1
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Wang L, Song K, Yu J, Da LT. Computational investigations on target-site searching and recognition mechanisms by thymine DNA glycosylase during DNA repair process. Acta Biochim Biophys Sin (Shanghai) 2022; 54:796-806. [PMID: 35593467 PMCID: PMC9828053 DOI: 10.3724/abbs.2022050] [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] [Indexed: 12/22/2022] Open
Abstract
DNA glycosylase, as one member of DNA repair machineries, plays an essential role in correcting mismatched/damaged DNA nucleotides by cleaving the N-glycosidic bond between the sugar and target nucleobase through the base excision repair (BER) pathways. Efficient corrections of these DNA lesions are critical for maintaining genome integrity and preventing premature aging and cancers. The target-site searching/recognition mechanisms and the subsequent conformational dynamics of DNA glycosylase, however, remain challenging to be characterized using experimental techniques. In this review, we summarize our recent studies of sequential structural changes of thymine DNA glycosylase (TDG) during the DNA repair process, achieved mostly by molecular dynamics (MD) simulations. Computational simulations allow us to reveal atomic-level structural dynamics of TDG as it approaches the target-site, and pinpoint the key structural elements responsible for regulating the translocation of TDG along DNA. Subsequently, upon locating the lesions, TDG adopts a base-flipping mechanism to extrude the mispaired nucleobase into the enzyme active-site. The constructed kinetic network model elucidates six metastable states during the base-extrusion process and suggests an active role of TDG in flipping the intrahelical nucleobase. Finally, the molecular mechanism of product release dynamics after catalysis is also summarized. Taken together, we highlight to what extent the computational simulations advance our knowledge and understanding of the molecular mechanism underlying the conformational dynamics of TDG, as well as the limitations of current theoretical work.
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Affiliation(s)
- Lingyan Wang
- Key Laboratory of Systems Biomedicine (Ministry of Education)Shanghai Center for Systems BiomedicineShanghai Jiao Tong UniversityShanghai200240China
| | - Kaiyuan Song
- Key Laboratory of Systems Biomedicine (Ministry of Education)Shanghai Center for Systems BiomedicineShanghai Jiao Tong UniversityShanghai200240China
| | - Jin Yu
- Department of Physics and AstronomyDepartment of ChemistryNSF-Simons Center for Multiscale Cell Fate ResearchUniversity of CaliforniaIrvineCA92697USA
| | - Lin-Tai Da
- Key Laboratory of Systems Biomedicine (Ministry of Education)Shanghai Center for Systems BiomedicineShanghai Jiao Tong UniversityShanghai200240China,Correspondence address. Tel: +86-21-34207348; E-mail:
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2
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Tian J, Wang L, Da LT. Atomic resolution of short-range sliding dynamics of thymine DNA glycosylase along DNA minor-groove for lesion recognition. Nucleic Acids Res 2021; 49:1278-1293. [PMID: 33469643 PMCID: PMC7897493 DOI: 10.1093/nar/gkaa1252] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 12/10/2020] [Accepted: 12/15/2020] [Indexed: 02/06/2023] Open
Abstract
Thymine DNA glycosylase (TDG), as a repair enzyme, plays essential roles in maintaining the genome integrity by correcting several mismatched/damaged nucleobases. TDG acquires an efficient strategy to search for the lesions among a vast number of cognate base pairs. Currently, atomic-level details of how TDG translocates along DNA as it approaches the lesion site and the molecular mechanisms of the interplay between TDG and DNA are still elusive. Here, by constructing the Markov state model based on hundreds of molecular dynamics simulations with an integrated simulation time of ∼25 μs, we reveal the rotation-coupled sliding dynamics of TDG along a 9 bp DNA segment containing one G·T mispair. We find that TDG translocates along DNA at a relatively faster rate when distant from the lesion site, but slows down as it approaches the target, accompanied by deeply penetrating into the minor-groove, opening up the mismatched base pair and significantly sculpturing the DNA shape. Moreover, the electrostatic interactions between TDG and DNA are found to be critical for mediating the TDG translocation. Notably, several uncharacterized TDG residues are identified to take part in regulating the conformational switches of TDG occurred in the site-transfer process, which warrants further experimental validations.
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Affiliation(s)
- Jiaqi Tian
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lingyan Wang
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lin-Tai Da
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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3
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Tran A, Zheng S, White DS, Curry AM, Cen Y. Retracted Article: Divergent synthesis of 5-substituted pyrimidine 2'-deoxynucleosides and their incorporation into oligodeoxynucleotides for the survey of uracil DNA glycosylases. Chem Sci 2020; 11:11818-11826. [PMID: 34123208 PMCID: PMC8162711 DOI: 10.1039/d0sc04161k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/07/2020] [Indexed: 11/21/2022] Open
Abstract
Recent studies have indicated that 5-methylcytosine (5mC) residues in DNA can be oxidized and potentially deaminated to the corresponding thymine analogs. Some of these oxidative DNA damages have been implicated as new epigenetic markers that could have profound influences on chromatin function as well as disease pathology. In response to oxidative damage, the cells have a complex network of repair systems that recognize, remove and rebuild the lesions. However, how the modified nucleobases are detected and repaired remains elusive, largely due to the limited availability of synthetic oligodeoxynucleotides (ODNs) containing these novel DNA modifications. A concise and divergent synthetic strategy to 5mC derivatives has been developed. These derivatives were further elaborated to the corresponding phosphoramidites to enable the site-specific incorporation of modified nucleobases into ODNs using standard solid-phase DNA synthesis. The synthetic methodology, along with the panel of ODNs, is of great value to investigate the biological functions of epigenetically important nucleobases, and to elucidate the diversity in chemical lesion repair.
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Affiliation(s)
- Ai Tran
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences Colchester VT 05446 USA
| | - Song Zheng
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences Colchester VT 05446 USA
| | - Dawanna S White
- Department of Medicinal Chemistry, Virginia Commonwealth University Richmond VA 23219 USA +1-804-828-7405
| | - Alyson M Curry
- Department of Medicinal Chemistry, Virginia Commonwealth University Richmond VA 23219 USA +1-804-828-7405
| | - Yana Cen
- Department of Medicinal Chemistry, Virginia Commonwealth University Richmond VA 23219 USA +1-804-828-7405
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University Richmond VA 23219 USA
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4
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Grøsvik K, Tesfahun AN, Muruzábal-Lecumberri I, Haugland GT, Leiros I, Ruoff P, Kvaløy JT, Knævelsrud I, Ånensen H, Alexeeva M, Sato K, Matsuda A, Alseth I, Klungland A, Bjelland S. The Escherichia coli alkA Gene Is Activated to Alleviate Mutagenesis by an Oxidized Deoxynucleoside. Front Microbiol 2020; 11:263. [PMID: 32158436 PMCID: PMC7051996 DOI: 10.3389/fmicb.2020.00263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/04/2020] [Indexed: 12/01/2022] Open
Abstract
The cellular methyl donor S-adenosylmethionine (SAM) and other endo/exogenous agents methylate DNA bases non-enzymatically into products interfering with replication and transcription. An important product is 3-methyladenine (m3A), which in Escherichia coli is removed by m3A-DNA glycosylase I (Tag) and II (AlkA). The tag gene is constitutively expressed, while alkA is induced by sub-lethal concentrations of methylating agents. We previously found that AlkA exhibits activity for the reactive oxygen-induced thymine (T) lesion 5-formyluracil (fU) in vitro. Here, we provide evidence for AlkA involvement in the repair of oxidized bases by showing that the adenine (A) ⋅ T → guanine (G) ⋅ cytosine (C) mutation rate increased 10-fold in E. coli wild-type and alkA– cells exposed to 0.1 mM 5-formyl-2′-deoxyuridine (fdU) compared to a wild-type specific reduction of the mutation rate at 0.2 mM fdU, which correlated with alkA gene induction. G⋅C → A⋅T alleviation occurred without alkA induction (at 0.1 mM fdU), correlating with a much higher AlkA efficiency for fU opposite to G than for that to A. The common keto form of fU is the AlkA substrate. Mispairing with G by ionized fU is favored by its exclusion from the AlkA active site.
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Affiliation(s)
- Kristin Grøsvik
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Almaz Nigatu Tesfahun
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Izaskun Muruzábal-Lecumberri
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | | | - Ingar Leiros
- The Norwegian Structural Biology Centre, Department of Chemistry, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Peter Ruoff
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Jan Terje Kvaløy
- Department of Mathematics and Physics, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Ingeborg Knævelsrud
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Hilde Ånensen
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Marina Alexeeva
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
| | - Kousuke Sato
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Tobetsu, Japan
| | - Akira Matsuda
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Ingrun Alseth
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital, Oslo, Norway.,Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Svein Bjelland
- Department of Chemistry, Bioscience and Environmental Technology, Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway
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5
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Reading Targeted DNA Damage in the Active Demethylation Pathway: Role of Accessory Domains of Eukaryotic AP Endonucleases and Thymine-DNA Glycosylases. J Mol Biol 2020:S0022-2836(19)30720-X. [DOI: 10.1016/j.jmb.2019.12.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/24/2019] [Accepted: 12/05/2019] [Indexed: 01/07/2023]
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6
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Waterworth SC, Flórez LV, Rees ER, Hertweck C, Kaltenpoth M, Kwan JC. Horizontal Gene Transfer to a Defensive Symbiont with a Reduced Genome in a Multipartite Beetle Microbiome. mBio 2020; 11:e02430-19. [PMID: 32098813 PMCID: PMC7042692 DOI: 10.1128/mbio.02430-19] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/13/2020] [Indexed: 12/20/2022] Open
Abstract
Symbiotic mutualisms of bacteria and animals are ubiquitous in nature, running a continuum from facultative to obligate from the perspectives of both partners. The loss of functions required for living independently but not within a host gives rise to reduced genomes in many symbionts. Although the phenomenon of genome reduction can be explained by existing evolutionary models, the initiation of the process is not well understood. Here, we describe the microbiome associated with the eggs of the beetle Lagria villosa, consisting of multiple bacterial symbionts related to Burkholderia gladioli, including a reduced-genome symbiont thought to be the exclusive producer of the defensive compound lagriamide. We show that the putative lagriamide-producing symbiont is the only member of the microbiome undergoing genome reduction and that it has already lost the majority of its primary metabolism and DNA repair pathways. The key step preceding genome reduction in the symbiont was likely the horizontal acquisition of the putative lagriamide lga biosynthetic gene cluster. Unexpectedly, we uncovered evidence of additional horizontal transfers to the symbiont's genome while genome reduction was occurring and despite a current lack of genes needed for homologous recombination. These gene gains may have given the genome-reduced symbiont a selective advantage in the microbiome, especially given the maintenance of the large lga gene cluster despite ongoing genome reduction.IMPORTANCE Associations between microorganisms and an animal, plant, or fungal host can result in increased dependence over time. This process is due partly to the bacterium not needing to produce nutrients that the host provides, leading to loss of genes that it would need to live independently and to a consequent reduction in genome size. It is often thought that genome reduction is aided by genetic isolation-bacteria that live in monocultures in special host organs, or inside host cells, have less access to other bacterial species from which they can obtain genes. Here, we describe exposure of a genome-reduced beetle symbiont to a community of related bacteria with nonreduced genomes. We show that the symbiont has acquired genes from other bacteria despite going through genome reduction, suggesting that isolation has not yet played a major role in this case of genome reduction, with horizontal gene gains still offering a potential route for adaptation.
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Affiliation(s)
- Samantha C Waterworth
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Laura V Flórez
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenburg University, Mainz, Germany
| | - Evan R Rees
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Products Research and Infection Biology, Jena, Germany
- Department of Natural Product Chemistry, Friedrich Schiller University, Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenburg University, Mainz, Germany
| | - Jason C Kwan
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
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7
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Sahakyan AB, Mahtey A, Kawasaki F, Balasubramanian S. A Spontaneous Ring-Opening Reaction Leads to a Repair-Resistant Thymine Oxidation Product in Genomic DNA. Chembiochem 2020; 21:320-323. [PMID: 31386787 DOI: 10.1002/cbic.201900484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Indexed: 11/09/2022]
Abstract
The alphabet of modified DNA bases goes beyond the conventional four letters, with biological roles being found for many such modifications. Herein, we describe the observation of a modified thymine base that arises from spontaneous N1 -C2 ring opening of the oxidation product 5-formyl uracil, after N3 deprotonation. We first observed this phenomenon in silico through ab initio calculations, followed by in vitro experiments to verify its formation at a mononucleoside level and in a synthetic DNA oligonucleotide context. We show that the new base modification (Trex , thymine ring expunged) can form under physiological conditions, and is resistant to the action of common repair machineries. Furthermore, we found cases of the natural existence of Trex while screening a number of human cell types and mESC (E14), thus suggesting potential biological relevance of this modification.
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Affiliation(s)
- Aleksandr B Sahakyan
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Present address: MRC WIMM Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Headington, Oxford, OX3 9DS, UK
| | - Areeb Mahtey
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Fumiko Kawasaki
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Present address: RIKEN, Center for Advanced Intelligence Project, Tokyo, 103-0027, Japan
| | - Shankar Balasubramanian
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Cancer Research (UK), Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
- School of Clinical Medicine, University of Cambridge, Cambridge, CB2 0SP, UK
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8
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Francés-Monerris A, Lineros-Rosa M, Miranda MA, Lhiaubet-Vallet V, Monari A. Photoinduced intersystem crossing in DNA oxidative lesions and epigenetic intermediates. Chem Commun (Camb) 2020; 56:4404-4407. [DOI: 10.1039/d0cc01132k] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The propensity of 5-formyluracil and 5-formylcytosine, i.e. oxidative lesions and epigenetic intermediates, in acting as intrinsic DNA photosensitizers is unraveled by using a combination of molecular modeling, simulation and spectroscopy.
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Affiliation(s)
| | - Mauricio Lineros-Rosa
- Instituto Universitario Mixto de Tecnologia Química UPV-CSIC
- Universitat Politècnica de València
- 46022 Valencia
- Spain
| | - Miguel Angel Miranda
- Instituto Universitario Mixto de Tecnologia Química UPV-CSIC
- Universitat Politècnica de València
- 46022 Valencia
- Spain
| | - Virginie Lhiaubet-Vallet
- Instituto Universitario Mixto de Tecnologia Química UPV-CSIC
- Universitat Politècnica de València
- 46022 Valencia
- Spain
| | - Antonio Monari
- Université de Lorraine and CNRS
- LPCT UMR 7019
- F-54000 Nancy
- France
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9
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Petri net-based model of the human DNA base excision repair pathway. PLoS One 2019; 14:e0217913. [PMID: 31518347 PMCID: PMC6743755 DOI: 10.1371/journal.pone.0217913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 05/21/2019] [Indexed: 12/14/2022] Open
Abstract
Cellular DNA is daily exposed to several damaging agents causing a plethora of DNA lesions. As a first aid to restore DNA integrity, several enzymes got specialized in damage recognition and lesion removal during the process called base excision repair (BER). A large number of DNA damage types and several different readers of nucleic acids lesions during BER pathway as well as two sub-pathways were considered in the definition of a model using the Petri net framework. The intuitive graphical representation in combination with precise mathematical analysis methods are the strong advantages of the Petri net-based representation of biological processes and make Petri nets a promising approach for modeling and analysis of human BER. The reported results provide new information that will aid efforts to characterize in silico knockouts as well as help to predict the sensitivity of the cell with inactivated repair proteins to different types of DNA damage. The results can also help in identifying the by-passing pathways that may lead to lack of pronounced phenotypes associated with mutations in some of the proteins. This knowledge is very useful when DNA damage-inducing drugs are introduced for cancer therapy, and lack of DNA repair is desirable for tumor cell death.
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10
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Wang Y, Zhang X, Zou G, Peng S, Liu C, Zhou X. Detection and Application of 5-Formylcytosine and 5-Formyluracil in DNA. Acc Chem Res 2019; 52:1016-1024. [PMID: 30666870 DOI: 10.1021/acs.accounts.8b00543] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nucleic acids contain a variety of different base modifications, such as decoration at the fifth position of cytosine, which is one of the most important epigenetic modifications. Nucleic acid epigenetics mediate a wide variety of biological processes, including embryonic development and gene regulation, genomic imprinting, differentiation, and X-chromosome inactivation. Furthermore, the modification level can be aberrantly expressed in distinct sets of tissue that can indicate different tumor onsets and canceration. Thus, the analysis of modified nucleobases may contribute to the understanding of epigenetic modification-related biological processes and the correlation of modified nucleobase patterns with disease states for clinical diagnosis and treatment. In addition to 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxycytosine are found in organisms at a low content but are nevertheless extremely important chemical modifications, and 5-hydroxyuracil and 5-formyluracil compounds are also present. 5-Formyluracil is found in bacteriophages, prokaryotes, and mammalian cells. The 5-formyluracil content is higher in certain cancer tissues than in the normal tissues adjacent to the tumor. The content of 5-formyluracil in different cell tissues may have cell type specificity. With the continuous use of chemical tools, new detection technologies have greatly advanced the research on natural pyrimidine modifications. These modifications dynamically regulate the gene expression in eukaryotes and prokaryotes and provide mechanistic insights into the occurrence of diseases. Natural pyrimidine modifications act not only as intermediates for DNA demethylation or oxidative damage products but also as modulators of gene expression. Therefore, the development of more effective chemical tools will help us better understand the dynamic changes of natural pyrimidine modifications in vivo. In this Account, we summarize the recent advanced techniques for the detection of 5-formylpyrimidine (5-formylcytosine and 5-formyluracil) and highlight their great potential as biomarkers in biomedical applications. Focusing on the great urgency for the detection of epigenetic modifications, our group developed a series of methods for the qualitative and quantitative analysis of 5-formylpyrimidine in the past few years, aiming at facilitating the accurate detection and mapping of these epigenetic modifications. By the construction of probes, 5-formylpyrimidine can be selectively labeled. Using mass spectrometry, the epigenetic modifications can be quantified. Upon treatment under specific conditions, 5-formylcytosine can be recognized at single-base resolution. With this Account, we anticipate providing chemical and biological researchers with some insight to unlock the complex mechanism involved in 5-formylpyrimidine-related biological processes and stimulate more collaborative research interests from the different fields of materials, biological, medicine, and chemistry to promote the translational research of epigenetics in tumor diagnosis and treatment.
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Affiliation(s)
- Yafen Wang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Xiong Zhang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Guangrong Zou
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Shuang Peng
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Chaoxing Liu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Xiang Zhou
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
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11
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Kawasaki F, Murat P, Li Z, Santner T, Balasubramanian S. Synthesis and biophysical analysis of modified thymine-containing DNA oligonucleotides. Chem Commun (Camb) 2017; 53:1389-1392. [PMID: 28074944 PMCID: PMC5759927 DOI: 10.1039/c6cc08670e] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the synthesis of a 5-formyl-2'-deoxyuridine (5fU) phosphoramidite and the preparation of oligonucleotides comprising all known, naturally observed eukaryotic thymidine modifications. Biophysical characterization of the synthetic oligonucleotides indicates that 5fU, but not the other T-derivatives, can alter DNA structures.
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Affiliation(s)
- F Kawasaki
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - P Murat
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Z Li
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - T Santner
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - S Balasubramanian
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. and Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK and School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SP, UK
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12
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Yu Y, Cui Y, Niedernhofer LJ, Wang Y. Occurrence, Biological Consequences, and Human Health Relevance of Oxidative Stress-Induced DNA Damage. Chem Res Toxicol 2016; 29:2008-2039. [PMID: 27989142 DOI: 10.1021/acs.chemrestox.6b00265] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A variety of endogenous and exogenous agents can induce DNA damage and lead to genomic instability. Reactive oxygen species (ROS), an important class of DNA damaging agents, are constantly generated in cells as a consequence of endogenous metabolism, infection/inflammation, and/or exposure to environmental toxicants. A wide array of DNA lesions can be induced by ROS directly, including single-nucleobase lesions, tandem lesions, and hypochlorous acid (HOCl)/hypobromous acid (HOBr)-derived DNA adducts. ROS can also lead to lipid peroxidation, whose byproducts can also react with DNA to produce exocyclic DNA lesions. A combination of bioanalytical chemistry, synthetic organic chemistry, and molecular biology approaches have provided significant insights into the occurrence, repair, and biological consequences of oxidatively induced DNA lesions. The involvement of these lesions in the etiology of human diseases and aging was also investigated in the past several decades, suggesting that the oxidatively induced DNA adducts, especially bulky DNA lesions, may serve as biomarkers for exploring the role of oxidative stress in human diseases. The continuing development and improvement of LC-MS/MS coupled with the stable isotope-dilution method for DNA adduct quantification will further promote research about the clinical implications and diagnostic applications of oxidatively induced DNA adducts.
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Affiliation(s)
| | | | - Laura J Niedernhofer
- Department of Metabolism and Aging, The Scripps Research Institute Florida , Jupiter, Florida 33458, United States
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13
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Drohat AC, Coey CT. Role of Base Excision "Repair" Enzymes in Erasing Epigenetic Marks from DNA. Chem Rev 2016; 116:12711-12729. [PMID: 27501078 DOI: 10.1021/acs.chemrev.6b00191] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Base excision repair (BER) is one of several DNA repair pathways found in all three domains of life. BER counters the mutagenic and cytotoxic effects of damage that occurs continuously to the nitrogenous bases in DNA, and its critical role in maintaining genomic integrity is well established. However, BER also performs essential functions in processes other than DNA repair, where it acts on naturally modified bases in DNA. A prominent example is the central role of BER in mediating active DNA demethylation, a multistep process that erases the epigenetic mark 5-methylcytosine (5mC), and derivatives thereof, converting them back to cytosine. Herein, we review recent advances in the understanding of how BER mediates this critical component of epigenetic regulation in plants and animals.
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Affiliation(s)
- Alexander C Drohat
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland 21201, United States
| | - Christopher T Coey
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland 21201, United States
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14
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Patel JP, Sowers ML, Herring JL, Theruvathu JA, Emmett MR, Hawkins BE, Zhang K, DeWitt DS, Prough DS, Sowers LC. Measurement of Postreplicative DNA Metabolism and Damage in the Rodent Brain. Chem Res Toxicol 2015; 28:2352-63. [PMID: 26447562 PMCID: PMC7986959 DOI: 10.1021/acs.chemrestox.5b00359] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The DNA of all organisms is metabolically active due to persistent endogenous DNA damage, repair, and enzyme-mediated base modification pathways important for epigenetic reprogramming and antibody diversity. The free bases released from DNA either spontaneously or by base excision repair pathways constitute DNA metabolites in living tissues. In this study, we have synthesized and characterized the stable-isotope standards for a series of pyrimidines derived from the normal DNA bases by oxidation and deamination. We have used these standards to measure free bases in small molecule extracts from rat brain. Free bases are observed in extracts, consistent with both endogenous DNA damage and 5-methylcytosine demethylation pathways. The most abundant free base observed is uracil, and the potential sources of uracil are discussed. The free bases measured in tissue extracts constitute the end product of DNA metabolism and could be used to reveal metabolic disturbances in human disease.
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Affiliation(s)
- Jay P. Patel
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Mark L. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Jason L. Herring
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Jacob A. Theruvathu
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Mark R. Emmett
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Bridget E. Hawkins
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Kangling Zhang
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Douglas S. DeWitt
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Donald S. Prough
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
| | - Lawrence C. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Department of Internal Medicine, Division of Hematology and Oncology, University of Texas Medical Branch, Galveston, Texas 77555, United States
- Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, United States
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15
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Bauer NC, Corbett AH, Doetsch PW. The current state of eukaryotic DNA base damage and repair. Nucleic Acids Res 2015; 43:10083-101. [PMID: 26519467 PMCID: PMC4666366 DOI: 10.1093/nar/gkv1136] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/16/2015] [Indexed: 12/15/2022] Open
Abstract
DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair.
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Affiliation(s)
- Nicholas C Bauer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Paul W Doetsch
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA
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16
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Henry LG, Aruni W, Sandberg L, Fletcher HM. Protective role of the PG1036-PG1037-PG1038 operon in oxidative stress in Porphyromonas gingivalis W83. PLoS One 2013; 8:e69645. [PMID: 23990885 PMCID: PMC3747172 DOI: 10.1371/journal.pone.0069645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/13/2013] [Indexed: 12/15/2022] Open
Abstract
As an anaerobe, Porphyromonas gingivalis is significantly affected by the harsh inflammatory environment of the periodontal pocket during initial colonization and active periodontal disease. We reported previously that the repair of oxidative stress-induced DNA damage involving 8-oxo-7,8-dihydroguanine (8-oxoG) may occur by an undescribed mechanism in P. gingivalis. DNA affinity fractionation identified PG1037, a conserved hypothetical protein, among other proteins, that were bound to the 8-oxoG lesion. PG1037 is part of the uvrA-PG1037-pcrA operon in P. gingivalis which is known to be upregulated under H2O2 induced stress. A PCR-based linear transformation method was used to inactivate the uvrA and pcrA genes by allelic exchange mutagenesis. Several attempts to inactivate PG1037 were unsuccessful. Similar to the wild-type when plated on Brucella blood agar, the uvrA and pcrA-defective mutants were black-pigmented and beta-hemolytic. These isogenic mutants also had reduced gingipain activities and were more sensitive to H2O2 and UV irradiation compared to the parent strain. Additionally, glycosylase assays revealed that 8-oxoG repair activities were similar in both wild-type and mutant P. gingivalis strains. Several proteins, some of which are known to have oxidoreducatse activity, were shown to interact with PG1037. The purified recombinant PG1037 protein could protect DNA from H2O2-induced damage. Collectively, these findings suggest that the uvrA-PG1037-pcrA operon may play an important role in hydrogen peroxide stress-induced resistance in P. gingivalis.
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Affiliation(s)
- Leroy G. Henry
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
| | - Wilson Aruni
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
| | - Lawrence Sandberg
- Division of Biochemistry, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
| | - Hansel M. Fletcher
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
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17
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Mullins EA, Rubinson EH, Pereira KN, Calcutt MW, Christov PP, Eichman BF. An HPLC-tandem mass spectrometry method for simultaneous detection of alkylated base excision repair products. Methods 2013; 64:59-66. [PMID: 23876937 DOI: 10.1016/j.ymeth.2013.07.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 11/25/2022] Open
Abstract
DNA glycosylases excise a broad spectrum of alkylated, oxidized, and deaminated nucleobases from DNA as the initial step in base excision repair. Substrate specificity and base excision activity are typically characterized by monitoring the release of modified nucleobases either from a genomic DNA substrate that has been treated with a modifying agent or from a synthetic oligonucleotide containing a defined lesion of interest. Detection of nucleobases from genomic DNA has traditionally involved HPLC separation and scintillation detection of radiolabeled nucleobases, which in the case of alkylation adducts can be laborious and costly. Here, we describe a mass spectrometry method to simultaneously detect and quantify multiple alkylpurine adducts released from genomic DNA that has been treated with N-methyl-N-nitrosourea (MNU). We illustrate the utility of this method by monitoring the excision of N3-methyladenine (3 mA) and N7-methylguanine (7 mG) by a panel of previously characterized prokaryotic and eukaryotic alkylpurine DNA glycosylases, enabling a comparison of substrate specificity and enzyme activity by various methods. Detailed protocols for these methods, along with preparation of genomic and oligonucleotide alkyl-DNA substrates, are also described.
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Affiliation(s)
- Elwood A Mullins
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
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18
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Otani J, Arita K, Kato T, Kinoshita M, Kimura H, Suetake I, Tajima S, Ariyoshi M, Shirakawa M. Structural basis of the versatile DNA recognition ability of the methyl-CpG binding domain of methyl-CpG binding domain protein 4. J Biol Chem 2013; 288:6351-62. [PMID: 23316048 DOI: 10.1074/jbc.m112.431098] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The methyl-CpG binding domain (MBD) protein MBD4 participates in DNA repair as a glycosylase that excises mismatched thymine bases in CpG sites and also functions in transcriptional repression. Unlike other MBD proteins, MBD4 recognizes not only methylated CpG dinucleotides ((5m)CG/(5m)CG) but also T/G mismatched sites generated by spontaneous deamination of 5-methylcytosine ((5m)CG/TG). The glycosylase activity of MBD4 is also implicated in active DNA demethylation initiated by the deaminase-catalyzed conversion of 5-methylcytosine to thymine. Here, we report the crystal structures of the MBD of MBD4 (MBDMBD4) complexed with (5m)CG/(5m)CG and (5m)CG/TG. The crystal structures show that the DNA interface of MBD4 has flexible structural features and harbors an extensive water network that supports its dual base specificities. Combined with the results of biochemical analyses, the crystal structure of MBD4 bound to 5-hydroxymethylcytosine further demonstrates that MBDMBD4 is able to recognize a wide range of 5-methylcytosine modifications through the unique water network. The versatile base recognition ability of MBDMBD4 implies multifunctional roles for MBD4 in the regulation of dynamic DNA methylation patterns coupled with deamination and/or oxidation of 5-methylcytosine.
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Affiliation(s)
- Junji Otani
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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19
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Kim CH, Darwanto A, Theruvathu JA, Herring JL, Sowers LC. Polymerase incorporation and miscoding properties of 5-chlorouracil. Chem Res Toxicol 2010; 23:740-8. [PMID: 20104909 DOI: 10.1021/tx900302j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Inflammation-mediated hypochlorous acid (HOCl) can damage DNA, DNA precursors, and other biological molecules, thereby producing an array of damage products such as 5-chlorouracil (ClU). In this study, we prepared and studied 5-chloro-2'-deoxyuridine (CldU) and ClU-containing oligonucleotide templates. We demonstrate that human K-562 cells grown in culture with 10 muM CldU incorporate substantial amounts of CldU without significant toxicity. When in the template, ClU residues pair with dATP but also with dGTP, in a pH-dependent manner with incorporation by human polymerase beta, avian myeloblastosis virus reverse transcriptase (AMV-RT), and Escherichia coli Klenow fragment (exo(-)) polymerase. The enhanced miscoding of ClU is attributed to the electron-withdrawing 5-chlorine substituent that promotes the formation of an ionized ClU-G mispair. When mispaired with G, ClU is targeted for removal by human glycosylases. The formation, incorporation, and repair of ClU could promote transition mutations and other forms of heritable DNA damage.
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Affiliation(s)
- Cherine H Kim
- Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California 92350, USA
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20
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Theruvathu JA, Kim CH, Darwanto A, Neidigh JW, Sowers LC. pH-Dependent configurations of a 5-chlorouracil-guanine base pair. Biochemistry 2009; 48:11312-8. [PMID: 19863157 DOI: 10.1021/bi901154t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Hypochlorous acid (HOCl) from activated neutrophils at sites of inflammation can react with and damage biological molecules, including nucleic acids. The reaction of HOCl with cytosine analogues can generate multiple products, including 5-chlorouracil (ClU). In this paper, we have constructed oligonucleotides containing ClU paired opposite guanine (ClU-G). Melting studies indicate that oligonucleotide duplexes containing the ClU-G mispair are substantially less stable than those containing a ClU-A base pair. The melting temperature of the ClU-G mispair is not experimentally distinguishable from that of a T-G pair. NMR studies indicate that the ClU-G base pair adopts a wobble geometry at neutral pH, similar to a T-G mispair. The exchangeable protons of the ClU-G mispair broaden rapidly with an increase in temperature, indicating that the ClU-G mispair is less stable and opens more easily than the surrounding adjacent base pairs. Unlike the ClU-A base pair studied previously [Theruvathu, J. A., et al. (2009) Biochemistry 48, 7539-7546], the ClU-G mispair undergoes a pH-dependent structural change, assuming an ionized base pair configuration that approximates a Watson-Crick base pair at higher pH. Ionization of ClU in a DNA template could promote mispair formation and mutation, in accord with previous studies on other 5-halouracil analogues. The electron-withdrawing 5-chloro substituent facilitates ionization of the ClU N3 proton, promoting mispair formation, but it also renders the glycosidic bond susceptible to base cleavage by DNA repair glycosylases.
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Affiliation(s)
- Jacob A Theruvathu
- Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California 92350, USA
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21
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Darwanto A, Farrel A, Rogstad DK, Sowers LC. Characterization of DNA glycosylase activity by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Anal Biochem 2009; 394:13-23. [PMID: 19607800 PMCID: PMC3990469 DOI: 10.1016/j.ab.2009.07.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/07/2009] [Accepted: 07/09/2009] [Indexed: 11/25/2022]
Abstract
The DNA of all organisms is persistently damaged by endogenous reactive molecules. Most of the single-base endogenous damage is repaired through the base excision repair (BER) pathway that is initiated by members of the DNA glycosylase family. Although the BER pathway is often considered to proceed through a common abasic site intermediate, emerging evidence indicates that there are likely distinct branches reflected by the multitude of chemically different 3' and 5' ends generated at the repair site. In this study, we have applied matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to the analysis of model DNA substrates acted on by recombinant glycosylases. We examine the chemical identity of several possible abasic site and nicked intermediates generated by monofunctional and bifunctional glycosylases. Our results suggest that the intermediate from endoIII/Nth might not be a simple beta-elimination product as described previously. On the basis of (18)O incorporation experiments, we propose a new mechanism for the endoIII/Nth family of glycosylases that may resolve several of the previous controversies. We further demonstrate that the use of an array of lesion-containing oligonucleotides can be used to rapidly examine the substrate preferences of a given glycosylase. Some of the lesions examined here can be acted on by more than one glycosylase, resulting in a spectrum of damaged intermediates for each lesion, suggesting that the sequence and coordination of repair activities that act on these lesions may influence the biological outcome of damage repair.
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Affiliation(s)
- Agus Darwanto
- Department of Basic Science, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Alvin Farrel
- Department of Basic Science, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Daniel K. Rogstad
- Department of Basic Science, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Lawrence C. Sowers
- Department of Basic Science, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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22
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Knaevelsrud I, Slupphaug G, Leiros I, Matsuda A, Ruoff P, Bjelland S. Opposite-base dependent excision of 5-formyluracil from DNA by hSMUG1. Int J Radiat Biol 2009; 85:413-20. [PMID: 19365746 DOI: 10.1080/09553000902818915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE The aim of this study was to determine the excision efficiency of hSMUG1 (human single-strand-selective monofunctional uracil-DNA glycosylase) for 5-formyluracil (fU), a major thymine lesion formed by ionizing radiation, opposite all normal bases in DNA, to possibly explain mutation induction by fU in the DNA of mammalian cells. MATERIALS AND METHODS An enzymatically [(32)P]labelled fU-containing 36 nucleotide DNA sequence plus its complementary sequence (with an A, C, G or T residue inserted opposite fU) was subjected to hSMUG1 in a pH 7.5-buffer, followed by NaOH-mediated cleavage of the resultant abasic sites. Cleaved and uncleaved DNA were separated by denaturing electrophoresis and quantified by autoradiography. RESULTS The hSMUG1 excised fU from DNA opposite all normal bases with the highest activity when opposite non-cognate C or T followed by G and cognate A. CONCLUSIONS The predominant T --> G and T --> A transversions induced by fU in mammalian cells may be explained by replicative incorporation of C and T, respectively, opposite the lesion and subsequent SMUG1-initiated repair of fU.
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Affiliation(s)
- Ingeborg Knaevelsrud
- Faculty of Science and Technology, Department of Mathematics and Natural Sciences, University of Stavanger, Stavanger, Norway
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23
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Kathiravan A, Anbazhagan V, Asha Jhonsi M, Renganathan R. Interaction of meso-tetrakis (p-sulfonatophenyl) porphyrin (TSPP) with pyrimidines: A steady state and time-resolved fluorescence quenching study. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2008.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Baute J, Depicker A. Base excision repair and its role in maintaining genome stability. Crit Rev Biochem Mol Biol 2008; 43:239-76. [PMID: 18756381 DOI: 10.1080/10409230802309905] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
For all living organisms, genome stability is important, but is also under constant threat because various environmental and endogenous damaging agents can modify the structural properties of DNA bases. As a defense, organisms have developed different DNA repair pathways. Base excision repair (BER) is the predominant pathway for coping with a broad range of small lesions resulting from oxidation, alkylation, and deamination, which modify individual bases without large effect on the double helix structure. As, in mammalian cells, this damage is estimated to account daily for 10(4) events per cell, the need for BER pathways is unquestionable. The damage-specific removal is carried out by a considerable group of enzymes, designated as DNA glycosylases. Each DNA glycosylase has its unique specificity and many of them are ubiquitous in microorganisms, mammals, and plants. Here, we review the importance of the BER pathway and we focus on the different roles of DNA glycosylases in various organisms.
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Affiliation(s)
- Joke Baute
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Gent, Belgium
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25
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Abstract
The persistence of Porphyromonas gingivalis in the inflammatory environment of the periodontal pocket requires an ability to overcome oxidative stress. DNA damage is a major consequence of oxidative stress. Unlike the case for other organisms, our previous report suggests a role for a non-base excision repair mechanism for the removal of 8-oxo-7,8-dihydroguanine (8-oxo-G) in P. gingivalis. Because the uvrB gene is known to be important in nucleotide excision repair, the role of this gene in the repair of oxidative stress-induced DNA damage was investigated. A 3.1-kb fragment containing the uvrB gene was PCR amplified from the chromosomal DNA of P. gingivalis W83. This gene was insertionally inactivated using the ermF-ermAM antibiotic cassette and used to create a uvrB-deficient mutant by allelic exchange. When plated on brucella blood agar, the mutant strain, designated P. gingivalis FLL144, was similar in black pigmentation and beta-hemolysis to the parent strain. In addition, P. gingivalis FLL144 demonstrated no significant difference in growth rate, proteolytic activity, or sensitivity to hydrogen peroxide from that of the parent strain. However, in contrast to the wild type, P. gingivalis FLL144 was significantly sensitive to UV irradiation. The enzymatic removal of 8-oxo-G from duplex DNA was unaffected by the inactivation of the uvrB gene. DNA affinity fractionation identified unique proteins that preferentially bound to the oligonucleotide fragment carrying the 8-oxo-G lesion. Collectively, these results suggest that the repair of oxidative stress-induced DNA damage involving 8-oxo-G may occur by a still undescribed mechanism in P. gingivalis.
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26
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Xu G, Herzig M, Rotrekl V, Walter CA. Base excision repair, aging and health span. Mech Ageing Dev 2008; 129:366-82. [PMID: 18423806 PMCID: PMC2526234 DOI: 10.1016/j.mad.2008.03.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 02/28/2008] [Accepted: 03/05/2008] [Indexed: 12/18/2022]
Abstract
DNA damage and mutagenesis are suggested to contribute to aging through their ability to mediate cellular dysfunction. The base excision repair (BER) pathway ameliorates a large number of DNA lesions that arise spontaneously. Many of these lesions are reported to increase with age. Oxidized guanine, repaired largely via base excision repair, is particularly well studied and shown to increase with age. Spontaneous mutant frequencies also increase with age which suggests that mutagenesis may contribute to aging. It is widely accepted that genetic instability contributes to age-related occurrences of cancer and potentially other age-related pathologies. BER activity decreases with age in multiple tissues. The specific BER protein that appears to limit activity varies among tissues. DNA polymerase-beta is reduced in brain from aged mice and rats while AP endonuclease is reduced in spermatogenic cells obtained from old mice. The differences in proteins that appear to limit BER activity among tissues may represent true tissue-specific differences in activity or may be due to differences in techniques, environmental conditions or other unidentified differences among the experimental approaches. Much remains to be addressed concerning the potential role of BER in aging and age-related health span.
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Affiliation(s)
- Guogang Xu
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
| | - Maryanne Herzig
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
| | - Vladimir Rotrekl
- Institute of Experimental Medicine, Department of Molecular Embryology, Masaryk University, Faculty of Medicine, Department of Biology, Kamenice 5, Building A6, 62500 Brno, Czech Republic
| | - Christi A. Walter
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
- South Texas Veteran’s Health Care System, 7400 Merton Minter Blvd, San Antonio, TX 78229
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27
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Pereira E, Faure S, Aitken DJ. Photochemical behaviour of 5-formyl and 5-acetyl uracils in the presence of ethene. Tetrahedron Lett 2008. [DOI: 10.1016/j.tetlet.2008.01.088] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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28
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Liu P, Theruvathu JA, Darwanto A, Lao VV, Pascal T, Goddard W, Sowers LC. Mechanisms of base selection by the Escherichia coli mispaired uracil glycosylase. J Biol Chem 2008; 283:8829-36. [PMID: 18208817 DOI: 10.1074/jbc.m707174200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The repair of the multitude of single-base lesions formed daily in cells of all living organisms is accomplished primarily by the base excision repair pathway that initiates repair through a series of lesion-selective glycosylases. In this article, single-turnover kinetics have been measured on a series of oligonucleotide substrates containing both uracil and purine analogs for the Escherichia coli mispaired uracil glycosylase (MUG). The relative rates of glycosylase cleavage have been correlated with the free energy of helix formation and with the size and electronic inductive properties of a series of uracil 5-substituents. Data are presented that MUG can exploit the reduced thermodynamic stability of mispairs to distinguish U:A from U:G pairs. Discrimination against the removal of thymine results primarily from the electron-donating property of the thymine 5-methyl substituent, whereas the size of the methyl group relative to a hydrogen atom is a secondary factor. A series of parameters have been obtained that allow prediction of relative MUG cleavage rates that correlate well with observed relative rates that vary over 5 orders of magnitude for the series of base analogs examined. We propose that these parameters may be common among DNA glycosylases; however, specific glycosylases may focus more or less on each of the parameters identified. The presence of a series of glycosylases that focus on different lesion properties, all coexisting within the same cell, would provide a robust and partially redundant repair system necessary for the maintenance of the genome.
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Affiliation(s)
- Pingfang Liu
- Department of Basic Science, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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29
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Rogstad DK, Darwanto A, Herring JL, Rogstad KN, Burdzy A, Hadley S, Neidigh JW, Sowers LC. Measurement of the incorporation and repair of exogenous 5-hydroxymethyl-2'-deoxyuridine in human cells in culture using gas chromatography-negative chemical ionization-mass spectrometry. Chem Res Toxicol 2007; 20:1787-96. [PMID: 17914883 PMCID: PMC2532841 DOI: 10.1021/tx700221x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The DNA of all organisms is constantly damaged by oxidation. Among the array of damage products is 5-hydroxymethyluracil, derived from oxidation of the thymine methyl group. Previous studies have established that HmU can be a sensitive and valuable marker of DNA damage. More recently, the corresponding deoxynucleoside, 5-hydroxymethyl-2'-deoxyuridine (HmdU), has proven to be valuable for the introduction of controlled amounts of a single type of damage lesion into the DNA of replicating cells, which is subsequently repaired by the base excision repair pathway. Complicating the study of HmU formation and repair, however, is the known chemical reactivity of the hydroxymethyl group of HmU under conditions used to hydrolyze DNA. In the work reported here, this chemical property has been exploited by creating conditions that convert HmU to the corresponding methoxymethyluracil (MmU) derivative that can be further derivatized to the 3,5-bis-(trifluoromethyl)benzyl analogue. This derivatized compound can be detected by gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) with good sensitivity. Using isotopically enriched exogenous HmdU and human osteosarcoma cells (U2OS) in culture, we demonstrate that this method allows for the measurement of HmU in DNA formed from the incorporation of exogenous HmdU. We further demonstrate that the addition of isotopically enriched uridine to the culture medium allows for the simultaneous measurement of DNA replication and repair kinetics. This sensitive and facile method should prove valuable for studies on DNA oxidation damage and repair in living cells.
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Affiliation(s)
| | | | | | | | | | | | | | - Lawrence C. Sowers
- *To whom correspondence should be addressed. Tel: 909-558-4480. Fax: 909-558-4035 E-mail:
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Morgan MT, Bennett MT, Drohat AC. Excision of 5-halogenated uracils by human thymine DNA glycosylase. Robust activity for DNA contexts other than CpG. J Biol Chem 2007; 282:27578-86. [PMID: 17602166 PMCID: PMC2818988 DOI: 10.1074/jbc.m704253200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Thymine DNA glycosylase (TDG) excises thymine from G.T mispairs and removes a variety of damaged bases (X) with a preference for lesions in a CpG.X context. We recently reported that human TDG rapidly excises 5-halogenated uracils, exhibiting much greater activity for CpG.FU, CpG.ClU, and CpG.BrU than for CpG.T. Here we examine the effects of altering the CpG context on the excision activity for U, T, FU, ClU, and BrU. We show that the maximal activity (k(max)) for G.X substrates depends significantly on the 5' base pair. For example, k(max) decreases by 6-, 11-, and 82-fold for TpG.ClU, GpG.ClU, and ApG.ClU, respectively, as compared with CpG.ClU. For the other G.X substrates, the 5'-neighbor effects have a similar trend but vary in magnitude. The activity for G.FU, G.ClU, and G.BrU, with any 5'-flanking pair, meets and in most cases significantly exceeds the CpG.T activity. Strikingly, human TDG activity is reduced 10(2.3)-10(4.3)-fold for A.X relative to G.X pairs and reduced further for A.X pairs with a 5' pair other than C.G. The effect of altering the 5' pair and/or the opposing base (G.X versus A.X) is greater for substrates that are larger (bromodeoxyuridine, dT) or have a more stable N-glycosidic bond (such as dT). The largest CpG context effects are observed for the excision of thymine. The potential role played by human TDG in the cytotoxic effects of ClU and BrU incorporation into DNA, which can occur under inflammatory conditions and in the cytotoxicity of FU, a widely used anticancer agent, are discussed.
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Affiliation(s)
- Michael T. Morgan
- Department of Biochemistry and Molecular Biology, Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201
| | - Matthew T. Bennett
- Department of Biochemistry and Molecular Biology, Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201
| | - Alexander C. Drohat
- Department of Biochemistry and Molecular Biology, Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201
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Bader SA, Walker M, Harrison DJ. A human cancer-associated truncation of MBD4 causes dominant negative impairment of DNA repair in colon cancer cells. Br J Cancer 2007; 96:660-6. [PMID: 17285135 PMCID: PMC2360052 DOI: 10.1038/sj.bjc.6603592] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 12/04/2006] [Accepted: 12/18/2006] [Indexed: 12/30/2022] Open
Abstract
MBD4 binds to methylated DNA and acts as a thymine DNA glycosylase in base excision repair. Deficiency of MBD4 in mice enhances mutation at CpG sites and alters apoptosis in response to DNA damage, but does not increase tumorigenesis in mismatch repair-deficient mice. However, in humans, frameshift mutation of MBD4, rather than deletion, is what occurs in up to 43% of microsatellite unstable colon cancers. There is no murine equivalent of this mutation. We now show that recombinant truncated MBD4 (MBD4(tru)) inhibits glycosylase activities of normal MBD4 or Uracil DNA glycosylase in cell-free assays as a dominant negative effect. Furthermore, overexpression of MBD4(tru) in Big Blue (lacI)-transfected, MSI human colorectal carcinoma cells doubled mutation frequency, indicating that the modest dominant negative effect on DNA repair can occur in living cells in short-term experiments. Intriguingly, the whole mutation spectrum was increased, not only at CpG sites, suggesting that truncated MBD4 has a more widespread effect on genomic stability. This demonstration of a dominant negative effect may be of significance in tumour progression and acquisition of drug resistance.
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Affiliation(s)
- S A Bader
- Department of Pathology, Edinburgh Cancer Research Centre, University of Edinburgh, Crewe Road, Edinburgh EH4 2XR, UK.
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32
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Irie D, Ono A, Izuta S. Recognition of oxidized thymine base on the single-stranded DNA by replication protein A. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2006; 25:439-51. [PMID: 16838837 DOI: 10.1080/01457630600684138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Replication protein A (RAP) is a eukaryotic single-stranded DNA binding protein involved in DNA replication, repair, and recombination. Recent studies indicate that RPA preferentially binds the damaged sites rather than the undamaged sites. Therefore, RPA is thought to be a member ofrepair factories or a sensor of lesion on DNA. To obtain further information of behavior of RPA against the oxidized lesion, we studied the binding affinity of RPA for the single-stranded DNA containing 5-formyluracil, a major lesion of thymine base yielded by the oxidation, using several synthetic oligonucleotides. The affinity of RPA for oligonucleotides was determined by gel shift assay. Results suggest that the surrounding sequence of 5-formyluracil may affect the affinity for RPA, and that the 5-formyluracil on the purine stretch but not the pyrimidine stretch increases the affinity for RPA. Results of affinity labeling experiment of RPA with the oligonucleotides containing 5-formyluracil indicate that RPA1 subunit may directly recognize and bind to the 5-formyluracil on the single-stranded DNA.
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Affiliation(s)
- Daisuke Irie
- Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan
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Bennett MT, Rodgers MT, Hebert AS, Ruslander LE, Eisele L, Drohat AC. Specificity of human thymine DNA glycosylase depends on N-glycosidic bond stability. J Am Chem Soc 2006; 128:12510-9. [PMID: 16984202 PMCID: PMC2809119 DOI: 10.1021/ja0634829] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Initiating the DNA base excision repair pathway, DNA glycosylases find and hydrolytically excise damaged bases from DNA. While some DNA glycosylases exhibit narrow specificity, others remove multiple forms of damage. Human thymine DNA glycosylase (hTDG) cleaves thymine from mutagenic G.T mispairs, recognizes many additional lesions, and has a strong preference for nucleobases paired with guanine rather than adenine. Yet, hTDG avoids cytosine, despite the million-fold excess of normal G.C pairs over G.T mispairs. The mechanism of this remarkable and essential specificity has remained obscure. Here, we examine the possibility that hTDG specificity depends on the stability of the scissile base-sugar bond by determining the maximal activity (k(max)) against a series of nucleobases with varying leaving-group ability. We find that hTDG removes 5-fluorouracil 78-fold faster than uracil, and 5-chlorouracil, 572-fold faster than thymine, differences that can be attributed predominantly to leaving-group ability. Moreover, hTDG readily excises cytosine analogues with improved leaving ability, including 5-fluorocytosine, 5-bromocytosine, and 5-hydroxycytosine, indicating that cytosine has access to the active site. A plot of log(k(max)) versus leaving-group pK(a) reveals a Brønsted-type linear free energy relationship with a large negative slope of beta(lg) = -1.6 +/- 0.2, consistent with a highly dissociative reaction mechanism. Further, we find that the hydrophobic active site of hTDG contributes to its specificity by enhancing the inherent differences in substrate reactivity. Thus, hTDG specificity depends on N-glycosidic bond stability, and the discrimination against cytosine is due largely to its very poor leaving ability rather than its exclusion from the active site.
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Affiliation(s)
- Matthew T. Bennett
- Department of Biochemistry and Molecular Biology and Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201
| | - M. T. Rodgers
- Department of Chemistry, Wayne State University, Detroit, MI 48202
| | | | | | - Leslie Eisele
- Wadsworth Center, New York State Department of Health, Albany, NY 12201
| | - Alexander C. Drohat
- Department of Biochemistry and Molecular Biology and Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201
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Valinluck V, Liu P, Kang JI, Burdzy A, Sowers LC. 5-halogenated pyrimidine lesions within a CpG sequence context mimic 5-methylcytosine by enhancing the binding of the methyl-CpG-binding domain of methyl-CpG-binding protein 2 (MeCP2). Nucleic Acids Res 2005; 33:3057-64. [PMID: 15917437 PMCID: PMC1140371 DOI: 10.1093/nar/gki612] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Perturbations in cytosine methylation signals are observed in the majority of human tumors; however, it is as yet unknown how methylation patterns become altered. Epigenetic changes can result in the activation of transforming genes as well as in the silencing of tumor suppressor genes. We report that methyl-CpG-binding proteins (MBPs), specific for methyl-CpG dinucleotides, bind with high affinity to halogenated pyrimidine lesions, previously shown to result from peroxidase-mediated inflammatory processes. Emerging data suggest that the initial binding of MBPs to methyl-CpG sequences may be a seeding event that recruits chromatin-modifying enzymes and DNA methyltransferase, initiating a cascade of events that result in gene silencing. MBD4, a protein with both methyl-binding and glycosylase activity demonstrated repair activity against a series of 5-substituted pyrimidines, with the greatest efficiency against 5-chlorouracil, but undetectable activity against 5-chlorocytosine. The data presented here suggest that halogenated pyrimidine damage products can potentially accumulate and mimic endogenous methylation signals.
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Affiliation(s)
- Victoria Valinluck
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda UniversityLoma Linda, CA 92350, USA
| | - Pingfang Liu
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda UniversityLoma Linda, CA 92350, USA
- Graduate School of Biological Sciences, City of Hope National Medical Center1500 East Duarte Road, Duarte, CA 91010, USA
| | - Joseph I. Kang
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda UniversityLoma Linda, CA 92350, USA
| | - Artur Burdzy
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda UniversityLoma Linda, CA 92350, USA
| | - Lawrence C. Sowers
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda UniversityLoma Linda, CA 92350, USA
- Graduate School of Biological Sciences, City of Hope National Medical Center1500 East Duarte Road, Duarte, CA 91010, USA
- To whom correspondence should be addressed. Tel: +1 909 558 4480; Fax: +1 909 558 4035;
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35
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An Q, Robins P, Lindahl T, Barnes DE. C --> T mutagenesis and gamma-radiation sensitivity due to deficiency in the Smug1 and Ung DNA glycosylases. EMBO J 2005; 24:2205-13. [PMID: 15902269 PMCID: PMC1150883 DOI: 10.1038/sj.emboj.7600689] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Accepted: 04/29/2005] [Indexed: 01/03/2023] Open
Abstract
The most common genetic change in aerobic organisms is a C:G to T:A mutation. C --> T transitions can arise through spontaneous hydrolytic deamination of cytosine to give a miscoding uracil residue. This is also a frequent DNA lesion induced by oxidative damage, through exposure to agents such as ionizing radiation, or from endogenous sources that are implicated in the aetiology of degenerative diseases, ageing and cancer. The Ung and Smug1 enzymes excise uracil from DNA to effect repair in mammalian cells, and gene-targeted Ung(-/-) mice exhibit a moderate increase in genome-wide spontaneous mutagenesis. Here, we report that stable siRNA-mediated silencing of Smug1 in mouse embryo fibroblasts also generates a mutator phenotype. However, an additive 10-fold increase in spontaneous C:G to T:A transitions in cells deficient in both Smug1 and Ung demonstrates that these enzymes have distinct and nonredundant roles in suppressing C --> T mutability at non-CpG sites. Such cells are also hypersensitive to ionizing radiation, and reveal a role of Smug1 in the repair of lesions generated by oxidation of cytosine.
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Affiliation(s)
- Qian An
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Peter Robins
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, UK
| | - Tomas Lindahl
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, UK
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms EN6 3LD, UK. Tel.: +44 207 269 3983/3985; Fax: +44 207 269 3819; E-mail:
| | - Deborah E Barnes
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, UK
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36
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Guerniou V, Rapin D, Millau JF, Bufflier E, Favier A, Cadet J, Sauvaigo S. Repair of oxidative damage of thymine by HeLa whole-cell extracts: simultaneous analysis using a microsupport and comparison with traditional PAGE analysis. Biochimie 2005; 87:151-9. [PMID: 15760707 DOI: 10.1016/j.biochi.2004.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2004] [Accepted: 12/05/2004] [Indexed: 10/26/2022]
Abstract
In mammalian cells, the base excision repair (BER) pathway allows the remove of small DNA base lesions such as oxidized bases. It is initiated by glycosylases that removed the modified base leaving an abasic site that is subsequently processed by AP endonuclease activities. Measurement of BER activities in cell extracts is time consuming and hazardous when radioactive material is used. We report in this study, the parallelized fluorescent analysis of excision of several oxidation products of thymine by cell extracts. To conduct the study, 5-(hydroxymethyl)uracil, 5-formyluracil, 5-carboxyuracil and formylamine together with uracil and the control thymine, were incorporated into oligonucleotides of identical sequences and paired either with adenine or with guanine containing DNA fragments. The oligonucleotides were fixed by sandwich hybridization in wells of a microplate (OLISA technology). Excision by HeLa extracts of the six different DNA base lesions could be followed simultaneously in the same well. Our results showed that the extent of excision of the lesions was the same on support and in solution using classical PAGE analysis approach with modified (32)P-labeled oligonucleotides. We demonstrated that the simultaneous analysis on support is a successful approach to facilitate high-throughput screening of BER activities present in cell extracts. Moreover, extended study of 5-carboxyuracil revealed that this lesion displays similar biological properties as 5-formyluracil.
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Affiliation(s)
- Valérie Guerniou
- Laboratoire Lésions des Acides Nucléiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, 17, rue des Martyrs, 38054 Grenoble cedex 9, France
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37
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Eot-Houllier G, Eon-Marchais S, Gasparutto D, Sage E. Processing of a complex multiply damaged DNA site by human cell extracts and purified repair proteins. Nucleic Acids Res 2005; 33:260-71. [PMID: 15647508 PMCID: PMC546153 DOI: 10.1093/nar/gki165] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Clustered DNA lesions, possibly induced by ionizing radiation, constitute a trial for repair processes. Indeed, recent studies suggest that repair of such lesions may be compromised, potentially leading to the formation of lethal double-strand breaks (DSBs). A complex multiply damaged site (MDS) composed of 8-oxoguanine and 8-oxoadenine on one strand, 5-hydroxyuracil, 5-formyluracil and a 1 nt gap on the other strand, within 17 bp was built and used to challenge several steps of base excision repair (BER) pathway with human whole-cell extracts and purified repair enzymes as well. We show a hierarchy in the processing of lesions within the MDS, in particular at the base excision step. In the present configuration, efficient excision of 5-hydroxyuracil and low cleavage at 8-oxoguanine prevent DSB formation and generate a short single-stranded region carrying the 8-oxoguanine. On the other hand, rejoining of the 1 nt gap occurs by the short-patch BER pathway, but is slightly retarded by the presence of the oxidized bases. Taken together, our results suggest a hierarchy in the processing of the lesions within the MDS, which prevents the formation of DSB, but would dramatically enhance mutagenesis. They also indicate that the mutagenic (or lethal) consequences of a complex MDS will largely depend on the first event in the processing of the MDS.
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Affiliation(s)
| | | | - Didier Gasparutto
- Laboratoire ‘Lésions des Acides Nucléiques’, Service de Chimie Inorganique et Biologique, Département de Recherche Fondamentale sur la Matière CondenséeCEA-Grenoble, F-38054 Grenoble Cedex 9, France
| | - Evelyne Sage
- To whom correspondence should be addressed. Tel: +33 1 69 86 71 87; Fax: +33 1 69 86 94 29;
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Johnson NA, McKenzie R, McLean L, Sowers LC, Fletcher HM. 8-oxo-7,8-dihydroguanine is removed by a nucleotide excision repair-like mechanism in Porphyromonas gingivalis W83. J Bacteriol 2004; 186:7697-703. [PMID: 15516584 PMCID: PMC524907 DOI: 10.1128/jb.186.22.7697-7703.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A consequence of oxidative stress is DNA damage. The survival of Porphyromonas gingivalis in the inflammatory microenvironment of the periodontal pocket requires an ability to overcome oxidative stress caused by reactive oxygen species (ROS). 8-oxo-7,8-dihydroguanine (8-oxoG) is typical of oxidative damage induced by ROS. There is no information on the presence of 8-oxoG in P. gingivalis under oxidative stress conditions or on a putative mechanism for its repair. High-pressure liquid chromatography with electrochemical detection analysis of chromosomal DNA revealed higher levels of 8-oxoG in P. gingivalis FLL92, a nonpigmented isogenic mutant, than in the wild-type strain. 8-oxoG repair activity was also increased in cell extracts from P. gingivalis FLL92 compared to those from the parent strain. Enzymatic removal of 8-oxoG was catalyzed by a nucleotide excision repair (NER)-like mechanism rather than the base excision repair (BER) observed in Escherichia coli. In addition, in comparison with other anaerobic periodontal pathogens, the removal of 8-oxoG was unique to P. gingivalis. Taken together, the increased 8-oxoG levels in P. gingivalis FLL92 could further support a role for the hemin layer as a unique mechanism in oxidative stress resistance in this organism. In addition, this is the first observation of an NER-like mechanism as the major mechanism for removal of 8-oxoG in P. gingivalis.
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Affiliation(s)
- N A Johnson
- Department of Biochemistry and Microbiology, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA.
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Evans MD, Dizdaroglu M, Cooke MS. Oxidative DNA damage and disease: induction, repair and significance. MUTATION RESEARCH/REVIEWS IN MUTATION RESEARCH 2004; 567:1-61. [PMID: 15341901 DOI: 10.1016/j.mrrev.2003.11.001] [Citation(s) in RCA: 877] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Revised: 11/12/2003] [Accepted: 11/12/2003] [Indexed: 04/08/2023]
Abstract
The generation of reactive oxygen species may be both beneficial to cells, performing a function in inter- and intracellular signalling, and detrimental, modifying cellular biomolecules, accumulation of which has been associated with numerous diseases. Of the molecules subject to oxidative modification, DNA has received the greatest attention, with biomarkers of exposure and effect closest to validation. Despite nearly a quarter of a century of study, and a large number of base- and sugar-derived DNA lesions having been identified, the majority of studies have focussed upon the guanine modification, 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-OH-dG). For the most part, the biological significance of other lesions has not, as yet, been investigated. In contrast, the description and characterisation of enzyme systems responsible for repairing oxidative DNA base damage is growing rapidly, being the subject of intense study. However, there remain notable gaps in our knowledge of which repair proteins remove which lesions, plus, as more lesions identified, new processes/substrates need to be determined. There are many reports describing elevated levels of oxidatively modified DNA lesions, in various biological matrices, in a plethora of diseases; however, for the majority of these the association could merely be coincidental, and more detailed studies are required. Nevertheless, even based simply upon reports of studies investigating the potential role of 8-OH-dG in disease, the weight of evidence strongly suggests a link between such damage and the pathogenesis of disease. However, exact roles remain to be elucidated.
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Affiliation(s)
- Mark D Evans
- Oxidative Stress Group, Department of Clinical Biochemistry, University of Leicester, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, LE2 7LX, UK
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