1
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Crisalli AM, Chen YT, Cai A, Li D, Cho BP. Conformation-dependent lesion bypass of bulky arylamine-dG adducts generated from 2-nitrofluorene in epigenetic sequence contexts. Nucleic Acids Res 2023; 51:12043-12053. [PMID: 37953358 PMCID: PMC10711442 DOI: 10.1093/nar/gkad1038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/27/2023] [Accepted: 10/24/2023] [Indexed: 11/14/2023] Open
Abstract
Sequence context influences structural characteristics and repair of DNA adducts, but there is limited information on how epigenetic modulation affects conformational heterogeneity and bypass of DNA lesions. Lesions derived from the environmental pollutant 2-nitrofluorene have been extensively studied as chemical carcinogenesis models; they adopt a sequence-dependent mix of two significant conformers: major groove binding (B) and base-displaced stacked (S). We report a conformation-dependent bypass of the N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (dG-FAF) lesion in epigenetic sequence contexts (d[5'-CTTCTC#G*NCCTCATTC-3'], where C# is C or 5-methylcytosine (5mC), G* is G or G-FAF, and N is A, T, C or G). FAF-modified sequences with a 3' flanking pyrimidine were better bypassed when the 5' base was 5mC, whereas sequences with a 3' purine exhibited the opposite effect. The conformational basis behind these variations differed; for -CG*C- and -CG*T-, bypass appeared to be inversely correlated with population of the duplex-destabilizing S conformer. On the other hand, the connection between conformation and a decrease in bypass for flanking purines in the 5mC sequences relative to C was more complex. It could be related to the emergence of a disruptive non-S/B conformation. The present work provides novel conformational insight into how 5mC influences the bypass efficiency of bulky DNA damage.
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Affiliation(s)
- Alicia M Crisalli
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Yi-Tzai Chen
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Ang Cai
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Bongsup P Cho
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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2
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Romero AH, Fuentes G, Suescun L, Piro O, Echeverría G, Gotopo L, Pezaroglo H, Álvarez G, Cabrera G, Cerecetto H, Couto M. Tautomerism and Rotamerism of Favipiravir and Halogenated Analogues in Solution and in the Solid State. J Org Chem 2023; 88:10735-10752. [PMID: 37452781 DOI: 10.1021/acs.joc.3c00777] [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: 07/18/2023]
Abstract
Favipiravir is an important selective antiviral against RNA-based viruses, and currently, it is being repurposed as a potential drug for the treatment of COVID-19. This type of chemical system presents different carboxamide-rotameric and hydroxyl-tautomeric states, which could be essential for interpreting its selective antiviral activity. Herein, the tautomeric 3-hydroxypyrazine/3-pyrazinone pair of favipiravir and its 6-substituted analogues, 6-Cl, 6-Br, 6-I, and 6-H, were fully investigated in solution and in the solid state through ultraviolet-visible, 1H nuclear magnetic resonance, infrared spectroscopy, and X-ray diffraction techniques. Also, a study of the gas phase was performed using density functional theory calculations. In general, the keto-enol balance in these 3-hydroxy-2-pyrazinecarboxamides is finely modulated by external and internal electrical variations via changes in solvent polarity or by replacement of substituents at position 6. The enol tautomer was prevalent in an apolar environment, whereas an increase in the level of the keto tautomer was favored by an increase in solvent polarity and, even moreso, with a strong hydrogen-donor solvent. Keto tautomerization was favored either in solution or in the solid state with a decrease in 6-substituent electronegativity as follows: H ≫ I ≈ Br > Cl ≥ F. Specific rotameric states based on carboxamide, "cisoide" and "transoide", were identified for the enol and keto tautomer, respectively; their rotamerism is dependent on the tautomerism and not the aggregation state.
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Affiliation(s)
- Angel H Romero
- Grupo de Química Orgánica Medicinal, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
| | - Germán Fuentes
- Grupo de Química Orgánica Medicinal, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
| | - Leopoldo Suescun
- Cryssmat-Lab/DETEMA, Facultad de Química, Universidad de la República, 11800 Montevideo, Uruguay
| | - Oscar Piro
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de la Plata, La Plata 1900, Argentina
| | - Gustavo Echeverría
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de la Plata, La Plata 1900, Argentina
| | - Lourdes Gotopo
- Laboratorio de Síntesis Orgánica, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Los Chaguaramos, 1040 Caracas, Venezuela
| | - Horacio Pezaroglo
- Laboratorio de Resonancia Magnética Nuclear, Facultad de Química, Universidad de la República, 11800 Montevideo, Uruguay
| | - Guzmán Álvarez
- Laboratorio de Moléculas Bioactivas, CENUR Litoral Norte, Universidad de la República, 60000 Paysandú, Uruguay
| | - Gustavo Cabrera
- Laboratorio de Síntesis Orgánica, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Los Chaguaramos, 1040 Caracas, Venezuela
| | - Hugo Cerecetto
- Grupo de Química Orgánica Medicinal, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
- Area de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Mataojo 2055, 11400 Montevideo, Uruguay
| | - Marcos Couto
- Grupo de Química Orgánica Medicinal, Facultad de Ciencias, Universidad de la República, 11400 Montevideo, Uruguay
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3
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Tang C, Stuyver T, Lu T, Liu J, Ye Y, Gao T, Lin L, Zheng J, Liu W, Shi J, Shaik S, Xia H, Hong W. Voltage-driven control of single-molecule keto-enol equilibrium in a two-terminal junction system. Nat Commun 2023; 14:3657. [PMID: 37339947 DOI: 10.1038/s41467-023-39198-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/30/2023] [Indexed: 06/22/2023] Open
Abstract
Keto-enol tautomerism, describing an equilibrium involving two tautomers with distinctive structures, provides a promising platform for modulating nanoscale charge transport. However, such equilibria are generally dominated by the keto form, while a high isomerization barrier limits the transformation to the enol form, suggesting a considerable challenge to control the tautomerism. Here, we achieve single-molecule control of a keto-enol equilibrium at room temperature by using a strategy that combines redox control and electric field modulation. Based on the control of charge injection in the single-molecule junction, we could access charged potential energy surfaces with opposite thermodynamic driving forces, i.e., exhibiting a preference for the conducting enol form, while the isomerization barrier is also significantly reduced. Thus, we could selectively obtain desired and stable tautomers, which leads to significant modulation of the single-molecule conductance. This work highlights the concept of single-molecule control of chemical reactions on more than one potential energy surface.
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Affiliation(s)
- Chun Tang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Thijs Stuyver
- Institute of Chemistry, Edmond J. Safra Campus at Givat Ram, The Hebrew University, Jerusalem, 91904, Israel
- Ecole Nationale Supérieure de Chimie de Paris, Université PSL, CNRS, Institute of Chemistry for Life and Health Sciences, 75 005, Paris, France
| | - Taige Lu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Yiling Ye
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Tengyang Gao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Luchun Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jueting Zheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Wenqing Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Jia Shi
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Sason Shaik
- Institute of Chemistry, Edmond J. Safra Campus at Givat Ram, The Hebrew University, Jerusalem, 91904, Israel.
| | - Haiping Xia
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
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Jena NR, Das P, Shukla PK. Complementary base pair interactions between different rare tautomers of the second-generation artificial genetic alphabets. J Mol Model 2023; 29:125. [PMID: 37014428 DOI: 10.1007/s00894-023-05537-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/29/2023] [Indexed: 04/05/2023]
Abstract
The functionality of a semisynthetic DNA in the biological environment will depend on the base pair nature of its complementary base pairs. To understand this, base pair interactions between complementary bases of recently proposed eight second-generation artificial nucleobases are studied herein by considering their rare tautomeric conformations and a dispersion-corrected density functional theoretic method. It is found that the binding energies of two hydrogen-bonded complementary base pairs are more negative than those of the three hydrogen-bonded base pairs. However, as the former base pairs are endothermic, the semisynthetic duplex DNA would involve the latter base pairs.
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Affiliation(s)
- N R Jena
- Discipline of Natural Sciences, Indian Institute of Information Technology, Design, and Manufacturing, Jabalpur, 482005, India.
| | - P Das
- Discipline of Natural Sciences, Indian Institute of Information Technology, Design, and Manufacturing, Jabalpur, 482005, India
| | - P K Shukla
- Department of Physics, Assam University, Silchar, 788011, India
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5
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Hyperpolarizing DNA Nucleobases via NMR Signal Amplification by Reversible Exchange. Molecules 2023; 28:molecules28031198. [PMID: 36770865 PMCID: PMC9921525 DOI: 10.3390/molecules28031198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 01/27/2023] Open
Abstract
The present work investigates the potential for enhancing the NMR signals of DNA nucleobases by parahydrogen-based hyperpolarization. Signal amplification by reversible exchange (SABRE) and SABRE in Shield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) of selected DNA nucleobases is demonstrated with the enhancement (ε) of 1H, 15N, and/or 13C spins in 3-methyladenine, cytosine, and 6-O-guanine. Solutions of the standard SABRE homogenous catalyst Ir(1,5-cyclooctadeine)(1,3-bis(2,4,6-trimethylphenyl)imidazolium)Cl ("IrIMes") and a given nucleobase in deuterated ethanol/water solutions yielded low 1H ε values (≤10), likely reflecting weak catalyst binding. However, we achieved natural-abundance enhancement of 15N signals for 3-methyladenine of ~3300 and ~1900 for the imidazole ring nitrogen atoms. 1H and 15N 3-methyladenine studies revealed that methylation of adenine affords preferential binding of the imidazole ring over the pyrimidine ring. Interestingly, signal enhancements (ε~240) of both 15N atoms for doubly labelled cytosine reveal the preferential binding of specific tautomer(s), thus giving insight into the matching of polarization-transfer and tautomerization time scales. 13C enhancements of up to nearly 50-fold were also obtained for this cytosine isotopomer. These efforts may enable the future investigation of processes underlying cellular function and/or dysfunction, including how DNA nucleobase tautomerization influences mismatching in base-pairing.
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Goyal K, Goel H, Baranwal P, Dixit A, Khan F, Jha NK, Kesari KK, Pandey P, Pandey A, Benjamin M, Maurya A, Yadav V, Sinh RS, Tanwar P, Upadhyay TK, Mittan S. Unravelling the molecular mechanism of mutagenic factors impacting human health. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:61993-62013. [PMID: 34410595 DOI: 10.1007/s11356-021-15442-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
Environmental mutagens are chemical and physical substances in the environment that has a potential to induce a wide range of mutations and generate multiple physiological, biochemical, and genetic modifications in humans. Most mutagens are having genotoxic effects on the following generation through germ cells. The influence of germinal mutations on health will be determined by their frequency, nature, and the mechanisms that keep a specific mutation in the population. Early prenatal lethal mutations have less public health consequences than genetic illnesses linked with long-term medical and social difficulties. Physical and chemical mutagens are common mutagens found in the environment. These two environmental mutagens have been associated with multiple neurological disorders and carcinogenesis in humans. Thus in this study, we aim to unravel the molecular mechanism of physical mutagens (UV rays, X-rays, gamma rays), chemical mutagens (dimethyl sulfate (DMS), bisphenol A (BPA), polycyclic aromatic hydrocarbons (PAHs), 5-chlorocytosine (5ClC)), and several heavy metals (Ar, Pb, Al, Hg, Cd, Cr) implicated in DNA damage, carcinogenesis, chromosomal abnormalities, and oxidative stress which leads to multiple disorders and impacting human health. Biological tests for mutagen detection are crucial; therefore, we also discuss several approaches (Ames test and Mutatox test) to estimate mutagenic factors in the environment. The potential risks of environmental mutagens impacting humans require a deeper basic knowledge of human genetics as well as ongoing research on humans, animals, and their tissues and fluids.
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Affiliation(s)
- Keshav Goyal
- Department of Microbiology, Ram Lal Anand College, University of Delhi, New Delhi, India
| | - Harsh Goel
- Department of Laboratory Oncology, All India Institute of Medical Sciences, New Delhi, India
| | - Pritika Baranwal
- Department of Microbiology, Ram Lal Anand College, University of Delhi, New Delhi, India
| | - Aman Dixit
- Department of Microbiology, Ram Lal Anand College, University of Delhi, New Delhi, India
| | - Fahad Khan
- Department of Biotechnology, Noida Institute of Engineering & Technology, 19, Knowledge Park-II, Institutional Area, Greater Noida, 201306, India
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering and Technology (SET), Sharda University, Greater Noida, India
| | | | - Pratibha Pandey
- Department of Biotechnology, Noida Institute of Engineering & Technology, 19, Knowledge Park-II, Institutional Area, Greater Noida, 201306, India
| | - Avanish Pandey
- Department of Laboratory Oncology, All India Institute of Medical Sciences, New Delhi, India
| | - Mercilena Benjamin
- Department of Laboratory Oncology, All India Institute of Medical Sciences, New Delhi, India
| | - Ankit Maurya
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Vandana Yadav
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Rana Suryauday Sinh
- Department of Microbiology and Biotechnology Centre, Maharaja Sayajirao University, Baroda, India
| | - Pranay Tanwar
- Department of Laboratory Oncology, All India Institute of Medical Sciences, New Delhi, India
| | - Tarun Kumar Upadhyay
- Department of Biotechnology, Parul Institute of Applied Sciences & Centre of Research for Development, Parul University, Vadodara, Gujarat, India.
| | - Sandeep Mittan
- Department of Cardiology, Ichan School of Medicine, Mount Sinai Hospital, 1 Gustave L. Levy Place, New York, NY, USA
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7
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Lethal Mutagenesis of RNA Viruses and Approved Drugs with Antiviral Mutagenic Activity. Viruses 2022; 14:v14040841. [PMID: 35458571 PMCID: PMC9024455 DOI: 10.3390/v14040841] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 12/11/2022] Open
Abstract
In RNA viruses, a small increase in their mutation rates can be sufficient to exceed their threshold of viability. Lethal mutagenesis is a therapeutic strategy based on the use of mutagens, driving viral populations to extinction. Extinction catastrophe can be experimentally induced by promutagenic nucleosides in cell culture models. The loss of HIV infectivity has been observed after passage in 5-hydroxydeoxycytidine or 5,6-dihydro-5-aza-2′-deoxycytidine while producing a two-fold increase in the viral mutation frequency. Among approved nucleoside analogs, experiments with polioviruses and other RNA viruses suggested that ribavirin can be mutagenic, although its mechanism of action is not clear. Favipiravir and molnupiravir exert an antiviral effect through lethal mutagenesis. Both drugs are broad-spectrum antiviral agents active against RNA viruses. Favipiravir incorporates into viral RNA, affecting the G→A and C→U transition rates. Molnupiravir (a prodrug of β-d-N4-hydroxycytidine) has been recently approved for the treatment of SARS-CoV-2 infection. Its triphosphate derivative can be incorporated into viral RNA and extended by the coronavirus RNA polymerase. Incorrect base pairing and inefficient extension by the polymerase promote mutagenesis by increasing the G→A and C→U transition frequencies. Despite having remarkable antiviral action and resilience to drug resistance, carcinogenic risks and genotoxicity are important concerns limiting their extended use in antiviral therapy.
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8
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Bahadoor A, Watt S, Rajotte I, Bates J. Tautomerization and Isomerization in Quantitative NMR: A Case Study with 4-Deoxynivalenol (DON). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:2733-2740. [PMID: 35171597 DOI: 10.1021/acs.jafc.1c08053] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The regulated mycotoxin 4-deoxynivalenol (DON) has a heterocyclic structure that is readily amenable to tautomerization and conformational isomerization in solution. An analysis of DON in solution by NMR revealed the presence of hemiacetal tautomer(s) and putative conformational isomers, which maintain the intact enone functional group. The extent and type of tautomerization/isomerization vary according to the NMR solvent used and produce different signal patterns in the NMR spectra. Thus, the same proton produces multiple signals depending on which isomer/tautomer it belongs to. To maintain the accuracy of quantitative NMR (qNMR) measurements, it was essential to conclusively identify all signals belonging to the same proton to avoid underestimating its integral value. A strategy to overcome the complications of DON tautomerization and isomerization in solution during qNMR is reported. Of all proton atoms on the DON carbo-skeleton, H-10 produced clearly defined signals centered at 6.6 ppm for suspected conformational isomers and at 5.5 ppm for hemiacetal tautomers. To determine the purity of DON by quantitative proton NMR, the collective integrals of all isomeric and tautomeric signals belonging to H-10 provided the most accurate value. The purity of DON obtained with this protocol is highly accurate and suitable for the value assignment of certified reference materials (CRMs).
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Affiliation(s)
- Adilah Bahadoor
- National Research Council, Metrology, Ottawa, Ontario K1A 0R6, Canada
| | - Sarah Watt
- National Research Council, Metrology, Ottawa, Ontario K1A 0R6, Canada
| | - Isabelle Rajotte
- National Research Council, Metrology, Ottawa, Ontario K1A 0R6, Canada
| | - Jennifer Bates
- National Research Council, Metrology, Ottawa, Ontario K1A 0R6, Canada
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9
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Zhang L, Farkhondeh H, Rahsepar FR, Chatterjee A, Leung KT. Surface-Induced Keto-Enol Tautomerization of DNA Base Molecules and Consequent [4 + 2]-like Cycloaddition on Si(111)7×7. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1266-1276. [PMID: 35020402 DOI: 10.1021/acs.langmuir.1c03173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Adsorption and film growth of deoxyribonucleic acid (DNA) base molecules (cytosine, guanine, thymine, and adenine) on Si(111)7×7 have been studied by combining X-ray photoelectron spectroscopy (XPS) with ab initio calculations based on the density functional theory (DFT). Multiple tautomeric forms and keto-enol tautomerization are revealed by the O 1s, N 1s, and C 1s XPS spectra of the O-containing DNA bases: cytosine, guanine, and thymine. While the carbonyl group-containing keto tautomer is more stable in a thick film and in powder, the hydroxyl group-containing enol tautomer is found at the interface. The keto-enol tautomerization, as induced by the reactive Si(111)7×7 surface, leads to the formation of a conjugated aromatic six-membered ring with a delocalized π electron system and to the consequent [4 + 2]-like cycloaddition between the enol tautomer and the 7×7 surface. The DFT calculation suggests that the enol tautomer exhibits a kinetic advantage over the keto one for the [4 + 2]-like cycloaddition. Among the several plausible pathways for the cycloaddition provided by the enol tautomer, the experimentally determined one involves a ring N and ring C atom (a polar pair), rather than two ring C atoms (a nonpolar pair), to better match the polar Si adatom-restatom pair of the 7×7 surface. Furthermore, the reacted ring C atom does not have any attached terminal functional group (e.g., -NH2 and -OH). Further deposition leads to continuous film growth in the keto tautomeric form for cytosine and guanine. For the only O-free DNA base molecule, adenine, dative bonding N → Si, rather than the [4 + 2]-like cycloaddition, is observed on the 7×7 surface. Of the four DNA base molecules, adenine is also the only one with its aromaticity maintained when adsorbed on the Si(111)7×7 surface. A reactive surface like the 7×7 surface could therefore provide a new control to trigger tautomerization that is often associated with genetic mutation.
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Affiliation(s)
- Lei Zhang
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Hanieh Farkhondeh
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Fatemeh Rahnemaye Rahsepar
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- School of Chemistry, College of Science, University of Tehran, Tehran 1417614411, Iran
| | - Avisek Chatterjee
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Kam Tong Leung
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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10
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Fedeles BI, Li D, Singh V. Structural Insights Into Tautomeric Dynamics in Nucleic Acids and in Antiviral Nucleoside Analogs. Front Mol Biosci 2022; 8:823253. [PMID: 35145998 PMCID: PMC8822119 DOI: 10.3389/fmolb.2021.823253] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 12/30/2021] [Indexed: 11/20/2022] Open
Abstract
DNA (2'-deoxyribonucleic acid) and RNA (ribonucleic acid) play diverse functional roles in biology and disease. Despite being comprised primarily of only four cognate nucleobases, nucleic acids can adopt complex three-dimensional structures, and RNA in particular, can catalyze biochemical reactions to regulate a wide variety of biological processes. Such chemical versatility is due in part to the phenomenon of nucleobase tautomerism, whereby the bases can adopt multiple, yet distinct isomeric forms, known as tautomers. For nucleobases, tautomers refer to structural isomers that differ from one another by the position of protons. By altering the position of protons on nucleobases, many of which play critical roles for hydrogen bonding and base pairing interactions, tautomerism has profound effects on the biochemical processes involving nucleic acids. For example, the transient formation of minor tautomers during replication could generate spontaneous mutations. These mutations could arise from the stabilization of mismatches, in the active site of polymerases, in conformations involving minor tautomers that are indistinguishable from canonical base pairs. In this review, we discuss the evidence for tautomerism in DNA, and its consequences to the fidelity of DNA replication. Also reviewed are RNA systems, such as the riboswitches and self-cleaving ribozymes, in which tautomerism plays a functional role in ligand recognition and catalysis, respectively. We also discuss tautomeric nucleoside analogs that are efficacious as antiviral drug candidates such as molnupiravir for coronaviruses and KP1212 for HIV. The antiviral efficacy of these analogs is due, in part, to their ability to exist in multiple tautomeric forms and induce mutations in the replicating viral genomes. From a technical standpoint, minor tautomers of nucleobases are challenging to identify directly because they are rare and interconvert on a fast, millisecond to nanosecond, time scale. Nevertheless, many approaches including biochemical, structural, computational and spectroscopic methods have been developed to study tautomeric dynamics in RNA and DNA systems, and in antiviral nucleoside analogs. An overview of these methods and their applications is included here.
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Affiliation(s)
- Bogdan I. Fedeles
- Departments of Chemistry and Biological Engineering and Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Deyu Li
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States
| | - Vipender Singh
- Department of Biochemistry and Biophysics, Novartis Institute of Biomedical Research, Cambridge, MA, United States
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11
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Thakkar Y, Joshi K, Hickey C, Wahler J, Wall B, Etter S, Smith B, Griem P, Tate M, Jones F, Oudraogo G, Pfuhler S, Choi C, Williams G, Greim H, Eisenbrand G, Dekant W, Api AM. OUP accepted manuscript. Mutagenesis 2022; 37:13-23. [PMID: 35302169 PMCID: PMC8976226 DOI: 10.1093/mutage/geac004] [Citation(s) in RCA: 181] [Impact Index Per Article: 90.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 02/04/2022] [Indexed: 12/04/2022] Open
Abstract
BlueScreen HC is a mammalian cell-based assay for measuring the genotoxicity and cytotoxicity of chemical compounds and mixtures. The BlueScreen HC assay has been utilized at the Research Institute for Fragrance Materials in a safety assessment program as a screening tool to prioritize fragrance materials for higher-tier testing, as supporting evidence when using a read-across approach, and as evidence to adjust the threshold of toxicological concern. Predictive values for the BlueScreen HC assay were evaluated based on the ability of the assay to predict the outcome of in vitro and in vivo mutagenicity and chromosomal damage genotoxicity assays. A set of 371 fragrance materials was assessed in the BlueScreen HC assay along with existing or newly generated in vitro and in vivo genotoxicity data. Based on a weight-of-evidence approach, the majority of materials in the data set were deemed negative and concluded not to have the potential to be genotoxic, while only a small proportion of materials were determined to show genotoxic effects in these assays. Analysis of the data set showed a combination of high positive agreement but low negative agreement between BlueScreen HC results, in vitro regulatory genotoxicity assays, and higher-tier test results. The BlueScreen HC assay did not generate any false negatives, thereby providing robustness when utilizing it as a high-throughput screening tool to evaluate the large inventory of fragrance materials. From the perspective of protecting public health, it is desirable to have no or minimal false negatives, as a false-negative result may incorrectly indicate the lack of a genotoxicity hazard. However, the assay did have a high percentage of false-positive results, resulting in poor positive predictivity of the in vitro genotoxicity test battery outcome. Overall, the assay generated 100% negative predictivity and 3.9% positive predictivity. In addition to the data set of 371 fragrance materials, 30 natural complex substances were evaluated for BlueScreen HC, Ames, and in vitro micronucleus assay, and a good correlation in all three assays was observed. Overall, while a positive result may have to be further investigated, these findings suggest that the BlueScreen HC assay can be a valuable screening tool to detect the genotoxic potential of fragrance materials and mixtures.
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Affiliation(s)
- Yax Thakkar
- Research Institute for Fragrance Materials, Inc., 50 Tice Blvd, Woodcliff Lake, NJ 07677, United States
- Corresponding author. Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ 07677-7654, United States. E-mail:
| | - Kaushal Joshi
- Research Institute for Fragrance Materials, Inc., 50 Tice Blvd, Woodcliff Lake, NJ 07677, United States
| | - Christina Hickey
- Firmenich, Inc., 250 Plainsboro Rd, Plainsboro Township, NJ 08536, United States
| | - Joseph Wahler
- Research Institute for Fragrance Materials, Inc., 50 Tice Blvd, Woodcliff Lake, NJ 07677, United States
- Present address: 15211 North Kierland Blvd Scottsdale, AZ 85254, United States
| | - Brian Wall
- Global Product Safety, Colgate-Palmolive Company, 909 River Rd, Piscataway, NJ 08854, United States
| | - Sylvain Etter
- Firmenich, Inc., Rue de la Bergère 7, 1242 Satigny, Switzerland
| | - Benjamin Smith
- Innovations in Food & Chemical Safety Programme, Agency for Science, Technology and Research (A*STAR), 1, #20-10 Fusionopolis Way, Connexis, North Tower, 138632, Singapore
- Singapore Institute of Food & Biotechnology Innovation, A*STAR, 1, #20-10 Fusionopolis Way, Connexis, North Tower, 138632, Singapore
| | - Peter Griem
- Symrise AG, Mühlenfeldstr 1, 37603, Holzminden, Niedersachsen, Germany
| | - Matthew Tate
- Gentronix, Alderley Edge, Macclesfield SK10 4TG, United Kingdom
| | - Frank Jones
- SC Johnson, 1525 Howe St, Racine, WI 53403, United States
| | - Gladys Oudraogo
- L'Oreal Life Sciences Research, 1, Av Eugene Schueller 93600 Aulnay sous Bois, France
| | - Stefan Pfuhler
- The Procter & Gamble Company, Mason Business Centre, Mason, OH, United States
| | | | - Gary Williams
- New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, United States
| | - Helmut Greim
- Technical University of Munich, Arcisstraße 21, 80333 München, Germany
| | - Gerhard Eisenbrand
- University of Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern, Germany (Retired)
| | - Wolfgang Dekant
- Department of Pharmacology and Toxicology of the University of Würzburg, Sanderring 2, 97070 Würzburg, Germany
| | - Anne Marie Api
- Research Institute for Fragrance Materials, Inc., 50 Tice Blvd, Woodcliff Lake, NJ 07677, United States
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12
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Dey G, Chakraborty A. Conformational Landscape and Tautomerisation in (Z)-4-(hydroxymethylene) isochroman-1,3-dione: Analysis through Energy and Hardness profiles. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130859] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Multiscale Modeling of Wobble to Watson-Crick-Like Guanine-Uracil Tautomerization Pathways in RNA. Int J Mol Sci 2021; 22:ijms22115411. [PMID: 34063755 PMCID: PMC8196565 DOI: 10.3390/ijms22115411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/05/2021] [Accepted: 05/09/2021] [Indexed: 01/02/2023] Open
Abstract
Energetically unfavorable Watson–Crick (WC)-like tautomeric forms of nucleobases are known to introduce spontaneous mutations, and contribute to replication, transcription, and translation errors. Recent NMR relaxation dispersion techniques were able to show that wobble (w) G•U mispair exists in equilibrium with the short-lived, low-population WC-like enolic tautomers. Presently, we have investigated the wG•U → WC-like enolic reaction pathway using various theoretical methods: quantum mechanics (QM), molecular dynamics (MD), and combined quantum mechanics/molecular mechanics (QM/MM). The previous studies on QM gas phase calculations were inconsistent with experimental data. We have also explored the environmental effects on the reaction energies by adding explicit water. While the QM-profile clearly becomes endoergic in the presence of water, the QM/MM-profile remains consistently endoergic in the presence and absence of water. Hence, by including microsolvation and QM/MM calculations, the experimental data can be explained. For the G•Uenol→ Genol•U pathway, the latter appears to be energetically more favorable throughout all computational models. This study can be considered as a benchmark of various computational models of wG•U to WC-like tautomerization pathways with and without the environmental effects, and may contribute on further studies of other mispairs as well.
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14
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Parshotam S, Joy M, Rossano-Tapia M, Mora-Gomez VA, Brown A. The thermochemical, structural, and spectroscopic analyses of the tautomers of sulfur and selenium modified emissive nucleobases. CAN J CHEM 2021. [DOI: 10.1139/cjc-2020-0294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, density functional theory (DFT) and time dependent density functional theory (TD-DFT) are used to investigate the stabilities and spectral properties [IR, UV–vis, and two-photon absorption (2PA)] of two sets of modified RNA nucleobase tautomers. The modifications introduce either a sulfur or selenium atom to form an isothiazolo[4,3-d]pyrimidine or isoselenazolo[4,3-d]pyrimidine heterocyclic core, respectively. The relative stabilities of both sets of modified tautomers determined with B3LYP/6-31++G(d,p) reveal that in water (with a polarizable continuum model), the 6-keto-2-amino tautomer of guanine and the rare 4-imino-2-keto tautomer of cytosine may be present at significant populations, whereas the 6-enol-2-amino tautomer of guanine is more common in the gas phase. The identification of these modified tautomers is possible due to the natural differences in their vibrational modes and hence IR spectra. Furthermore, the photophysical properties of both these sets of modified tautomers indicate that excitation and emission energies are shifted relative to their more abundant form in both one photon absorption and emission and 2PA spectra, as determined at the B3LYP/6-31++G(d,p) and CAM-B3LYP/aug-cc-pVDZ levels of theory, respectively. Even though the 2PA cross sections in water for all of the species are small (0.3–2.3 GM), the modified cytosine tautomer shows promise, as its cross section is larger than the more dominant form. The spectral separation between the dominant form and the tautomers of isoselenazole and isothiazole modified cytosine and guanine are relatively similar, suggesting both modifications could be useful in elucidating the tautomers from their more abundant counterparts.
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Affiliation(s)
- Shyam Parshotam
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Megan Joy
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Maria Rossano-Tapia
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - V. A. Mora-Gomez
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Alex Brown
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
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15
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Büchner R, Fondell M, Mascarenhas EJ, Pietzsch A, Vaz da Cruz V, Föhlisch A. How Hydrogen Bonding Amplifies Isomeric Differences in Pyridones toward Strong Changes in Acidity and Tautomerism. J Phys Chem B 2021; 125:2372-2379. [PMID: 33562959 PMCID: PMC7957858 DOI: 10.1021/acs.jpcb.0c10873] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Steric hindrance
of hydration and hydrogen bond enhancement by
localized charges have been identified as key factors for the massive
chemical differences between the hydroxypyridine/pyridone isomers
in aqueous solution. While all isomers occur mainly in the hydroxypyridine
form in the gas phase, they differ by more than 3 orders of magnitude
both in their acidity and tautomeric equilibrium constants upon hydration.
By monitoring the electronic and solvation structures as a function
of the protonation state and the O– substitution
position on the pyridine ring, the amplification of the isomeric differences
in aqueous solution has been investigated. Near-edge X-ray absorption
fine structure (NEXAFS) measurements at the N K-edge served as the
probe of the chemical state. The combination of molecular dynamics
simulations, complete active space self-consistent field (CASSCF),
and time-dependent density functional theory (TD-DFT) spectral calculations
contributes to unraveling the principles of tautomerism and acidity
in multiple biochemical systems based on tautomerism.
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Affiliation(s)
- Robby Büchner
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Mattis Fondell
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Eric J Mascarenhas
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.,Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Annette Pietzsch
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Vinícius Vaz da Cruz
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Alexander Föhlisch
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.,Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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16
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Miao S, Liang Y, Rundell S, Bhunia D, Devari S, Munyaradzi O, Bong D. Unnatural bases for recognition of noncoding nucleic acid interfaces. Biopolymers 2021; 112:e23399. [PMID: 32969496 PMCID: PMC7855516 DOI: 10.1002/bip.23399] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/14/2020] [Accepted: 08/25/2020] [Indexed: 12/20/2022]
Abstract
The notion of using synthetic heterocycles instead of the native bases to interface with DNA and RNA has been explored for nearly 60 years. Unnatural bases compatible with the DNA/RNA coding interface have the potential to expand the genetic code and co-opt the machinery of biology to access new macromolecular function; accordingly, this body of research is core to synthetic biology. While much of the literature on artificial bases focuses on code expansion, there is a significant and growing effort on docking synthetic heterocycles to noncoding nucleic acid interfaces; this approach seeks to illuminate major processes of nucleic acids, including regulation of transcription, translation, transport, and transcript lifetimes. These major avenues of research at the coding and noncoding interfaces have in common fundamental principles in molecular recognition. Herein, we provide an overview of foundational literature in biophysics of base recognition and unnatural bases in coding to provide context for the developing area of targeting noncoding nucleic acid interfaces with synthetic bases, with a focus on systems developed through iterative design and biophysical study.
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Affiliation(s)
- Shiqin Miao
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Yufeng Liang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Sarah Rundell
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Debmalya Bhunia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Shekar Devari
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Oliver Munyaradzi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Dennis Bong
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
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17
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Rangadurai A, Szymanski ES, Kimsey I, Shi H, Al-Hashimi HM. Probing conformational transitions towards mutagenic Watson-Crick-like G·T mismatches using off-resonance sugar carbon R 1ρ relaxation dispersion. JOURNAL OF BIOMOLECULAR NMR 2020; 74:457-471. [PMID: 32789613 PMCID: PMC7508749 DOI: 10.1007/s10858-020-00337-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 07/13/2020] [Indexed: 05/30/2023]
Abstract
NMR off-resonance R1ρ relaxation dispersion measurements on base carbon and nitrogen nuclei have revealed that wobble G·T/U mismatches in DNA and RNA duplexes exist in dynamic equilibrium with short-lived, low-abundance, and mutagenic Watson-Crick-like conformations. As Watson-Crick-like G·T mismatches have base pairing geometries similar to Watson-Crick base pairs, we hypothesized that they would mimic Watson-Crick base pairs with respect to the sugar-backbone conformation as well. Using off-resonance R1ρ measurements targeting the sugar C3' and C4' nuclei, a structure survey, and molecular dynamics simulations, we show that wobble G·T mismatches adopt sugar-backbone conformations that deviate from the canonical Watson-Crick conformation and that transitions toward tautomeric and anionic Watson-Crick-like G·T mismatches restore the canonical Watson-Crick sugar-backbone. These measurements also reveal kinetic isotope effects for tautomerization in D2O versus H2O, which provide experimental evidence in support of a transition state involving proton transfer. The results provide additional evidence in support of mutagenic Watson-Crick-like G·T mismatches, help rule out alternative inverted wobble conformations in the case of anionic G·T-, and also establish sugar carbons as new non-exchangeable probes of this exchange process.
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Affiliation(s)
- Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Eric S Szymanski
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
- Nymirum, 4324 S. Alston Avenue, Durham, NC, 27713, USA
| | - Isaac Kimsey
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
- Nymirum, 4324 S. Alston Avenue, Durham, NC, 27713, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, 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, 27710, USA.
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18
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Baker CM, Kidley NJ, Papachristos K, Hotson M, Carson R, Gravestock D, Pouliot M, Harrison J, Dowling A. Tautomer Standardization in Chemical Databases: Deriving Business Rules from Quantum Chemistry. J Chem Inf Model 2020; 60:3781-3791. [PMID: 32644790 DOI: 10.1021/acs.jcim.0c00232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Databases of small, potentially bioactive molecules are ubiquitous across the industry and academia. Designed such that each unique compound should appear only once, the multiplicity of ways in which many compounds can be represented means that these databases require methods for standardizing the representation of chemistry. This is commonly achieved through the use of "Chemistry Business Rules", sets of predefined rules that describe the "house style" of the database in question. At Syngenta, the historical approach to the design of chemistry business rules has been to focus on consistency of representation, with chemical relevance given secondary consideration. In this work, we overturn that convention. Through the use of quantum chemistry calculations, we define a set of chemistry business rules for tautomer standardization that reproduces gas-phase energetic preferences. We go on to show that, compared to our historic approach, this method yields tautomers that are in better agreement with those observed experimentally in condensed phases and that are better suited for use in predictive models.
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Affiliation(s)
- Christopher M Baker
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
| | - Nathan J Kidley
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
| | | | - Matthew Hotson
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
| | - Rob Carson
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
| | - David Gravestock
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
| | - Martin Pouliot
- Syngenta Crop Protection, Schaffhauserstrasse, Stein CH-4332, Switzerland
| | - Jim Harrison
- Datacraft Technologies, 110 Parkwood Place, Anstead, QLD 4070, Australia
| | - Alan Dowling
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, U.K
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19
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Li P, Rangadurai A, Al-Hashimi HM, Hammes-Schiffer S. Environmental Effects on Guanine-Thymine Mispair Tautomerization Explored with Quantum Mechanical/Molecular Mechanical Free Energy Simulations. J Am Chem Soc 2020; 142:11183-11191. [PMID: 32459476 DOI: 10.1021/jacs.0c03774] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
DNA bases can adopt energetically unfavorable tautomeric forms that enable the formation of Watson-Crick-like (WC-like) mispairs, which have been proposed to give rise to spontaneous mutations in DNA and misincorporation errors in DNA replication and translation. Previous NMR and computational studies have indicated that the population of WC-like guanine-thymine (G-T) mispairs depends on the environment, such as the local nucleic acid sequence and solvation. To investigate these environmental effects, herein G-T mispair tautomerization processes are studied computationally in aqueous solution, in A-form and B-form DNA duplexes, and within the active site of a DNA polymerase λ variant. The wobble G-T (wG-T), WC-like G-T*, and WC-like G*-T forms are considered, where * indicates the enol tautomer of the base. The minimum free energy paths for the tautomerization from the wG-T to the WC-like G-T* and from the WC-like G-T* to the WC-like G*-T are computed with mixed quantum mechanical/molecular mechanical (QM/MM) free energy simulations. The reaction free energies and free energy barriers are found to be significantly influenced by the environment. The wG-T→G-T* tautomerization is predicted to be endoergic in aqueous solution and the DNA duplexes but slightly exoergic in the polymerase, with Arg517 and Asn513 providing electrostatic stabilization of G-T*. The G-T*→G*-T tautomerization is also predicted to be slightly more thermodynamically favorable in the polymerase relative to these DNA duplexes. These simulations are consistent with an experimentally driven kinetic misincorporation model suggesting that G-T mispair tautomerization occurs in the ajar polymerase conformation or concertedly with the transition from the ajar to the closed polymerase conformation. Furthermore, the order of the associated two proton transfer reactions is predicted to be different in the polymerase than in aqueous solution and the DNA duplexes. These studies highlight the impact of the environment on the thermodynamics, kinetics, and fundamental mechanisms of G-T mispair tautomerization, which plays a role in a wide range of biochemically important processes.
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Affiliation(s)
- Pengfei Li
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Atul Rangadurai
- Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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20
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Bomzon B, Khunger Y, Subramanian R. A dielectric and spectrophotometric study of the tautomerization of 2-hydroxypyridine and 2-mercaptopyridine in water. RSC Adv 2020; 10:2389-2395. [PMID: 35494609 PMCID: PMC9048638 DOI: 10.1039/c9ra08392h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/17/2019] [Indexed: 11/21/2022] Open
Abstract
The basic ionization (pk1) and acidic ionization (pk2) constants and equilibrium constant (KT) of 2HPy and 2MPy were determined. The pk1(s) of their N- and X-methyl derivatives (X = O, S) were also determined. The equilibrium constant of 2MPy is approximately 60 times greater than its oxygen analog, 2HPy. The micro-ionization constants of the functional groups, –NH (pkA and pkC) and –XH (pkB and pkD), were determined to provide further insights into the ionization equilibria of these N-heteroaromatic XH compounds (2HPy and 2MPy). The relaxation time of water (τ) in aqueous solutions of 2HPy and 2MPy are collectively used with the KT values to determine the forward (kf) and backward (kb) rate constants of tautomerization. Subsequently, the kf and kb are used to provide the rationale for the KT and τ values. The basic ionization (pk1) and acidic ionization (pk2) constants and equilibrium constant (KT) of 2HPy and 2MPy were determined.![]()
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Affiliation(s)
- Biswadeep Bomzon
- Department of Chemistry, Indian Institute of Technology Patna 801106 India
| | - Yashita Khunger
- Department of Chemistry, Indian Institute of Technology Patna 801106 India
| | - Ranga Subramanian
- Department of Chemistry, Indian Institute of Technology Patna 801106 India
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21
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Jena NR. Role of different tautomers in the base-pairing abilities of some of the vital antiviral drugs used against COVID-19. Phys Chem Chem Phys 2020; 22:28115-28122. [DOI: 10.1039/d0cp05297c] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Base-pair mutations induced by different tautomers of anti-viral drugs are the main reasons for their anti-viral activities.
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Affiliation(s)
- N. R. Jena
- Discipline of Natural Sciences
- Indian Institute of Information Technology
- Design, and Manufacturing
- Khamaria
- India
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22
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Taccone MI, Cruz-Ortiz AF, Dezalay J, Soorkia S, Broquier M, Grégoire G, Sánchez CG, Pino GA. UV Photofragmentation of Cold Cytosine–M+ Complexes (M+: Na+, K+, Ag+). J Phys Chem A 2019; 123:7744-7750. [DOI: 10.1021/acs.jpca.9b06495] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Martín I. Taccone
- INFIQC (CONICET), Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina
- Departamento de Fisicoquímica, Fac. de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA Córdoba, Argentina
- Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria,
Pabellón Argentina, X5000HUA Córdoba, Argentina
| | - Andrés F. Cruz-Ortiz
- INFIQC (CONICET), Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina
- Departamento de Fisicoquímica, Fac. de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA Córdoba, Argentina
- Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria,
Pabellón Argentina, X5000HUA Córdoba, Argentina
| | - Jordan Dezalay
- Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Satchin Soorkia
- Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Michel Broquier
- Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
- Centre Laser de I’Université Paris-Sud (CLUPS/LUMAT), Univ. Paris-Sud, CNRS, IOGS, Université Paris-Saclay, F-91405 Orsay, France
| | - Gilles Grégoire
- Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Cristián G. Sánchez
- INFIQC (CONICET), Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina
- Departamento de Química Teórica y Computacional, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
| | - Gustavo A. Pino
- INFIQC (CONICET), Ciudad Universitaria, Pabellón Argentina, 5000 Córdoba, Argentina
- Departamento de Fisicoquímica, Fac. de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón Argentina, X5000HUA Córdoba, Argentina
- Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria,
Pabellón Argentina, X5000HUA Córdoba, Argentina
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23
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Biological Evaluation of DNA Biomarkers in a Chemically Defined and Site-Specific Manner. TOXICS 2019; 7:toxics7020036. [PMID: 31242562 PMCID: PMC6631660 DOI: 10.3390/toxics7020036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 02/06/2023]
Abstract
As described elsewhere in this Special Issue on biomarkers, much progress has been made in the detection of modified DNA within organisms at endogenous and exogenous levels of exposure to chemical species, including putative carcinogens and chemotherapeutic agents. Advances in the detection of damaged or unnatural bases have been able to provide correlations to support or refute hypotheses between the level of exposure to oxidative, alkylative, and other stresses, and the resulting DNA damage (lesion formation). However, such stresses can form a plethora of modified nucleobases, and it is therefore difficult to determine the individual contribution of a particular modification to alter a cell's genetic fate, as measured in the form of toxicity by stalled replication past the damage, by subsequent mutation, and by lesion repair. Chemical incorporation of a modification at a specific site within a vector (site-specific mutagenesis) has been a useful tool to deconvolute what types of damage quantified in biologically relevant systems may lead to toxicity and/or mutagenicity, thereby allowing researchers to focus on the most relevant biomarkers that may impact human health. Here, we will review a sampling of the DNA modifications that have been studied by shuttle vector techniques.
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24
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Kathuria D, Gupta P, Chourasiya SS, Sahoo SC, Beifuss U, Chakraborti AK, Bharatam PV. An unprecedented intramolecular to intermolecular mechanistic switch in 1,1-diaminoazines leading to differential product formation during the I2-induced tandem oxidative transformation. Org Biomol Chem 2019; 17:4129-4138. [DOI: 10.1039/c9ob00610a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Intermolecular cyclization of 1,1-diaminoazine.
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Affiliation(s)
- Deepika Kathuria
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar – 160 062
- India
| | - Pankaj Gupta
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar – 160 062
- India
| | - Sumit S. Chourasiya
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar – 160 062
- India
| | - Subash C. Sahoo
- Department of Chemistry
- Panjab University
- Chandigarh – 160014
- India
| | - Uwe Beifuss
- Bioorganische Chemie
- Institut für Chemie
- Universität
- D-70599 Stuttgart
- Germany
| | - Asit K. Chakraborti
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar – 160 062
- India
| | - Prasad V. Bharatam
- Department of Medicinal Chemistry
- National Institute of Pharmaceutical Education and Research (NIPER)
- S.A.S. Nagar – 160 062
- India
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25
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N-(acridin-9-yl)arenesulfonamides: Synthesis, quantum chemical studies and crystal structure analysis to establish the tautomeric preferences. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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26
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Gharat PM, Maity DK, Pal H, Dutta Choudhury S. Inhibition of the prototropic tautomerism in chrysazine by p-sulfonatocalixarene hosts. Org Biomol Chem 2018; 16:5178-5187. [DOI: 10.1039/c8ob00978c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study reveals the unusual inhibition of excited-state prototropic tautomerism of Chrysazine by p-sulfonatocalix[4,6]arene hosts.
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Affiliation(s)
- Poojan Milan Gharat
- Radiation & Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - Dilip Kumar Maity
- Homi Bhabha National Institute
- Training School Complex
- Mumbai 400094
- India
| | - Haridas Pal
- Radiation & Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
- Homi Bhabha National Institute
| | - Sharmistha Dutta Choudhury
- Radiation & Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
- Homi Bhabha National Institute
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27
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Wang C, McPherson JR, Zhang LH, Rozen S, Sabapathy K. Transcription-associated mutation of lasR in Pseudomonas aeruginosa. DNA Repair (Amst) 2016; 46:9-19. [DOI: 10.1016/j.dnarep.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/24/2016] [Accepted: 09/07/2016] [Indexed: 01/10/2023]
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28
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Horvath R, Huff GS, Gordon KC, George MW. Probing the excited state nature of coordination complexes with blended organic and inorganic chromophores using vibrational spectroscopy. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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29
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Abstract
Herpes simplex virus (HSV), a member of the Herpesviridae family, is a significant human pathogen that results in mucocutaneous lesions in the oral cavity or genital infections. Acyclovir (ACV) and related nucleoside analogues can successfully treat HSV infections, but the emergence of drug resistance to ACV has created a barrier for the treatment of HSV infections, especially in immunocompromised patients. There is an urgent need to explore new and effective tactics to circumvent drug resistance to HSV. This review summarises the current strategies in the development of new targets (the DNA helicase/primase (H/P) complex), new types of molecules (nature products) and new antiviral mechanisms (lethal mutagenesis of Janus-type nucleosides) to fight the drug resistance of HSV.
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30
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Gupta V, Dixit NM. Scaling law characterizing the dynamics of the transition of HIV-1 to error catastrophe. Phys Biol 2015; 12:054001. [PMID: 26331636 DOI: 10.1088/1478-3975/12/5/054001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Increasing the mutation rate, μ of viruses above a threshold, μ(c) has been predicted to trigger a catastrophic loss of viral genetic information and is being explored as a novel intervention strategy. Here, we examine the dynamics of this transition using stochastic simulations mimicking within-host HIV-1 evolution. We find a scaling law governing the characteristic time of the transition: τ ≈ 0.6/(μ - μ(c)). The law is robust to variations in underlying evolutionary forces and presents guidelines for treatment of HIV-1 infection with mutagens. We estimate that many years of treatment would be required before HIV-1 can suffer an error catastrophe.
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Affiliation(s)
- Vipul Gupta
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India
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31
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Ho JJ, Skoff DR, Ghosh A, Zanni MT. Structural Characterization of Single-Stranded DNA Monolayers Using Two-Dimensional Sum Frequency Generation Spectroscopy. J Phys Chem B 2015. [PMID: 26222775 DOI: 10.1021/acs.jpcb.5b07078] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
DNA-covered materials are important in technological applications such as biosensors and microarrays, but obtaining structural information on surface-bound biomolecules is experimentally challenging. In this paper, we structurally characterize single-stranded DNA monolayers of poly(thymine) from 10 to 25 bases in length with an emerging surface technique called two-dimensional sum frequency generation (2D SFG) spectroscopy. These experiments are carried out by adding a mid-IR pulse shaper to a femtosecond broad-band SFG spectrometer. Cross peaks and 2D line shapes in the 2D SFG spectra provide information about structure and dynamics. Because the 2D SFG spectra are heterodyne detected, the monolayer spectra can be directly compared to 2D infrared (2D IR) spectra of poly(thymine) in solution, which aids interpretation. We simulate the 2D SFG spectra using DFT calculations and an excitonic Hamiltonian that relates the molecular geometry to the vibrational coupling. Intrabase cross peaks help define the orientation of the bases and interbase cross peaks, created by coupling between bases, and resolves features not observed in 1D SFG spectra that constrain the relative geometries of stacked bases. We present a structure for the poly(T) oligomer that is consistent with the 2D SFG data. These experiments provide insight into the DNA monolayer structure and set precedent for studying complex biomolecules on surfaces with 2D SFG spectroscopy.
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Affiliation(s)
- Jia-Jung Ho
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - David R Skoff
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Ayanjeet Ghosh
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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32
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Intrinsic mutagenic properties of 5-chlorocytosine: A mechanistic connection between chronic inflammation and cancer. Proc Natl Acad Sci U S A 2015; 112:E4571-80. [PMID: 26243878 DOI: 10.1073/pnas.1507709112] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
During chronic inflammation, neutrophil-secreted hypochlorous acid can damage nearby cells inducing the genomic accumulation of 5-chlorocytosine (5ClC), a known inflammation biomarker. Although 5ClC has been shown to promote epigenetic changes, it has been unknown heretofore if 5ClC directly perpetrates a mutagenic outcome within the cell. The present work shows that 5ClC is intrinsically mutagenic, both in vitro and, at a level of a single molecule per cell, in vivo. Using biochemical and genetic approaches, we have quantified the mutagenic and toxic properties of 5ClC, showing that this lesion caused C→T transitions at frequencies ranging from 3-9% depending on the polymerase traversing the lesion. X-ray crystallographic studies provided a molecular basis for the mutagenicity of 5ClC; a snapshot of human polymerase β replicating across a primed 5ClC-containing template uncovered 5ClC engaged in a nascent base pair with an incoming dATP analog. Accommodation of the chlorine substituent in the template major groove enabled a unique interaction between 5ClC and the incoming dATP, which would facilitate mutagenic lesion bypass. The type of mutation induced by 5ClC, the C→T transition, has been previously shown to occur in substantial amounts both in tissues under inflammatory stress and in the genomes of many inflammation-associated cancers. In fact, many sequence-specific mutational signatures uncovered in sequenced cancer genomes feature C→T mutations. Therefore, the mutagenic ability of 5ClC documented in the present study may constitute a direct functional link between chronic inflammation and the genetic changes that enable and promote malignant transformation.
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33
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Brovarets' OO, Hovorun DM. How many tautomerization pathways connect Watson-Crick-like G*·T DNA base mispair and wobble mismatches? J Biomol Struct Dyn 2015; 33:2297-315. [PMID: 25932960 DOI: 10.1080/07391102.2015.1046936] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this study, we have theoretically demonstrated the intrinsic ability of the wobble G·T(w)/G*·T*(w)/G·T(w1)/G·T(w2) and Watson-Crick-like G*·T(WC) DNA base mispairs to interconvert into each other via the DPT tautomerization. We have established that among all these transitions, only one single G·T(w) ↔ G*·T(WC) pathway is eligible from a biological perspective. It involves short-lived intermediate - the G·T*(WC) base mispair - and is governed by the planar, highly stable, and zwitterionic [Formula: see text] transition state stabilized by the participation of the unique pattern of the five intermolecular O6(+)H⋯O4(-), O6(+)H⋯N3(-), N1(+)H⋯N3(-), N1(+)H⋯O2(-), and N2(+)H⋯O2(-) H-bonds. This non-dissociative G·T(w) ↔ G*·T(WC) tautomerization occurs without opening of the pair: Bases within mispair remain connected by 14 different patterns of the specific intermolecular interactions that successively change each other along the IRC. Novel kinetically controlled mechanism of the thermodynamically non-equilibrium spontaneous point GT/TG incorporation errors has been suggested. The mutagenic effect of the analogues of the nucleotide bases, in particular 5-bromouracil, can be attributed to the decreasing of the barrier of the acquisition by the wobble pair containing these compounds of the enzymatically competent Watson-Crick's geometry via the intrapair mutagenic tautomerization directly in the essentially hydrophobic recognition pocket of the replication DNA-polymerase machinery. Proposed approaches are able to explain experimental data, namely growth of the rate of the spontaneous point incorporation errors during DNA biosynthesis with increasing temperature.
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Affiliation(s)
- Ol'ha O Brovarets'
- a Department of Molecular and Quantum Biophysics , Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine , 150 Akademika Zabolotnoho Str., Kyiv 03680 , Ukraine.,b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
| | - Dmytro M Hovorun
- a Department of Molecular and Quantum Biophysics , Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine , 150 Akademika Zabolotnoho Str., Kyiv 03680 , Ukraine.,b Department of Molecular Biotechnology and Bioinformatics , Institute of High Technologies, Taras Shevchenko National University of Kyiv , 2-h Akademika Hlushkova Ave., Kyiv 03022 , Ukraine
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34
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Visualizing transient Watson-Crick-like mispairs in DNA and RNA duplexes. Nature 2015; 519:315-20. [PMID: 25762137 DOI: 10.1038/nature14227] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/09/2015] [Indexed: 11/08/2022]
Abstract
Rare tautomeric and anionic nucleobases are believed to have fundamental biological roles, but their prevalence and functional importance has remained elusive because they exist transiently, in low abundance, and involve subtle movements of protons that are difficult to visualize. Using NMR relaxation dispersion, we show here that wobble dG•dT and rG•rU mispairs in DNA and RNA duplexes exist in dynamic equilibrium with short-lived, low-populated Watson-Crick-like mispairs that are stabilized by rare enolic or anionic bases. These mispairs can evade Watson-Crick fidelity checkpoints and form with probabilities (10(-3) to 10(-5)) that strongly imply a universal role in replication and translation errors. Our results indicate that rare tautomeric and anionic bases are widespread in nucleic acids, expanding their structural and functional complexity beyond that attainable with canonical bases.
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35
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Two-dimensional IR spectroscopy of the anti-HIV agent KP1212 reveals protonated and neutral tautomers that influence pH-dependent mutagenicity. Proc Natl Acad Sci U S A 2015; 112:3229-34. [PMID: 25733867 DOI: 10.1073/pnas.1415974112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Antiviral drugs designed to accelerate viral mutation rates can drive a viral population to extinction in a process called lethal mutagenesis. One such molecule is 5,6-dihydro-5-aza-2'-deoxycytidine (KP1212), a selective mutagen that induces A-to-G and G-to-A mutations in the genome of replicating HIV. The mutagenic property of KP1212 was hypothesized to originate from its amino-imino tautomerism, which would explain its ability to base pair with either G or A. To test the multiple tautomer hypothesis, we used 2D IR spectroscopy, which offers subpicosecond time resolution and structural sensitivity to distinguish among rapidly interconverting tautomers. We identified several KP1212 tautomers and found that >60% of neutral KP1212 is present in the enol-imino form. The abundant proportion of this traditionally rare tautomer offers a compelling structure-based mechanism for pairing with adenine. Additionally, the pKa of KP1212 was measured to be 7.0, meaning a substantial population of KP1212 is protonated at physiological pH. Furthermore, the mutagenicity of KP1212 was found to increase dramatically at pH <7, suggesting a significant biological role for the protonated KP1212 molecules. Overall, our data reveal that the bimodal mutagenic properties of KP1212 result from its unique shape shifting ability that utilizes both tautomerization and protonation.
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36
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Abstract
Heterocyclic nucleic acid bases and their analogs can adopt multiple tautomeric forms due to the presence of multiple solvent-exchangeable protons. In DNA, spontaneous formation of minor tautomers has been speculated to contribute to mutagenic mispairings during DNA replication, whereas in RNA, minor tautomeric forms have been proposed to enhance the structural and functional diversity of RNA enzymes and aptamers. This review summarizes the role of tautomerism in RNA biochemistry, specifically focusing on the role of tautomerism in catalysis of small self-cleaving ribozymes and recognition of ligand analogs by riboswitches. Considering that the presence of multiple tautomers of nucleic acid bases is a rare occurrence, and that tautomers typically interconvert on a fast time scale, methods for studying rapid tautomerism in the context of nucleic acids under biologically relevant aqueous conditions are also discussed.
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Affiliation(s)
- Vipender Singh
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bogdan I Fedeles
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - John M Essigmann
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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Vivet-Boudou V, Isel C, El Safadi Y, Smyth RP, Laumond G, Moog C, Paillart JC, Marquet R. Evaluation of anti-HIV-1 mutagenic nucleoside analogues. J Biol Chem 2014; 290:371-83. [PMID: 25398876 DOI: 10.1074/jbc.m114.616383] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Because of their high mutation rates, RNA viruses and retroviruses replicate close to the threshold of viability. Their existence as quasi-species has pioneered the concept of "lethal mutagenesis" that prompted us to synthesize pyrimidine nucleoside analogues with antiviral activity in cell culture consistent with an accumulation of deleterious mutations in the HIV-1 genome. However, testing all potentially mutagenic compounds in cell-based assays is tedious and costly. Here, we describe two simple in vitro biophysical/biochemical assays that allow prediction of the mutagenic potential of deoxyribonucleoside analogues. The first assay compares the thermal stabilities of matched and mismatched base pairs in DNA duplexes containing or not the nucleoside analogues as follows. A promising candidate should display a small destabilization of the matched base pair compared with the natural nucleoside and the smallest gap possible between the stabilities of the matched and mismatched base pairs. From this assay, we predicted that two of our compounds, 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine, should be mutagenic. The second in vitro reverse transcription assay assesses DNA synthesis opposite nucleoside analogues inserted into a template strand and subsequent extension of the newly synthesized base pairs. Once again, only 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine are predicted to be efficient mutagens. The predictive potential of our fast and easy first line screens was confirmed by detailed analysis of the mutation spectrum induced by the compounds in cell culture because only compounds 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine were found to increase the mutation frequency by 3.1- and 3.4-fold, respectively.
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Affiliation(s)
- Valérie Vivet-Boudou
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
| | - Catherine Isel
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
| | - Yazan El Safadi
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
| | - Redmond P Smyth
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
| | - Géraldine Laumond
- the Unité INSERM 748, Université de Strasbourg, Institut de Virologie, 67000 Strasbourg, France
| | - Christiane Moog
- the Unité INSERM 748, Université de Strasbourg, Institut de Virologie, 67000 Strasbourg, France
| | - Jean-Christophe Paillart
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
| | - Roland Marquet
- From the Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg Cedex and
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