1
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Maghsoud Y, Roy A, Leddin EM, Cisneros GA. Effects of the Y432S Cancer-Associated Variant on the Reaction Mechanism of Human DNA Polymerase κ. J Chem Inf Model 2024; 64:4231-4249. [PMID: 38717969 PMCID: PMC11181361 DOI: 10.1021/acs.jcim.4c00339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2024]
Abstract
Human DNA polymerases are vital for genetic information management. Their function involves catalyzing the synthesis of DNA strands with unparalleled accuracy, which ensures the fidelity and stability of the human genomic blueprint. Several disease-associated mutations and their functional impact on DNA polymerases have been reported. One particular polymerase, human DNA polymerase kappa (Pol κ), has been reported to be susceptible to several cancer-associated mutations. The Y432S mutation in Pol κ, associated with various cancers, is of interest due to its impact on polymerization activity and markedly reduced thermal stability. Here, we have used computational simulations to investigate the functional consequences of the Y432S using classical molecular dynamics (MD) and coupled quantum mechanics/molecular mechanics (QM/MM) methods. Our findings suggest that Y432S induces structural alterations in domains responsible for nucleotide addition and ternary complex stabilization while retaining structural features consistent with possible catalysis in the active site. Calculations of the minimum energy path associated with the reaction mechanism of the wild type (WT) and Y432S Pol κ indicate that, while both enzymes are catalytically competent (in terms of energetics and the active site's geometries), the cancer mutation results in an endoergic reaction and an increase in the catalytic barrier. Interactions with a third magnesium ion and environmental effects on nonbonded interactions, particularly involving key residues, contribute to the kinetic and thermodynamic distinctions between the WT and mutant during the catalytic reaction. The energetics and electronic findings suggest that active site residues favor the catalytic reaction with dCTP3- over dCTP4-.
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Affiliation(s)
- Yazdan Maghsoud
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Arkanil Roy
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Emmett M Leddin
- Department of Chemistry, University of North Texas, Denton, Texas 76201, United States
| | - G Andrés Cisneros
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Physics, University of Texas at Dallas, Richardson, Texas 75080, United States
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2
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Bagale SS, Deshmukh PU, Lad SB, Sudarsan A, Sudhakar S, Mandal S, Kondabagil K, Pradeepkumar PI. Synthesis of N2- trans-isosafrole-dG-adduct Bearing DNAs and the Bypass Studies with Human TLS Polymerases κ and η. J Org Chem 2024. [PMID: 38739842 DOI: 10.1021/acs.joc.4c00368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Safrole is a natural product present in many plants and plant products, including spices and essential oils. During cellular metabolism, it converts to a highly reactive trans-isosafrole (SF) intermediate that reacts with genomic DNA and forms N2-SF-dG and N6-SF-dA DNA adducts, which are detected in the oral tissue of cancer patients with betel quid chewing history. To study the SF-induced carcinogenesis and to probe the role of low fidelity translesion synthesis (TLS) polymerases in bypassing SF adducts, herein, we report the synthesis of N2-SF-dG modified DNAs using phosphoramidite chemistry. The N2-SF-dG modification in the duplex DNA does not affect the thermal stability and retains the B-form of helical conformation, indicating that this adduct may escape the radar of common DNA repair mechanisms. Primer extension studies showed that the N2-SF-dG adduct is bypassed by human TLS polymerases hpolκ and hpolη, which perform error-free replication across this adduct. Furthermore, molecular modeling and dynamics studies revealed that the adduct reorients to pair with the incoming nucleotide, thus allowing the effective bypass. Overall, the results indicate that hpolκ and hpolη do not distinguish the N2-SF-dG adduct, suggesting that they may not be involved in the safrole-induced carcinogenicity.
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Affiliation(s)
| | - Priyanka U Deshmukh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Shailesh B Lad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Akhil Sudarsan
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sruthi Sudhakar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Soumyadeep Mandal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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3
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Pathira Kankanamge L, Mora A, Ondrechen MJ, Beuning PJ. Biochemical Activity of 17 Cancer-Associated Variants of DNA Polymerase Kappa Predicted by Electrostatic Properties. Chem Res Toxicol 2023; 36:1789-1803. [PMID: 37883788 PMCID: PMC10664756 DOI: 10.1021/acs.chemrestox.3c00233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/28/2023]
Abstract
DNA damage and repair have been widely studied in relation to cancer and therapeutics. Y-family DNA polymerases can bypass DNA lesions, which may result from external or internal DNA damaging agents, including some chemotherapy agents. Overexpression of the Y-family polymerase human pol kappa can result in tumorigenesis and drug resistance in cancer. This report describes the use of computational tools to predict the effects of single nucleotide polymorphism variants on pol kappa activity. Partial Order Optimum Likelihood (POOL), a machine learning method that uses input features from Theoretical Microscopic Titration Curve Shapes (THEMATICS), was used to identify amino acid residues most likely involved in catalytic activity. The μ4 value, a metric obtained from POOL and THEMATICS that serves as a measure of the degree of coupling between one ionizable amino acid and its neighbors, was then used to identify which protein mutations are likely to impact the biochemical activity. Bioinformatic tools SIFT, PolyPhen-2, and FATHMM predicted most of these variants to be deleterious to function. Along with computational and bioinformatic predictions, we characterized the catalytic activity and stability of 17 cancer-associated DNA pol kappa variants. We identified pol kappa variants R48I, H105Y, G147D, G154E, V177L, R298C, E362V, and R470C as having lower activity relative to wild-type pol kappa; the pol kappa variants T102A, H142Y, R175Q, E210K, Y221C, N330D, N338S, K353T, and L383F were identified as being similar in catalytic efficiency to WT pol kappa. We observed that POOL predictions can be used to predict which variants have decreased activity. Predictions from bioinformatic tools like SIFT, PolyPhen-2, and FATHMM are based on sequence comparisons and therefore are complementary to POOL but are less capable of predicting biochemical activity. These bioinformatic and computational tools can be used to identify SNP variants with deleterious effects and altered biochemical activity from a large data set.
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Affiliation(s)
- Lakindu
S. Pathira Kankanamge
- Department
of Chemistry and Chemical Biology and Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Alexandra Mora
- Department
of Chemistry and Chemical Biology and Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Mary Jo Ondrechen
- Department
of Chemistry and Chemical Biology and Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Penny J. Beuning
- Department
of Chemistry and Chemical Biology and Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
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4
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Deshmukh PU, Lad SB, Sudarsan A, Sudhakar S, Aggarwal T, Mandal S, Bagale SS, Kondabagil K, Pradeepkumar PI. Human Translesion Synthesis Polymerases polκ and polη Perform Error-Free Replication across N2-dG Methyleugenol and Estragole DNA Adducts. Biochemistry 2023; 62:2391-2406. [PMID: 37486230 DOI: 10.1021/acs.biochem.2c00663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
The secondary metabolites of polypropanoids, methyleugenol (MEG), and estragole (EG), found in many herbs and spices, are commonly used as food flavoring agents and as ingredients in cosmetics. MEG and EG have been reported to cause hepatocarcinogenicity in rodents, human livers, and lung cells. The formation of N2-dG and N6-dA DNA adducts is primarily attributed to the carcinogenicity of these compounds. Therefore, these compounds have been classified as "possible human carcinogens" by the International Agency for Research on Cancer and "reasonably anticipated to be a human carcinogen" by the National Toxicology Program. Herein, we report the synthesis of the N2-MEG-dG and N2-EG-dG modified oligonucleotides to study the mutagenicity of these DNA adducts. Our studies show that N2-MEG-dG and N2-EG-dG could be bypassed by human translesion synthesis (TLS) polymerases hpolκ and hpolη in an error-free manner. The steady-state kinetics of dCTP incorporation by hpolκ across N2-MEG-dG and N2-EG-dG adducts show that the catalytic efficiencies (kcat/Km) were ∼2.5- and ∼4.4-fold higher, respectively, compared to the unmodified dG template. A full-length primer extension assay demonstrates that hpolκ exhibits better catalytic efficiency than hpolη. Molecular modeling and dynamics studies capturing pre-insertion, insertion, and post-insertion steps reveal the structural features associated with the efficient bypass of the N2-MEG-dG adduct by hpolκ and indicate the reorientation of the adduct in the active site allowing the successful insertion of the incoming nucleotide. Together, these results suggest that though hpolκ and hpolη perform error-free TLS across MEG and EG during DNA replication, the observed carcinogenicity of these adducts could be attributed to the involvement of other low fidelity polymerases.
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Affiliation(s)
- Priyanka U Deshmukh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Shailesh B Lad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Akhil Sudarsan
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sruthi Sudhakar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Tanvi Aggarwal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Soumyadeep Mandal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | | | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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5
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Anand J, Chiou L, Sciandra C, Zhang X, Hong J, Wu D, Zhou P, Vaziri C. Roles of trans-lesion synthesis (TLS) DNA polymerases in tumorigenesis and cancer therapy. NAR Cancer 2023; 5:zcad005. [PMID: 36755961 PMCID: PMC9900426 DOI: 10.1093/narcan/zcad005] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/10/2022] [Accepted: 01/30/2023] [Indexed: 02/08/2023] Open
Abstract
DNA damage tolerance and mutagenesis are hallmarks and enabling characteristics of neoplastic cells that drive tumorigenesis and allow cancer cells to resist therapy. The 'Y-family' trans-lesion synthesis (TLS) DNA polymerases enable cells to replicate damaged genomes, thereby conferring DNA damage tolerance. Moreover, Y-family DNA polymerases are inherently error-prone and cause mutations. Therefore, TLS DNA polymerases are potential mediators of important tumorigenic phenotypes. The skin cancer-propensity syndrome xeroderma pigmentosum-variant (XPV) results from defects in the Y-family DNA Polymerase Pol eta (Polη) and compensatory deployment of alternative inappropriate DNA polymerases. However, the extent to which dysregulated TLS contributes to the underlying etiology of other human cancers is unclear. Here we consider the broad impact of TLS polymerases on tumorigenesis and cancer therapy. We survey the ways in which TLS DNA polymerases are pathologically altered in cancer. We summarize evidence that TLS polymerases shape cancer genomes, and review studies implicating dysregulated TLS as a driver of carcinogenesis. Because many cancer treatment regimens comprise DNA-damaging agents, pharmacological inhibition of TLS is an attractive strategy for sensitizing tumors to genotoxic therapies. Therefore, we discuss the pharmacological tractability of the TLS pathway and summarize recent progress on development of TLS inhibitors for therapeutic purposes.
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Affiliation(s)
- Jay Anand
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
| | - Lilly Chiou
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Carly Sciandra
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Xingyuan Zhang
- Department of Biostatistics, University of North Carolina at Chapel Hill, 135 Dauer Drive, 3101 McGavran-Greenberg Hall, Chapel Hill, NC 27599, USA
| | - Jiyong Hong
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | - Di Wu
- Department of Biostatistics, University of North Carolina at Chapel Hill, 135 Dauer Drive, 3101 McGavran-Greenberg Hall, Chapel Hill, NC 27599, USA
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Cyrus Vaziri
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
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6
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Fahrer J, Christmann M. DNA Alkylation Damage by Nitrosamines and Relevant DNA Repair Pathways. Int J Mol Sci 2023; 24:ijms24054684. [PMID: 36902118 PMCID: PMC10003415 DOI: 10.3390/ijms24054684] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/17/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023] Open
Abstract
Nitrosamines occur widespread in food, drinking water, cosmetics, as well as tobacco smoke and can arise endogenously. More recently, nitrosamines have been detected as impurities in various drugs. This is of particular concern as nitrosamines are alkylating agents that are genotoxic and carcinogenic. We first summarize the current knowledge on the different sources and chemical nature of alkylating agents with a focus on relevant nitrosamines. Subsequently, we present the major DNA alkylation adducts induced by nitrosamines upon their metabolic activation by CYP450 monooxygenases. We then describe the DNA repair pathways engaged by the various DNA alkylation adducts, which include base excision repair, direct damage reversal by MGMT and ALKBH, as well as nucleotide excision repair. Their roles in the protection against the genotoxic and carcinogenic effects of nitrosamines are highlighted. Finally, we address DNA translesion synthesis as a DNA damage tolerance mechanism relevant to DNA alkylation adducts.
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Affiliation(s)
- Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Erwin-Schrödinger Strasse 52, D-67663 Kaiserslautern, Germany
- Correspondence: (J.F.); (M.C.); Tel.: +496312052974 (J.F.); Tel: +496131179066 (M.C.)
| | - Markus Christmann
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
- Correspondence: (J.F.); (M.C.); Tel.: +496312052974 (J.F.); Tel: +496131179066 (M.C.)
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7
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Boldinova EO, Ghodke PP, Sudhakar S, Mishra VK, Manukyan AA, Miropolskaya N, Pradeepkumar PI, Makarova AV. Translesion Synthesis across the N2-Ethyl-deoxyguanosine Adduct by Human PrimPol. ACS Chem Biol 2022; 17:3238-3250. [PMID: 36318733 DOI: 10.1021/acschembio.2c00717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Primase-DNA polymerase (PrimPol) is involved in reinitiating DNA synthesis at stalled replication forks. PrimPol also possesses DNA translesion (TLS) activity and bypasses several endogenous nonbulky DNA lesions in vitro. Little is known about the TLS activity of PrimPol across bulky carcinogenic adducts. We analyzed the DNA polymerase activity of human PrimPol on DNA templates with seven N2-dG lesions of different steric bulkiness. In the presence of Mg2+ ions, bulky N2-isobutyl-dG, N2-benzyl-dG, N2-methyl(1-naphthyl)-dG, N2-methyl(9-anthracenyl)-dG, N2-methyl(1-pyrenyl)-dG, and N2-methyl(1,3-dimethoxyanthraquinone)-dG adducts fully blocked PrimPol activity. At the same time, PrimPol incorporated complementary deoxycytidine monophosphate (dCMP) opposite N2-ethyl-dG with moderate efficiency but did not extend DNA beyond the lesion. We also demonstrated that mutation of the Arg288 residue abrogated dCMP incorporation opposite the lesion in the presence of Mn2+ ions. When Mn2+ replaced Mg2+, PrimPol carried out DNA synthesis on all DNA templates with N2-dG adducts in standing start reactions with low efficiency and accuracy, possibly utilizing a lesion "skipping" mechanism. The TLS activity of PrimPol opposite N2-ethyl-dG but not bulkier adducts was stimulated by accessory proteins, polymerase delta-interacting protein 2 (PolDIP2), and replication protein A (RPA). Molecular dynamics studies demonstrated the absence of stable interactions with deoxycytidine triphosphate (dCTP), large reactions, and C1'-C1' distances for the N2-isobutyl-dG and N2-benzyl-dG PrimPol complexes, suggesting that the size of the adduct is a limiting factor for efficient TLS across minor groove adducts by PrimPol.
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Affiliation(s)
- Elizaveta O Boldinova
- Institute of Molecular Genetics, National Research Center Kurchatov Institute, Kurchatov sq. 2, Moscow 123182, Russia
| | - Pratibha P Ghodke
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sruthi Sudhakar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Vipin Kumar Mishra
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Anna A Manukyan
- Institute of Molecular Genetics, National Research Center Kurchatov Institute, Kurchatov sq. 2, Moscow 123182, Russia
| | - Nataliya Miropolskaya
- Institute of Molecular Genetics, National Research Center Kurchatov Institute, Kurchatov sq. 2, Moscow 123182, Russia
| | | | - Alena V Makarova
- Institute of Molecular Genetics, National Research Center Kurchatov Institute, Kurchatov sq. 2, Moscow 123182, Russia
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8
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Ling JA, Frevert Z, Washington MT. Recent Advances in Understanding the Structures of Translesion Synthesis DNA Polymerases. Genes (Basel) 2022; 13:genes13050915. [PMID: 35627300 PMCID: PMC9141541 DOI: 10.3390/genes13050915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 12/10/2022] Open
Abstract
DNA damage in the template strand causes replication forks to stall because replicative DNA polymerases are unable to efficiently incorporate nucleotides opposite template DNA lesions. To overcome these replication blocks, cells are equipped with multiple translesion synthesis polymerases that have evolved specifically to incorporate nucleotides opposite DNA lesions. Over the past two decades, X-ray crystallography has provided a wealth of information about the structures and mechanisms of translesion synthesis polymerases. This approach, however, has been limited to ground state structures of these polymerases bound to DNA and nucleotide substrates. Three recent methodological developments have extended our understanding of the structures and mechanisms of these polymerases. These include time-lapse X-ray crystallography, which allows one to identify novel reaction intermediates; full-ensemble hybrid methods, which allow one to examine the conformational flexibility of the intrinsically disordered regions of proteins; and cryo-electron microscopy, which allows one to determine the high-resolution structures of larger protein complexes. In this article, we will discuss how these three methodological developments have added to our understanding of the structures and mechanisms of translesion synthesis polymerases.
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9
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Wilson KA, Jeong YER, Wetmore SD. Multiscale computational investigations of the translesion synthesis bypass of tobacco-derived DNA adducts: critical insights that complement experimental biochemical studies. Phys Chem Chem Phys 2022; 24:10667-10683. [PMID: 35502640 DOI: 10.1039/d2cp00481j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Among the numerous agents that damage DNA, tobacco products remain one of the most lethal and result in the most diverse set of DNA lesions. This perspective aims to provide an overview of computational work conducted to complement experimental biochemical studies on the mutagenicity of adducts derived from the most potent tobacco carcinogen, namely 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosaminoketone or NNK). Lesions ranging from the smallest methylated thymine derivatives to the larger, flexible pyridyloxobutyl (POB) guanine adducts are considered. Insights are obtained from density functional theory (DFT) calculations and molecular dynamics (MD) simulations into the damaged nucleobase and nucleoside structures, the accommodation of the lesions in the active site of key human polymerases, the intrinsic base pairing potentials of the adducts, and dNTP incorporation opposite the lesions. Overall, the computational data provide atomic level information that can rationalize the differential mutagenic properties of tobacco-derived lesions and uncover important insights into the impact of adduct size, nucleobase, position, and chemical composition of the bulky moiety.
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Affiliation(s)
- Katie A Wilson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute (ARRTI) and Southern Alberta Genome Sciences Center (SAGSC), University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, T1K 3M4, Canada.
| | - Ye Eun Rebecca Jeong
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute (ARRTI) and Southern Alberta Genome Sciences Center (SAGSC), University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, T1K 3M4, Canada.
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute (ARRTI) and Southern Alberta Genome Sciences Center (SAGSC), University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, T1K 3M4, Canada.
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10
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Vaisman A, McDonald JP, Smith MR, Aspelund SL, Evans TC, Woodgate R. Identification and Characterization of Thermostable Y-Family DNA Polymerases η, ι, κ and Rev1 From a Lower Eukaryote, Thermomyces lanuginosus. Front Mol Biosci 2021; 8:778400. [PMID: 34805283 PMCID: PMC8595933 DOI: 10.3389/fmolb.2021.778400] [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: 09/16/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
Y-family DNA polymerases (pols) consist of six phylogenetically separate subfamilies; two UmuC (polV) branches, DinB (pol IV, Dpo4, polκ), Rad30A/POLH (polη), and Rad30B/POLI (polι) and Rev1. Of these subfamilies, DinB orthologs are found in all three domains of life; eubacteria, archaea, and eukarya. UmuC orthologs are identified only in bacteria, whilst Rev1 and Rad30A/B orthologs are only detected in eukaryotes. Within eukaryotes, a wide array of evolutionary diversity exists. Humans possess all four Y-family pols (pols η, ι, κ, and Rev1), Schizosaccharomyces pombe has three Y-family pols (pols η, κ, and Rev1), and Saccharomyces cerevisiae only has polη and Rev1. Here, we report the cloning, expression, and biochemical characterization of the four Y-family pols from the lower eukaryotic thermophilic fungi, Thermomyces lanuginosus. Apart from the expected increased thermostability of the T. lanuginosus Y-family pols, their major biochemical properties are very similar to properties of their human counterparts. In particular, both Rad30B homologs (T. lanuginosus and human polɩ) exhibit remarkably low fidelity during DNA synthesis that is template sequence dependent. It was previously hypothesized that higher organisms had acquired this property during eukaryotic evolution, but these observations imply that polι originated earlier than previously known, suggesting a critical cellular function in both lower and higher eukaryotes.
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Affiliation(s)
- Alexandra Vaisman
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - John P McDonald
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Mallory R Smith
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Sender L Aspelund
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Thomas C Evans
- New England Biolabs Incorporated, Ipswich, MA, United States
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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11
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Ghodke PP, Guengerich FP. DNA polymerases η and κ bypass N 2-guanine-O 6-alkylguanine DNA alkyltransferase cross-linked DNA-peptides. J Biol Chem 2021; 297:101124. [PMID: 34461101 PMCID: PMC8463853 DOI: 10.1016/j.jbc.2021.101124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 11/27/2022] Open
Abstract
DNA-protein cross-links are formed when proteins become covalently trapped with DNA in the presence of exogenous or endogenous alkylating agents. If left unrepaired, they inhibit transcription as well as DNA unwinding during replication and may result in genome instability or even cell death. The DNA repair protein O6-alkylguanine DNA-alkyltransferase (AGT) is known to form DNA cross-links in the presence of the carcinogen 1,2-dibromoethane, resulting in G:C to T:A transversions and other mutations in both bacterial and mammalian cells. We hypothesized that AGT-DNA cross-links would be processed by nuclear proteases to yield peptides small enough to be bypassed by translesion (TLS) polymerases. Here, a 15-mer and a 36-mer peptide from the active site of AGT were cross-linked to the N2 position of guanine via conjugate addition of a thiol containing a peptide dehydroalanine moiety. Bypass studies with DNA polymerases (pols) η and κ indicated that both can accurately bypass the cross-linked DNA peptides. The specificity constant (kcat/Km) for steady-state incorporation of the correct nucleotide dCTP increased by 6-fold with human (h) pol κ and 3-fold with hpol η, with hpol η preferentially inserting nucleotides in the order dC > dG > dA > dT. LC-MS/MS analysis of the extension product also revealed error-free bypass of the cross-linked 15-mer peptide by hpol η. We conclude that a bulky 15-mer AGT peptide cross-linked to the N2 position of guanine can retard polymerization, but that overall fidelity is not compromised because only correct bases are inserted and extended.
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Affiliation(s)
- Pratibha P Ghodke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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12
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Meier B, Volkova NV, Hong Y, Bertolini S, González-Huici V, Petrova T, Boulton S, Campbell PJ, Gerstung M, Gartner A. Protection of the C. elegans germ cell genome depends on diverse DNA repair pathways during normal proliferation. PLoS One 2021; 16:e0250291. [PMID: 33905417 PMCID: PMC8078821 DOI: 10.1371/journal.pone.0250291] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/01/2021] [Indexed: 12/13/2022] Open
Abstract
Maintaining genome integrity is particularly important in germ cells to ensure faithful transmission of genetic information across generations. Here we systematically describe germ cell mutagenesis in wild-type and 61 DNA repair mutants cultivated over multiple generations. ~44% of the DNA repair mutants analysed showed a >2-fold increased mutagenesis with a broad spectrum of mutational outcomes. Nucleotide excision repair deficiency led to higher base substitution rates, whereas polh-1(Polη) and rev-3(Polζ) translesion synthesis polymerase mutants resulted in 50-400 bp deletions. Signatures associated with defective homologous recombination fall into two classes: 1) brc-1/BRCA1 and rad-51/RAD51 paralog mutants showed increased mutations across all mutation classes, 2) mus-81/MUS81 and slx-1/SLX1 nuclease, and him-6/BLM, helq-1/HELQ or rtel-1/RTEL1 helicase mutants primarily accumulated structural variants. Repetitive and G-quadruplex sequence-containing loci were more frequently mutated in specific DNA repair backgrounds. Tandem duplications embedded in inverted repeats were observed in helq-1 helicase mutants, and a unique pattern of 'translocations' involving homeologous sequences occurred in rip-1 recombination mutants. atm-1/ATM checkpoint mutants harboured structural variants specifically enriched in subtelomeric regions. Interestingly, locally clustered mutagenesis was only observed for combined brc-1 and cep-1/p53 deficiency. Our study provides a global view of how different DNA repair pathways contribute to prevent germ cell mutagenesis.
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Affiliation(s)
- Bettina Meier
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland
| | - Nadezda V. Volkova
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, United Kingdom
| | - Ye Hong
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland
| | - Simone Bertolini
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland
| | | | - Tsvetana Petrova
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland
| | | | - Peter J. Campbell
- Cancer, Ageing and Somatic Mutation Program, Wellcome Sanger Institute, Hinxton, United Kingdom
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
- Department of Haematology, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Moritz Gerstung
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, United Kingdom
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Anton Gartner
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, Scotland
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
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13
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Shilkin ES, Boldinova EO, Stolyarenko AD, Goncharova RI, Chuprov-Netochin RN, Khairullin RF, Smal MP, Makarova AV. Translesion DNA Synthesis and Carcinogenesis. BIOCHEMISTRY (MOSCOW) 2021; 85:425-435. [PMID: 32569550 DOI: 10.1134/s0006297920040033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Tens of thousands of DNA lesions are formed in mammalian cells each day. DNA translesion synthesis is the main mechanism of cell defense against unrepaired DNA lesions. DNA polymerases iota (Pol ι), eta (Pol η), kappa (Pol κ), and zeta (Pol ζ) have active sites that are less stringent toward the DNA template structure and efficiently incorporate nucleotides opposite DNA lesions. However, these polymerases display low accuracy of DNA synthesis and can introduce mutations in genomic DNA. Impaired functioning of these enzymes can lead to an increased risk of cancer.
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Affiliation(s)
- E S Shilkin
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia
| | - E O Boldinova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia
| | - A D Stolyarenko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia
| | - R I Goncharova
- Institute of Genetics and Cytology, National Academy of Sciences of Belarus, Minsk, 220072, Republic of Belarus
| | - R N Chuprov-Netochin
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - R F Khairullin
- Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, 420012, Russia
| | - M P Smal
- Institute of Genetics and Cytology, National Academy of Sciences of Belarus, Minsk, 220072, Republic of Belarus.
| | - A V Makarova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia.
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14
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Ghodke PP, Pradeepkumar PI. Site‐Specific
N
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‐dG DNA Adducts: Formation, Synthesis, and TLS Polymerase‐Mediated Bypass. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000298] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pratibha P. Ghodke
- Department of Biochemistry Vanderbilt University School of Medicine 638B Robinson Research Building 2200 Pierce Avenue 37323‐0146 Nashville Tennessee United States
- Department of Chemistry Indian Institute of Technology Bombay 400076 Mumbai Powai India
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15
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Kondratick CM, Washington MT, Spies M. Making Choices: DNA Replication Fork Recovery Mechanisms. Semin Cell Dev Biol 2020; 113:27-37. [PMID: 33967572 DOI: 10.1016/j.semcdb.2020.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
DNA replication is laden with obstacles that slow, stall, collapse, and break DNA replication forks. At each obstacle, there is a decision to be made whether to bypass the lesion, repair or restart the damaged fork, or to protect stalled forks from further demise. Each "decision" draws upon multitude of proteins participating in various mechanisms that allow repair and restart of replication forks. Specific functions for many of these proteins have been described and an understanding of how they come together in supporting replication forks is starting to emerge. Many questions, however, remain regarding selection of the mechanisms that enable faithful genome duplication and how "normal" intermediates in these mechanisms are sometimes funneled into "rogue" processes that destabilize the genome and lead to cancer, cell death, and emergence of chemotherapeutic resistance. In this review we will discuss molecular mechanisms of DNA damage bypass and replication fork protection and repair. We will specifically focus on the key players that define which mechanism is employed including: PCNA and its control by posttranslational modifications, translesion synthesis DNA polymerases, molecular motors that catalyze reversal of stalled replication forks, proteins that antagonize fork reversal and protect reversed forks from nucleolytic degradation, and the machinery of homologous recombination that helps to reestablish broken forks. We will also discuss risks to genome integrity inherent in each of these mechanisms.
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Affiliation(s)
- Christine M Kondratick
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - M Todd Washington
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.,Department of Radiation Oncology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.,Department of Radiation Oncology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
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16
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Wilkinson NA, Mnuskin KS, Ashton NW, Woodgate R. Ubiquitin and Ubiquitin-Like Proteins Are Essential Regulators of DNA Damage Bypass. Cancers (Basel) 2020; 12:cancers12102848. [PMID: 33023096 PMCID: PMC7600381 DOI: 10.3390/cancers12102848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/24/2020] [Accepted: 09/29/2020] [Indexed: 11/18/2022] Open
Abstract
Simple Summary Ubiquitin and ubiquitin-like proteins are conjugated to many other proteins within the cell, to regulate their stability, localization, and activity. These modifications are essential for normal cellular function and the disruption of these processes contributes to numerous cancer types. In this review, we discuss how ubiquitin and ubiquitin-like proteins regulate the specialized replication pathways of DNA damage bypass, as well as how the disruption of these processes can contribute to cancer development. We also discuss how cancer cell survival relies on DNA damage bypass, and how targeting the regulation of these pathways by ubiquitin and ubiquitin-like proteins might be an effective strategy in anti-cancer therapies. Abstract Many endogenous and exogenous factors can induce genomic instability in human cells, in the form of DNA damage and mutations, that predispose them to cancer development. Normal cells rely on DNA damage bypass pathways such as translesion synthesis (TLS) and template switching (TS) to replicate past lesions that might otherwise result in prolonged replication stress and lethal double-strand breaks (DSBs). However, due to the lower fidelity of the specialized polymerases involved in TLS, the activation and suppression of these pathways must be tightly regulated by post-translational modifications such as ubiquitination in order to limit the risk of mutagenesis. Many cancer cells rely on the deregulation of DNA damage bypass to promote carcinogenesis and tumor formation, often giving them heightened resistance to DNA damage from chemotherapeutic agents. In this review, we discuss the key functions of ubiquitin and ubiquitin-like proteins in regulating DNA damage bypass in human cells, and highlight ways in which these processes are both deregulated in cancer progression and might be targeted in cancer therapy.
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Affiliation(s)
| | | | - Nicholas W. Ashton
- Correspondence: (N.W.A.); (R.W.); Tel.: +1-301-435-1115 (N.W.A.); +1-301-435-0740 (R.W.)
| | - Roger Woodgate
- Correspondence: (N.W.A.); (R.W.); Tel.: +1-301-435-1115 (N.W.A.); +1-301-435-0740 (R.W.)
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17
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Pande P, Rebello KR, Chatterjee A, Naldiga S, Basu AK. Site-Specific Incorporation of N-(2'-Deoxyguanosine-8-yl)-6-aminochrysene Adduct in DNA and Its Replication in Human Cells. Chem Res Toxicol 2020; 33:1997-2005. [PMID: 32551527 DOI: 10.1021/acs.chemrestox.0c00197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The environmental pollutant 6-nitrochrysene (6-NC) is a potent mutagen and a mammary carcinogen in rats. 6-NC is the most potent carcinogen ever tested in the newborn mouse assay. In mammalian cells, it is metabolically activated by nitroreduction and a combination of ring oxidation and nitroreduction pathways. The nitroreduction pathway yields two major adducts with 2'-deoxyguanosine (dG), one at the C8-position, N-(dG-8-yl)-6-AC, and the other at the exocyclic N2-position, 5-(dG-N2-yl)-6-AC. Here, we report the total synthesis of a site-specific oligonucleotide containing the 6-NC-derived C8 dG adduct, N-(dG-8-yl)-6-AC. Pd-catalyzed Buchwald-Hartwig cross coupling of 6-aminochrysene with protected C8-bromo-dG derivative served as the key reaction to furnish protected N-(dG-8-yl)-6-AC in 56% yield. The monomer for solid-phase DNA synthesis was prepared by its deprotection followed by conversion to the corresponding 5'-O-dimethoxytrityl 3'-phosphoramidite, which was used to synthesize a site-specifically adducted oligonucleotide. After purification and characterization, the adduct-containing oligonucleotide was incorporated into a plasmid and replicated in human embryonic kidney (HEK) 293T cells, which showed that N-(dG-8-yl)-6-AC stalls DNA replication as evidenced by 77% translesion synthesis (TLS) efficiency relative to the control and that the adduct is mutagenic (mutation frequency (MF) 17.8%) inducing largely G→T transversions. We also investigated the roles of several translesion synthesis DNA polymerases in the bypass of N-(dG-8-yl)-6-AC using siRNA knockdown approach. TLS efficiency was reduced in hPol η-, hPol κ-, hPol ζ-, and hREV1-deficient HEK 293T cells to 66%, 45%, 37%, and 32%, respectively. Notably, TLS efficiency was reduced to 18% in cells with concurrent knockdown of hPol κ, hPol ζ, and REV1, suggesting that these three polymerases play critical roles in bypassing N-(dG-8-yl)-6-AC. MF increased to 23.1% and 32.2% in hPol κ- and hREV1-deficient cells, whereas it decreased to 11.8% in hPol ζ-deficient cells. This suggests that hPol κ and hREV1 are involved in error-free TLS of this lesion, whereas hPol ζ performs error-prone bypass.
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Affiliation(s)
- Paritosh Pande
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Kimberly R Rebello
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Arindom Chatterjee
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Spandana Naldiga
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Ashis K Basu
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
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18
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Zhang H. Mechanisms of mutagenesis induced by DNA lesions: multiple factors affect mutations in translesion DNA synthesis. Crit Rev Biochem Mol Biol 2020; 55:219-251. [PMID: 32448001 DOI: 10.1080/10409238.2020.1768205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Environmental mutagens lead to mutagenesis. However, the mechanisms are very complicated and not fully understood. Environmental mutagens produce various DNA lesions, including base-damaged or sugar-modified DNA lesions, as well as epigenetically modified DNA. DNA polymerases produce mutation spectra in translesion DNA synthesis (TLS) through misincorporation of incorrect nucleotides, frameshift deletions, blockage of DNA replication, imbalance of leading- and lagging-strand DNA synthesis, and genome instability. Motif or subunit in DNA polymerases further affects the mutations in TLS. Moreover, protein interactions and accessory proteins in DNA replisome also alter mutations in TLS, demonstrated by several representative DNA replisomes. Finally, in cells, multiple DNA polymerases or cellular proteins collaborate in TLS and reduce in vivo mutagenesis. Summaries and perspectives were listed. This review shows mechanisms of mutagenesis induced by DNA lesions and the effects of multiple factors on mutations in TLS in vitro and in vivo.
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Affiliation(s)
- Huidong Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
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19
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Du H, Wang P, Wu J, He X, Wang Y. The roles of polymerases ν and θ in replicative bypass of O6- and N2-alkyl-2'-deoxyguanosine lesions in human cells. J Biol Chem 2020; 295:4556-4562. [PMID: 32098870 PMCID: PMC7135994 DOI: 10.1074/jbc.ra120.012830] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/20/2020] [Indexed: 12/28/2022] Open
Abstract
Exogenous and endogenous chemicals can react with DNA to produce DNA lesions that may block DNA replication. Not much is known about the roles of polymerase (Pol) ν and Pol θ in translesion synthesis (TLS) in cells. Here we examined the functions of these two polymerases in bypassing major-groove O6-alkyl-2'-deoxyguanosine (O6-alkyl-dG) and minor-groove N2-alkyl-dG lesions in human cells, where the alkyl groups are ethyl, n-butyl (nBu), and, for O6-alkyl-dG, pyridyloxobutyl. We found that Pol ν and Pol θ promote TLS across major-groove O6-alkyl-dG lesions. O6-alkyl-dG lesions mainly induced G→A mutations that were modulated by the two TLS polymerases and the structures of the alkyl groups. Simultaneous ablation of Pol ν and Pol θ resulted in diminished mutation frequencies for all three O6-alkyl-dG lesions. Depletion of Pol ν alone reduced mutations only for O6-nBu-dG, and sole loss of Pol θ attenuated the mutation rates for O6-nBu-dG and O6-pyridyloxobutyl-dG. Replication across the two N2-alkyl-dG lesions was error-free, and Pol ν and Pol θ were dispensable for their replicative bypass. Together, our results provide critical knowledge about the involvement of Pol ν and Pol θ in bypassing alkylated guanine lesions in human cells.
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Affiliation(s)
- Hua Du
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Jun Wu
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Xiaomei He
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, California 92521-0403
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20
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Ghodke PP, Pradeepkumar PI. Synthesis of N 2 -Aryl-2'-Deoxyguanosine Modified Phosphoramidites and Oligonucleotides. ACTA ACUST UNITED AC 2020; 78:e93. [PMID: 31529784 DOI: 10.1002/cpnc.93] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The N2 -position of 2'-deoxyguanosine (N2 -position in dG) is well known for forming carcinogenic minor groove DNA adducts, which originate from environmental pollutants, chemicals, and tobacco smoke. The N2 -dG DNA adducts have strong implications on biological processes such as DNA replication and repair and may, therefore, result in genomic instability by generating mutations or even cell death. It is crucial to know the role of DNA polymerases when they encounter the N2 -dG damaged site in DNA. To get detailed insights on the in vitro DNA damage tolerance or bypass mechanism, there is a need to synthetically access N2 -dG damaged DNAs. This article describes a detailed protocol of the synthesis of N2 -aryl-dG modified nucleotides using the Buchwald-Hartwig reaction as a main step and incorporation of the modified nucleotides into DNA. In Basic Protocol 1, we focused on the synthesis of five different N2 -dG modified phosphoramidites with varying bulkiness (benzyl to pyrenyl). Basic Protocol 2 describes the details of synthesizing N2 -dG modified oligonucleotides employing the standard solid phase synthesis protocol. This strategy provides robust synthetic access to various modifications at the N2 -position of dG; the modified dGs serve as good substrates to study translesion synthesis and repair pathways. Overall data presented in this article are based on earlier published reports. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- Pratibha P Ghodke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee.,Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
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21
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Wu J, Du H, Li L, Price NE, Liu X, Wang Y. The Impact of Minor-Groove N2-Alkyl-2'-deoxyguanosine Lesions on DNA Replication in Human Cells. ACS Chem Biol 2019; 14:1708-1716. [PMID: 31347832 DOI: 10.1021/acschembio.9b00129] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Endogenous metabolites and exogenous chemicals can induce covalent modifications on DNA, producing DNA lesions. The N2 of guanine was shown to be a common alkylation site in DNA; however, not much is known about the influence of the size of the alkyl group in N2-alkyldG lesions on cellular DNA replication or how translesion synthesis (TLS) polymerases modulate DNA replication past these lesions in human cells. To answer these questions, we employ a robust shuttle vector method to investigate the impact of four N2-alkyldG lesions (i.e., with the alkyl group being a methyl, ethyl, n-propyl, or n-butyl group) on DNA replication in human cells. We find that replication through the N2-alkyldG lesions was highly efficient and accurate in HEK293T cells or isogenic CRISPR-engineered cells with deficiency in polymerase (Pol) ζ or Pol η. Genetic ablation of Pol ι, Pol κ, or Rev1, however, results in decreased bypass efficiencies and elicits substantial frequencies of G → A transition and G → T transversion mutations for these lesions. Moreover, further depletion of Pol ζ in Pol κ- or Pol ι-deficient cells gives rise to elevated rates of G → A and G → T mutations and substantially decreased bypass efficiencies. Cumulatively, we demonstrate that the error-free replication past the N2-alkyldG lesions is facilitated by a specific subset of TLS polymerases, and we find that longer alkyl chains in these lesions induce diminished bypass efficiency and fidelity in DNA replication.
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Affiliation(s)
- Jun Wu
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Hua Du
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Lin Li
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Nathan E. Price
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Xiaochuan Liu
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
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22
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Mammalian DNA Polymerase Kappa Activity and Specificity. Molecules 2019; 24:molecules24152805. [PMID: 31374881 PMCID: PMC6695781 DOI: 10.3390/molecules24152805] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 07/27/2019] [Accepted: 07/30/2019] [Indexed: 12/31/2022] Open
Abstract
DNA polymerase (pol) kappa is a Y-family translesion DNA polymerase conserved throughout all domains of life. Pol kappa is special6 ized for the ability to copy DNA containing minor groove DNA adducts, especially N2-dG adducts, as well as to extend primer termini containing DNA damage or mismatched base pairs. Pol kappa generally cannot copy DNA containing major groove modifications or UV-induced photoproducts. Pol kappa can also copy structured or non-B-form DNA, such as microsatellite DNA, common fragile sites, and DNA containing G quadruplexes. Thus, pol kappa has roles both in maintaining and compromising genomic integrity. The expression of pol kappa is altered in several different cancer types, which can lead to genome instability. In addition, many cancer-associated single-nucleotide polymorphisms have been reported in the POLK gene, some of which are associated with poor survival and altered chemotherapy response. Because of this, identifying inhibitors of pol kappa is an active area of research. This review will address these activities of pol kappa, with a focus on lesion bypass and cellular mutagenesis.
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23
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Ketkar A, Maddukuri L, Penthala NR, Reed MR, Zafar MK, Crooks PA, Eoff RL. Inhibition of Human DNA Polymerases Eta and Kappa by Indole-Derived Molecules Occurs through Distinct Mechanisms. ACS Chem Biol 2019; 14:1337-1351. [PMID: 31082191 DOI: 10.1021/acschembio.9b00304] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Overexpression of human DNA polymerase kappa (hpol κ) in glioblastoma is associated with shorter survival time and resistance to the alkylating agent temozolomide (TMZ), making it an attractive target for the development of small-molecule inhibitors. We previously reported on the development and characterization of indole barbituric acid-derived (IBA) inhibitors of translesion DNA synthesis polymerases (TLS pols). We have now identified a potent and selective inhibitor of hpol κ based on the indole-aminoguanidine (IAG) chemical scaffold. The most promising IAG analogue, IAG-10, exhibited greater inhibitory action against hpol κ than any other human Y-family member, as well as pols from the A-, B-, and X-families. Inhibition of hpol κ by IAG analogues appears to proceed through a mechanism that is distinct from inhibition of hpol η based on changes in DNA binding affinity and nucleotide insertion kinetics. By way of comparison, both IAG and IBA analogues inhibited binary complex formation by hpol κ and ternary complex formation by hpol η. Decreasing the concentration of enzyme and DNA in the reaction mixture lowered the IC50 value of IAG-10 to submicromolar values, consistent with inhibition of binary complex formation for hpol κ. Chemical footprinting experiments revealed that IAG-10 binds to a cleft between the finger, little finger, and N-clasp domains on hpol κ and that this likely disrupts the interaction between the N-clasp and the TLS pol core. In cell culture, IAG-10 potentiated the antiproliferative activity and DNA damaging effects of TMZ in hpol κ-proficient cells but not in hpol κ-deficient cells, indicative of a target-dependent effect. Mutagenic replication across alkylation damage increased in hpol κ-proficient cells treated with IAG-10, while no change in mutation frequency was observed for hpol κ-deficient cells. In summary, we developed a potent and selective small-molecule inhibitor of hpol κ that takes advantage of structural features unique to this TLS enzyme to potentiate TMZ, a standard-of-care drug used in the treatment of malignant brain tumors. Furthermore, the IAG scaffold represents a new chemical space for the exploration of TLS pol inhibitors, which could prove useful as a strategy for improving patient response to genotoxic drugs.
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Affiliation(s)
- Amit Ketkar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Leena Maddukuri
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Narsimha R. Penthala
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Megan R. Reed
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Maroof K. Zafar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Peter A. Crooks
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Robert L. Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
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24
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Hakura A, Sui H, Sonoda J, Matsuda T, Nohmi T. DNA polymerase kappa counteracts inflammation-induced mutagenesis in multiple organs of mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:320-330. [PMID: 30620413 DOI: 10.1002/em.22272] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/26/2018] [Accepted: 12/28/2018] [Indexed: 05/07/2023]
Abstract
In vitro studies indicate that DNA polymerase kappa (Polκ) is able to accurately and efficiently perform DNA synthesis using templates containing various types of DNA damage, including benzo[a]pyrene (BP)-induced N2 -deoxyguanosine adducts. In this study, we examined sensitivity of inactivated Polk knock-in (Polk-/- ) mice to BP carcinogenicity in the colon by administering an oral dose of BP plus dextran sulfate sodium (DSS), an inflammation causing promoter of carcinogenesis. Although colon cancer was successfully induced by BP plus DSS, there was no significant difference in tumor incidence or multiplicity between Polk-/- and Polk+/+ mice. Malignant lymphoma was induced in thymus by the treatment only in Polk-/- mice, but it lacked statistical significance. Mutant frequencies (MFs) in the gpt reporter gene were strongly enhanced in colon; almost to the same extent in both types of mice. Micronucleus formation in bone marrow at the high dose of BP and DNA adducts in colon and lung was not significantly different between two types of mice. Surprisingly, however, Polk-/- mice exhibited significantly higher MFs in colon and lung than did Polk+/+ mice when they were treated with DSS alone. The most prominent mutation induced by DSS treatment was G:C to C:G transversion, whose specific MF in proximal colon was 30 times higher in Polk-/- than in Polk+/+ mice. DSS alone did not enhance MF at all in Polk+/+ mice. The results indicate that Polκ does not suppress BP-induced mutagenesis and carcinogenesis in the colon, but counteracts inflammation-induced mutagenesis in multiple organs. Environ. Mol. Mutagen. 60:320-330, 2019. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Atsushi Hakura
- Tsukuba Drug Safety, Eisai Co., Ltd., Tsukuba-shi, Ibaraki, Japan
| | - Hajime Sui
- Food and Drug Safety Center, Hatano Research Institute, Hadano, Kanagawa, Japan
| | - Jiro Sonoda
- GLP, Eisai Co., Ltd., Tsukuba-shi, Ibaraki, Japan
| | - Tomonari Matsuda
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga, Japan
| | - Takehiko Nohmi
- Biological Safety Research Center, National Institute of Health Sciences, Kawasaki-ku, Kawasaki-shi, Kanagawa, Japan
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25
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Wang P, Leng J, Wang Y. DNA replication studies of N-nitroso compound-induced O6-alkyl-2'-deoxyguanosine lesions in Escherichia coli. J Biol Chem 2019; 294:3899-3908. [PMID: 30655287 PMCID: PMC6422096 DOI: 10.1074/jbc.ra118.007358] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 01/16/2019] [Indexed: 12/30/2022] Open
Abstract
N-Nitroso compounds (NOCs) are common DNA-alkylating agents, are abundantly present in food and tobacco, and can also be generated endogenously. Metabolic activation of some NOCs can give rise to carboxymethylation and pyridyloxobutylation/pyridylhydroxybutylation of DNA, which are known to be carcinogenic and can lead to gastrointestinal and lung cancer, respectively. Herein, using the competitive replication and adduct bypass (CRAB) assay, along with MS- and NMR-based approaches, we assessed the cytotoxic and mutagenic properties of three O6-alkyl-2'-deoxyguanosine (O6-alkyl-dG) adducts, i.e. O6-pyridyloxobutyl-dG (O6-POB-dG) and O6-pyridylhydroxybutyl-dG (O6-PHB-dG), derived from tobacco-specific nitrosamines, and O6-carboxymethyl-dG (O6-CM-dG), induced by endogenous N-nitroso compounds. We also investigated two neutral analogs of O6-CM-dG, i.e. O6-aminocarbonylmethyl-dG (O6-ACM-dG) and O6-hydroxyethyl-dG (O6-HOEt-dG). We found that, in Escherichia coli cells, these lesions mildly (O6-POB-dG), moderately (O6-PHB-dG), or strongly (O6-CM-dG, O6-ACM-dG, and O6-HOEt-dG) impede DNA replication. The strong blockage effects of the last three lesions were attributable to the presence of hydrogen-bonding donor(s) located on the alkyl functionality of these lesions. Except for O6-POB-dG, which also induced a low frequency of G → T transversions, all other lesions exclusively stimulated G → A transitions. SOS-induced DNA polymerases played redundant roles in bypassing all the O6-alkyl-dG lesions investigated. DNA polymerase IV (Pol IV) and Pol V, however, were uniquely required for inducing the G → A transition for O6-CM-dG exposure. Together, our study expands our knowledge about the recognition of important NOC-derived O6-alkyl-dG lesions by the E. coli DNA replication machinery.
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Affiliation(s)
- Pengcheng Wang
- From the Department of Chemistry, University of California, Riverside, California 92521-0403 and
- the Institute of Surface Analysis and Chemical Biology, University of Jinan, Jinan, Shandong 250022, China
| | - Jiapeng Leng
- From the Department of Chemistry, University of California, Riverside, California 92521-0403 and
| | - Yinsheng Wang
- From the Department of Chemistry, University of California, Riverside, California 92521-0403 and
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Wilson KA, Holland CD, Wetmore SD. Uncovering a unique approach for damaged DNA replication: A computational investigation of a mutagenic tobacco-derived thymine lesion. Nucleic Acids Res 2019; 47:1871-1879. [PMID: 30605521 PMCID: PMC6393286 DOI: 10.1093/nar/gky1265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 12/03/2018] [Accepted: 12/06/2018] [Indexed: 01/01/2023] Open
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone is a potent nicotine carcinogen that leads to many DNA lesions, the most persistent being the O2-[4-oxo-4-(3-pyridyl)butyl]thymine adduct (POB-T). Although the experimental mutagenic profile for the minor groove POB-T lesion has been previously reported, the findings are puzzling in terms of the human polymerases involved. Specifically, while pol κ typically replicates minor groove adducts, in vivo studies indicate pol η replicates POB-T despite being known for processing major groove adducts. Our multiscale modeling approach reveals that the canonical (anti) glycosidic orientation of POB-T can fit in the pol κ active site, but only a unique (syn) POB-T conformation is accommodated by pol η. These distinct binding orientations rationalize the differential in vitro mutagenic spectra based on the preferential stabilization of dGTP and dTTP opposite the lesion for pol κ and η, respectively. Overall, by uncovering the first evidence for the replication of a damaged pyrimidine in the syn glycosidic orientation, the current work provides the insight necessary to clarify a discrepancy in the DNA replication literature, expand the biological role of the critical human pol η, and understand the mutational signature in human cancers associated with tobacco exposure.
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Affiliation(s)
- Katie A Wilson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Carl D Holland
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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2.0 Å resolution crystal structure of human polκ reveals a new catalytic function of N-clasp in DNA replication. Sci Rep 2018; 8:15125. [PMID: 30310122 PMCID: PMC6181923 DOI: 10.1038/s41598-018-33371-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/27/2018] [Indexed: 12/20/2022] Open
Abstract
Human polymerase kappa (polκ) is a distinct Y-family DNA polymerase with a unique N-terminal N-clasp domain. The N-clasp renders polκ’s high efficiency and accuracy in DNA replication and lesion bypass. How N-clasp empowers polκ in replication remains unclear due to the disordering of N-clasp. Here, we present a 2.0-Å resolution crystal structure of a polκ ternary complex with DNA and an incoming nucleotide. The structure-function study reveals an ordered N-clasp domain that brings conserved and functionally important residues in contact with the replicating basepair in the active site and contributes to the nucleotidyl transfer reaction. Particularly, a fully ordered Lys25 from the N-clasp domain is in H-bonding with the α- and γ-phosphates of the incoming nucleotide. K25A mutation reduces the polymerase activity of polκ significantly. This lysine is structurally analogous to a conserved lysine in the A-family DNA polymerases in the closed form. In contrast, Lys25 in the previous structures of polκ does not have any contacts with the incoming nucleotide, resembling an open form of a DNA polymerase. Based on structural and functional similarity, we propose a local open/closed mechanism for polκ in DNA replication catalysis, which mimics the common mechanism for all DNA polymerases.
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Antczak NM, Walker AR, Stern HR, Leddin EM, Palad C, Coulther TA, Swett RJ, Cisneros GA, Beuning PJ. Characterization of Nine Cancer-Associated Variants in Human DNA Polymerase κ. Chem Res Toxicol 2018; 31:697-711. [PMID: 30004685 DOI: 10.1021/acs.chemrestox.8b00055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Specialized DNA damage-bypass Y-family DNA polymerases contribute to cancer prevention by providing cellular tolerance to DNA damage that can lead to mutations and contribute to cancer progression by increasing genomic instability. Y-family polymerases can also bypass DNA adducts caused by chemotherapy agents. One of the four human Y-family DNA polymerases, DNA polymerase (pol) κ, has been shown to be specific for bypass of minor groove adducts and inhibited by major groove adducts. In addition, mutations in the gene encoding pol κ are associated with different types of cancers as well as with chemotherapy responses. We characterized nine variants of pol κ whose identity was inferred from cancer-associated single nucleotide polymorphisms for polymerization activity on undamaged and damaged DNA, their abilities to extend from mismatched or damaged base pairs at primer termini, and overall stability and dynamics. We find that these pol κ variants generally fall into three categories: similar activity to wild-type (WT) pol κ (L21F, I39T, P169T, F192C, and E292K), more active than WT pol κ (S423R), and less active than pol κ (R219I, R298H, and Y432S). Of these, only pol κ variants R298H and Y432S had markedly reduced thermal stability. Molecular dynamics (MD) simulations with undamaged DNA revealed that the active variant F192C and more active variant S423R with either correct or incorrect incoming nucleotide mimic WT pol κ with the correct incoming nucleotide, whereas the less active variants R219I, R298H, and Y432S with the correct incoming nucleotide mimic WT pol κ with the incorrect incoming nucleotide. Thus, the observations from MD simulations suggest a possible explanation for the observed experimental results that pol κ adopts specific active and inactive conformations that depend on both the protein variant and the identity of the DNA adduct.
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Affiliation(s)
- Nicole M Antczak
- Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Alice R Walker
- Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
| | - Hannah R Stern
- Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Emmett M Leddin
- Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
| | - Carl Palad
- Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Timothy A Coulther
- Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Rebecca J Swett
- Vertex Pharmaceuticals , Boston , Massachusetts 02210 , United States
| | - G Andrés Cisneros
- Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States
| | - Penny J Beuning
- Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
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29
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Jha V, Ling H. Structural Basis for Human DNA Polymerase Kappa to Bypass Cisplatin Intrastrand Cross-Link (Pt-GG) Lesion as an Efficient and Accurate Extender. J Mol Biol 2018; 430:1577-1589. [DOI: 10.1016/j.jmb.2018.04.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/16/2018] [Accepted: 04/23/2018] [Indexed: 10/17/2022]
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Masumura K, Toyoda-Hokaiwado N, Niimi N, Grúz P, Wada NA, Takeiri A, Jishage KI, Mishima M, Nohmi T. Limited ability of DNA polymerase kappa to suppress benzo[a]pyrene-induced genotoxicity in vivo. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2017; 58:644-653. [PMID: 29076178 DOI: 10.1002/em.22146] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/20/2017] [Accepted: 09/20/2017] [Indexed: 05/07/2023]
Abstract
DNA polymerase kappa (Polk) is a specialized DNA polymerase involved in translesion DNA synthesis. To understand the protective roles against genotoxins in vivo, we established inactivated Polk knock-in gpt delta (inactivated Polk KI) mice that possessed reporter genes for mutations and expressed inactive Polk. In this study, we examined genotoxicity of benzo[a]pyrene (BP) to determine whether Polk actually suppressed BP-induced genotoxicity as predicted by biochemistry and in vitro cell culture studies. Seven-week-old inactivated Polk KI and wild-type (WT) mice were treated with BP at doses of 5, 15, or 50 mg/(kg·day) for three consecutive days by intragastric gavage, and mutations in the colon and micronucleus formation in the peripheral blood were examined. Surprisingly, no differences were observed in the frequencies of mutations and micronucleus formation at 5 or 50 mg/kg doses. Inactivated Polk KI mice exhibited approximately two times higher gpt mutant frequency than did WT mice only at the 15 mg/kg dose. The frequency of micronucleus formation was slightly higher in inactivated Polk KI than in WT mice at the same dose, but it was statistically insignificant. The results suggest that Polk has a limited ability to suppress BP-induced genotoxicity in the colon and bone marrow and also that the roles of specialized DNA polymerases in mutagenesis and carcinogenesis should be examined not only by in vitro assays but also by in vivo mouse studies. We also report the spontaneous mutagenesis in inactivated Polk KI mice at young and old ages. Environ. Mol. Mutagen. 58:644-653, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Kenichi Masumura
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501, Japan
| | - Naomi Toyoda-Hokaiwado
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501, Japan
| | - Naoko Niimi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501, Japan
| | - Petr Grúz
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501, Japan
| | - Naoko A Wada
- Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba, Shizuoka, 412-8513, Japan
| | - Akira Takeiri
- Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba, Shizuoka, 412-8513, Japan
| | - Kou-Ichi Jishage
- Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba, Shizuoka, 412-8513, Japan
| | - Masayuki Mishima
- Research Division, Chugai Pharmaceutical Co., Ltd., 1-135 Komakado, Gotemba, Shizuoka, 412-8513, Japan
| | - Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo, 158-8501, Japan
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31
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Antczak NM, Packer MR, Lu X, Zhang K, Beuning PJ. Human Y-Family DNA Polymerase κ Is More Tolerant to Changes in Its Active Site Loop than Its Ortholog Escherichia coli DinB. Chem Res Toxicol 2017; 30:2002-2012. [PMID: 28823149 DOI: 10.1021/acs.chemrestox.7b00175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA damage is a constant threat and can be bypassed in a process called translesion synthesis, which is typically carried out by Y-family DNA polymerases. Y-family DNA polymerases are conserved in all domains of life and tend to have specificity for certain types of DNA damage. Escherichia coli DinB and its human ortholog pol κ can bypass specific minor groove deoxyguanine adducts efficiently and are inhibited by major groove adducts, as Y-family DNA polymerases make contacts with the minor groove side of the DNA substrate and lack contacts with the major groove at the nascent base pair. DinB is inhibited by major groove adducts more than pol κ, and they each have active site loops of different lengths, with four additional amino acids in the DinB loop. We previously showed that the R35A active site loop mutation in DinB allows for bypass of the major groove adduct N6-furfuryl-dA. These observations led us to investigate the different active site loops by creating loop swap chimeras of DinB with a pol κ loop and vice versa by changing the loop residues in a stepwise fashion. We then determined their activity with undamaged DNA or DNA containing N2-furfuryl-dG or N6-furfuryl-dA. The DinB proteins with the pol kappa loop have low activity on all templates but have decreased misincorporation compared to either wild-type protein. The kappa proteins with the DinB loop retain activity on all templates and have decreased misincorporation compared to either wild-type protein. We assessed the thermal stability of the proteins and observed an increase in stability in the presence of all DNA templates and additional increases generally only in the presence of the undamaged and N2-furfuryl-dG adduct and dCTP, which correlates with activity. Overall we find that pol κ is more tolerant to changes in the active site loop than DinB.
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Affiliation(s)
- Nicole M Antczak
- Department of Chemistry & Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Morgan R Packer
- Department of Chemistry & Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Xueguang Lu
- Department of Chemistry & Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Ke Zhang
- Department of Chemistry & Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Penny J Beuning
- Department of Chemistry & Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
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32
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Yockey OP, Jha V, Ghodke PP, Xu T, Xu W, Ling H, Pradeepkumar PI, Zhao L. Mechanism of Error-Free DNA Replication Past Lucidin-Derived DNA Damage by Human DNA Polymerase κ. Chem Res Toxicol 2017; 30:2023-2032. [PMID: 28972744 DOI: 10.1021/acs.chemrestox.7b00227] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone derivative present in madder root, which has been used as a coloring agent and food additive. LuP can be metabolically converted to genotoxic compound lucidin, which subsequently forms lucidin-specific N2-2'-deoxyguanosine (N2-dG) and N6-2'-deoxyadenosine (N6-dA) DNA adducts. Lucidin is mutagenic and carcinogenic in rodents but has low carcinogenic risks in humans. To understand the molecular mechanism of low carcinogenicity of lucidin in humans, we performed DNA replication assays using site-specifically modified oligodeoxynucleotides containing a structural analogue (LdG) of lucidin-N2-dG DNA adduct and determined the crystal structures of DNA polymerase (pol) κ in complex with LdG-bearing DNA and an incoming nucleotide. We examined four human pols (pol η, pol ι, pol κ, and Rev1) in their efficiency and accuracy during DNA replication with LdG; these pols are key players in translesion DNA synthesis. Our results demonstrate that pol κ efficiently and accurately replicates past the LdG adduct, whereas DNA replication by pol η, pol ι is compromised to different extents. Rev1 retains its ability to incorporate dCTP opposite the lesion albeit with decreased efficiency. Two ternary crystal structures of pol κ illustrate that the LdG adduct is accommodated by pol κ at the enzyme active site during insertion and postlesion-extension steps. The unique open active site of pol κ allows the adducted DNA to adopt a standard B-form for accurate DNA replication. Collectively, these biochemical and structural data provide mechanistic insights into the low carcinogenic risk of lucidin in humans.
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Affiliation(s)
| | - Vikash Jha
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario , London, Ontario N6A 5C1, Canada
| | - Pratibha P Ghodke
- Department of Chemistry, Indian Institute of Technology Bombay , Mumbai 400076, India
| | | | | | - Hong Ling
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario , London, Ontario N6A 5C1, Canada
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay , Mumbai 400076, India
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Trakselis MA, Cranford MT, Chu AM. Coordination and Substitution of DNA Polymerases in Response to Genomic Obstacles. Chem Res Toxicol 2017; 30:1956-1971. [PMID: 28881136 DOI: 10.1021/acs.chemrestox.7b00190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability for DNA polymerases (Pols) to overcome a variety of obstacles in its path to maintain genomic stability during replication is a complex endeavor. It requires the coordination of multiple Pols with differing specificities through molecular control and access to the replisome. Although a number of contacts directly between Pols and accessory proteins have been identified, forming the basis of a variety of holoenzyme complexes, the dynamics of Pol active site substitutions remain uncharacterized. Substitutions can occur externally by recruiting new Pols to replisome complexes through an "exchange" of enzyme binding or internally through a "switch" in the engagement of DNA from preformed associated enzymes contained within supraholoenzyme complexes. Models for how high fidelity (HiFi) replication Pols can be substituted by translesion synthesis (TLS) Pols at sites of damage during active replication will be discussed. These substitution mechanisms may be as diverse as the number of Pol families and types of damage; however, common themes can be recognized across species. Overall, Pol substitutions will be controlled by explicit protein contacts, complex multiequilibrium processes, and specific kinetic activities. Insight into how these dynamic processes take place and are regulated will be of utmost importance for our greater understanding of the specifics of TLS as well as providing for future novel chemotherapeutic and antimicrobial strategies.
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Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Matthew T Cranford
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Aurea M Chu
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
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Molecular Mechanisms of Acetaldehyde-Mediated Carcinogenesis in Squamous Epithelium. Int J Mol Sci 2017; 18:ijms18091943. [PMID: 28891965 PMCID: PMC5618592 DOI: 10.3390/ijms18091943] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/29/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022] Open
Abstract
Acetaldehyde is a highly reactive compound that causes various forms of damage to DNA, including DNA adducts, single- and/or double-strand breaks (DSBs), point mutations, sister chromatid exchanges (SCEs), and DNA-DNA cross-links. Among these, DNA adducts such as N²-ethylidene-2'-deoxyguanosine, N²-ethyl-2'-deoxyguanosine, N²-propano-2'-deoxyguanosine, and N²-etheno-2'-deoxyguanosine are central to acetaldehyde-mediated DNA damage because they are associated with the induction of DNA mutations, DNA-DNA cross-links, DSBs, and SCEs. Acetaldehyde is produced endogenously by alcohol metabolism and is catalyzed by aldehyde dehydrogenase 2 (ALDH2). Alcohol consumption increases blood and salivary acetaldehyde levels, especially in individuals with ALDH2 polymorphisms, which are highly associated with the risk of squamous cell carcinomas in the upper aerodigestive tract. Based on extensive epidemiological evidence, the International Agency for Research on Cancer defined acetaldehyde associated with the consumption of alcoholic beverages as a "group 1 carcinogen" (definite carcinogen) for the esophagus and/or head and neck. In this article, we review recent advances from studies of acetaldehyde-mediated carcinogenesis in the squamous epithelium, focusing especially on acetaldehyde-mediated DNA adducts. We also give attention to research on acetaldehyde-mediated DNA repair pathways such as the Fanconi anemia pathway and refer to our studies on the prevention of acetaldehyde-mediated DNA damage.
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Gowda ASP, Lee M, Spratt TE. N 2
-Substituted 2′-Deoxyguanosine Triphosphate Derivatives as Selective Substrates for Human DNA Polymerase κ. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- A. S. Prakasha Gowda
- Department of Biochemistry and Molecular Biology; Pennsylvania State University; 500 University Dr. Hershey PA 17033 USA
| | - Marietta Lee
- Department of Biochemistry and Molecular Biology; New York Medical College; Valhalla NY 10595 USA
| | - Thomas E. Spratt
- Department of Biochemistry and Molecular Biology; Pennsylvania State University; 500 University Dr. Hershey PA 17033 USA
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Gowda ASP, Lee M, Spratt TE. N 2 -Substituted 2'-Deoxyguanosine Triphosphate Derivatives as Selective Substrates for Human DNA Polymerase κ. Angew Chem Int Ed Engl 2017; 56:2628-2631. [PMID: 28140505 DOI: 10.1002/anie.201611607] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/12/2017] [Indexed: 11/09/2022]
Abstract
N2 -Alkyl-2'-deoxyguanosine triphosphate (N2 -alkyl-dGTP) derivatives with methyl, butyl, benzyl, or 4-ethynylbenzyl substituents were prepared and tested as substrates for human DNA polymerases. N2 -Benzyl-dGTP was equal to dGTP as a substrate for DNA polymerase κ (pol κ), but was a poor substrate for pols β, δ, η, ι, or ν. In vivo reactivity was evaluated through incubation of N2 -4-ethynylbenzyl-dG with wild-type and pol κ deficient mouse embryonic fibroblasts. CuAAC reaction with 5(6)-FAM-azide demonstrated that only cells containing pol κ were able to incorporate N2 -4-ethynylbenzyl-dG into the nucleus. This is the first instance of a Y-family-polymerase-specific dNTP, and this method could be used to probe the activity of pol κ in vivo.
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Affiliation(s)
- A S Prakasha Gowda
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, 500 University Dr., Hershey, PA, 17033, USA
| | - Marietta Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY, 10595, USA
| | - Thomas E Spratt
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, 500 University Dr., Hershey, PA, 17033, USA
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Zhao L, Washington MT. Translesion Synthesis: Insights into the Selection and Switching of DNA Polymerases. Genes (Basel) 2017; 8:genes8010024. [PMID: 28075396 PMCID: PMC5295019 DOI: 10.3390/genes8010024] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 01/05/2023] Open
Abstract
DNA replication is constantly challenged by DNA lesions, noncanonical DNA structures and difficult-to-replicate DNA sequences. Two major strategies to rescue a stalled replication fork and to ensure continuous DNA synthesis are: (1) template switching and recombination-dependent DNA synthesis; and (2) translesion synthesis (TLS) using specialized DNA polymerases to perform nucleotide incorporation opposite DNA lesions. The former pathway is mainly error-free, and the latter is error-prone and a major source of mutagenesis. An accepted model of translesion synthesis involves DNA polymerase switching steps between a replicative DNA polymerase and one or more TLS DNA polymerases. The mechanisms that govern the selection and exchange of specialized DNA polymerases for a given DNA lesion are not well understood. In this review, recent studies concerning the mechanisms of selection and switching of DNA polymerases in eukaryotic systems are summarized.
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Affiliation(s)
- Linlin Zhao
- Department of Chemistry and Biochemistry, Central Michigan University, Mount Pleasant, MI 48859, USA.
- Science of Advanced Materials Program, Central Michigan University, Mount Pleasant, MI 48859, USA.
| | - M Todd Washington
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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Jha V, Ling H. Structural basis of accurate replication beyond a bulky major benzo[a]pyrene adduct by human DNA polymerase kappa. DNA Repair (Amst) 2016; 49:43-50. [PMID: 27894903 DOI: 10.1016/j.dnarep.2016.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/14/2016] [Accepted: 11/14/2016] [Indexed: 12/19/2022]
Abstract
Human Y-family DNA polymerase kappa (polκ) is specialized to bypass bulky lesions in DNA in an error-free way, thus protecting cells from carcinogenic bulky DNA adducts. Benzo[a]pyrene (BP) is one of the most ubiquitous polycyclic aromatic hydrocarbons and an environmental carcinogen. BP covalently modifies DNA and generates mutagenic, bulky adducts. The major BP adduct formed in cells is 10S (+)-trans-anti-BP-N2-dG adduct (BP-dG), which is associated with cancer. The molecular mechanism of how polκ replicates BP-dG accurately is not clear. Here we report the structure of polκ captured at the lesion-extension stage: the enzyme is extending the primer strand after the base pair containing the BP-dG adduct in the template strand at the -1 position. Polκ accommodates the BP adduct in the nascent DNA's minor groove and keeps the adducted DNA helix in a B-form. Two water molecules cover the edge of the minor groove of the replicating base pair (0 position), which is secured by the BP ring in the -1 position in a 5' orientation. The 5' oriented BP adduct keeps correct Watson-Crick base pairing in the active site and promotes high fidelity replication. Our structural and biochemical data reveal a unique molecular basis for accurate DNA replication right after the bulky lesion BP-dG.
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Affiliation(s)
- Vikash Jha
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Hong Ling
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada.
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40
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Xu W, Kool D, O'Flaherty DK, Keating AM, Sacre L, Egli M, Noronha A, Wilds CJ, Zhao L. O 6-2'-Deoxyguanosine-butylene-O 6-2'-deoxyguanosine DNA Interstrand Cross-Links Are Replication-Blocking and Mutagenic DNA Lesions. Chem Res Toxicol 2016; 29:1872-1882. [PMID: 27768841 DOI: 10.1021/acs.chemrestox.6b00278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
DNA interstrand cross-links (ICLs) are cytotoxic DNA lesions derived from reactions of DNA with a number of anti-cancer reagents as well as endogenous bifunctional electrophiles. Deciphering the DNA repair mechanisms of ICLs is important for understanding the toxicity of DNA cross-linking agents and for developing effective chemotherapies. Previous research has focused on ICLs cross-linked with the N7 and N2 atoms of guanine as well as those formed at the N6 atom of adenine; however, little is known about the mutagenicity of O6-dG-derived ICLs. Although less abundant, O6-alkylated guanine DNA lesions are chemically stable and highly mutagenic. Here, O6-2'-deoxyguanosine-butylene-O6-2'-deoxyguanosine (O6-dG-C4-O6-dG) is designed as a chemically stable ICL, which can be induced by the action of bifunctional alkylating agents. We investigate the DNA replication-blocking and mutagenic properties of O6-dG-C4-O6-dG ICLs during an important step in ICL repair, translesion DNA synthesis (TLS). The model replicative DNA polymerase (pol) Sulfolobus solfataricus P2 DNA polymerase B1 (Dpo1) is able to incorporate a correct nucleotide opposite the cross-linked template guanine of ICLs with low efficiency and fidelity but cannot extend beyond the ICLs. Translesion synthesis by human pol κ is completely inhibited by O6-dG-C4-O6-dG ICLs. Moderate bypass activities are observed for human pol η and S. solfataricus P2 DNA polymerase IV (Dpo4). Among the pols tested, pol η exhibits the highest bypass activity; however, 70% of the bypass products are mutagenic containing substitutions or deletions. The increase in the size of unhooked repair intermediates elevates the frequency of deletion mutation. Lastly, the importance of pol η in O6-dG-derived ICL bypass is demonstrated using whole cell extracts of Xeroderma pigmentosum variant patient cells and those complemented with pol η. Together, this study provides the first set of biochemical evidence for the mutagenicity of O6-dG-derived ICLs.
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Affiliation(s)
| | | | - Derek K O'Flaherty
- Department of Chemistry and Biochemistry, Concordia University , 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6, Canada
| | | | - Lauralicia Sacre
- Department of Chemistry and Biochemistry, Concordia University , 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6, Canada
| | - Martin Egli
- Department of Biochemistry, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
| | - Anne Noronha
- Department of Chemistry and Biochemistry, Concordia University , 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6, Canada
| | - Christopher J Wilds
- Department of Chemistry and Biochemistry, Concordia University , 7141 Sherbrooke Street West, Montréal, Québec H4B 1R6, Canada
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41
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Basu AK, Pande P, Bose A. Translesion Synthesis of 2'-Deoxyguanosine Lesions by Eukaryotic DNA Polymerases. Chem Res Toxicol 2016; 30:61-72. [PMID: 27760288 PMCID: PMC5241707 DOI: 10.1021/acs.chemrestox.6b00285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
With the discovery
of translesion synthesis DNA polymerases, great
strides have been made in the last two decades in understanding the
mode of replication of various DNA lesions in prokaryotes and eukaryotes.
A database search indicated that approximately 2000 articles on this
topic have been published in this period. This includes research involving
genetic and structural studies as well as in vitro experiments using purified DNA polymerases and accessory proteins.
It is a daunting task to comprehend this exciting and rapidly emerging
area of research. Even so, as the majority of DNA damage occurs at
2′-deoxyguanosine residues, this perspective attempts to summarize
a subset of this field, focusing on the most relevant eukaryotic DNA
polymerases responsible for their bypass.
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Affiliation(s)
- Ashis K Basu
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Paritosh Pande
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Arindam Bose
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States
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42
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Kim JK, Yeom M, Hong JK, Song I, Lee YS, Guengerich FP, Choi JY. Six Germline Genetic Variations Impair the Translesion Synthesis Activity of Human DNA Polymerase κ. Chem Res Toxicol 2016; 29:1741-1754. [PMID: 27603496 DOI: 10.1021/acs.chemrestox.6b00244] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
DNA polymerase (pol) κ efficiently catalyzes error-free translesion DNA synthesis (TLS) opposite bulky N2-guanyl lesions induced by carcinogens such as polycyclic aromatic hydrocarbons. We investigated the biochemical effects of nine human nonsynonymous germline POLK variations on the TLS properties of pol κ, utilizing recombinant pol κ (residues 1-526) enzymes and DNA templates containing an N2-CH2(9-anthracenyl)G (N2-AnthG), 8-oxo-7,8-dihydroguanine (8-oxoG), O6-methyl(Me)G, or an abasic site. In steady-state kinetic analyses, the R246X, R298H, T473A, and R512W variants displayed 7- to 18-fold decreases in kcat/Km for dCTP insertion opposite G and N2-AnthG, with 2- to 3-fold decreases in DNA binding affinity, compared to that of the wild-type, and further showed 5- to 190-fold decreases in kcat/Km for next-base extension from C paired with N2-AnthG. The A471V variant showed 2- to 4-fold decreases in kcat/Km for correct nucleotide insertion opposite and beyond G (or N2-AnthG) compared to that of the wild-type. These five hypoactive variants also showed similar patterns of attenuation of TLS activity opposite 8-oxoG, O6-MeG, and abasic lesions. By contrast, the T44M variant exhibited 7- to 11-fold decreases in kcat/Km for dCTP insertion opposite N2-AnthG and O6-MeG (as well as for dATP insertion opposite an abasic site) but not opposite both G and 8-oxoG, nor beyond N2-AnthG, compared to that of the wild-type. These results suggest that the R246X, R298H, T473A, R512W, and A471V variants cause a general catalytic impairment of pol κ opposite G and all four lesions, whereas the T44M variant induces opposite lesion-dependent catalytic impairment, i.e., only opposite O6-MeG, abasic, and bulky N2-G lesions but not opposite G and 8-oxoG, in pol κ, which might indicate that these hypoactive pol κ variants are genetic factors in modifying individual susceptibility to genotoxic carcinogens in certain subsets of populations.
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Affiliation(s)
- Jae-Kwon Kim
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine , Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Mina Yeom
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine , Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jin-Kyung Hong
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine , Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Insil Song
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine , Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Young-Sam Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology , Daegu 42988, Republic of Korea
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
| | - Jeong-Yun Choi
- Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine , Suwon, Gyeonggi-do 16419, Republic of Korea
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43
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Eddy S, Tillman M, Maddukuri L, Ketkar A, Zafar MK, Eoff RL. Human Translesion Polymerase κ Exhibits Enhanced Activity and Reduced Fidelity Two Nucleotides from G-Quadruplex DNA. Biochemistry 2016; 55:5218-29. [PMID: 27525498 DOI: 10.1021/acs.biochem.6b00374] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have investigated the in vitro properties of human Y-family polymerase κ (hpol κ) on G-quadruplex DNA (G4 DNA). Similar to hpol η, another Y-family member implicated in replication of G4 motifs, hpol κ bound G4 DNA with a 5.7-fold preference over control, non-G4 DNA. Results from pol extension assays are consistent with the notion that G-quadruplexes present a stronger barrier to DNA synthesis by hpol κ than they do to that by hpol η. However, kinetic analysis revealed that hpol κ activity increases considerably when the enzyme is 2-3 nucleotides from the G4 motif, a trend that was reported previously for hpol η, though the increase was less pronounced. The increase in hpol κ activity on G4 DNA was readily observed in the presence of either potassium or sodium but much less so when lithium was used in the buffer. The increased activity 2-3 nucleotides from the G4 motif was accompanied by a decrease in the fidelity of hpol κ when the counterion was either potassium or sodium but not in the presence of lithium. The activity of hpol κ decreased progressively as the primer was moved closer than 2 nucleotides from the G4 motif when either potassium or sodium was used to stabilize the G-quadruplex. Interestingly, the decrease in catalytic activity at the site of the quadruplex observed in potassium-containing buffer was accompanied by an increase in fidelity on G4 substrates versus control non-G4 substrates. This trend of increased fidelity in copying a tetrad-associated guanine was observed previously for hpol η, but not for the B-family member hpol ε, which exhibited a large decrease in both efficiency and fidelity in the attempt to copy the first guanine in the G4 motif. In summary, hpol κ activity was enhanced relative to those of other Y-family members when the enzyme is 2-3 nucleotides from the G4 motif, but hpol κ appears to be less competent than hpol η at copying tetrad-associated guanines.
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Affiliation(s)
- Sarah Eddy
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Magdalena Tillman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Leena Maddukuri
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Amit Ketkar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Maroof K Zafar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Robert L Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
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44
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Choi JY, Patra A, Yeom M, Lee YS, Zhang Q, Egli M, Guengerich FP. Kinetic and Structural Impact of Metal Ions and Genetic Variations on Human DNA Polymerase ι. J Biol Chem 2016; 291:21063-21073. [PMID: 27555320 DOI: 10.1074/jbc.m116.748285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Indexed: 12/13/2022] Open
Abstract
DNA polymerase (pol) ι is a Y-family polymerase involved in translesion synthesis, exhibiting higher catalytic activity with Mn2+ than Mg2+ The human germline R96G variant impairs both Mn2+-dependent and Mg2+-dependent activities of pol ι, whereas the Δ1-25 variant selectively enhances its Mg2+-dependent activity. We analyzed pre-steady-state kinetic and structural effects of these two metal ions and genetic variations on pol ι using pol ι core (residues 1-445) proteins. The presence of Mn2+ (0.15 mm) instead of Mg2+ (2 mm) caused a 770-fold increase in efficiency (kpol/Kd,dCTP) of pol ι for dCTP insertion opposite G, mainly due to a 450-fold decrease in Kd,dCTP The R96G and Δ1-25 variants displayed a 53-fold decrease and a 3-fold increase, respectively, in kpol/Kd,dCTP for dCTP insertion opposite G with Mg2+ when compared with wild type, substantially attenuated by substitution with Mn2+ Crystal structures of pol ι ternary complexes, including the primer terminus 3'-OH and a non-hydrolyzable dCTP analogue opposite G with the active-site Mg2+ or Mn2+, revealed that Mn2+ achieves more optimal octahedral coordination geometry than Mg2+, with lower values in average coordination distance geometry in the catalytic metal A-site. Crystal structures of R96G revealed the loss of three H-bonds of residues Gly-96 and Tyr-93 with an incoming dNTP, due to the lack of an arginine, as well as a destabilized Tyr-93 side chain secondary to the loss of a cation-π interaction between both side chains. These results provide a mechanistic basis for alteration in pol ι catalytic function with coordinating metals and genetic variation.
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Affiliation(s)
- Jeong-Yun Choi
- From the Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Gyeonggi-do 16419, Republic of Korea
| | - Amritaj Patra
- the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, and
| | - Mina Yeom
- From the Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Gyeonggi-do 16419, Republic of Korea
| | - Young-Sam Lee
- the Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Qianqian Zhang
- the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, and
| | - Martin Egli
- the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, and
| | - F Peter Guengerich
- the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, and
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45
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Bostian ACL, Eoff RL. Aberrant Kynurenine Signaling Modulates DNA Replication Stress Factors and Promotes Genomic Instability in Gliomas. Chem Res Toxicol 2016; 29:1369-80. [PMID: 27482758 DOI: 10.1021/acs.chemrestox.6b00255] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metabolism of the essential amino acid L-tryptophan (TRP) is implicated in a number of neurological conditions including depression, neurodegenerative diseases, and cancer. The TRP catabolite kynurenine (KYN) has recently emerged as an important neuroactive factor in brain tumor pathogenesis, with additional studies implicating KYN in other types of cancer. Often highlighted as a modulator of the immune response and a contributor to immune escape for malignant tumors, it is well-known that KYN has effects on the production of the coenzyme nicotinamide adenine dinucleotide (NAD(+)), which can have a direct impact on DNA repair, replication, cell division, redox signaling, and mitochondrial function. Additional effects of KYN signaling are imparted through its role as an endogenous agonist for the aryl hydrocarbon receptor (AhR), and it is largely through activation of the AhR that KYN appears to mediate malignant progression in gliomas. We have recently reported on the ability of KYN signaling to modulate expression of human DNA polymerase kappa (hpol κ), a translesion enzyme involved in bypass of bulky DNA lesions and activation of the replication stress response. Given the impact of KYN on NAD(+) production, AhR signaling, and translesion DNA synthesis, it follows that dysregulation of KYN signaling in cancer may promote malignancy through alterations in the level of endogenous DNA damage and replication stress. In this perspective, we discuss the connections between KYN signaling, DNA damage tolerance, and genomic instability, as they relate to cancer.
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Affiliation(s)
- April C L Bostian
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , 4301 W. Markham Street, Little Rock, Arkansas 72205-7199, United States
| | - Robert L Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , 4301 W. Markham Street, Little Rock, Arkansas 72205-7199, United States
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46
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Bose A, Surugihalli C, Pande P, Champeil E, Basu AK. Comparative Error-Free and Error-Prone Translesion Synthesis of N(2)-2'-Deoxyguanosine Adducts Formed by Mitomycin C and Its Metabolite, 2,7-Diaminomitosene, in Human Cells. Chem Res Toxicol 2016; 29:933-9. [PMID: 27082015 PMCID: PMC4871107 DOI: 10.1021/acs.chemrestox.6b00087] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Indexed: 11/28/2022]
Abstract
Mitomycin C (MC) is a cytotoxic and mutagenic antitumor agent that alkylates DNA upon reductive activation. 2,7-Diaminomitosene (2,7-DAM) is a major metabolite of MC in tumor cells, which also alkylates DNA. MC forms seven DNA adducts, including monoadducts and inter- and intrastrand cross-links, whereas 2,7-DAM forms two monoadducts. Herein, the biological effects of the dG-N(2) adducts formed by MC and 2,7-DAM have been compared by constructing single-stranded plasmids containing these adducts and replicating them in human embryonic kidney 293T cells. Translesion synthesis (TLS) efficiencies of dG-N(2)-MC and dG-N(2)-2,7-DAM were 38 ± 3 and 27 ± 3%, respectively, compared to that of a control plasmid. This indicates that both adducts block DNA synthesis and that dG-N(2)-2,7-DAM is a stronger replication block than dG-N(2)-MC. TLS of each adducted construct was reduced upon siRNA knockdown of pol η, pol κ, or pol ζ. For both adducts, the most significant reduction occurred with knockdown of pol κ, which suggests that pol κ plays a major role in TLS of these dG-N(2) adducts. Analysis of the progeny showed that both adducts were mutagenic, and the mutation frequencies (MF) of dG-N(2)-MC and dG-N(2)-2,7-DAM were 18 ± 3 and 10 ± 1%, respectively. For both adducts, the major type of mutation was G → T transversions. Knockdown of pol η and pol ζ reduced the MF of dG-N(2)-MC and dG-N(2)-2,7-DAM, whereas knockdown of pol κ increased the MF of these adducts. This suggests that pol κ predominantly carries out error-free TLS, whereas pol η and pol ζ are involved in error-prone TLS. The largest reduction in MF by 78 and 80%, respectively, for dG-N(2)-MC and dG-N(2)-2,7-DAM constructs occurred when pol η, pol ζ, and Rev1 were simultaneously knocked down. This result strongly suggests that, unlike pol κ, these three TLS polymerases cooperatively perform the error-prone TLS of these adducts.
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Affiliation(s)
- Arindam Bose
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Chaitra Surugihalli
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Paritosh Pande
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Elise Champeil
- Department
of Science, John Jay College of Criminal
Justice, New York, New York 10019, United
States
| | - Ashis K. Basu
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
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47
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Liu B, Xue Q, Tang Y, Cao J, Guengerich FP, Zhang H. Mechanisms of mutagenesis: DNA replication in the presence of DNA damage. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2016; 768:53-67. [PMID: 27234563 PMCID: PMC5237373 DOI: 10.1016/j.mrrev.2016.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 02/07/2016] [Accepted: 03/14/2016] [Indexed: 10/22/2022]
Abstract
Environmental mutagens cause DNA damage that disturbs replication and produces mutations, leading to cancer and other diseases. We discuss mechanisms of mutagenesis resulting from DNA damage, from the level of DNA replication by a single polymerase to the complex DNA replisome of some typical model organisms (including bacteriophage T7, T4, Sulfolobus solfataricus, Escherichia coli, yeast and human). For a single DNA polymerase, DNA damage can affect replication in three major ways: reducing replication fidelity, causing frameshift mutations, and blocking replication. For the DNA replisome, protein interactions and the functions of accessory proteins can yield rather different results even with a single DNA polymerase. The mechanism of mutation during replication performed by the DNA replisome is a long-standing question. Using new methods and techniques, the replisomes of certain organisms and human cell extracts can now be investigated with regard to the bypass of DNA damage. In this review, we consider the molecular mechanism of mutagenesis resulting from DNA damage in replication at the levels of single DNA polymerases and complex DNA replisomes, including translesion DNA synthesis.
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Affiliation(s)
- Binyan Liu
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, PR China
| | - Qizhen Xue
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, PR China
| | - Yong Tang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, PR China
| | - Jia Cao
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, PR China
| | - F Peter Guengerich
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Huidong Zhang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, PR China.
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48
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Jha V, Bian C, Xing G, Ling H. Structure and mechanism of error-free replication past the major benzo[a]pyrene adduct by human DNA polymerase κ. Nucleic Acids Res 2016; 44:4957-67. [PMID: 27034468 PMCID: PMC4889944 DOI: 10.1093/nar/gkw204] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 03/16/2016] [Indexed: 01/28/2023] Open
Abstract
Benzo[a]pyrene (BP) is a well-known and frequently encountered carcinogen which generates a bulky DNA adduct (+)-trans-10S-BP-N(2)-dG (BP-dG) in cells. DNA polymerase kappa (polκ) is the only known Y-family polymerase that bypasses BP-dG accurately and thus protects cells from genotoxic BP. Here, we report the structures of human polκ in complex with DNA containing either a normal guanine (G) base or a BP-dG adduct at the active site and a correct deoxycytidine. The structures and supporting biochemical data reveal a unique mechanism for accurate replication by translesion synthesis past the major bulky adduct. The active site of polκ opens at the minor groove side of the DNA substrate to accommodate the bulky BP-dG that is attached there. More importantly, polκ stabilizes the lesion DNA substrate in the same active conformation as for regular B-form DNA substrates and the bulky BPDE ring in a 5' end pointing conformation. The BP-dG adducted DNA substrate maintains a Watson-Crick (BP-dG:dC) base pair within the active site, governing correct nucleotide insertion opposite the bulky adduct. In addition, polκ's unique N-clasp domain supports the open conformation of the enzyme and the extended conformation of the single-stranded template to allow bypass of the bulky lesion. This work illustrates the first molecular mechanism for how a bulky major adduct is replicated accurately without strand misalignment and mis-insertion.
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Affiliation(s)
- Vikash Jha
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Chuanbing Bian
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Guangxin Xing
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Hong Ling
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
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49
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Gowda ASP, Spratt TE. DNA Polymerases η and ζ Combine to Bypass O(2)-[4-(3-Pyridyl)-4-oxobutyl]thymine, a DNA Adduct Formed from Tobacco Carcinogens. Chem Res Toxicol 2016; 29:303-16. [PMID: 26868090 PMCID: PMC5081176 DOI: 10.1021/acs.chemrestox.5b00468] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) are important human carcinogens in tobacco products. They are metabolized to produce a variety 4-(3-pyridyl)-4-oxobutyl (POB) DNA adducts including O(2)-[4-(3-pyridyl)-4-oxobut-1-yl]thymidine (O(2)-POB-dT), the most abundant POB adduct in NNK- and NNN-treated rodents. To evaluate the mutagenic properties of O(2)-POB-dT, we measured the rate of insertion of dNTPs opposite and extension past O(2)-POB-dT and O(2)-Me-dT by purified human DNA polymerases η, κ, ι, and yeast polymerase ζ in vitro. Under conditions of polymerase in excess, polymerase η was most effective at the insertion of dNTPs opposite O(2)-alkyl-dTs. The time courses were biphasic suggesting the formation of inactive DNA-polymerase complexes. The kpol parameter was reduced approximately 100-fold in the presence of the adduct for pol η, κ, and ι. Pol η was the most reactive polymerase for the adducts due to a higher burst amplitude. For all three polymerases, the nucleotide preference was dATP > dTTP ≫ dGTP and dCTP. Yeast pol ζ was most effective in bypassing the adducts; the kcat/Km values were reduced only 3-fold in the presence of the adducts. The identity of the nucleotide opposite the O(2)-alkyl-dT did not significantly affect the ability of pol ζ to bypass the adducts. The data support a model in which pol η inserts ATP or dTTP opposite O(2)-POB-dT, and then, pol ζ extends past the adduct.
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Affiliation(s)
- A. S. Prakasha Gowda
- Department of Biochemistry and Molecular Biology Penn State Hershey Cancer Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, United States
| | - Thomas E. Spratt
- Department of Biochemistry and Molecular Biology Penn State Hershey Cancer Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, United States
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Bostian ACL, Maddukuri L, Reed MR, Savenka T, Hartman JH, Davis L, Pouncey DL, Miller GP, Eoff RL. Kynurenine Signaling Increases DNA Polymerase Kappa Expression and Promotes Genomic Instability in Glioblastoma Cells. Chem Res Toxicol 2015; 29:101-8. [PMID: 26651356 DOI: 10.1021/acs.chemrestox.5b00452] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Overexpression of the translesion synthesis polymerase hpol κ in glioblastomas has been linked to poor patient prognosis; however, the mechanism promoting higher expression in these tumors remains unknown. We determined that activation of the aryl hydrocarbon receptor (AhR) pathway in glioblastoma cells leads to increased hpol κ mRNA and protein levels. We blocked nuclear translocation and DNA binding by AhR in glioblastoma cells using a small-molecule and observed decreased hpol κ expression. Pharmacological inhibition of tryptophan-2,3-dioxygenase (TDO), the enzyme largely responsible for activating AhR in glioblastoma, led to a decrease in the endogenous AhR agonist kynurenine and a corresponding decrease in hpol κ protein levels. Importantly, we discovered that inhibiting TDO activity, AhR signaling, or suppressing hpol κ expression with RNA interference led to decreased chromosomal damage in glioblastoma cells. Epistasis assays further supported the idea that TDO activity, activation of AhR signaling, and the resulting overexpression of hpol κ function primarily in the same pathway to increase endogenous DNA damage. These findings indicate that upregulation of hpol κ through glioblastoma-specific TDO activity and activation of AhR signaling likely contributes to the high levels of replication stress and genomic instability observed in these tumors.
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Affiliation(s)
- April C L Bostian
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Leena Maddukuri
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Megan R Reed
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Tatsiana Savenka
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Jessica H Hartman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Lauren Davis
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Dakota L Pouncey
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Grover P Miller
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Robert L Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
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