1
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Tew DJ, Hebert JM, Schmier BJ. Discovery and properties of a monoclonal antibody targeting 8-oxoA, an oxidized adenine lesion in DNA and RNA. Redox Biol 2023; 62:102658. [PMID: 36989571 PMCID: PMC10074937 DOI: 10.1016/j.redox.2023.102658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/04/2023] [Indexed: 03/17/2023] Open
Abstract
8-oxoA, a major oxidation product of adenosine, is a mispairing, mutagenic lesion that arises in DNA and RNA when •OH radicals or one-electron oxidants attack the C8 adenine atom or polymerases misincorporate 8-oxo(d)ATP. The danger of 8-oxoA is underscored by the existence of dedicated cellular repair machinery that explicitly excise it from DNA, the attenuation of translation induced by 8-oxoA-mRNA or damaged ribosomes, and its potency as a TLR7 agonist. Here we present the discovery, purification, and biochemical characterization of a new mouse IgGk1 monoclonal antibody (6E4) that specifically targets 8-oxoA. Utilizing an AchE-based competitive ELISA assay, we demonstrate the selectivity of 6E4 for 8-oxoA over a plethora of canonical and chemically modified nucleosides including 8-oxoG, A, m6A, 2-oxoA, and 5-hoU. We further show the ability of 6E4 to exclusively recognize 8-oxoA in nucleoside triphosphates (8-oxoATP) and DNA/RNA oligonucleotides containing a single 8-oxoA. 6E4 also binds 8-oxoA in duplex DNA/RNA antigens where the lesion is either paired correctly or base mismatched. Our findings define the 8-oxoAde nucleobase as the critical epitope and indicate mAb 6E4 is ideally suited for a broad range of immunological applications in nucleic acid detection and quality control.
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2
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Servius HW, Pidugu LS, Sherman ME, Drohat AC. Rapid excision of oxidized adenine by human thymine DNA glycosylase. J Biol Chem 2022; 299:102756. [PMID: 36460098 PMCID: PMC9800633 DOI: 10.1016/j.jbc.2022.102756] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Oxidation of DNA bases generates mutagenic and cytotoxic lesions that are implicated in cancer and other diseases. Oxidative base lesions, including 7,8-dihydro-8-oxoguanine, are typically removed through base excision repair. In addition, oxidized deoxynucleotides such as 8-oxo-dGTP are depleted by sanitizing enzymes to preclude DNA incorporation. While pathways that counter threats posed by 7,8-dihydro-8-oxoguanine are well characterized, mechanisms protecting against the major adenine oxidation product, 7,8-dihydro-8-oxoadenine (oxoA), are poorly understood. Human DNA polymerases incorporate dGTP or dCTP opposite oxoA, producing mispairs that can cause A→C or A→G mutations. oxoA also perturbs the activity of enzymes acting on DNA and causes interstrand crosslinks. To inform mechanisms for oxoA repair, we characterized oxoA excision by human thymine DNA glycosylase (TDG), an enzyme known to remove modified pyrimidines, including deaminated and oxidized forms of cytosine and 5-methylcystosine. Strikingly, TDG excises oxoA from G⋅oxoA, A⋅oxoA, or C⋅oxoA pairs much more rapidly than it acts on the established pyrimidine substrates, whereas it exhibits comparable activity for T⋅oxoA and pyrimidine substrates. The oxoA activity depends strongly on base pairing and is 370-fold higher for G⋅oxoA versus T⋅oxoA pairs. The intrinsically disordered regions of TDG contribute minimally to oxoA excision, whereas two conserved residues (N140 and N191) are catalytically essential. Escherichia coli mismatch-specific uracil DNA-glycosylase lacks significant oxoA activity, exhibiting excision rates 4 to 5 orders of magnitude below that of its ortholog, TDG. Our results reveal oxoA as an unexpectedly efficient purine substrate for TDG and underscore the large evolutionary divergence of TDG and mismatch-specific uracil DNA-glycosylase.
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3
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Skinner A, Yang C, Hincks K, Wang H, Resendiz MJE. Experimental and theoretical rationalization for the base pairing abilities of inosine, guanosine, adenosine, and their corresponding 8-oxo-7,8-dihydropurine, and 8-bromopurine analogues within A-form duplexes of RNA. Biopolymers 2020; 111:e23410. [PMID: 33216981 PMCID: PMC7780609 DOI: 10.1002/bip.23410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 12/13/2022]
Abstract
Inosine is an important RNA modification, furthermore RNA oxidation has gained interest due, in part, to its potential role in the development/progression of disease as well as on its impact on RNA structure and function. In this report we established the base pairing abilities of purine nucleobases G, I, A, as well as their corresponding, 8-oxo-7,8-dihydropurine (common products of oxidation at the C8-position of purines), and 8-bromopurine (as probes to explore conformational changes), derivatives, namely 8-oxoG, 8-oxoI, 8-oxoA, 8-BrG, and 8-BrI. Dodecamers of RNA were obtained using standard phosphoramidite chemistry via solid-phase synthesis, and used as models to establish the impact that each of these nucleobases have on the thermal stability of duplexes, when base pairing to canonical and noncanonical nucleobases. Thermal stabilities were obtained from thermal denaturation transition (Tm ) measurements, via circular dichroism (CD). The results were then rationalized using models of base pairs between two monomers, via density functional theory (DFT), that allowed us to better understand potential contributions from H-bonding patterns arising from distinct conformations. Overall, some of the important results indicate that: (a) an anti-I:syn-A base pair provides thermal stability, due to the absence of the exocyclic amine; (b) 8-oxoG base pairs like U, and does not induce destabilization within the duplex when compared to the pyrimidine ring; (c) a U:G wobble-pair is only stabilized by G; and (d) 8-oxoA displays an inherited base pairing promiscuity in this sequence context. Gaining a better understanding of how this oxidatively generated lesions potentially base pair with other nucleobases will be useful to predict various biological outcomes, as well as in the design of biomaterials and/or nucleotide derivatives with biological potential.
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Affiliation(s)
- Austin Skinner
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Chou‐Hsun Yang
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Kazuki Hincks
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
| | - Haobin Wang
- Department of ChemistryUniversity of Colorado DenverDenverColoradoUSA
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4
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Willi J, Küpfer P, Evéquoz D, Fernandez G, Katz A, Leumann C, Polacek N. Oxidative stress damages rRNA inside the ribosome and differentially affects the catalytic center. Nucleic Acids Res 2019; 46:1945-1957. [PMID: 29309687 PMCID: PMC5829716 DOI: 10.1093/nar/gkx1308] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/20/2017] [Indexed: 01/19/2023] Open
Abstract
Intracellular levels of reactive oxygen species (ROS) increase as a consequence of oxidative stress and represent a major source of damage to biomolecules. Due to its high cellular abundance RNA is more frequently the target for oxidative damage than DNA. Nevertheless the functional consequences of damage on stable RNA are poorly understood. Using a genome-wide approach, based on 8-oxo-guanosine immunoprecipitation, we present evidence that the most abundant non-coding RNA in a cell, the ribosomal RNA (rRNA), is target for oxidative nucleobase damage by ROS. Subjecting ribosomes to oxidative stress, we demonstrate that oxidized 23S rRNA inhibits the ribosome during protein biosynthesis. Placing single oxidized nucleobases at specific position within the ribosome's catalytic center by atomic mutagenesis resulted in markedly different functional outcomes. While some active site nucleobases tolerated oxidative damage well, oxidation at others had detrimental effects on protein synthesis by inhibiting different sub-steps of the ribosomal elongation cycle. Our data provide molecular insight into the biological consequences of RNA oxidation in one of the most central cellular enzymes and reveal mechanistic insight on the role of individual active site nucleobases during translation.
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Affiliation(s)
- Jessica Willi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Pascal Küpfer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Damien Evéquoz
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Guillermo Fernandez
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Assaf Katz
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Christian Leumann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Norbert Polacek
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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5
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Manlove AH, McKibbin PL, Doyle EL, Majumdar C, Hamm ML, David SS. Structure-Activity Relationships Reveal Key Features of 8-Oxoguanine: A Mismatch Detection by the MutY Glycosylase. ACS Chem Biol 2017; 12:2335-2344. [PMID: 28723094 PMCID: PMC5603899 DOI: 10.1021/acschembio.7b00389] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Base excision repair
glycosylases locate and remove damaged bases
in DNA with remarkable specificity. The MutY glycosylases, unusual
for their excision of undamaged adenines mispaired to the oxidized
base 8-oxoguanine (OG), must recognize both bases of the mispair in
order to prevent promutagenic activity. Moreover, MutY must effectively
find OG:A mismatches within the context of highly abundant and structurally
similar T:A base pairs. Very little is known about the factors that
initiate MutY’s interaction with the substrate when it first
encounters an intrahelical OG:A mispair, or about the order of recognition
checkpoints. Here, we used structure–activity relationships
(SAR) to investigate the features that influence the in vitro measured parameters of mismatch affinity and adenine base excision
efficiency by E. coli MutY. We also evaluated the
impacts of the same substrate alterations on MutY-mediated repair
in a cellular context. Our results show that MutY relies strongly
on the presence of the OG base and recognizes multiple structural
features at different stages of recognition and catalysis to ensure
that only inappropriately mispaired adenines are excised. Notably,
some OG modifications resulted in more dramatic reductions in cellular
repair than in the in vitro kinetic parameters, indicating
their importance for initial recognition events needed to locate the
mismatch within DNA. Indeed, the initial encounter of MutY with its
target base pair may rely on specific interactions with the 2-amino
group of OG in the major groove, a feature that distinguishes OG:A
from T:A base pairs. These results furthermore suggest that inefficient
substrate location in human MutY homologue variants may prove predictive
for the early onset colorectal cancer phenotype known as MUTYH-Associated
Polyposis, or MAP.
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Affiliation(s)
- Amelia H. Manlove
- Department
of Chemistry, University of California at Davis, One Shields Avenue, Davis, California 95616, United States
| | - Paige L. McKibbin
- Department
of Chemistry, University of California at Davis, One Shields Avenue, Davis, California 95616, United States
| | - Emily L. Doyle
- Department
of Chemistry, University of California at Davis, One Shields Avenue, Davis, California 95616, United States
| | - Chandrima Majumdar
- Department
of Chemistry, University of California at Davis, One Shields Avenue, Davis, California 95616, United States
| | - Michelle L. Hamm
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Sheila S. David
- Department
of Chemistry, University of California at Davis, One Shields Avenue, Davis, California 95616, United States
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6
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Choi YJ, Chang SJ, Gibala KS, Resendiz MJE. 8-Oxo-7,8-dihydroadenine and 8-Oxo-7,8-dihydroadenosine-Chemistry, Structure, and Function in RNA and Their Presence in Natural Products and Potential Drug Derivatives. Chemistry 2017; 23:6706-6716. [PMID: 27960050 DOI: 10.1002/chem.201605163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Indexed: 01/02/2023]
Abstract
A description and history of the role that 8-oxo-7,8-dihydroadenine (8-oxoAde) and 8-oxo-7,8-dihydroadenosine (8-oxoA) have in various fields has been compiled. This Review focusses on 1) the formation of this oxidatively generated modification in RNA, its interactions with other biopolymers, and its potential role in the development/progression of disease; 2) the independent synthesis and incorporation of this modified nucleoside into oligonucleotides of RNA to display the progress that has been made in establishing its behavior in biologically relevant systems; 3) reported synthetic routes, which date back to 1890, along with the progress that has been made in the total synthesis of the nucleobase, nucleoside, and their corresponding derivatives; and 4) the isolation, total synthesis, and biological activity of natural products containing these moieties as the backbone. The current state of research regarding this oxidatively generated lesion as well as its importance in the context of RNA, natural products, and potential as drug derivatives is illustrated using all available examples reported to date.
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Affiliation(s)
- Yu Jung Choi
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St., Denver, CO, 80204, USA
| | - Stephanie J Chang
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St., Denver, CO, 80204, USA
| | - Krzysztof S Gibala
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St., Denver, CO, 80204, USA
| | - Marino J E Resendiz
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St., Denver, CO, 80204, USA
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7
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Chauca-Diaz AM, Choi YJ, Resendiz MJE. Biophysical properties and thermal stability of oligonucleotides of RNA containing 7,8-dihydro-8-hydroxyadenosine. Biopolymers 2016; 103:167-74. [PMID: 25363418 PMCID: PMC4302245 DOI: 10.1002/bip.22579] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 10/22/2014] [Accepted: 10/22/2014] [Indexed: 12/14/2022]
Abstract
Circular dichroism (CD) was used to assess the stabilization/destabilization imposed by oxidative lesion 7,8-dihydro-8-hydroxyadenosine (8-oxoA) on strands of RNA with different structural motifs. RNA:RNA homoduplex destabilization was observed in a position dependent manner using 10-mers as models that displayed differences between 12.7 and 15.1°C. We found that increasing the number of modifications resulted in depressed Tm values of about 12-15°C per lesion. The same effect was observed on RNA:DNA heteroduplex samples. We also tested the effects of this lesion in short hairpins containing the tetraloop UUCX (X = A, 8-oxoA). We found that the stem was hypersensitive to substitution of A by 8-oxoA and that it destabilized the structure by >23°C. Concomitant substitution at the stem and loop prevented formation of this secondary structure or lead to other less-stable hairpins. Incorporation of this lesion at the first base of the loop had no effect on either structure. Overall, we found that the effects of 8-oxoA on RNA structure are position dependent and that its stabilization may vary from sharp decreases to small increments, in some cases, leading to the formation of other more/less stable structures. These structural changes may have larger biological implications, particularly if the oxidatively modified RNA persists, thus leading to changes in RNA reactivity and function.
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Affiliation(s)
- Ana M Chauca-Diaz
- Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St, Denver, CO, 80204
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8
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Calabretta A, Küpfer PA, Leumann CJ. The effect of RNA base lesions on mRNA translation. Nucleic Acids Res 2015; 43:4713-20. [PMID: 25897124 PMCID: PMC4482091 DOI: 10.1093/nar/gkv377] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 04/09/2015] [Indexed: 11/26/2022] Open
Abstract
The biological effect of oxidatively damaged RNA, unlike oxidatively damaged DNA, has rarely been investigated, although it poses a threat to any living cell. Here we report on the effect of the commonly known RNA base-lesions 8-oxo-rG, 8-oxo-rA, ε-rC, ε-rA, 5-HO-rC, 5-HO-rU and the RNA abasic site (rAS) on ribosomal translation. To this end we have developed an in vitro translation assay based on the mRNA display methodology. A short synthetic mRNA construct containing the base lesion in a predefined position of the open reading frame was 32P-labeled at the 5′-end and equipped with a puromycin unit at the 3′-end. Upon in vitro translation in rabbit reticulocyte lysates, the encoded peptide chain is transferred to the puromycin unit and the products analyzed by gel electrophoresis. Alternatively, the unlabeled mRNA construct was used and incubated with 35S-methionine to prove peptide elongation of the message. We find that all base-lesions interfere substantially with ribosomal translation. We identified two classes, the first containing modifications at the base coding edge (ε-rC, ε-rA and rAS) which completely abolish peptide synthesis at the site of modification, and the second consisting of 8-oxo-rG, 8-oxo-rA, 5-HO-rC and 5-HO-rU that significantly retard full-length peptide synthesis, leading to some abortive peptides at the site of modification.
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Affiliation(s)
- Alessandro Calabretta
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Pascal A Küpfer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Christian J Leumann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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9
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Development of ABEEMσπ polarizable force field for oxidized adenine base pairs: investigation of the interaction and mutagenic mechanism. Theor Chem Acc 2014. [DOI: 10.1007/s00214-014-1469-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Calabretta A, Leumann CJ. Base pairing and miscoding properties of 1,N(6)-ethenoadenine- and 3,N(4)-ethenocytosine-containing RNA oligonucleotides. Biochemistry 2013; 52:1990-7. [PMID: 23425279 DOI: 10.1021/bi400116y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Two RNA phosphoramidites containing the bases 1,N(6)-ethenoadenine (εA) and 3,N(4)-ethenocytosine (εC) were synthesized. These building blocks were incorporated into two 12-mer oligoribonucleotides for evaluation of the base pairing properties of these base lesions by UV melting curve (Tm) and circular dichroism measurements. The Tm data of the resulting duplexes with the etheno modifications opposing all natural bases showed a substantial destabilization compared to the corresponding natural duplexes, confirming their inability to form base pairs. The coding properties of these lesions were further investigated by introducing them into 31-mer oligonucleotides and assessing their ability to serve as templates in primer extension reactions with HIV, AMV, and MMLV reverse transcriptases (RT). Primer extension reactions showed complete arrest of the incorporation process using MMLV RT and AMV RT, while HIV RT preferentially incorporates dAMP opposite εA and dAMP as well as dTMP opposite εC. The properties of these RNA lesions are discussed in the context of its putative biological role.
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Affiliation(s)
- Alessandro Calabretta
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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11
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Küpfer PA, Leumann CJ. Synthesis, base pairing properties and trans-lesion synthesis by reverse transcriptases of oligoribonucleotides containing the oxidatively damaged base 5-hydroxycytidine. Nucleic Acids Res 2011; 39:9422-32. [PMID: 21852326 PMCID: PMC3241664 DOI: 10.1093/nar/gkr673] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The synthesis of a caged RNA phosphoramidite building block containing the oxidatively damaged base 5-hydroxycytidine (5-HOrC) has been accomplished. To determine the effect of this highly mutagenic lesion on complementary base recognition and coding properties, this building block was incorporated into a 12-mer oligoribonucleotide for Tm and CD measurements and a 31-mer template strand for primer extension experiments with HIV-, AMV- and MMLV-reverse transcriptase (RT). In UV-melting experiments, we find an unusual biphasic transition with two distinct Tm's when 5-HOrC is paired against a DNA or RNA complement with the base guanine in opposing position. The higher Tm closely matches that of a C-G base pair while the lower is close to that of a C-A mismatch. In single nucleotide extension reactions, we find substantial misincorporation of dAMP and to a lesser extent dTMP, with dAMP almost equaling that of the parent dGMP in the case of HIV-RT. A working hypothesis for the biphasic melting transition does not invoke tautomeric variability of 5-HOrC but rather local structural perturbations of the base pair at low temperature induced by interactions of the 5-HO group with the phosphate backbone. The properties of this RNA damage is discussed in the context of its putative biological function.
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Affiliation(s)
- Pascal A Küpfer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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12
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Shanmugasundaram M, Puranik M. Vibrational markers of structural distortion in adenine nucleobases upon DNA damage. Phys Chem Chem Phys 2011; 13:3851-62. [DOI: 10.1039/c0cp01731k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Cui S, Kim YH, Jin CH, Kim SK, Rhee MH, Kwon OS, Moon BJ. Synthesis and base pairing properties of DNA-RNA heteroduplex containing 5-hydroxyuridine. BMB Rep 2009; 42:373-9. [PMID: 19558797 DOI: 10.5483/bmbrep.2009.42.6.373] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
5-Hydroxyuridine (5-OHU) is a major lesion of uridine and cytosine produced in RNA by various chemical oxidants. To elucidate its biochemical and biophysical effects on RNA replication, the site-specifically modified oligoribonucleotides containing 5-OHU were synthesized with C5-hydroxy-5'-O-DMTr-2'-TBDMS-uridine phosphoramidite using automated solid phase synthesis. The base-pairing properties of nucleotides opposite 5-OHU in 24 mer oligoribonulcleotides with dNTP were studied using three reverse transcriptases (Super-Script(TM)II-, AMV-, MMLV-RT) in cDNA synthesis. Adenine as well as guanine was incorporated preferentially by all reverse transcriptases. In the UV-melting temperature experiment, the results from the relative stabilities of the base pairs were A : 5-OHU > G : 5-OHU > T : 5-OHU approximately C : 5-OHU. Circular Dichroism (CD) studies showed that DNA-RNA containing 5-OHU heteroduplexes exhibit a similar conformation between the A-type RNA and B-type DNA. These results suggest that 5-OHU from oxidative damage was mainly influenced by adenine mismatch.
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Affiliation(s)
- Song Cui
- Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea.
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14
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Kim SK, Lee SH, Kwon OS, Moon BJ. DNA . RNA heteroduplex containing 8-oxo-7,8-dihydroguanosine: base pairing, structures, and thermodynamic stability. BMB Rep 2005; 37:657-62. [PMID: 15607023 DOI: 10.5483/bmbrep.2004.37.6.657] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oligoribonucleotides containing 8-oxo-7,8-dihydroguanosine (8-oxoG) and 8-oxo-7,8-dihydro-2'-O-methylguanosine (8-oxoG-Me) were synthesized. The base pairing properties of 8-oxoG and 8-oxoG-Me in oligoribonucleotide in cDNA synthesis by reverse transcriptases were studied. dCMP was preferentially incorporated into the site opposite 8-oxoG or 8-oxoG-Me than into other dNMPs. TMP and dCMP were inserted preferentially into sites opposite 8-oxoG or 8-oxoG by reverse transcriptases. HIV-RT did not incorporate TMP, but RAV2-RT incorporated 50% more TMP than dCMP into the site opposite 8-oxoG. In the site opposite 8-oxoG-Me TMP was substantially incorporated by HIV-RT or RAV2-RT. Thermodynamic analysis of the DNA.RNA heteroduplex containing 8-oxoG revealed that 8-oxoG and 8-oxoG-Me formed base pairs with cytidine and thymidine with similar stability. The thermodynamic parameter (DeltaG degrees ) demonstrated that the formation of duplexes between 8-oxoG or 8-oxoG-Me and cytidine or thymidine is more thermodynamically favorable than with adenosine and guanosine. However, differences in the melting temperature and DeltaG degrees 's of 8-oxoG/dC and 8-oxoG/T were much smaller than between G/dC and G/T. CD spectra showed that DNA . RNA containing 8-oxoG or 8-oxoG-Me duplexes showed similarities between the A-type RNA and B-type DNA conformations.
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Affiliation(s)
- Sang Kook Kim
- Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea
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