1
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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 2024:168710. [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] [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, New York 10032, United States
| | - Stephanie Gu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, United States.
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2
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Bessi I, Stiller C, Schroeder T, Schäd B, Grüne M, Dietzsch J, Höbartner C. The Tautomeric State of N4-Hydroxycytidine within Base-Paired RNA. ACS CENTRAL SCIENCE 2024; 10:1084-1093. [PMID: 38799674 PMCID: PMC11117714 DOI: 10.1021/acscentsci.4c00146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 05/29/2024]
Abstract
Antiviral nucleoside analogues (e.g., Molnupiravir, Remdesivir) played key roles in the treatment of COVID-19 by targeting SARS-CoV-2 RNA-dependent RNA polymerase (RdRp). The nucleoside of Molnupiravir, N4-hydroxycytidine (NHC), exists in two tautomeric forms that pair either with G or A within the RdRp active site, causing an accumulation of viral RNA mutations during replication. Detailed insights into the tautomeric states within base pairs and the structural influence of NHC in RNA are still missing. In this study, we investigate the properties of NHC:G and NHC:A base pairs in a self-complementary RNA duplex by UV thermal melting and NMR spectroscopy using atom-specifically 15N-labeled versions of NHC that were incorporated into oligonucleotides by solid-phase synthesis. NMR analysis revealed that NHC forms a Watson-Crick base pair with G via its amino form, whereas two equally populated conformations were detected for the NHC:A base pair: a weakly hydrogen-bonded Watson-Crick base pair with NHC in the imino form and another conformation with A shifted toward the minor groove. Moreover, we found a variable influence of NHC:G and NHC:A base pairs on the neighboring duplex environment. This study provides conclusive experimental evidence for the existence of two tautomeric forms of NHC within RNA base pairs.
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Affiliation(s)
- Irene Bessi
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Carina Stiller
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Till Schroeder
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Benedikt Schäd
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Matthias Grüne
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Julia Dietzsch
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
| | - Claudia Höbartner
- Institute
of Organic Chemistry, Julius-Maximilians-University
Würzburg, Am Hubland, 97074 Würzburg, Bavaria, Germany
- Center
for Nanosystems Chemistry, Julius-Maximilians-University
Würzburg, 97074 Würzburg, Bavaria, Germany
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3
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González‐Olvera JC, Fiala R, Pless RC. Protonation of Guanine:5‐Methylcytosine and Guanine:Cytosine Base Pairs in Duplex Oligodeoxyribonucleotides. ChemistrySelect 2022. [DOI: 10.1002/slct.202200835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Julio C. González‐Olvera
- Universidad Politécnica de Santa Rosa Jáuregui Carretera Federal 57 QRO-SLP km 31-150, Parque Industrial Querétaro, Santa Rosa Jáuregui Querétaro 76220 Mexico
| | - Radovan Fiala
- CEITEC-Central European Institute of Technology Masaryk University Kamenice 753/5 62500 Brno Czech Republic
| | - Reynaldo C. Pless
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Instituto Politécnico Nacional Cerro Blanco 141 Querétaro Querétaro 76090 Mexico
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4
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Dayie TK, Olenginski LT, Taiwo KM. Isotope Labels Combined with Solution NMR Spectroscopy Make Visible the Invisible Conformations of Small-to-Large RNAs. Chem Rev 2022; 122:9357-9394. [PMID: 35442658 PMCID: PMC9136934 DOI: 10.1021/acs.chemrev.1c00845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Indexed: 02/07/2023]
Abstract
RNA is central to the proper function of cellular processes important for life on earth and implicated in various medical dysfunctions. Yet, RNA structural biology lags significantly behind that of proteins, limiting mechanistic understanding of RNA chemical biology. Fortunately, solution NMR spectroscopy can probe the structural dynamics of RNA in solution at atomic resolution, opening the door to their functional understanding. However, NMR analysis of RNA, with only four unique ribonucleotide building blocks, suffers from spectral crowding and broad linewidths, especially as RNAs grow in size. One effective strategy to overcome these challenges is to introduce NMR-active stable isotopes into RNA. However, traditional uniform labeling methods introduce scalar and dipolar couplings that complicate the implementation and analysis of NMR measurements. This challenge can be circumvented with selective isotope labeling. In this review, we outline the development of labeling technologies and their application to study biologically relevant RNAs and their complexes ranging in size from 5 to 300 kDa by NMR spectroscopy.
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Affiliation(s)
- Theodore K. Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Lukasz T. Olenginski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Kehinde M. Taiwo
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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5
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Liu B, Rangadurai A, Shi H, Al-Hashimi H. Rapid assessment of Watson-Crick to Hoogsteen exchange in unlabeled DNA duplexes using high-power SELOPE imino 1H CEST. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:715-731. [PMID: 37905209 PMCID: PMC10539785 DOI: 10.5194/mr-2-715-2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 09/05/2021] [Indexed: 11/01/2023]
Abstract
In duplex DNA, Watson-Crick A-T and G-C base pairs (bp's) exist in dynamic equilibrium with an alternative Hoogsteen conformation, which is low in abundance and short-lived. Measuring how the Hoogsteen dynamics varies across different DNA sequences, structural contexts and physiological conditions is key for identifying potential Hoogsteen hot spots and for understanding the potential roles of Hoogsteen base pairs in DNA recognition and repair. However, such studies are hampered by the need to prepare 13 C or 15 N isotopically enriched DNA samples for NMR relaxation dispersion (RD) experiments. Here, using SELective Optimized Proton Experiments (SELOPE) 1 H CEST experiments employing high-power radiofrequency fields (B 1 > 250 Hz) targeting imino protons, we demonstrate accurate and robust characterization of Watson-Crick to Hoogsteen exchange, without the need for isotopic enrichment of the DNA. For 13 residues in three DNA duplexes under different temperature and pH conditions, the exchange parameters deduced from high-power imino 1 H CEST were in very good agreement with counterparts measured using off-resonance 13 C / 15 N spin relaxation in the rotating frame (R 1 ρ ). It is shown that 1 H-1 H NOE effects which typically introduce artifacts in 1 H-based measurements of chemical exchange can be effectively suppressed by selective excitation, provided that the relaxation delay is short (≤ 100 ms). The 1 H CEST experiment can be performed with ∼ 10× higher throughput and ∼ 100× lower cost relative to 13 C / 15 N R 1 ρ and enabled Hoogsteen chemical exchange measurements undetectable by R 1 ρ . The results reveal an increased propensity to form Hoogsteen bp's near terminal ends and a diminished propensity within A-tract motifs. The 1 H CEST experiment provides a basis for rapidly screening Hoogsteen breathing in duplex DNA, enabling identification of unusual motifs for more in-depth characterization.
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Affiliation(s)
- Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Department of Chemistry, Duke University, Durham, NC, USA
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6
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Jaladeep A, Varghese CN, Sekhar A. Measuring radiofrequency fields in NMR spectroscopy using offset-dependent nutation profiles. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 330:107032. [PMID: 34311422 PMCID: PMC7612739 DOI: 10.1016/j.jmr.2021.107032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 06/13/2023]
Abstract
The application of NMR spectroscopy for studying molecular and reaction dynamics relies crucially on the measurement of the magnitude of radiofrequency (RF) fields that are used to nutate or lock the nuclear magnetization. Here, we report a method for measuring RF field amplitudes that leverages the intrinsic modulations observed in offset-dependent NMR nutation profiles of small molecules. Such nutation profiles are exquisitely sensitive to the magnitude of the RF field, and B1 values ranging from 1 to 2000 Hz, as well the inhomogeneity in B1 distributions, can be determined with high accuracy and precision using this approach. In order to measure B1 fields associated with NMR experiments carried out on protein or nucleic acids, where these modulations are obscured by the large transverse relaxation rate constants of the analyte, our approach can be used in conjunction with a suitable external small molecule standard, expanding the scope of the method for large biomolecules.
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Affiliation(s)
- Ahallya Jaladeep
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Claris Niya Varghese
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Ashok Sekhar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
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7
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Kim H, Yang C, Pak Y. Free-Energy Landscape of a pH-Modulated G·C Base Pair Transition from Watson-Crick to Hoogsteen State in Duplex DNA. J Chem Theory Comput 2021; 17:2556-2565. [PMID: 33689343 DOI: 10.1021/acs.jctc.0c01330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In double-helical DNAs, the most stable Watson-Crick (WC) base pair (bp) can be in thermal equilibrium with much less abundant Hoogsteen (HG) bp by the spontaneous rotation of the glycosidic angle in purine bases. Previous experimental studies showed that in the case of a G·C bp, the population of the transient HG is enhanced as a protonated form (HG+) through the protonation of the cytosine base under weakly acidic conditions. Hence, pH is a key factor that can modulate this transition event from the WC to HG+ bp. In this study, to computationally probe the overall free-energy landscapes of this pH-modulated G·C HG breathing, a comprehensive classical molecular dynamics (MD) simulation protocol is proposed using an enhanced sampling MD in conjunction with the standard thermodynamic integration method. From this MD protocol proposed, the free-energy surfaces of the G·C bp transition from the WC to HG bp were constructed successfully at any pH range, producing pH-dependent free-energy quantities in close agreement with previously reported experimental results. The simulation protocol is expected to provide valuable atomistic insight into the DNA bp transition events coupled with protonation or tautomeric shift in a target bp.
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Affiliation(s)
- Hyeonjun Kim
- Department of Chemistry and Institute of Functional Materials, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, South Korea
| | - Changwon Yang
- Department of Chemistry, Sejong University, 209, Neungdong-ro, Gwangjin-gu, Seoul 05006, South Korea
| | - Youngshang Pak
- Department of Chemistry and Institute of Functional Materials, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, South Korea
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8
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Liu B, Shi H, Al-Hashimi HM. Developments in solution-state NMR yield broader and deeper views of the dynamic ensembles of nucleic acids. Curr Opin Struct Biol 2021; 70:16-25. [PMID: 33836446 DOI: 10.1016/j.sbi.2021.02.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 12/21/2022]
Abstract
Nucleic acids do not fold into a single conformation, and dynamic ensembles are needed to describe their propensities to cycle between different conformations when performing cellular functions. We review recent advances in solution-state nuclear magnetic resonance (NMR) methods and their integration with computational techniques that are improving the ability to probe the dynamic ensembles of DNA and RNA. These include computational approaches for predicting chemical shifts from structure and generating conformational libraries from sequence, measurements of exact nuclear Overhauser effects, development of new probes to study chemical exchange using relaxation dispersion, faster and more sensitive real-time NMR techniques, and new NMR approaches to tackle large nucleic acid assemblies. We discuss how these advances are leading to new mechanistic insights into gene expression and regulation.
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Affiliation(s)
- Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA; Department of Chemistry, Duke University, Durham, NC, USA.
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9
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Abou Assi H, Rangadurai AK, Shi H, Liu B, Clay MC, Erharter K, Kreutz C, Holley CL, Al-Hashimi H. 2'-O-Methylation can increase the abundance and lifetime of alternative RNA conformational states. Nucleic Acids Res 2020; 48:12365-12379. [PMID: 33104789 PMCID: PMC7708057 DOI: 10.1093/nar/gkaa928] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/10/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
2'-O-Methyl (Nm) is a highly abundant post-transcriptional RNA modification that plays important biological roles through mechanisms that are not entirely understood. There is evidence that Nm can alter the biological activities of RNAs by biasing the ribose sugar pucker equilibrium toward the C3'-endo conformation formed in canonical duplexes. However, little is known about how Nm might more broadly alter the dynamic ensembles of flexible RNAs containing bulges and internal loops. Here, using NMR and the HIV-1 transactivation response (TAR) element as a model system, we show that Nm preferentially stabilizes alternative secondary structures in which the Nm-modified nucleotides are paired, increasing both the abundance and lifetime of low-populated short-lived excited states by up to 10-fold. The extent of stabilization increased with number of Nm modifications and was also dependent on Mg2+. Through phi-value analysis, the Nm modification also provided rare insights into the structure of the transition state for conformational exchange. Our results suggest that Nm could alter the biological activities of Nm-modified RNAs by modulating their secondary structural ensembles as well as establish the utility of Nm as a tool for the discovery and characterization of RNA excited state conformations.
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Affiliation(s)
- Hala Abou Assi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Atul K Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | - Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mary C Clay
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kevin Erharter
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Christopher L Holley
- Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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10
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Semyonov DA, Eltsov IV, Nechipurenko YD. A New Bias Site for Epigenetic Modifications: How Non-Canonical GC Base Pairs Favor Mechanochemical Cleavage of DNA. Bioessays 2020; 42:e2000051. [PMID: 32830350 DOI: 10.1002/bies.202000051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/23/2020] [Indexed: 11/11/2022]
Abstract
Properties of non-canonical GC base pairs and their relations with mechanochemical cleavage of DNA are analyzed. A hypothesis of the involvement of the transient GC wobble base pairs both in the mechanisms of the mechanochemical cleavage of DNA and epigenetic mechanisms involving of 5-methylcytosine, is proposed. The hypothesis explains the increase in the frequency of the breaks of the sugar-phosphate backbone of DNA after cytosines, the asymmetric character of these breaks, and an increase in break frequency in CpG after cytosine methylation. As an alternative hypothesis, probable implication of GC+ Hoogsteen base pairs is considered, which now exemplify the best-studied non-canonical GC base pairs in the DNA double helix. Also see the video abstract here https://youtu.be/EUunVWL0ptw.
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Affiliation(s)
- Denis A Semyonov
- Institute of Biophysics, Institute of Biophysics, Siberian Branch of Russian Academy of Science., Akademgorodok 50, Krasnoyarsk, 660036, Russia
| | | | - Yury D Nechipurenko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
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