-N1. Subsequent NMR and X-ray crystallography studies showed that the protonated A-C wobble was in dynamic equilibrium with a neutral inverted wobble. The mismatch was shown to destabilize duplex DNA in a sequence- and pH-dependent manner by 2.4-3.8 kcal/mol and to have an apparent pKa ranging between 7.2 and 7.7. The A-C mismatch conformational repertoire expanded as structures were determined for damaged and protein-bound DNA. These structures included Watson-Crick-like conformations forming through tautomerization of the bases that drive replication errors, the reverse wobble forming through rotation of the entire nucleotide proposed to increase the fidelity of DNA replication, and the Hoogsteen base-pair forming through the flipping of the adenine base which explained the unusual specificity of DNA polymerases that bypass DNA damage. Thus, the A-C mismatch ensemble encompasses various conformational states that can be selectively stabilized in response to environmental changes such as pH shifts, intermolecular interactions, and chemical modifications, and these adaptations facilitate critical biological processes. This review also highlights the utility of existing 3D structures to build ensemble models for nucleic acid motifs.
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Affiliation(s)
- Yeongjoon Lee
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, United States of America
| | - Stephanie Gu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, United States of America
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, United States of America.
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Toews S, Wacker A, Faison EM, Duchardt-Ferner E, Richter C, Mathieu D, Bottaro S, Zhang Q, Schwalbe H. The 5'-terminal stem-loop RNA element of SARS-CoV-2 features highly dynamic structural elements that are sensitive to differences in cellular pH. Nucleic Acids Res 2024; 52:7971-7986. [PMID: 38842942 PMCID: PMC11260494 DOI: 10.1093/nar/gkae477] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 05/16/2024] [Accepted: 05/22/2024] [Indexed: 07/23/2024] Open
Abstract
We present the nuclear magnetic resonance spectroscopy (NMR) solution structure of the 5'-terminal stem loop 5_SL1 (SL1) of the SARS-CoV-2 genome. SL1 contains two A-form helical elements and two regions with non-canonical structure, namely an apical pyrimidine-rich loop and an asymmetric internal loop with one and two nucleotides at the 5'- and 3'-terminal part of the sequence, respectively. The conformational ensemble representing the averaged solution structure of SL1 was validated using NMR residual dipolar coupling (RDC) and small-angle X-ray scattering (SAXS) data. We show that the internal loop is the major binding site for fragments of low molecular weight. This internal loop of SL1 can be stabilized by an A12-C28 interaction that promotes the transient formation of an A+•C base pair. As a consequence, the pKa of the internal loop adenosine A12 is shifted to 5.8, compared to a pKa of 3.63 of free adenosine. Furthermore, applying a recently developed pH-differential mutational profiling (PD-MaP) approach, we not only recapitulated our NMR findings of SL1 but also unveiled multiple sites potentially sensitive to pH across the 5'-UTR of SARS-CoV-2.
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Affiliation(s)
- Sabrina Toews
- Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
| | - Anna Wacker
- Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
| | - Edgar M Faison
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC27599, USA
| | - Elke Duchardt-Ferner
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
- Institute of Molecular Biosciences, Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
| | - Christian Richter
- Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
| | - Daniel Mathieu
- Bruker BioSpin GmbH, Ettlingen, Baden-Württemberg 76275, Germany
| | - Sandro Bottaro
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen 2200, Denmark
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC27599, USA
| | - Harald Schwalbe
- Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/Main, Hesse 60438, Germany
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Juen F, Glänzer D, Plangger R, Kugler V, Fleischmann J, Stefan E, Case DA, Kovacs H, Dayie TK, Kreutz C. Enhanced TROSY Effect in [2- 19 F, 2- 13 C] Adenosine and ATP Analogs Facilitates NMR Spectroscopy of Very Large Biological RNAs in Solution. Angew Chem Int Ed Engl 2024; 63:e202316273. [PMID: 38185473 PMCID: PMC10922520 DOI: 10.1002/anie.202316273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/28/2023] [Accepted: 12/27/2023] [Indexed: 01/09/2024]
Abstract
Large RNAs are central to cellular functions, but characterizing such RNAs remains challenging by solution NMR. We present two labeling technologies based on [2-19 F, 2-13 C]-adenosine, which allow the incorporation of aromatic 19 F-13 C spin pairs. The labels when coupled with the transverse relaxation optimized spectroscopy (TROSY) enable us to probe RNAs comprising up to 124 nucleotides. With our new [2-19 F, 2-13 C]-adenosine-phosphoramidite, all resonances of the human hepatitis B virus epsilon RNA could be readily assigned. With [2-19 F, 2-13 C]-adenosine triphosphate, the 124 nt pre-miR-17-NPSL1-RNA was produced via in vitro transcription and the TROSY spectrum of this 40 kDa [2-19 F, 2-13 C]-A-labeled RNA featured sharper resonances than the [2-1 H, 2-13 C]-A sample. The mutual cancelation of the chemical-shift-anisotropy and the dipole-dipole-components of TROSY-resonances leads to narrow linewidths over a wide range of molecular weights. With the synthesis of a non-hydrolysable [2-19 F, 2-13 C]-adenosine-triphosphate, we facilitate the probing of co-factor binding in kinase complexes and NMR-based inhibitor binding studies in such systems. Our labels allow a straightforward assignment for larger RNAs via a divide-and-conquer/mutational approach. The new [2-19 F, 2-13 C]-adenosine precursors are a valuable addition to the RNA NMR toolbox and will allow the study of large RNAs/RNA protein complexes in vitro and in cells.
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Affiliation(s)
- Fabian Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - David Glänzer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Raphael Plangger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Valentina Kugler
- Institute of Molecular Biology and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Jakob Fleischmann
- Institute of Molecular Biology and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Eduard Stefan
- Institute of Molecular Biology and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
- Tyrolean Cancer Research Institute (TKFI), Innrain 66, 6020 Innsbruck, Austria
| | - David A. Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | | | - Theodore Kwaku Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20782, USA
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
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