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He Z, Wu J, Li W, Du Y, Lu L. Investigation of G-Quadruplex DNA-Mediated Charge Transport for Exploring DNA Oxidative Damage in Telomeres. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39177475 DOI: 10.1021/acs.langmuir.4c01604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
The human telomeric DNA 3' single-stranded overhang comprises tandem repeats of the sequence d(TTAGGG), which can fold into the stable secondary structure G-quadruplex (G4) and is susceptible to oxidative damage due to the enrichment of G bases. 8-Oxoguanine (8-oxoG) formed in telomeric DNA destabilizes G4 secondary structures and then inhibits telomere functions such as the binding of G4 proteins and the regulation of the length of telomeres. In this work, we developed a G4-DNA self-assembled monolayer electrochemical sensing interface using copper-free click chemistry based on the reaction of dibenzocyclooctyl with azide, resulting in a high yield of DNA tethers with order and homogeneity surfaces, that is more suitable for G-quadruplex DNA charge transport (CT) research. At high DNA coverage density surfaces, G-quadruplex DNA is 4 times more conductive than double-stranded DNA owing to the well-stacked aromatic rings of G-quartets acting as good charge transfer channels. The effect of telomeric oxidative damage on G-quadruplex-mediated CT is investigated. The accommodation of 8-oxoG at G sites originally in the syn or anti conformation around the glycosyl bond in the nonsubstituted hTel G-quadruplex causes structural perturbation and a conformational shift, which disrupts the π-stack, affecting the charge transfer and attenuating the electrochemical signal. The current intensity was found to correlate with the amount of 8-oxodG, and the detection limit was estimated to be approximately one lesion in 286 DNA bases, which can be converted into 64.7 fmol on the basis of the total surface DNA coverage. The improved G4-DNA order and homogeneity sensing interface represent a major step forward in this regard, providing a reliable and controlled electrochemical platform for the accurate measurement and diagnosis of G4-DNA oxidative damage.
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Affiliation(s)
- Zhangjin He
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, Beijing University of Technology, Beijing 100124, P. R. China
| | - Jiening Wu
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, Beijing University of Technology, Beijing 100124, P. R. China
| | - Wei Li
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, Beijing University of Technology, Beijing 100124, P. R. China
| | - Yuying Du
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, Beijing University of Technology, Beijing 100124, P. R. China
| | - Liping Lu
- Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, Beijing University of Technology, Beijing 100124, P. R. China
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Howpay Manage SA, Zhu J, Fleming AM, Burrows CJ. Promoters vs. telomeres: AP-endonuclease 1 interactions with abasic sites in G-quadruplex folds depend on topology. RSC Chem Biol 2023; 4:261-270. [PMID: 37034403 PMCID: PMC10074553 DOI: 10.1039/d2cb00233g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/12/2023] [Indexed: 01/19/2023] Open
Abstract
The DNA repair endonuclease APE1 is responsible for the cleavage of abasic sites (AP) in DNA as well as binding AP in promoter G-quadruplex (G4) folds in some genes to regulate transcription. The present studies focused on the topological properties of AP-bearing G4 folds and how they impact APE1 interaction. The human telomere sequence with a tetrahydrofuran model (F) of an AP was folded in K+- or Na+-containing buffers to adopt hybrid- or basket-folds, respectively. Endonuclease and binding assays were performed with APE1 and the G4 substrates, and the data were compared to prior work with parallel-stranded VEGF and NEIL3 promoter G4s to identify topological differences. The APE1-catalyzed endonuclease assays led to the conclusion that telomere G4 folds were slightly better substrates than the promoter G4s, but the yields were all low compared to duplex DNA. In the binding assays, G4 topological differences were observed in which APE1 bound telomere G4s with dissociation constants similar to single-stranded DNA, and promoter G4s were bound with nearly ten-fold lower values similar to duplex DNA. An in-cellulo assay with the telomere G4 in a model promoter bearing a lesion failed to regulate transcription. These data support a hypothesis that G4 topology in gene promoters is a critical feature that APE1 recognizes for gene regulation.
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Affiliation(s)
| | - Judy Zhu
- Department of Chemistry, University of Utah 315 S. 1400 E. Salt Lake City UT 84112-0850 USA
| | - Aaron M Fleming
- Department of Chemistry, University of Utah 315 S. 1400 E. Salt Lake City UT 84112-0850 USA
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah 315 S. 1400 E. Salt Lake City UT 84112-0850 USA
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Allred DR. Integration of DNA Repair, Antigenic Variation, Cytoadhesion, and Chance in Babesia Survival: A Perspective. Front Cell Infect Microbiol 2022; 12:869696. [PMID: 35493746 PMCID: PMC9047050 DOI: 10.3389/fcimb.2022.869696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites live in hostile environments in which they are challenged chemically and their hosts attempt in many ways to kill them. In response, the parasites have evolved multiple mechanisms that take advantage of these challenges to enhance their survival. Perhaps the most impressive example is the evolutionary co-option of DNA repair mechanisms by the parasites as a means to rapidly manipulate the structure, antigenicity, and expression of the products of specific multigene families. The purpose of variant proteins that mediate cytoadhesion has long been thought to be primarily the avoidance of splenic clearance. Based upon known biology, I present an alternative perspective in which it is survival of the oxidative environment within which Babesia spp. parasites live that has driven integration of DNA repair, antigenic variation, and cytoadhesion, and speculate on how genome organization affects that integration. This perspective has ramifications for the development of parasite control strategies.
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Affiliation(s)
- David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, United States
- Genetics Institute, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
- *Correspondence: David R. Allred,
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Kumar A, Sevilla MD. Proton-Transfer Reactions in One-Electron-Oxidized G-Quadruplexes: A Density Functional Theory Study. J Phys Chem B 2022; 126:1483-1491. [PMID: 35152699 PMCID: PMC8881324 DOI: 10.1021/acs.jpcb.1c10529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recently, G-quadruplexes (Gq) formed in B-DNA as secondary structures are found to be important therapeutic targets and material for developing nanodevices. Gq are guanine-rich and thus susceptible to oxidative damage by producing short-lived intermediate radicals via proton-transfer reactions. Understanding the mechanisms of radical formation in Gq is of fundamental interest to understand the early stages of DNA damage. Herein, we used density functional theory including aqueous phase (ωB97XD-PCM/6-31++G**) and considered single layer of Gq [G-quartets (G4): association of four guanines in a cyclic Hoogsteen hydrogen-bonded arrangement (Scheme 1)] to unravel the mechanisms of formation of intermediates by calculating the relative Gibbs free energies and spin density distributions of one-electron-oxidized G4 and its various proton-transfer states: G•+, G(N1-H)•, G(N2-H')•, G(N2-H″)•, G(N1-H)•-(H+O6)G, and G(N2-H)•-(H+N7)G. The present calculation predicts the formation of G(N2-H)•-(H+N7)G, which is only ca. 0.8 kcal/mol higher in energy than the initially formed G•+. The formation of G(N2-H)•-(H+N7)G plays a key role in explaining the formation of 8-OG along with G(N1-H)• formation via tautomerization from G(N2-H)•, as proposed recently.
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Affiliation(s)
- Anil Kumar
- Corresponding Author: . Tel: +1 248 370 2327, . Tel: +1 248 370 2328
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De Rosa M, Johnson SA, Opresko PL. Roles for the 8-Oxoguanine DNA Repair System in Protecting Telomeres From Oxidative Stress. Front Cell Dev Biol 2021; 9:758402. [PMID: 34869348 PMCID: PMC8640134 DOI: 10.3389/fcell.2021.758402] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/27/2021] [Indexed: 11/27/2022] Open
Abstract
Telomeres are protective nucleoprotein structures that cap linear chromosome ends and safeguard genome stability. Progressive telomere shortening at each somatic cell division eventually leads to critically short and dysfunctional telomeres, which can contribute to either cellular senescence and aging, or tumorigenesis. Human reproductive cells, some stem cells, and most cancer cells, express the enzyme telomerase to restore telomeric DNA. Numerous studies have shown that oxidative stress caused by excess reactive oxygen species is associated with accelerated telomere shortening and dysfunction. Telomeric repeat sequences are remarkably susceptible to oxidative damage and are preferred sites for the production of the mutagenic base lesion 8-oxoguanine, which can alter telomere length homeostasis and integrity. Therefore, knowledge of the repair pathways involved in the processing of 8-oxoguanine at telomeres is important for advancing understanding of the pathogenesis of degenerative diseases and cancer associated with telomere instability. The highly conserved guanine oxidation (GO) system involves three specialized enzymes that initiate distinct pathways to specifically mitigate the adverse effects of 8-oxoguanine. Here we introduce the GO system and review the studies focused on investigating how telomeric 8-oxoguanine processing affects telomere integrity and overall genome stability. We also discuss newly developed technologies that target oxidative damage selectively to telomeres to investigate roles for the GO system in telomere stability.
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Affiliation(s)
- Mariarosaria De Rosa
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and UPMC Hillman Cancer Center, Pittsburgh, PA, United States
| | - Samuel A Johnson
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and UPMC Hillman Cancer Center, Pittsburgh, PA, United States
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and UPMC Hillman Cancer Center, Pittsburgh, PA, United States
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An J, Yin M, Yin J, Wu S, Selby CP, Yang Y, Sancar A, Xu GL, Qian M, Hu J. Genome-wide analysis of 8-oxo-7,8-dihydro-2'-deoxyguanosine at single-nucleotide resolution unveils reduced occurrence of oxidative damage at G-quadruplex sites. Nucleic Acids Res 2021; 49:12252-12267. [PMID: 34788860 PMCID: PMC8643665 DOI: 10.1093/nar/gkab1022] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/28/2021] [Accepted: 10/13/2021] [Indexed: 02/06/2023] Open
Abstract
8-Oxo-7,8-dihydro-2′-deoxyguanosine (OG), one of the most common oxidative DNA damages, causes genome instability and is associated with cancer, neurological diseases and aging. In addition, OG and its repair intermediates can regulate gene transcription, and thus play a role in sensing cellular oxidative stress. However, the lack of methods to precisely map OG has hindered the study of its biological roles. Here, we developed a single-nucleotide resolution OG-sequencing method, named CLAPS-seq (Chemical Labeling And Polymerase Stalling Sequencing), to measure the genome-wide distribution of both exogenous and endogenous OGs with high specificity. Our data identified decreased OG occurrence at G-quadruplexes (G4s), in association with underrepresentation of OGs in promoters which have high GC content. Furthermore, we discovered that potential quadruplex sequences (PQSs) were hotspots of OGs, implying a role of non-G4-PQSs in OG-mediated oxidative stress response.
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Affiliation(s)
- Jiao An
- Shanghai Fifth People's Hospital, Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Mengdie Yin
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Jiayong Yin
- Institute of Pediatrics and Department of Hematology and Oncology, Children's Hospital of Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Sizhong Wu
- Shanghai Fifth People's Hospital, Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Christopher P Selby
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7260, USA
| | - Yanyan Yang
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7260, USA
| | - Aziz Sancar
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7260, USA
| | - Guo-Liang Xu
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Maoxiang Qian
- Institute of Pediatrics and Department of Hematology and Oncology, Children's Hospital of Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Jinchuan Hu
- Shanghai Fifth People's Hospital, Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
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7
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Hassler E, Almer G, Reishofer G, Marsche G, Mangge H, Deutschmann H, Herrmann M, Leber S, Gunzer F, Renner W. Sex-Specific Association of Serum Anti-Oxidative Capacity and Leukocyte Telomere Length. Antioxidants (Basel) 2021; 10:1908. [PMID: 34943011 PMCID: PMC8750675 DOI: 10.3390/antiox10121908] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/25/2021] [Accepted: 11/26/2021] [Indexed: 12/20/2022] Open
Abstract
Telomeres are a crucial factor in the preservation of genomic integrity, and an elevated risk for diseases such as cancer and cardiovascular events is related to shortened telomeres. However, telomere deterioration could be caused by factors such as chronic oxidative stress and inflammation, which are promoted by an imbalance among reactive oxygen species (ROS) and antioxidants. In this cross-sectional study, we investigated the relationship between telomeres and oxidative stress. The serum leucocyte telomer length (LTL), serum total antioxidant capacity (TAC) and the total serum lipid panel of 180 healthy athletic volunteers (90 males, 90 females) were measured Additionally, a questionnaire about sports behaviour and the type of training was completed. We observed a positive significant relation between serum LTL and TAC in the male group (cc = 3.4/p = 0.001) but not in females. There was no statistically significant correlation between age and physical activity and LTL in both groups. This is the first cross sectional study demonstrating an association between total serum TAC and LTL in healthy males, but interestingly, not in the females. Nevertheless, these results should be interpreted as preliminary, and further studies in independent cohorts are needed to investigate the sex-specific effects of oxidative stress on telomere length and telomerase activity.
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Affiliation(s)
- Eva Hassler
- Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University Graz, 8036 Graz, Austria; (E.H.); (H.D.); (S.L.); (F.G.)
| | - Gunter Almer
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University Graz, 8036 Graz, Austria; (G.A.); (H.M.); (M.H.); (W.R.)
| | - Gernot Reishofer
- Department of Radiology, Medical University Graz, 8036 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
| | - Gunther Marsche
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, 8036 Graz, Austria;
| | - Harald Mangge
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University Graz, 8036 Graz, Austria; (G.A.); (H.M.); (M.H.); (W.R.)
- Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, 8036 Graz, Austria;
| | - Hannes Deutschmann
- Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University Graz, 8036 Graz, Austria; (E.H.); (H.D.); (S.L.); (F.G.)
| | - Markus Herrmann
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University Graz, 8036 Graz, Austria; (G.A.); (H.M.); (M.H.); (W.R.)
| | - Stefan Leber
- Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University Graz, 8036 Graz, Austria; (E.H.); (H.D.); (S.L.); (F.G.)
| | - Felix Gunzer
- Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University Graz, 8036 Graz, Austria; (E.H.); (H.D.); (S.L.); (F.G.)
| | - Wilfried Renner
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University Graz, 8036 Graz, Austria; (G.A.); (H.M.); (M.H.); (W.R.)
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8
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Zhou W, Liu J. Reaction mechanism and dynamics for C8-hydroxylation of 9-methylguanine radical cation by water molecules. Phys Chem Chem Phys 2021; 23:24464-24477. [PMID: 34698322 DOI: 10.1039/d1cp03884b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In contrast to their spontaneous deprotonation in aqueous solution, reactions of guanine and guanosine radical cations with water in the gas phase are exclusively initiated by hydration of the radical cations as reported in recent work (Y. Sun et al., Phys. Chem. Chem. Phys., 2018, 20, 27510). As gas-phase hydration reactions closely mimic the actual scenario for guanine radical cations in double-stranded DNA, exploration of subsequent reactions within their water complexes can provide an insight into the resulting oxidative damage to nucleosides. Herein guided-ion beam mass spectrometry experiment and direct dynamics trajectory simulations were carried out to examine prototype complexes of the 9-methylguanine radical cation with one and two water ligands (i.e., 9MG˙+·(H2O)1-2) in the gas phase, wherein the complexes were activated by collisional activation in the experiment and by thermal excitation at high temperatures in the simulations. Guided by mass spectroscopic measurements, trajectory results and reaction potential energy surface, three reaction pathways were identified. The first two reaction pathways start with H-atom abstraction from water by the O6 and N7 atoms in 9MG˙+ and are referred to as HAO6 and HAN7, respectively. The primary products of HAO6 and HAN7 reactions, including [9MG + HO6]+/[9MG + HN7]+ and ˙OH, react further to either form [8OH-9MG + HO6]˙+ and [8OH-9MG + HN7]˙+via C8-hydroxylation or form radical cations of 6-enol-guanine (6-enol-G˙+) and 7H-guanine (7HG˙+) via SN2-type methanol elimination. The third reaction pathway corresponds to the formation of 8OH-9MG+ by H elimination from the complex, referred to as HE. Among these product channels, [8OH-9MG + HN7]˙+ has the most favorable formation probability, especially in the presence of additional water molecules. This product may serve as a preceding structure to the 8-oxo-7,8-dihydroguanine lesion in DNA and has implications for health effects of radiation exposure and radiation therapy.
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Affiliation(s)
- Wenjing Zhou
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. .,PhD Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
| | - Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, NY 11367, USA. .,PhD Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Ave., New York, NY 10016, USA
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Balanikas E, Banyasz A, Baldacchino G, Markovitsi D. Deprotonation Dynamics of Guanine Radical Cations †. Photochem Photobiol 2021; 98:523-531. [PMID: 34653259 DOI: 10.1111/php.13540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/08/2021] [Indexed: 01/25/2023]
Abstract
This review is dedicated to guanine radical cations (G+ )· that are precursors to oxidatively generated damage to DNA. (G+ )· are unstable in neutral aqueous solution and tend to lose a proton. The deprotonation process has been studied by time-resolved absorption experiments in which (G+ )· radicals are produced either by an electron abstraction reaction, using an external oxidant, or by low-energy/low-intensity photoionization of DNA. Both the position of the released proton and the dynamics of the process depend on the secondary DNA structure. While deprotonation in duplex DNA leads to (G-H1)· radicals, in guanine quadruplexes the (G-H2)· analogs are observed. Deprotonation in monomeric guanosine proceeds with a time constant of ˜60 ns; in genomic DNA, it is completed within 2 µs; and in guanine quadruplexes, it spans from at least 30 ns to over 50 µs. Such a deprotonation dynamics in four-stranded structures, extended over more than three decades of times, is correlated with the anisotropic structure of DNA and the mobility of its hydration shell. In this case, commonly used second-order reaction models are inappropriate for its description.
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Affiliation(s)
| | - Akos Banyasz
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France.,Univ Lyon, ENS de Lyon, CNRS, UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, Lyon, F-69342, France
| | - Gérard Baldacchino
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France
| | - Dimitra Markovitsi
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France
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The Two Faces of the Guanyl Radical: Molecular Context and Behavior. Molecules 2021; 26:molecules26123511. [PMID: 34207639 PMCID: PMC8227002 DOI: 10.3390/molecules26123511] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
The guanyl radical or neutral guanine radical G(-H)• results from the loss of a hydrogen atom (H•) or an electron/proton (e–/H+) couple from the guanine structures (G). The guanyl radical exists in two tautomeric forms. As the modes of formation of the two tautomers, their relationship and reactivity at the nucleoside level are subjects of intense research and are discussed in a holistic manner, including time-resolved spectroscopies, product studies, and relevant theoretical calculations. Particular attention is given to the one-electron oxidation of the GC pair and the complex mechanism of the deprotonation vs. hydration step of GC•+ pair. The role of the two G(-H)• tautomers in single- and double-stranded oligonucleotides and the G-quadruplex, the supramolecular arrangement that attracts interest for its biological consequences, are considered. The importance of biomarkers of guanine DNA damage is also addressed.
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11
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Balanikas E, Banyasz A, Baldacchino G, Markovitsi D. Populations and Dynamics of Guanine Radicals in DNA strands-Direct versus Indirect Generation. Molecules 2019; 24:molecules24132347. [PMID: 31247883 PMCID: PMC6651618 DOI: 10.3390/molecules24132347] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/14/2019] [Accepted: 06/18/2019] [Indexed: 01/17/2023] Open
Abstract
Guanine radicals, known to be involved in the damage of the genetic code and aging, are studied by nanosecond transient absorption spectroscopy. They are generated in single, double and four-stranded structures (G-quadruplexes) by one and two-photon ionization at 266 nm, corresponding to a photon energy lower than the ionization potential of nucleobases. The quantum yield of the one-photon process determined for telomeric G-quadruplexes (TEL25/Na+) is (5.2 ± 0.3) × 10−3, significantly higher than that found for duplexes containing in their structure GGG and GG sequences, (2.1 ± 0.4) × 10−3. The radical population is quantified in respect of the ejected electrons. Deprotonation of radical cations gives rise to (G-H1)• and (G-H2)• radicals for duplexes and G-quadruplexes, respectively. The lifetimes of deprotonated radicals determined for a given secondary structure strongly depend on the base sequence. The multiscale non-exponential dynamics of these radicals are discussed in terms of inhomogeneity of the reaction space and continuous conformational motions. The deviation from classical kinetic models developed for homogeneous reaction conditions could also be one reason for discrepancies between the results obtained by photoionization and indirect oxidation, involving a bi-molecular reaction between an oxidant and the nucleic acid.
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Affiliation(s)
| | - Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342 Lyon, France.
| | - Gérard Baldacchino
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
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Sun Y, Zhou W, Moe MM, Liu J. Reactions of water with radical cations of guanine, 9-methylguanine, 2′-deoxyguanosine and guanosine: keto–enol isomerization, C8-hydroxylation, and effects of N9-substitution. Phys Chem Chem Phys 2018; 20:27510-27522. [DOI: 10.1039/c8cp05453c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactions of D2O with guanine radical cations in nucleobases and nucleosides were studied in the gas phase using the guided-ion-beam experiment and computational modeling.
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Affiliation(s)
- Yan Sun
- Department of Chemistry and Biochemistry
- Queens College of the City University of New York
- Queens
- USA
- PhD Program in Chemistry
| | - Wenjing Zhou
- Department of Chemistry and Biochemistry
- Queens College of the City University of New York
- Queens
- USA
| | - May Myat Moe
- Department of Chemistry and Biochemistry
- Queens College of the City University of New York
- Queens
- USA
| | - Jianbo Liu
- Department of Chemistry and Biochemistry
- Queens College of the City University of New York
- Queens
- USA
- PhD Program in Chemistry
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