1
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Averill JR, Lin JC, Jung J, Jung H. Novel insights into the role of translesion synthesis polymerase in DNA incorporation and bypass of 5-fluorouracil in colorectal cancer. Nucleic Acids Res 2024; 52:4295-4312. [PMID: 38416579 PMCID: PMC11077093 DOI: 10.1093/nar/gkae102] [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: 09/10/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 03/01/2024] Open
Abstract
5-Fluorouracil (5-FU) is the first-line chemotherapeutic agent in colorectal cancer, and resistance to 5-FU easily emerges. One of the mechanisms of drug action and resistance of 5-FU is through DNA incorporation. Our quantitative reverse-transcription PCR data showed that one of the translesion synthesis (TLS) DNA polymerases, DNA polymerase η (polη), was upregulated within 72 h upon 5-FU administration at 1 and 10 μM, indicating that polη is one of the first responding polymerases, and the only TLS polymerase, upon the 5-FU treatment to incorporate 5-FU into DNA. Our kinetic studies revealed that 5-fluoro-2'-deoxyuridine triphosphate (5FdUTP) was incorporated across dA 41 and 28 times more efficiently than across dG and across inosine, respectively, by polη indicating that the mutagenicity of 5-FU incorporation is higher in the presence of inosine and that DNA lesions could lead to more mutagenic incorporation of 5-FU. Our polη crystal structures complexed with DNA and 5FdUTP revealed that dA:5FdUTP base pair is like dA:dTTP in the active site of polη, while 5FdUTP adopted 4-enol tautomer in the base pairs with dG and HX increasing the insertion efficiency compared to dG:dTTP for the incorrect insertions. These studies confirm that polη engages in the DNA incorporation and bypass of 5-FU.
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Affiliation(s)
- Jameson R Averill
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Jackson C Lin
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - John Jung
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Hunmin Jung
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
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2
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Tomar R, Li S, Egli M, Stone MP. Replication Bypass of the N-(2-Deoxy-d-erythro-pentofuranosyl)-urea DNA Lesion by Human DNA Polymerase η. Biochemistry 2024; 63:754-766. [PMID: 38413007 PMCID: PMC10956437 DOI: 10.1021/acs.biochem.3c00569] [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: 10/17/2023] [Revised: 12/26/2023] [Accepted: 12/27/2023] [Indexed: 02/29/2024]
Abstract
Urea lesions in DNA arise from thymine glycol (Tg) or 8-oxo-dG; their genotoxicity is thought to arise in part due to their potential to accommodate the insertion of all four dNTPs during error-prone replication. Replication bypass with human DNA polymerase η (hPol η) confirmed that all four dNTPs were inserted opposite urea lesions but with purines exhibiting greater incorporation efficiency. X-ray crystal structures of ternary replication bypass complexes in the presence of Mg2+ ions with incoming dNTP analogs dAMPnPP, dCMPnPP, dGMPnPP, and dTMPnPP bound opposite urea lesions (hPol η·DNA·dNMPnPP complexes) revealed all were accommodated by hPol η. In each, the Watson-Crick face of the dNMPnPP was paired with the urea lesion, exploiting the ability of the amine and carbonyl groups of the urea to act as H-bond donors or acceptors, respectively. With incoming dAMPnPP or dGMPnPP, the distance between the imino nitrogen of urea and the N9 atoms of incoming dNMPnPP approximated the canonical distance of 9 Å in B-DNA. With incoming dCMPnPP or dTMPnPP, the corresponding distance of about 7 Å was less ideal. Improved base-stacking interactions were also observed with incoming purines vs pyrimidines. Nevertheless, in each instance, the α-phosphate of incoming dNMPnPPs was close to the 3'-hydroxyl group of the primer terminus, consistent with the catalysis of nucleotidyl transfer and the observation that all four nucleotides could be inserted opposite urea lesions. Preferential insertion of purines by hPol η may explain, in part, why the urea-directed spectrum of mutations arising from Tg vs 8-oxo-dG lesions differs.
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Affiliation(s)
- Rachana Tomar
- Department
of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Songlin Li
- Department
of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Martin Egli
- Department
of Biochemistry, School of Medicine, Vanderbilt Ingram Cancer Center,
and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Michael P. Stone
- Department
of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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3
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Wang ZH, Li J, Liu Q, Qian JC, Li QQ, Wang QY, Zeng LT, Li SJ, Gao X, Pan JX, Gao XF, Wu K, Hu GX, Iwakuma T, Cai JP. A modified nucleoside O6-methyl-2'-deoxyguanosine-5'-triphosphate exhibits anti-glioblastoma activity in a caspase-independent manner. Pharmacol Res 2024; 199:106990. [PMID: 37984506 DOI: 10.1016/j.phrs.2023.106990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/07/2023] [Accepted: 11/13/2023] [Indexed: 11/22/2023]
Abstract
Resistance to temozolomide (TMZ), the frontline chemotherapeutic agent for glioblastoma (GBM), has emerged as a formidable obstacle, underscoring the imperative to identify alternative therapeutic strategies to improve patient outcomes. In this study, we comprehensively evaluated a novel agent, O6-methyl-2'-deoxyguanosine-5'-triphosphate (O6-methyl-dGTP) for its anti-GBM activity both in vitro and in vivo. Notably, O6-methyl-dGTP exhibited pronounced cytotoxicity against GBM cells, including those resistant to TMZ and overexpressing O6-methylguanine-DNA methyltransferase (MGMT). Mechanistic investigations revealed that O6-methyl-dGTP could be incorporated into genomic DNA, disrupting nucleotide pools balance, and inducing replication stress, resulting in S-phase arrest and DNA damage. The compound exerted its anti-tumor properties through the activation of AIF-mediated apoptosis and the parthanatos pathway. In vivo studies using U251 and Ln229 cell xenografts supported the robust tumor-inhibitory capacity of O6-methyl-dGTP. In an orthotopic transplantation model with U87MG cells, O6-methyl-dGTP showcased marginally superior tumor-suppressive activity compared to TMZ. In summary, our research, for the first time, underscores the potential of O6-methyl-dGTP as an effective candidate against GBM, laying a robust scientific groundwork for its potential clinical adoption in GBM treatment regimens.
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Affiliation(s)
- Zi-Hui Wang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China; Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jin Li
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Qian Liu
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China; Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jian-Chang Qian
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qing-Qing Li
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qing-Yu Wang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Lv-Tao Zeng
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Si-Jia Li
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Xin Gao
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Jia-Xin Pan
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China
| | - Xu-Fan Gao
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China; Department of Geriatrics, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Kun Wu
- Wu Xi AppTec (Tianjin) Co., Ltd, China
| | - Guo-Xin Hu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Tomoo Iwakuma
- Children's Mercy Research Institute, Kansas City, MO 64108, USA
| | - Jian-Ping Cai
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, China; Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
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4
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Balint E, Unk I. For the Better or for the Worse? The Effect of Manganese on the Activity of Eukaryotic DNA Polymerases. Int J Mol Sci 2023; 25:363. [PMID: 38203535 PMCID: PMC10779026 DOI: 10.3390/ijms25010363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/12/2024] Open
Abstract
DNA polymerases constitute a versatile group of enzymes that not only perform the essential task of genome duplication but also participate in various genome maintenance pathways, such as base and nucleotide excision repair, non-homologous end-joining, homologous recombination, and translesion synthesis. Polymerases catalyze DNA synthesis via the stepwise addition of deoxynucleoside monophosphates to the 3' primer end in a partially double-stranded DNA. They require divalent metal cations coordinated by active site residues of the polymerase. Mg2+ is considered the likely physiological activator because of its high cellular concentration and ability to activate DNA polymerases universally. Mn2+ can also activate the known DNA polymerases, but in most cases, it causes a significant decrease in fidelity and/or processivity. Hence, Mn2+ has been considered mutagenic and irrelevant during normal cellular function. Intriguingly, a growing body of evidence indicates that Mn2+ can positively influence some DNA polymerases by conferring translesion synthesis activity or altering the substrate specificity. Here, we review the relevant literature focusing on the impact of Mn2+ on the biochemical activity of a selected set of polymerases, namely, Polβ, Polλ, and Polµ, of the X family, as well as Polι and Polη of the Y family of polymerases, where congruous data implicate the physiological relevance of Mn2+ in the cellular function of these enzymes.
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Affiliation(s)
| | - Ildiko Unk
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, H-6726 Szeged, Hungary;
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5
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Richie-Jannetta R, Pallan P, Kingsley PJ, Kamdar N, Egli M, Marnett LJ. The peroxidation-derived DNA adduct, 6-oxo-M 1dG, is a strong block to replication by human DNA polymerase η. J Biol Chem 2023; 299:105067. [PMID: 37468099 PMCID: PMC10450521 DOI: 10.1016/j.jbc.2023.105067] [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: 03/22/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/21/2023] Open
Abstract
The DNA adduct 6-oxo-M1dG, (3-(2'-deoxy-β-D-erythro-pentofuranosyl)-6-oxo-pyrimido(1,2alpha)purin-10(3H)-one) is formed in the genome via oxidation of the peroxidation-derived adduct M1dG. However, the effect of 6-oxo-M1dG adducts on subsequent DNA replication is unclear. Here we investigated the ability of the human Y-family polymerase hPol η to bypass 6-oxo-M1dG. Using steady-state kinetics and analysis of DNA extension products by liquid chromatography-tandem mass spectrometry, we found hPol η preferentially inserts a dAMP or dGMP nucleotide into primer-templates across from the 6-oxo-M1dG adduct, with dGMP being slightly preferred. We also show primer-templates with a 3'-terminal dGMP or dAMP across from 6-oxo-M1dG were extended to a greater degree than primers with a dCMP or dTMP across from the adduct. In addition, we explored the structural basis for bypass of 6-oxo-M1dG by hPol η using X-ray crystallography of both an insertion-stage and an extension-stage complex. In the insertion-stage complex, we observed that the incoming dCTP opposite 6-oxo-M1dG, although present during crystallization, was not present in the active site. We found the adduct does not interact with residues in the hPol η active site but rather forms stacking interactions with the base pair immediately 3' to the adduct. In the extension-stage complex, we observed the 3' hydroxyl group of the primer strand dGMP across from 6-oxo-M1dG is not positioned correctly to form a phosphodiester bond with the incoming dCTP. Taken together, these results indicate 6-oxo-M1dG forms a strong block to DNA replication by hPol η and provide a structural basis for its blocking ability.
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Affiliation(s)
- Robyn Richie-Jannetta
- A. B. Hancock, Jr, Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Pradeep Pallan
- Department of Biochemistry, Center for Structural Biology and Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Philip J Kingsley
- A. B. Hancock, Jr, Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Nikhil Kamdar
- A. B. Hancock, Jr, Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Martin Egli
- Department of Biochemistry, Center for Structural Biology and Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Lawrence J Marnett
- A. B. Hancock, Jr, Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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6
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Kellum AH, Pallan PS, Nilforoushan A, Sturla SJ, Stone MP, Egli M. Conformation and Pairing Properties of an O6-Methyl-2'-deoxyguanosine-Directed Benzimidazole Nucleoside Analog in Duplex DNA. Chem Res Toxicol 2022; 35:1903-1913. [PMID: 35973057 PMCID: PMC9988402 DOI: 10.1021/acs.chemrestox.2c00165] [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: 01/06/2023]
Abstract
O6-Methyl-2'-deoxyguanosine (O6-MeG) is one of the most common DNA lesions and arises as a consequence of both xenobiotic carcinogens and endogenous methylation by S-adenosylmethionine. O6-MeG frequently causes G-to-A mutations during DNA replication due to the misincorporation of dTTP and continued DNA synthesis. Efforts to detect DNA adducts such as O6-MeG, and to understand their impacts on DNA structure and function, have motivated the creation of nucleoside analogs with altered base moieties to afford a more favorable interaction with the adduct as compared to the unmodified nucleotide. Such analogs directed at O6-MeG include benzimidazolinone and benzimidazole nucleotides, as well as their extended π surface analogs naphthimidazolinone and napthimidazole derivatives. These analogs form a more stable pair with O6-MeG than with G, most likely due to a combination of H-bonding and stacking. While extending the π surface of the analogs enhances their performance as adduct-directed probes, the precise origins of the increased affinity between the synthetic analogs and O6-MeG remain unclear. To better understand relevant conformational and pairing properties, we used X-ray crystallography and analyzed the structures of the DNA duplexes with naphthimidazolinone inserted opposite G or O6-MeG. The structures reveal a complex interaction of the analog found either in an anti orientation and stacked inside the duplex, either above or below G or O6-MeG, or in a syn orientation and paired opposite G with formation of a single H-bond. The experimental structural data are consistent with the stabilizing effect of the synthetic analog observed in UV melting experiments and calculations and moreover reveal that the origin of these observations appears to be superior stacking between O6-MeG and the extended π system of the synthetic probe.
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Affiliation(s)
- Andrew H Kellum
- Department of Chemistry, Vanderbilt University, College of Arts and Science, Nashville, Tennessee 37235, United States
| | - Pradeep S Pallan
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232, United States
| | - Arman Nilforoushan
- Department of Health Sciences and Technology, ETH Zürich, Zurich 8092, Switzerland
| | - Shana J Sturla
- Department of Health Sciences and Technology, ETH Zürich, Zurich 8092, Switzerland
| | - Michael P Stone
- Department of Chemistry, Vanderbilt University, College of Arts and Science, Nashville, Tennessee 37235, United States
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232, United States
| | - Martin Egli
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232, United States
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7
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Deaminated purine bypass by DNA polymerase η. Biochem J 2021; 478:1309-1313. [PMID: 33779688 PMCID: PMC8009656 DOI: 10.1042/bcj20200989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/01/2021] [Accepted: 03/05/2021] [Indexed: 11/26/2022]
Abstract
A recent work by Jung and colleagues (Biochem J.477, 4797–4810) provides an explanation of how DNA polymerase η replicates through deaminated purine bases such as xanthine and hypoxanthine. This commentary discusses the crystal structures of the polymerase η complexes that implicate the role of tautomerism in the bypass of these DNA lesions.
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8
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Ghodke PP, Mali JR, Patra A, Rizzo CJ, Guengerich FP, Egli M. Enzymatic bypass and the structural basis of miscoding opposite the DNA adduct 1,N 2-ethenodeoxyguanosine by human DNA translesion polymerase η. J Biol Chem 2021; 296:100642. [PMID: 33839151 PMCID: PMC8121704 DOI: 10.1016/j.jbc.2021.100642] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/01/2021] [Accepted: 04/05/2021] [Indexed: 11/26/2022] Open
Abstract
Etheno (ε)-adducts, e.g., 1,N2-ε−guanine (1,N2-ε-G) and 1,N6-ε−adenine (1,N6-ε-A), are formed through the reaction of DNA with metabolites of vinyl compounds or with lipid peroxidation products. These lesions are known to be mutagenic, but it is unknown how they lead to errors in DNA replication that are bypassed by DNA polymerases. Here we report the structural basis of misincorporation frequencies across from 1,N2-ε-G by human DNA polymerase (hpol) η. In single-nucleotide insertions opposite the adduct 1,N2-ε-G, hpol η preferentially inserted dGTP, followed by dATP, dTTP, and dCTP. This preference for purines was also seen in the first extension step. Analysis of full-length extension products by LC-MS/MS revealed that G accounted for 85% of nucleotides inserted opposite 1,N2-ε-G in single base insertion, and 63% of bases inserted in the first extension step. Extension from the correct nucleotide pair (C) was not observed, but the primer with A paired opposite 1,N2-ε-G was readily extended. Crystal structures of ternary hpol η insertion-stage complexes with nonhydrolyzable nucleotides dAMPnPP or dCMPnPP showed a syn orientation of the adduct, with the incoming A staggered between adducted base and the 5’-adjacent T, while the incoming C and adducted base were roughly coplanar. The formation of a bifurcated H-bond between incoming dAMPnPP and 1,N2-ε-G and T, compared with the single H-bond formed between incoming dCMPnPP and 1,N2-ε-G, may account for the observed facilitated insertion of dGTP and dATP. Thus, preferential insertion of purines by hpol η across from etheno adducts contributes to distinct outcomes in error-prone DNA replication.
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Affiliation(s)
- Pratibha P Ghodke
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Jyotirling R Mali
- Department of Chemistry, College of Arts and Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Amritraj Patra
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA
| | - Carmelo J Rizzo
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA; Department of Chemistry, College of Arts and Science, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, USA
| | - F Peter Guengerich
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, USA
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, USA.
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9
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Translesion synthesis of the major nitrogen mustard-induced DNA lesion by human DNA polymerase η. Biochem J 2021; 477:4543-4558. [PMID: 33175093 DOI: 10.1042/bcj20200767] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/05/2020] [Accepted: 11/11/2020] [Indexed: 12/16/2022]
Abstract
Nitrogen mustards are among the first modern anticancer chemotherapeutics that are still widely used as non-specific anticancer alkylating agents. While the mechanism of action of mustard drugs involves the generation of DNA interstrand cross-links, the predominant lesions produced by these drugs are nitrogen half-mustard-N7-dG (NHMG) adducts. The bulky major groove lesion NHMG, if left unrepaired, can be bypassed by translesion synthesis (TLS) DNA polymerases. However, studies of the TLS past NHMG have not been reported so far. Here, we present the first synthesis of an oligonucleotide containing a site-specific NHMG. We also report kinetic and structural characterization of human DNA polymerase η (polη) bypassing NHMG. The templating NHMG slows dCTP incorporation ∼130-fold, while it increases the misincorporation frequency ∼10-30-fold, highlighting the promutagenic nature of NHMG. A crystal structure of polη incorporating dCTP opposite NHMG shows a Watson-Crick NHMG:dCTP base pair with a large propeller twist angle. The nitrogen half-mustard moiety fits snugly into an open cleft created by the Arg61-Trp64 loop of polη, suggesting a role of the Arg61-Trp64 loop in accommodating bulky major groove adducts during lesion bypass. Overall, our results presented here to provide first insights into the TLS of the major DNA adduct formed by nitrogen mustard drugs.
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10
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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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11
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Zhang S, Li B, Du K, Liang T, Dai M, Huang W, Zhang H, Ling Y, Zhang H. Epigenetically modified N6-methyladenine inhibits DNA replication by human DNA polymerase iota. Biochimie 2020; 168:134-143. [DOI: 10.1016/j.biochi.2019.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 10/31/2019] [Indexed: 12/12/2022]
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12
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Epigenetic DNA modification N6-methyladenine inhibits DNA replication by Sulfolobus solfataricus Y-family DNA polymerase Dpo4. Arch Biochem Biophys 2019; 675:108120. [DOI: 10.1016/j.abb.2019.108120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 12/18/2022]
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13
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Abstract
7,8-Dihydro-8-oxoguanine (oxoG) is the most abundant oxidative DNA lesion with dual coding properties. It forms both Watson–Crick (anti)oxoG:(anti)C and Hoogsteen (syn)oxoG:(anti)A base pairs without a significant distortion of a B-DNA helix. DNA polymerases bypass oxoG but the accuracy of nucleotide incorporation opposite the lesion varies depending on the polymerase-specific interactions with the templating oxoG and incoming nucleotides. High-fidelity replicative DNA polymerases read oxoG as a cognate base for A while treating oxoG:C as a mismatch. The mutagenic effects of oxoG in the cell are alleviated by specific systems for DNA repair and nucleotide pool sanitization, preventing mutagenesis from both direct DNA oxidation and oxodGMP incorporation. DNA translesion synthesis could provide an additional protective mechanism against oxoG mutagenesis in cells. Several human DNA polymerases of the X- and Y-families efficiently and accurately incorporate nucleotides opposite oxoG. In this review, we address the mutagenic potential of oxoG in cells and discuss the structural basis for oxoG bypass by different DNA polymerases and the mechanisms of the recognition of oxoG by DNA glycosylases and dNTP hydrolases.
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14
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Du K, Zhang X, Zou Z, Li B, Gu S, Zhang S, Qu X, Ling Y, Zhang H. Epigenetically modified N 6-methyladenine inhibits DNA replication by human DNA polymerase η. DNA Repair (Amst) 2019; 78:81-90. [PMID: 30991231 DOI: 10.1016/j.dnarep.2019.03.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 01/06/2023]
Abstract
N6-methyladenine (6mA), as a newly reported epigenetic marker, plays significant roles in regulation of various biological processes in eukaryotes. However, the effect of 6mA on human DNA replication remain elusive. In this work, we used Y-family human DNA polymerase η as a model to investigate the kinetics of bypass of 6mA by hPol η. We found 6mA and its intermediate hypoxanthine (I) on template partially inhibited DNA replication by hPol η. dTMP incorporation opposite 6mA and dCMP incorporation opposite I can be considered as correct incorporation. However, both 6mA and I reduced correct incorporation efficiency, next-base extension efficiency, and the priority in extension beyond correct base pair. Both dTMP incorporation opposite 6mA and dCTP opposite I showed fast burst phases. However, 6mA and I reduced the burst incorporation rates (kpol) and increased the dissociation constant (Kd,dNTP), compared with that of dTMP incorporation opposite unmodified A. Biophysical binding assays revealed that both 6mA and I on template reduced the binding affinity of hPol η to DNA in binary or ternary complex compared with unmodified A. All the results explain the inhibition effects of 6mA and I on DNA replication by hPol η, providing new insight in the effects of epigenetically modified 6mA on human DNA replication.
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Affiliation(s)
- Ke Du
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China; Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiangqian Zhang
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China
| | - Zhenyu Zou
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Bianbian Li
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Shiling Gu
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Shuming Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiaoyi Qu
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China
| | - Yihui Ling
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao Panyu District, Guangzhou, China
| | - Huidong Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China.
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15
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The active site residues Gln55 and Arg73 play a key role in DNA damage bypass by S. cerevisiae Pol η. Sci Rep 2018; 8:10314. [PMID: 29985422 PMCID: PMC6037775 DOI: 10.1038/s41598-018-28664-8] [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: 10/23/2017] [Accepted: 06/12/2018] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic DNA polymerase eta (Pol η) plays a key role in the efficient and accurate DNA translesion synthesis (TLS) opposite UV-induced thymine dimers. Pol η is also involved in bypass of many other DNA lesions but possesses low fidelity on undamaged DNA templates. To better understand the mechanism of DNA synthesis by Pol η we investigated substitutions of evolutionary conserved active site residues Gln55 and Arg73 in Saccharomyces cerevisiae Pol η. We analyzed the efficiency and fidelity of DNA synthesis by the mutant Pol η variants opposite thymine dimers, abasic site, thymine glycol, 8-oxoguanine and on undamaged DNA. Substitutions Q55A and R73A decreased the catalytic activity and significantly affected DNA damage bypass by Pol η. In particular, the Q55A substitution reduced the efficiency of thymine dimers bypass, R73A had a stronger effect on the TLS-activity opposite abasic site, while both substitutions impaired replication opposite thymine glycol. Importantly, the R73A substitution also increased the fidelity of Pol η. Altogether, these results reveal a key role of residues Gln55 and Arg73 in DNA synthesis opposite various types of DNA lesions and highlight the evolutionary importance of the Pol η TLS function at the cost of DNA replication accuracy.
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16
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Zou Z, Chen Z, Xue Q, Xu Y, Xiong J, Yang P, Le S, Zhang H. Protein Interactions in the T7 DNA Replisome Facilitate DNA Damage Bypass. Chembiochem 2018; 19:1740-1749. [PMID: 29900646 DOI: 10.1002/cbic.201800203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Indexed: 01/07/2023]
Abstract
The DNA replisome inevitably encounters DNA damage during DNA replication. The T7 DNA replisome contains a DNA polymerase (gp5), the processivity factor thioredoxin (trx), a helicase-primase (gp4), and a ssDNA-binding protein (gp2.5). T7 protein interactions mediate this DNA replication. However, whether the protein interactions could promote DNA damage bypass is still little addressed. In this study, we investigated strand-displacement DNA synthesis past 8-oxoG or O6 -MeG lesions at the synthetic DNA fork by the T7 DNA replisome. DNA damage does not obviously affect the binding affinities between helicase, polymerase, and DNA fork. Relative to unmodified G, both 8-oxoG and O6 -MeG-as well as GC-rich template sequence clusters-inhibit strand-displacement DNA synthesis and produce partial extension products. Relative to the gp4 ΔC-tail, gp4 promotes DNA damage bypass. The presence of gp2.5 also promotes it. Thus, the interactions of polymerase with helicase and ssDNA-binding protein facilitate DNA damage bypass. Accessory proteins in other complicated DNA replisomes also facilitate bypassing DNA damage in similar manner. This work provides new mechanistic information relating to DNA damage bypass by the DNA replisome.
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Affiliation(s)
- Zhenyu Zou
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ze Chen
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Qizhen Xue
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ying Xu
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Jingyuan Xiong
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ping Yang
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou, 511439, P. R. China
| | - Shuai Le
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, P. R. China
| | - Huidong Zhang
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
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17
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Gu S, Xiong J, Shi Y, You J, Zou Z, Liu X, Zhang H. Error-prone bypass of O 6-methylguanine by DNA polymerase of Pseudomonas aeruginosa phage PaP1. DNA Repair (Amst) 2017. [PMID: 28651167 DOI: 10.1016/j.dnarep.2017.06.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
O6-Methylguanine (O6-MeG) is highly mutagenic and is commonly found in DNA exposed to methylating agents, generally leads to G:C to A:T mutagenesis. To study DNA replication encountering O6-MeG by the DNA polymerase (gp90) of P. aeruginosa phage PaP1, we analyzed steady-state and pre-steady-state kinetics of nucleotide incorporation opposite O6-MeG by gp90 exo-. O6-MeG partially inhibited full-length extension by gp90 exo-. O6-MeG greatly reduces dNTP incorporation efficiency, resulting in 67-fold preferential error-prone incorporation of dTTP than dCTP. Gp90 exo- extends beyond T:O6-MeG 2-fold more efficiently than C:O6-MeG. Incorporation of dCTP opposite G and incorporation of dCTP or dTTP opposite O6-MeG show fast burst phases. The pre-steady-state incorporation efficiency (kpol/Kd,dNTP) is decreased in the order of dCTP:G>dTTP:O6-MeG>dCTP:O6-MeG. The presence of O6-MeG at template does not affect the binding affinity of polymerase to DNA but it weakened their binding in the presence of dCTP and Mg2+. Misincorporation of dTTP opposite O6-MeG further weakens the binding affinity of polymerase to DNA. The priority of dTTP incorporation opposite O6-MeG is originated from the fact that dTTP can induce a faster conformational change step and a faster chemical step than dCTP. This study reveals that gp90 bypasses O6-MeG in an error-prone manner and provides further understanding in DNA replication encountering mutagenic alkylation DNA damage for P. aeruginosa phage PaP1.
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Affiliation(s)
- Shiling Gu
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Jingyuan Xiong
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Ying Shi
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Jia You
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Zhenyu Zou
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Xiaoying Liu
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China
| | - Huidong Zhang
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China.
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