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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 DOI: 10.1021/acs.jcim.4c00339] [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: 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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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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3
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Hakura A, Sui H, Seki Y, Sonoda J, Yoshida Y, Takagi H, Yokose S, Matsuda T, Asakura S, Nohmi T. DNA polymerase κ suppresses inflammation and inflammation-induced mutagenesis and carcinogenic potential in the colon of mice. Genes Environ 2023; 45:15. [PMID: 37087526 PMCID: PMC10122296 DOI: 10.1186/s41021-023-00272-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 04/05/2023] [Indexed: 04/24/2023] Open
Abstract
BACKGROUND Chronic inflammation induces DNA damage and promotes cell proliferation, thereby increasing the risk of cancer. DNA polymerase κ (Pol κ), involved in translesion DNA synthesis, counteracts mutagenesis induced by inflammation in the colon of mice. In the present study, we examined whether Pol κ suppressed inflammation-induced colon tumorigenesis by treating inactivated Polk knock-in (Polk-/-) mice with dextran sulfate sodium (DSS), an inducer of colon inflammation. RESULTS Male and female Polk-/- and Polk+/+ mice were administered 2% DSS in drinking water for six consecutive days, succeeded via a recovery period of 16 days, followed by 2% DSS for another two days. DSS treatment strongly induced colitis, and the severity of colitis was higher in Polk-/- mice than in Polk+/+ mice. The mice were sacrificed after 19 weeks from the initiation of the first DSS treatment and subjected to pathological examination and mutation analysis. DSS treatment induced colonic dysplasia, and the multiplicity of dysplasia was higher in Polk-/- mice than in Polk+/+mice. Some of the dysplasias in Polk-/- mice exhibited β-catenin-stained nucleus and/or cytoplasm. Mutation frequencies in the gpt reporter gene were increased by DSS treatment in Polk-/- mice, and were higher than those in Polk+/+ mice. CONCLUSIONS Pol κ suppresses inflammation and inflammation-induced dysplasia as well as inflammation-induced mutagenesis. The possible mechanisms by which Pol κ suppresses colitis- and colitis-induced dysplasia are discussed.
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Affiliation(s)
- Atsushi Hakura
- Global Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-Shi, Ibaraki, 300-2635, Japan.
| | - Hajime Sui
- Division of Safety Testing, Food and Drug Safety Center, Hatano Research Institute, Hadano, Kanagawa, 257-0025, Japan
| | - Yuki Seki
- Global Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-Shi, Ibaraki, 300-2635, Japan
| | - Jiro Sonoda
- Global Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-Shi, Ibaraki, 300-2635, Japan
- Present Address: Operations Department, Global Safety HQS, Eisai Co., Ltd., 4-6-10 Koishikawa, Bunkyo-Ku, Tokyo, 112-8088, Japan
| | - Yusaku Yoshida
- Biotechnical Center, Japan SLC, Inc., 3-5-1 Aoihigashi, Naka-Ku, Hamamatsu-Shi, Shizuoka, 433-8114, Japan
| | - Hisayoshi Takagi
- Biotechnical Center, Japan SLC, Inc., 3-5-1 Aoihigashi, Naka-Ku, Hamamatsu-Shi, Shizuoka, 433-8114, Japan
| | - Shigeo Yokose
- Biotechnical Center, Japan SLC, Inc., 3-5-1 Aoihigashi, Naka-Ku, Hamamatsu-Shi, Shizuoka, 433-8114, Japan
| | - Tomonari Matsuda
- Research Center for Environmental Quality Management, Kyoto University, Otsu, Shiga, 520-0811, Japan
| | - Shoji Asakura
- Global Drug Safety, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-Shi, Ibaraki, 300-2635, Japan
| | - Takehiko Nohmi
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-Ku, Kawasaki-Shi, Kanagawa, 210-9501, Japan.
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Yeom M, Hong JK, Shin JH, Lee Y, Guengerich FP, Choi JY. Identification of Three Human POLH Germline Variants Defective in Complementing the UV- and Cisplatin-Sensitivity of POLH-Deficient Cells. Int J Mol Sci 2023; 24:5198. [PMID: 36982269 PMCID: PMC10048814 DOI: 10.3390/ijms24065198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/04/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023] Open
Abstract
DNA polymerase (pol) η is responsible for error-free translesion DNA synthesis (TLS) opposite ultraviolet light (UV)-induced cis-syn cyclobutane thymine dimers (CTDs) and cisplatin-induced intrastrand guanine crosslinks. POLH deficiency causes one form of the skin cancer-prone disease xeroderma pigmentosum variant (XPV) and cisplatin sensitivity, but the functional impacts of its germline variants remain unclear. We evaluated the functional properties of eight human POLH germline in silico-predicted deleterious missense variants, using biochemical and cell-based assays. In enzymatic assays, utilizing recombinant pol η (residues 1-432) proteins, the C34W, I147N, and R167Q variants showed 4- to 14-fold and 3- to 5-fold decreases in specificity constants (kcat/Km) for dATP insertion opposite the 3'-T and 5'-T of a CTD, respectively, compared to the wild-type, while the other variants displayed 2- to 4-fold increases. A CRISPR/Cas9-mediated POLH knockout increased the sensitivity of human embryonic kidney 293 cells to UV and cisplatin, which was fully reversed by ectopic expression of wild-type pol η, but not by that of an inactive (D115A/E116A) or either of two XPV-pathogenic (R93P and G263V) mutants. Ectopic expression of the C34W, I147N, and R167Q variants, unlike the other variants, did not rescue the UV- and cisplatin-sensitivity in POLH-knockout cells. Our results indicate that the C34W, I147N, and R167Q variants-substantially reduced in TLS activity-failed to rescue the UV- and cisplatin-sensitive phenotype of POLH-deficient cells, which also raises the possibility that such hypoactive germline POLH variants may increase the individual susceptibility to UV irradiation and cisplatin chemotherapy.
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Affiliation(s)
- Mina Yeom
- Department of Pharmacology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Jin-Kyung Hong
- Department of Pharmacology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Joo-Ho Shin
- Department of Pharmacology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Yunjong Lee
- Department of Pharmacology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | | | - Jeong-Yun Choi
- Department of Pharmacology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
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Yeom M, Hong JK, Kim JK, Guengerich FP, Choi JY. Three Human Pol ι Variants with Impaired Polymerase Activity Fail to Rescue H 2O 2 Sensitivity in POLI-Deficient Cells. Chem Res Toxicol 2020; 33:2120-2129. [PMID: 32635723 DOI: 10.1021/acs.chemrestox.0c00127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human Y-family DNA polymerase (pol) ι is involved in translesion DNA synthesis (TLS) and base excision repair (BER) of oxidative DNA damage. Genetic variations may alter the function of pol ι and affect cellular susceptibility to oxidative genotoxic agents, but their effects remain unclear. We investigated the impacts of 10 human missense germline variations on pol ι function by biochemical and cell-based assays. Both polymerase and deoxyribose phosphate (dRP) lyase activities were determined utilizing recombinant pol ι (residues 1-445) proteins. The K209Q, K228I, and Q386R variants showed 4- to 53-fold decreases in specificity constants (kcat/Km) for dCTP insertion opposite G and 8-oxo-7,8-dihydroguanine compared to the wild-type. The R126C and K345E variants showed wild-type-like polymerase activity, although these two variants (as well as the R209Q, K228I, and Q386R variants) showed greater than 6-fold decreases in dRP lyase activity compared to the wild-type. A CRISPR/Cas9-mediated POLI knockout conferred higher sensitivity to H2O2 in human embryonic kidney (HEK293) cells. Exogenous expression of the full-length wild-type, R126C, and K345E variants fully rescued the H2O2 sensitivity in POLI-deficient cells, while full-length R209Q, K228I, and Q386R variants did not rescue the sensitivity. Our results indicate that the R126C and K345E variants (having wild-type-like polymerase activity, albeit impaired in dRP lyase activity) could fully rescue the H2O2 sensitivity in POLI-deficient cells, while the R209Q, K228I, and Q386R variants, all impaired in polymerase and dRP lyase activity, failed to rescue the sensitivity, indicating the relative importance of TLS-related polymerase function of pol ι rather than its BER-related dRP lyase function in protection from oxidative stress. The possibility exists that the hypoactive pol ι variants increase the individual susceptibility to oxidative genotoxic agents.
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Affiliation(s)
- Mina Yeom
- Department of Pharmacology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jin-Kyung Hong
- Department of Pharmacology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jae-Kwon Kim
- Department of Pharmacology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Jeong-Yun Choi
- Department of Pharmacology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi-do 16419, Republic of Korea
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Nohmi T, Matsumoto K. Effects of DNA polymerase kappa and mismatch repair on dose-responses of chromosome aberrations induced by three oxidative genotoxins in human cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:193-199. [PMID: 31294882 DOI: 10.1002/em.22315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/25/2019] [Accepted: 06/27/2019] [Indexed: 06/09/2023]
Abstract
Genotoxic carcinogens are regulated under the policy that there is no threshold or safe dose. It has been pointed out, however, that self-defense mechanisms, such as detoxification, DNA repair, and error-free translesion synthesis, may protect chromosome DNA from genotoxic insults, thereby constituting practical threshold. In this study, we examined dose responses of chromosome aberrations induced by three oxidative genotoxins, that is, hydrogen peroxide (H2 O2 ), menadione and paraquat, with or without DNA polymerase kappa (Polκ) activities and mismatch repair capacities in human cells. Polκ is involved in translesion synthesis across DNA damage and mismatch repair is responsible for correction of base-base mismatch in DNA. Polκ activity of the cells was inactivated either by point mutations in the catalytically essential amino acids (catalytically dead or CD) or by deletion of the POLK gene (knockout or KO). In the absence of mismatch repair, frequencies of chromosome aberrations induced by H2 O2 and menadione were not significantly different among CD, KO, and the wild type (WT) cells. In the presence of mismatch repair, however, cytotoxicity and clastogenicity were enhanced and Polκ modulated the sensitivity of the cells. No-observed-genotoxic-effect-levels (NOGELs) for H2 O2 and menadione were CD = KO < WT cells. In contrast, the sensitivities of the cells to paraquat were not significantly affected by the status of mismatch repair or Polκ activity. The results suggest that mismatch repair and Polκ coordinately modulate NOGELs for the clastogenicity of H2 O2 and menadione and also that DNA lesion(s) responsible for paraquat-induced chromosome aberrations are different from those induced by H2 O2 and menadione. Environ. Mol. Mutagen. 61:193-199, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Takehiko Nohmi
- Biological Safety Research Center, National Institute of Health Sciences, Kawasaki-shi, Kanagawa, Japan
| | - Kyomu Matsumoto
- Toxicology Division, The Institute of Environmental Toxicology, Joso-shi, Ibaraki, Japan
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7
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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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8
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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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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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