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Zhao T, He X, Liang X, Kellum AH, Tang F, Yin J, Guo S, Wang Y, Gao Z, Wang Y. HMGB3 and SUB1 Bind to and Facilitate the Repair of N2-Alkylguanine Lesions in DNA. J Am Chem Soc 2024. [PMID: 39101269 DOI: 10.1021/jacs.4c06680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
N2-Alkyl-2'-deoxyguanosine (N2-alkyl-dG) is a major type of minor-groove DNA lesions arising from endogenous metabolic processes and exogenous exposure to environmental contaminants. The N2-alkyl-dG lesions, if left unrepaired, can block DNA replication and transcription and induce mutations in these processes. Nevertheless, the repair pathways for N2-alkyl-dG lesions remain incompletely elucidated. By utilizing a photo-cross-linking coupled with mass spectrometry-based quantitative proteomic analysis, we identified a series of candidate N2-alkyl-dG-binding proteins. We found that two of these proteins, i.e., high-mobility group protein B3 (HMGB3) and SUB1, could bind directly to N2-nBu-dG-containing duplex DNA in vitro and promote the repair of this lesion in cultured human cells. In addition, HMGB3 and SUB1 protected cells against benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE). SUB1 exhibits preferential binding to both the cis and trans diastereomers of N2-BPDE-dG over unmodified dG. On the other hand, HMGB3 binds favorably to trans-N2-BPDE-dG; the protein, however, does not distinguish cis-N2-BPDE-dG from unmodified dG. Consistently, genetic ablation of HMGB3 conferred diminished repair of trans-N2-BPDE-dG, but not its cis counterpart, whereas loss of SUB1 conferred attenuated repair of both diastereomers. Together, we identified proteins involved in the cellular sensing and repair of minor-groove N2-alkyl-dG lesions and documented a unique role of HMGB3 in the stereospecific recognition and repair of N2-BPDE-dG.
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Affiliation(s)
- Ting Zhao
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Xiaomei He
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Xiaochen Liang
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Andrew H Kellum
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Feng Tang
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Jiekai Yin
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Su Guo
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Yinan Wang
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Zi Gao
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
| | - Yinsheng Wang
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521-0403, United States
- Department of Chemistry, University of California, Riverside, Riverside, California 92521-0403, United States
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Li J, Hu Z, Liu D, Wang P. Mass spectrometry-based assays for assessing replicative bypass and repair of DNA alkylation in cells. RSC Adv 2023; 13:15490-15497. [PMID: 37223415 PMCID: PMC10201546 DOI: 10.1039/d2ra08340j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 05/15/2023] [Indexed: 05/25/2023] Open
Abstract
Endogenous metabolism and environmental exposure can give rise to DNA alkylation, which can elicit deleterious biological consequences. In the search for reliable and quantitative analytical methods to elucidate the impact of DNA alkylation on the flow of genetic information, mass spectrometry (MS) has attracted increasing attention, owing to its unambiguous determination of molecular mass. The MS-based assays obviate conventional colony-picking methods and Sanger sequencing procedures, and retained the high sensitivity of postlabeling methods. With the help of the CRISPR/Cas9 gene editing method, MS-based assays showed high potential in studying individual functions of repair proteins and translesion synthesis (TLS) polymerases in DNA replication. In this mini-review, we have summarized the development of MS-based competitive and replicative adduct bypass (CRAB) assays and their recent applications in assessing the impact of alkylation on DNA replication. With further development of MS instruments for high resolving power and high throughput, these assays should be generally applicable and efficient in quantitative measurement of the biological consequences and repair of other DNA lesions.
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Affiliation(s)
- Jiaxian Li
- Institute of Surface Analysis and Chemical Biology, University of Jinan Jinan Shandong 250022 P. R. China
| | - Zhihai Hu
- Institute of Surface Analysis and Chemical Biology, University of Jinan Jinan Shandong 250022 P. R. China
| | - Dandan Liu
- Institute of Surface Analysis and Chemical Biology, University of Jinan Jinan Shandong 250022 P. R. China
| | - Pengcheng Wang
- Institute of Surface Analysis and Chemical Biology, University of Jinan Jinan Shandong 250022 P. R. China
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Kan Y, Jin Z, Ke Y, Lin D, Yan L, Wu L, He Y. Replicative bypass studies of l-deoxyribonucleosides in Vitro and in E. coli cell. Sci Rep 2022; 12:21183. [PMID: 36476762 PMCID: PMC9729220 DOI: 10.1038/s41598-022-24802-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
L-nucleosides were the most important antiviral lead compounds because they can inhibit viral DNA polymerase and DNA synthesis of many viruses, whereas they may lead to mutations in DNA replication and cause genomic instability. In this study, we reported the replicative bypass of L-deoxynucleosides in recombinant DNA by restriction enzyme-mediated assays to examine their impact on DNA replication in vitro and in E. coli cells. The results showed that a template L-dC inhibited Taq DNA polymerase reaction, whereas it can be bypassed by Vent (exo-) DNA polymerase as well as in cell replication, inserting correct nucleotides opposite L-dC. L-dG can be bypassed by Taq DNA polymerase and in E. coli cells, maintaining insertion of correct incoming nucleotides, and L-dG induced mutagenic replication by Vent (exo-) DNA polymerase. In contrast, L-dA can induced mutagenic replication in vitro and in E. coli cells. MD simulations were performed to investigate how DNA polymerase affected replicative bypass and mutations when D-nucleosides replaced with L-nucleosides. This study will provide a basis for the ability to assess the cytotoxic and mutagenic properties of the L-nucleoside drugs.
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Affiliation(s)
- Yuhe Kan
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China ,grid.411643.50000 0004 1761 0411School of Life Sciences, Inner Mongolia University, Hohhot, 010021 Inner Mongolia People’s Republic of China ,Qilu Pharmaceutical (Inner Mongolia) CO., LTD., Hohhot, 010080 Inner Mongolia People’s Republic of China
| | - Zhaoyang Jin
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Yongqi Ke
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Dao Lin
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Liang Yan
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Li Wu
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China ,grid.11135.370000 0001 2256 9319State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191 People’s Republic of China
| | - Yujian He
- grid.410726.60000 0004 1797 8419School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China ,grid.11135.370000 0001 2256 9319State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191 People’s Republic of China ,grid.410726.60000 0004 1797 8419School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
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Size- and Stereochemistry-Dependent Transcriptional Bypass of DNA Alkyl Phosphotriester Adducts in Mammalian Cells. DNA 2022; 2:221-230. [PMID: 36911626 PMCID: PMC9997456 DOI: 10.3390/dna2040016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Environmental, endogenous and therapeutic alkylating agents can react with internucleotide phosphate groups in DNA to yield alkyl phosphotriester (PTE) adducts. Alkyl-PTEs are induced at relatively high frequencies and are persistent in mammalian tissues; however, their biological consequences in mammalian cells have not been examined. Herein, we assessed how alkyl-PTEs with different alkyl group sizes and stereochemical configurations (S P and R P diastereomers of Me and nPr) affect the efficiency and fidelity of transcription in mammalian cells. We found that, while the R P diastereomer of Me- and nPr-PTEs constituted moderate and strong blockages to transcription, respectively, the S P diastereomer of the two lesions did not appreciably perturb transcription efficiency. In addition, none of the four alkyl-PTEs induced mutant transcripts. Furthermore, polymerase η assumed an important role in promoting transcription across the S P-Me-PTE, but not any of other three lesions. Loss of other translesion synthesis (TLS) polymerases tested, including Pol κ, Pol ι, Pol ξ and REV1, did not alter the transcription bypass efficiency or mutation frequency for any of the alkyl-PTE lesions. Together, our study provided important new knowledge about the impact of alkyl-PTE lesions on transcription and expanded the substrate pool of Pol η in transcriptional bypass.
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Guo S, Li L, Yu K, Tan Y, Wang Y. LC-MS/MS for Assessing the Incorporation and Repair of N2-Alkyl-2'-deoxyguanosine in Genomic DNA. Chem Res Toxicol 2022; 35:1814-1820. [PMID: 35584366 PMCID: PMC9588702 DOI: 10.1021/acs.chemrestox.2c00101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Understanding the occurrence, repair, and biological consequences of DNA damage is important in environmental toxicology and risk assessment. The most common way to assess DNA damage elicited by exogenous sources in a laboratory setting is to expose cells or experimental animals with chemicals that modify DNA. Owing to the lack of reaction specificities of DNA damaging agents, the approach frequently does not allow for induction of a specific DNA lesion. Herein, we employed metabolic labeling to selectively incorporate N2-methyl-dG (N2-MedG) and N2-n-butyl-dG (N2-nBudG) into genomic DNA of cultured mammalian cells, and investigated how the levels of the two lesions in cellular DNA are modulated by different DNA repair factors. Our results revealed that nucleotide excision repair (NER) exert moderate effects on the removal of N2-MedG and N2-nBudG from genomic DNA. We also observed that DNA polymerases κ and η contribute to the incorporation of N2-MedG into genomic DNA and modulate its repair in human cells. In addition, loss of ALKBH3 resulted in higher frequencies of N2-MedG and N2-nBuG incorporation into genomic DNA, suggesting a role of oxidative dealkylation in the reversal of these lesions. Together, our study provided new insights into the repair of minor-groove N2-alkyl-dG lesions in mammalian cells.
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Affiliation(s)
- Su Guo
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States
| | - Lin Li
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Kailin Yu
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Ying Tan
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States
| | - Yinsheng Wang
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
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6
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Tan Y, Guo S, Wu J, Du H, Li L, You C, Wang Y. DNA Polymerase η Promotes the Transcriptional Bypass of N2-Alkyl-2'-deoxyguanosine Adducts in Human Cells. J Am Chem Soc 2021; 143:16197-16205. [PMID: 34555898 DOI: 10.1021/jacs.1c07374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To cope with unrepaired DNA lesions, cells are equipped with DNA damage tolerance mechanisms, including translesion synthesis (TLS). While TLS polymerases are well documented in facilitating replication across damaged DNA templates, it remains unknown whether TLS polymerases participate in transcriptional bypass of DNA lesions in cells. Herein, we employed the competitive transcription and adduct bypass assay to examine the efficiencies and fidelities of transcription across N2-alkyl-2'-deoxyguanosine (N2-alkyl-dG, alkyl = methyl, ethyl, n-propyl, or n-butyl) lesions in HEK293T cells. We found that N2-alkyl-dG lesions strongly blocked transcription and elicited CC → AA tandem mutations in nascent transcripts, where adenosines were misincorporated opposite the lesions and their adjacent 5' nucleoside. Additionally, genetic ablation of Pol η, but not Pol κ, Pol ι, or Pol ζ, conferred marked diminutions in the transcriptional bypass efficiencies of the N2-alkyl-dG lesions, which is exacerbated by codepletion of Rev1 in Pol η-deficient background. We also observed that the repair of N2-nBu-dG was not pronouncedly affected by genetic depletion of Pol η or Rev1. Hence, our results provided insights into transcriptional perturbations induced by N2-alkyl-dG lesions and expanded the biological functions of TLS DNA polymerases.
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Affiliation(s)
- Ying Tan
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States
| | - Su Guo
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States
| | - 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
| | - Changjun You
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Yinsheng Wang
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, United States.,Department of Chemistry, University of California, Riverside, California 92521-0403, United States
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7
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Wang Y, Wu J, Wu J, Wang Y. DNA Polymerase II Supports the Replicative Bypass of N2-Alkyl-2'-deoxyguanosine Lesions in Escherichia coli Cells. Chem Res Toxicol 2021; 34:695-698. [PMID: 33417436 DOI: 10.1021/acs.chemrestox.0c00478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alkylation represents a main form of DNA damage. The N2 position of guanine is frequently alkylated in DNA. The SOS-induced polymerases have been shown to be capable of bypassing various DNA damage products in Escherichia coli. Herein, we explored the influences of four N2-alkyl-dG lesions (alkyl = ethyl, n-butyl, isobutyl, or sec-butyl) on DNA replication in AB1157 E. coli cells and the corresponding strains with polymerases (Pol) II, IV, and V being individually or simultaneously knocked out. We found that N2-Et-dG is slightly less blocking to DNA replication than the N2-Bu-dG lesions, which display very similar replication bypass efficiencies. Additionally, Pol II and, to a lesser degree, Pol IV and Pol V are required for the efficient bypass of the N2-alkyl-dG adducts, and none of these lesions was mutagenic. Together, our results support that the efficient replication across small N2-alkyl-dG DNA adducts in E. coli depends mainly on Pol II.
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8
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Ghodke PP, Pradeepkumar PI. Site‐Specific
N
2
‐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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Nookaew I, Jenjaroenpun P, Du H, Wang P, Wu J, Wongsurawat T, Moon SH, Huang E, Wang Y, Boysen G. Detection and Discrimination of DNA Adducts Differing in Size, Regiochemistry, and Functional Group by Nanopore Sequencing. Chem Res Toxicol 2020; 33:2944-2952. [PMID: 32799528 DOI: 10.1021/acs.chemrestox.0c00202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Chemically induced DNA adducts can lead to mutations and cancer. Unfortunately, because common analytical methods (e.g., liquid chromatography-mass spectrometry) require adducts to be digested or liberated from DNA before quantification, information about their positions within the DNA sequence is lost. Advances in nanopore sequencing technologies allow individual DNA molecules to be analyzed at single-nucleobase resolution, enabling us to study the dynamic of epigenetic modifications and exposure-induced DNA adducts in their native forms on the DNA strand. We applied and evaluated the commercially available Oxford Nanopore Technology (ONT) sequencing platform for site-specific detection of DNA adducts and for distinguishing individual alkylated DNA adducts. Using ONT and the publicly available ELIGOS software, we analyzed a library of 15 plasmids containing site-specifically inserted O6- or N2-alkyl-2'-deoxyguanosine lesions differing in sizes and regiochemistries. Positions of DNA adducts were correctly located, and individual DNA adducts were clearly distinguished from each other.
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Affiliation(s)
- Intawat Nookaew
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States.,Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
| | - Piroon Jenjaroenpun
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
| | - Hua Du
- Department of Chemistry, University of California, Riverside 501 Big Springs Road, Riverside, California 92521-0403, United States
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside 501 Big Springs Road, Riverside, California 92521-0403, United States
| | - Jun Wu
- Department of Chemistry, University of California, Riverside 501 Big Springs Road, Riverside, California 92521-0403, United States
| | - Thidathip Wongsurawat
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
| | - Sun Hee Moon
- Environmental and Occupational Health, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
| | - En Huang
- Environmental and Occupational Health, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside 501 Big Springs Road, Riverside, California 92521-0403, United States
| | - Gunnar Boysen
- Environmental and Occupational Health, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States.,Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, Arkansas 72205, United States
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10
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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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Cui Y, Yuan J, Wang P, Wu J, Yu Y, Wang Y. Collision-Induced Dissociation Studies of Protonated Ions of Alkylated Thymidine and 2'-Deoxyguanosine. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:927-937. [PMID: 32134268 PMCID: PMC7362892 DOI: 10.1021/jasms.9b00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mass spectrometry and tandem MS (MS/MS) have been widely employed for the identification and quantification of damaged nucleosides in DNA, including those induced by alkylating agents. Upon collisional activation, protonated ions of alkylated nucleosides frequently undergo facile neutral loss of a 2-deoxyribose in MS/MS, and further cleavage of the resulting protonated nucleobases in MS3 can sometimes be employed for differentiating regioisomeric alkylated DNA lesions. Herein, we investigated systematically the collision-induced dissociation (CID) of the protonated ions of O4-alkylthymidine (O4-alkyldT), O2-alkyldT, O6-alkyl-2'-deoxyguanosine (O6-alkyldG), and N2-alkyldG through MS3 analysis. The MS3 of O2- and O4-MedT exhibit different fragmentation patterns from each other and from other O2- and O4-alkyldT adducts carrying larger alkyl groups. Meanwhile, elimination of alkene via a six-membered ring transition state is the dominant fragmentation pathway for O2-alkyldT, O4-alkyldT, and O6-alkyldG adducts carrying larger alkyl groups, whereas O6-MedG mainly undergoes elimination of ammonia. The breakdown of N2-alkyldG is substantially influenced by the structure of the alkyl group, where the relative ease in eliminating ammonia and alkene is modulated by the chain length and branching of the alkyl groups. We also rationalize our observations with density functional theory (DFT) calculations.
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12
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McIntyre J. Polymerase iota - an odd sibling among Y family polymerases. DNA Repair (Amst) 2019; 86:102753. [PMID: 31805501 DOI: 10.1016/j.dnarep.2019.102753] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 12/14/2022]
Abstract
It has been two decades since the discovery of the most mutagenic human DNA polymerase, polymerase iota (Polι). Since then, the biochemical activity of this translesion synthesis (TLS) enzyme has been extensively explored, mostly through in vitro experiments, with some insight into its cellular activity. Polι is one of four members of the Y-family of polymerases, which are the best characterized DNA damage-tolerant polymerases involved in TLS. Polι shares some common Y-family features, including low catalytic efficiency and processivity, high infidelity, the ability to bypass some DNA lesions, and a deficiency in 3'→5' exonucleolytic proofreading. However, Polι exhibits numerous properties unique among the Y-family enzymes. Polι has an unusual catalytic pocket structure and prefers Hoogsteen over Watson-Crick pairing, and its replication fidelity strongly depends on the template; further, it prefers Mn2+ ions rather than Mg2+ as catalytic activators. In addition to its polymerase activity, Polι possesses also 5'-deoxyribose phosphate (dRP) lyase activity, and its ability to participate in base excision repair has been shown. As a highly error-prone polymerase, its regulation is crucial and mostly involves posttranslational modifications and protein-protein interactions. The upregulation and downregulation of Polι are correlated with different types of cancer and suggestions regarding the possible function of this polymerase have emerged from studies of various cancer lines. Nonetheless, after twenty years of research, the biological function of Polι certainly remains unresolved.
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Affiliation(s)
- Justyna McIntyre
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawinskiego 5a, 02-106, Warsaw, Poland.
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