1
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Yoon JH, Sellamuthu K, Prakash L, Prakash S. WRN exonuclease imparts high fidelity on translesion synthesis by Y family DNA polymerases. Genes Dev 2024; 38:213-232. [PMID: 38503516 PMCID: PMC11065173 DOI: 10.1101/gad.351410.123] [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: 12/04/2023] [Accepted: 02/26/2024] [Indexed: 03/21/2024]
Abstract
Purified translesion synthesis (TLS) DNA polymerases (Pols) replicate through DNA lesions with a low fidelity; however, TLS operates in a predominantly error-free manner in normal human cells. To explain this incongruity, here we determine whether Y family Pols, which play an eminent role in replication through a diversity of DNA lesions, are incorporated into a multiprotein ensemble and whether the intrinsically high error rate of the TLS Pol is ameliorated by the components in the ensemble. To this end, we provide evidence for an indispensable role of Werner syndrome protein (WRN) and WRN-interacting protein 1 (WRNIP1) in Rev1-dependent TLS by Y family Polη, Polι, or Polκ and show that WRN, WRNIP1, and Rev1 assemble together with Y family Pols in response to DNA damage. Importantly, we identify a crucial role of WRN's 3' → 5' exonuclease activity in imparting high fidelity on TLS by Y family Pols in human cells, as the Y family Pols that accomplish TLS in an error-free manner manifest high mutagenicity in the absence of WRN's exonuclease function. Thus, by enforcing high fidelity on TLS Pols, TLS mechanisms have been adapted to safeguard against genome instability and tumorigenesis.
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Affiliation(s)
- Jung-Hoon Yoon
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77555, USA
| | - Karthi Sellamuthu
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77555, USA
| | - Louise Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77555, USA
| | - Satya Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77555, USA
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2
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Menck CFM, Galhardo RS, Quinet A. The accurate bypass of pyrimidine dimers by DNA polymerase eta contributes to ultraviolet-induced mutagenesis. Mutat Res 2024; 828:111840. [PMID: 37984186 DOI: 10.1016/j.mrfmmm.2023.111840] [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: 06/10/2023] [Revised: 10/23/2023] [Accepted: 11/02/2023] [Indexed: 11/22/2023]
Abstract
Human xeroderma pigmentosum variant (XP-V) patients are mutated in the POLH gene, responsible for encoding the translesion synthesis (TLS) DNA polymerase eta (Pol eta). These patients suffer from a high frequency of skin tumors. Despite several decades of research, studies on Pol eta still offer an intriguing paradox: How does this error-prone polymerase suppress mutations? This review examines recent evidence suggesting that cyclobutane pyrimidine dimers (CPDs) are instructional for Pol eta. Consequently, it can accurately replicate these lesions, and the mutagenic effects induced by UV radiation stem from the deamination of C-containing CPDs. In this model, the deamination of C (forming a U) within CPDs leads to the correct insertion of an A opposite to the deaminated C (or U)-containing dimers. This intricate process results in C>T transitions, which represent the most prevalent mutations detected in skin cancers. Finally, the delayed replication in XP-V cells amplifies the process of C-deamination in CPDs and increases the burden of C>T mutations prevalent in XP-V tumors through the activity of backup TLS polymerases.
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Affiliation(s)
- C F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil.
| | - R S Galhardo
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - A Quinet
- Université Paris Cité, Inserm, CEA, Stabilité Génétique Cellules Souches et Radiations, LRS/iRCM/IBFJ, F-92265 Fontenay-aux-Roses, France; Université Paris-Saclay, Inserm, CEA, Stabilité Génétique Cellules Souches et Radiations, LRS/iRCM/IBFJ, F-92265 Fontenay-aux-Roses, France
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3
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Yoon JH, Basu D, Choudhury JR, Prakash S, Prakash L. DNA polymerase λ promotes error-free replication through Watson-Crick impairing N1-methyl-deoxyadenosine adduct in conjunction with DNA polymerase ζ. J Biol Chem 2021; 297:100868. [PMID: 34119520 PMCID: PMC8260881 DOI: 10.1016/j.jbc.2021.100868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/06/2021] [Accepted: 06/09/2021] [Indexed: 11/26/2022] Open
Abstract
In a previous study, we showed that replication through the N1-methyl-deoxyadenosine (1-MeA) adduct in human cells is mediated via three different Polι/Polθ, Polη, and Polζ-dependent pathways. Based on biochemical studies with these Pols, in the Polι/Polθ pathway, we inferred a role for Polι in the insertion of a nucleotide (nt) opposite 1-MeA and of Polθ in extension of synthesis from the inserted nt; in the Polη pathway, we inferred that this Pol alone would replicate through 1-MeA; in the Polζ pathway, however, the Pol required for inserting an nt opposite 1-MeA had remained unidentified. In this study, we provide biochemical and genetic evidence for a role for Polλ in inserting the correct nt T opposite 1-MeA, from which Polζ would extend synthesis. The high proficiency of purified Polλ for inserting a T opposite 1-MeA implicates a role for Polλ—which normally uses W-C base pairing for DNA synthesis—in accommodating 1-MeA in a syn confirmation and forming a Hoogsteen base pair with T. The potential of Polλ to replicate through DNA lesions by Hoogsteen base pairing adds another novel aspect to Polλ’s role in translesion synthesis in addition to its role as a scaffolding component of Polζ. We discuss how the action mechanisms of Polλ and Polζ could be restrained to inserting a T opposite 1-MeA and extending synthesis thereafter, respectively.
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Affiliation(s)
- Jung-Hoon Yoon
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Debashree Basu
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jayati Roy Choudhury
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Satya Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Louise Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
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4
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Feng X, Liu X, Xu R, Zhao R, Feng W, Liao J, Han W, She Q. A Unique B-Family DNA Polymerase Facilitating Error-Prone DNA Damage Tolerance in Crenarchaeota. Front Microbiol 2020; 11:1585. [PMID: 32793138 PMCID: PMC7390963 DOI: 10.3389/fmicb.2020.01585] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 06/17/2020] [Indexed: 12/20/2022] Open
Abstract
Sulfolobus islandicus codes for four DNA polymerases: three are of the B-family (Dpo1, Dpo2, and Dpo3), and one is of the Y-family (Dpo4). Western analysis revealed that among the four polymerases, only Dpo2 exhibited DNA damage-inducible expression. To investigate how these DNA polymerases could contribute to DNA damage tolerance in S. islandicus, we conducted genetic analysis of their encoding genes in this archaeon. Plasmid-borne gene expression revealed that Dpo2 increases cell survival upon DNA damage at the expense of mutagenesis. Gene deletion studies showed although dpo1 is essential, the remaining three genes are dispensable. Furthermore, although Dpo4 functions in housekeeping translesion DNA synthesis (TLS), Dpo2, a B-family DNA polymerase once predicted to be inactive, functions as a damage-inducible TLS enzyme solely responsible for targeted mutagenesis, facilitating GC to AT/TA conversions in the process. Together, our data indicate that Dpo2 is the main DNA polymerase responsible for DNA damage tolerance and is the primary source of targeted mutagenesis. Given that crenarchaea encoding a Dpo2 also have a low-GC composition genome, the Dpo2-dependent DNA repair pathway may be conserved in this archaeal lineage.
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Affiliation(s)
- Xu Feng
- CRISPR and Archaea Biology Research Center, Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xiaotong Liu
- CRISPR and Archaea Biology Research Center, Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ruyi Xu
- CRISPR and Archaea Biology Research Center, Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ruiliang Zhao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Wenqian Feng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jianglan Liao
- CRISPR and Archaea Biology Research Center, Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Wenyuan Han
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qunxin She
- CRISPR and Archaea Biology Research Center, Microbial Technology Institute and State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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5
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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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6
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Regulation of Cell Division in Bacteria by Monitoring Genome Integrity and DNA Replication Status. J Bacteriol 2020; 202:JB.00408-19. [PMID: 31548275 DOI: 10.1128/jb.00408-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
All organisms regulate cell cycle progression by coordinating cell division with DNA replication status. In eukaryotes, DNA damage or problems with replication fork progression induce the DNA damage response (DDR), causing cyclin-dependent kinases to remain active, preventing further cell cycle progression until replication and repair are complete. In bacteria, cell division is coordinated with chromosome segregation, preventing cell division ring formation over the nucleoid in a process termed nucleoid occlusion. In addition to nucleoid occlusion, bacteria induce the SOS response after replication forks encounter DNA damage or impediments that slow or block their progression. During SOS induction, Escherichia coli expresses a cytoplasmic protein, SulA, that inhibits cell division by directly binding FtsZ. After the SOS response is turned off, SulA is degraded by Lon protease, allowing for cell division to resume. Recently, it has become clear that SulA is restricted to bacteria closely related to E. coli and that most bacteria enforce the DNA damage checkpoint by expressing a small integral membrane protein. Resumption of cell division is then mediated by membrane-bound proteases that cleave the cell division inhibitor. Further, many bacterial cells have mechanisms to inhibit cell division that are regulated independently from the canonical LexA-mediated SOS response. In this review, we discuss several pathways used by bacteria to prevent cell division from occurring when genome instability is detected or before the chromosome has been fully replicated and segregated.
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7
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Peddu C, Zhang S, Zhao H, Wong A, Lee EYC, Lee MYWT, Zhang Z. Phosphorylation Alters the Properties of Pol η: Implications for Translesion Synthesis. iScience 2018; 6:52-67. [PMID: 30240625 PMCID: PMC6137289 DOI: 10.1016/j.isci.2018.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/26/2018] [Accepted: 07/13/2018] [Indexed: 12/28/2022] Open
Abstract
There are significant ambiguities regarding how DNA polymerase η is recruited to DNA lesion sites in stressed cells while avoiding normal replication forks in non-stressed cells. Even less is known about the mechanisms responsible for Pol η-induced mutations in cancer genomes. We show that there are two safeguards to prevent Pol η from adventitious participation in normal DNA replication. These include sequestration by a partner protein and low basal activity. Upon cellular UV irradiation, phosphorylation enables Pol η to be released from sequestration by PDIP38 and activates its polymerase function through increased affinity toward monoubiquitinated proliferating cell nuclear antigen (Ub-PCNA). Moreover, the high-affinity binding of phosphorylated Pol η to Ub-PCNA limits its subsequent displacement by Pol δ. Consequently, activated Pol η replicates DNA beyond the lesion site and potentially introduces clusters of mutations due to its low fidelity. This mechanism could account for the prevalence of Pol η signatures in cancer genome. Pol η activation requires both ATR and PKC phosphorylation Phosphorylation directly enhances the affinity of Pol η toward Ub-PCNA PDIP38 sequesters Pol η away from normal replication fork Pol δ is not able to displace phosphorylated Pol η from Ub-PCNA complex
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Affiliation(s)
- Chandana Peddu
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Sufang Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Hong Zhao
- Department of Pathology, New York Medical College, Valhalla, NY 10595, USA
| | - Agnes Wong
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Ernest Y C Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Marietta Y W T Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Zhongtao Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.
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8
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Lee YA, Lee YC, Geacintov NE, Shafirovich V. Translesion synthesis past guanine(C8)-thymine(N3) intrastrand cross-links catalyzed by selected A- and Y-family polymerases. MOLECULAR BIOSYSTEMS 2017; 12:1892-900. [PMID: 27102383 DOI: 10.1039/c6mb00160b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Oxidatively generated guanine radicals in DNA can undergo various nucleophilic reactions including the formation of C8-guanine cross-links with adjacent or nearby N3-thymines in DNA in the presence of O2. These G[8-3]T lesions have been identified in the DNA of human cells exposed to oxidative stress, and are most likely genotoxic if not removed by cellular defence mechanisms. The abilities of several representative polymerases to bypass the G[8-3]T lesions in two different sequence contexts, G*T* and G*CT*, were assessed in vitro. The polymerase BF (bacillus fragment) from Bacillus stearothermophilus, the Y-family archaeal polymerases Dpo4 from Sulfolobus sulfataricus P2, and human DNA pol κ and pol η were selected for the study. The A-family polymerase BF was strongly blocked, while relatively weak translesion synthesis was observed in the case of Y-family polymerases Dpo4 and pol κ. Primer extension catalyzed by pol η was also partially stalled at various positions at or near the G[8-3]T cross-linked bases, but a significant and distributive primer extension was observed beyond the sites of the lesions with the efficiency being consistently greater in the case of G*CT* than in the case of G*T* lesions. The results obtained with pol η are compared with translesion synthesis past other intrastrand cross-linked lesions with previously published results of others that include the isomeric G[8-5m]T lesions generated by ionizing radiation, the cis-syn cyclobutane pyrimidine dimer and the 6-4 photoproduct generated by UV irradiation, and the Pt-G*G* lesions derived from the reactions of the chemotherapeutic agent cisplatin with DNA.
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Affiliation(s)
- Young-Ae Lee
- Department of Chemistry, Yeungnam University, Gyeongsan, 38541, Korea
| | - Yuan-Cho Lee
- Chemistry Department, New York University, 31 Washington Place, New York, NY10003-5180, USA.
| | - Nicholas E Geacintov
- Chemistry Department, New York University, 31 Washington Place, New York, NY10003-5180, USA.
| | - Vladimir Shafirovich
- Chemistry Department, New York University, 31 Washington Place, New York, NY10003-5180, USA.
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9
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Conde J, Yoon JH, Roy Choudhury J, Prakash L, Prakash S. Genetic Control of Replication through N1-methyladenine in Human Cells. J Biol Chem 2015; 290:29794-800. [PMID: 26491020 DOI: 10.1074/jbc.m115.693010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Indexed: 11/06/2022] Open
Abstract
N1-methyl adenine (1-MeA) is formed in DNA by reaction with alkylating agents and naturally occurring methyl halides. The 1-MeA lesion impairs Watson-Crick base pairing and blocks normal DNA replication. Here we identify the translesion synthesis (TLS) DNA polymerases (Pols) required for replicating through 1-MeA in human cells and show that TLS through this lesion is mediated via three different pathways in which Pols ι and θ function in one pathway and Pols η and ζ, respectively, function in the other two pathways. Our biochemical studies indicate that in the Polι/Polθ pathway, Polι would carry out nucleotide insertion opposite 1-MeA from which Polθ would extend synthesis. In the Polη pathway, this Pol alone would function at both the nucleotide insertion and extension steps of TLS, and in the third pathway, Polζ would extend from the nucleotide inserted opposite 1-MeA by an as yet unidentified Pol. Whereas by pushing 1-MeA into the syn conformation and by forming Hoogsteen base pair with the T residue, Polι would carry out TLS opposite 1-MeA, the ability of Polη to replicate through 1-MeA suggests that despite its need for Watson-Crick hydrogen bonding, Polη can stabilize the adduct in its active site. Remarkably, even though Pols η and ι are quite error-prone at inserting nucleotides opposite 1-MeA, TLS opposite this lesion in human cells occurs in a highly error-free fashion. This suggests that the in vivo fidelity of TLS Pols is regulated by factors such as post-translational modifications, protein-protein interactions, and possibly others.
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Affiliation(s)
- Juan Conde
- From the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
| | - Jung-Hoon Yoon
- From the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
| | - Jayati Roy Choudhury
- From the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
| | - Louise Prakash
- From the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
| | - Satya Prakash
- From the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555-1061
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10
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Ikehata H, Chang Y, Yokoi M, Yamamoto M, Hanaoka F. Remarkable induction of UV-signature mutations at the 3'-cytosine of dipyrimidine sites except at 5'-TCG-3' in the UVB-exposed skin epidermis of xeroderma pigmentosum variant model mice. DNA Repair (Amst) 2014; 22:112-22. [PMID: 25128761 DOI: 10.1016/j.dnarep.2014.07.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/12/2014] [Accepted: 07/21/2014] [Indexed: 10/24/2022]
Abstract
The human POLH gene is responsible for the variant form of xeroderma pigmentosum (XP-V), a genetic disease highly susceptible to cancer on sun-exposed skin areas, and encodes DNA polymerase η (polη), which is specialized for translesion DNA synthesis (TLS) of UV-induced DNA photolesions. We constructed polη-deficient mice transgenic with lacZ mutational reporter genes to study the effect of Polh null mutation (Polh(-/-)) on mutagenesis in the skin after UVB irradiation. UVB induced lacZ mutations with remarkably higher frequency in the Polh(-/-) epidermis and dermis than in the wild-type (Polh(+/+)) and heterozygote. DNA sequences of a hundred lacZ mutants isolated from the epidermis of four UVB-exposed Polh(-/-) mice were determined and compared with mutant sequences from irradiated Polh(+)(/)(+) mice. The spectra of the mutations in the two genotypes were both highly UV-specific and dominated by C→T transitions at dipyrimidines, namely UV-signature mutations. However, sequence preferences of the occurrence of UV-signature mutations were quite different between the two genotypes: the mutations occurred at a higher frequency preferentially at the 5'-TCG-3' sequence context than at the other dipyrimidine contexts in the Polh(+/+) epidermis, whereas the mutations were induced remarkably and exclusively at the 3'-cytosine of almost all dipyrimidine contexts with no preference for 5'-TCG-3' in the Polh(-/-) epidermis. In addition, in Polh(-/-) mice, a small but remarkable fraction of G→T transversions was also observed exclusively at the 3'-cytosine of dipyrimidine sites, strongly suggesting that these transversions resulted not from oxidative damage but from UV photolesions. These results would reflect the characteristics of the error-prone TLS functioning in the bypass of UV photolesions in the absence of polη, which would be mediated by mechanisms based on the two-step model of TLS. On the other hand, the deamination model would explain well the mutation spectrum in the Polh(+/+) genotype.
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Affiliation(s)
- Hironobu Ikehata
- Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan; Department of Physiological Sciences, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
| | - Yumin Chang
- Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Masayuki Yokoi
- Department of Life Science, Faculty of Science, Gakushuin University, Tokyo 171-8588, Japan
| | - Masayuki Yamamoto
- Department of Physiological Sciences, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Fumio Hanaoka
- Department of Life Science, Faculty of Science, Gakushuin University, Tokyo 171-8588, Japan
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11
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Maxwell BA, Suo Z. Recent insight into the kinetic mechanisms and conformational dynamics of Y-Family DNA polymerases. Biochemistry 2014; 53:2804-14. [PMID: 24716482 PMCID: PMC4018064 DOI: 10.1021/bi5000405] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
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The
kinetic mechanisms by which DNA polymerases catalyze DNA replication
and repair have long been areas of active research. Recently discovered
Y-family DNA polymerases catalyze the bypass of damaged DNA bases
that would otherwise block replicative DNA polymerases and stall replication
forks. Unlike DNA polymerases from the five other families, the Y-family
DNA polymerases have flexible, solvent-accessible active sites that
are able to tolerate various types of damaged template bases and allow
for efficient lesion bypass. Their promiscuous active sites, however,
also lead to fidelities that are much lower than those observed for
other DNA polymerases and give rise to interesting mechanistic properties.
Additionally, the Y-family DNA polymerases have several other unique
structural features and undergo a set of conformational changes during
substrate binding and catalysis different from those observed for
replicative DNA polymerases. In recent years, pre-steady-state kinetic
methods have been extensively employed to reveal a wealth of information
about the catalytic properties of these fascinating noncanonical DNA
polymerases. Here, we review many of the recent findings on the kinetic
mechanisms of DNA polymerization with undamaged and damaged DNA substrates
by the Y-family DNA polymerases, and the conformational dynamics employed
by these error-prone enzymes during catalysis.
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Affiliation(s)
- Brian A Maxwell
- Ohio State Biophysics Program and ‡Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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12
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Pednekar V, Weerasooriya S, Jasti VP, Basu AK. Mutagenicity and genotoxicity of (5'S)-8,5'-cyclo-2'-deoxyadenosine in Escherichia coli and replication of (5'S)-8,5'-cyclopurine-2'-deoxynucleosides in vitro by DNA polymerase IV, exo-free Klenow fragment, and Dpo4. Chem Res Toxicol 2014; 27:200-10. [PMID: 24392701 PMCID: PMC3952113 DOI: 10.1021/tx4002786] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Reactive
oxygen species generate many lesions in DNA, including R and S diastereomers of 8,5′-cyclo-2′-deoxyadenosine
(cdA) and 8,5′-cyclo-2′-deoxyguanosine (cdG). Herein,
the result of replication of a plasmid containing S-cdA in Escherichia coli is reported. S-cdA was found mutagenic and highly genotoxic. Viability and mutagenicity
of the S-cdA construct were dependent on functional
pol V, but mutational frequencies (MFs) and types varied in pol II-
and pol IV-deficient strains relative to the wild-type strain. Both S-cdA → T and S-cdA → G substitutions
occurred in equal frequency in wild-type E. coli,
but the frequency of S-cdA → G dropped in
pol IV-deficient strain, especially when being SOS induced. This suggests
that pol IV plays a role in S-cdA → G mutations.
MF increased significantly in pol II-deficient strain, suggesting
pol II’s likely role in error-free translesion synthesis. Primer
extension and steady-state kinetic studies using pol IV, exo-free
Klenow fragment (KF (exo–)), and Dpo4 were performed
to further assess the replication efficiency and fidelity of S-cdA and S-cdG. Primer extension by pol
IV mostly stopped before the lesion, although a small fraction was
extended opposite the lesion. Kinetic studies showed that pol IV incorporated
dCMP almost as efficiently as dTMP opposite S-cdA,
whereas it incorporated the correct nucleotide dCMP opposite S-cdG 10-fold more efficiently than any other dNMP. Further
extension of each lesion containing pair, however, was very inefficient.
These results are consistent with the role of pol IV in S-cdA → G mutations in E. coli. KF (exo–) was also strongly blocked by both lesions, but it
could slowly incorporate the correct nucleotide opposite them. In
contrast, Dpo4 could extend a small fraction of the primer to a full-length
product on both S-cdG and S-cdA
templates. Dpo4 incorporated dTMP preferentially opposite S-cdA over the other dNMPs, but the discrimination was only
2- to 8-fold more proficient. Further extension of the S-cdA:T and S-cdA:C pair was not much different.
For S-cdG, conversely, the wrong nucleotide, dTMP,
was incorporated more efficiently than dCMP, although one-base extension
of the S-cdG:T pair was less efficient than the S-cdG:C pair. S-cdG, therefore, has the
propensity to cause G → A transition, as was reported to occur
in E. coli. The results of this study are consistent
with the strong replication blocking nature of S-cdA
and S-cdG, and their ability to initiate error-prone
synthesis by Y-family DNA polymerases.
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Affiliation(s)
- Varsha Pednekar
- Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States
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13
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Trakselis MA, Bauer RJ. Archaeal DNA Polymerases: Enzymatic Abilities, Coordination, and Unique Properties. NUCLEIC ACID POLYMERASES 2014. [DOI: 10.1007/978-3-642-39796-7_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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14
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Sherrer SM, Maxwell BA, Pack LR, Fiala KA, Fowler JD, Zhang J, Suo Z. Identification of an unfolding intermediate for a DNA lesion bypass polymerase. Chem Res Toxicol 2012; 25:1531-40. [PMID: 22667759 DOI: 10.1021/tx3002115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sulfolobus solfataricus DNA Polymerase IV (Dpo4), a prototype Y-family DNA polymerase, has been well characterized biochemically and biophysically at 37 °C or lower temperatures. However, the physiological temperature of the hyperthermophile S. solfataricus is approximately 80 °C. With such a large discrepancy in temperature, the in vivo relevance of these in vitro studies of Dpo4 has been questioned. Here, we employed circular dichroism spectroscopy and fluorescence-based thermal scanning to investigate the secondary structural changes of Dpo4 over a temperature range from 26 to 119 °C. Dpo4 was shown to display a high melting temperature characteristic of hyperthermophiles. Unexpectedly, the Little Finger domain of Dpo4, which is only found in the Y-family DNA polymerases, was shown to be more thermostable than the polymerase core. More interestingly, Dpo4 exhibited a three-state cooperative unfolding profile with an unfolding intermediate. The linker region between the Little Finger and Thumb domains of Dpo4 was found to be a source of structural instability. Through site-directed mutagenesis, the interactions between the residues in the linker region and the Palm domain were identified to play a critical role in the formation of the unfolding intermediate. Notably, the secondary structure of Dpo4 was not altered when the temperature was increased from 26 to 87.5 °C. Thus, in addition to providing structural insights into the thermal stability and an unfolding intermediate of Dpo4, our work also validated the relevance of the in vitro studies of Dpo4 performed at temperatures significantly lower than 80 °C.
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Affiliation(s)
- Shanen M Sherrer
- Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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15
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Zahn KE, Wallace SS, Doublié S. DNA polymerases provide a canon of strategies for translesion synthesis past oxidatively generated lesions. Curr Opin Struct Biol 2011; 21:358-69. [PMID: 21482102 DOI: 10.1016/j.sbi.2011.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 02/07/2023]
Abstract
Deducing the structure of the DNA double helix in 1953 implied the mode of its replication: Watson-Crick (WC) base pairing might instruct an enzyme, now known as the DNA polymerase, during the synthesis of a daughter stand complementary to a single strand of the parental double helix. What has become increasingly clear in the last 60 years, however, is that adducted and oxidatively generated DNA bases are ubiquitous in physiological DNA, and all organisms conserve multiple DNA polymerases specialized for DNA synthesis opposite these damaged templates. Here, we review recent crystal structures depicting replicative and bypass DNA polymerases encountering two typical lesions arising from the oxidation of DNA: abasic sites, which block the replication fork, and the miscoding premutagenic lesion 7,8-dihydro-8-oxoguanine (8-oxoG).
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Affiliation(s)
- Karl E Zahn
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
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16
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Lin LJ, Yoshinaga A, Lin Y, Guzman C, Chen YH, Mei S, Lagunas AM, Koike S, Iwai S, Spies MA, Nair SK, Mackie RI, Ishino Y, Cann IKO. Molecular analyses of an unusual translesion DNA polymerase from Methanosarcina acetivorans C2A. J Mol Biol 2010; 397:13-30. [PMID: 20080107 DOI: 10.1016/j.jmb.2010.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 12/08/2009] [Accepted: 01/05/2010] [Indexed: 11/24/2022]
Abstract
The domain Archaea is composed of several subdomains, and prominent among them are the Crenarchaeota and the Euryarchaeota. Biochemically characterized archaeal family Y DNA polymerases (Pols) or DinB homologs, to date, are all from crenarchaeal organisms, especially the genus Sulfolobus. Here, we demonstrate that archaeal family Y Pols fall into five clusters based on phylogenetic analysis. MacDinB-1, the homolog from the euryarchaeon Methanosarcina acetivorans that is characterized in this study, belongs to cluster II. Therefore, MacDinB-1 is different from the Sulfolobus DinB proteins, which are members of cluster I. In addition to translesion DNA synthesis activity, MacDinB-1 synthesized unusually long products ( approximately 7.2 kb) in the presence of its cognate proliferating cell nuclear antigen (PCNA). The PCNA-interacting site in MacDinB-1 was identified by mutational analysis in a C-terminally located heptapeptide akin to a PIP (PCNA-interacting protein) box. In vitro assays from the present report suggested that MacDinB-1 works in an error-free mode to repair cyclobutane pyrimidine dimers. This study on a euryarchaeal DinB homolog provides important insights into the functional diversity of the family Y Pols, and the availability of a genetic system for this archaeon should allow subsequent elucidation of the physiological significance of this enzyme in M. acetivorans cells.
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Affiliation(s)
- Li-Jung Lin
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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17
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Highly error-free role of DNA polymerase eta in the replicative bypass of UV-induced pyrimidine dimers in mouse and human cells. Proc Natl Acad Sci U S A 2009; 106:18219-24. [PMID: 19822754 DOI: 10.1073/pnas.0910121106] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cyclobutane pyrimidine dimers (CPDs) constitute the most frequent UV-induced DNA photoproduct. However, it has remained unclear how human and other mammalian cells mitigate the mutagenic and carcinogenic potential of CPDs emanating from their replicative bypass. Here, we examine in human cells the roles of translesion synthesis (TLS) DNA polymerases (Pols) in the replicative bypass of a cis-syn TT dimer carried on the leading or the lagging strand DNA template in a plasmid system we have designed, and we determine in mouse cells the frequencies and mutational spectra generated from TLS occurring specifically opposite CPDs formed at TT, TC, and CC dipyrimidine sites. From these studies we draw the following conclusions: (i) TLS makes a very prominent contribution to CPD bypass on both the DNA strands during replication; (ii) Pols eta, kappa, and zeta provide alternate pathways for TLS opposite CPDs wherein Pols kappa and zeta promote mutagenic TLS opposite CPDs; and (iii) the absence of mutagenic TLS events opposite a cis-syn TT dimer in human cells and opposite CPDs formed at TT, TC, and CC sites in mouse cells that we observe upon the simultaneous knockdown of Pols kappa and zeta implicates a highly error-free role of Poleta in TLS opposite CPDs in mammalian cells. Such a remarkably high in vivo fidelity of Poleta could not have been anticipated in view of its low intrinsic fidelity. These observations have important bearing on how mammalian cells have adapted to avoid the mutagenic and carcinogenic consequences of exposure to sunlight.
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18
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Valenti A, Perugino G, Nohmi T, Rossi M, Ciaramella M. Inhibition of translesion DNA polymerase by archaeal reverse gyrase. Nucleic Acids Res 2009; 37:4287-95. [PMID: 19443439 PMCID: PMC2715243 DOI: 10.1093/nar/gkp386] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Reverse gyrase is a unique DNA topoisomerase endowed with ATP-dependent positive supercoiling activity. It is typical of microorganisms living at high temperature and might play a role in maintenance of genome stability and repair. We have identified the translesion DNA polymerase SsoPolY/Dpo4 as one partner of reverse gyrase in the hyperthermophilic archaeon Sulfolobus solfataricus. We show here that in cell extracts, PolY and reverse gyrase co-immunoprecipitate with each other and with the single strand binding protein, SSB. The interaction is confirmed in vitro by far-western and Surface Plasmon Resonance. In functional assays, reverse gyrase inhibits PolY, but not the S. solfataricus B-family DNA polymerase PolB1. Mutational analysis shows that inhibition of PolY activity depends on both ATPase and topoisomerase activities of reverse gyrase, suggesting that the intact positive supercoiling activity is required for PolY inhibition. In vivo, reverse gyrase and PolY are degraded after induction of DNA damage. Inhibition by reverse gyrase and degradation might act as a double mechanism to control PolY and prevent its potentially mutagenic activity when undesired. Inhibition of a translesion polymerase by topoisomerase-induced modification of DNA structure may represent a previously unconsidered mechanism of regulation of these two-faced enzymes.
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Affiliation(s)
- Anna Valenti
- Institute of Protein Biochemistry, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy
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19
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Sherrer SM, Brown JA, Pack LR, Jasti VP, Fowler JD, Basu AK, Suo Z. Mechanistic studies of the bypass of a bulky single-base lesion catalyzed by a Y-family DNA polymerase. J Biol Chem 2009; 284:6379-88. [PMID: 19124465 PMCID: PMC2649090 DOI: 10.1074/jbc.m808161200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 12/29/2008] [Indexed: 12/27/2022] Open
Abstract
1-nitropyrene, the most abundant nitro polycyclic aromatic hydrocarbon in diesel emissions, has been found to react with DNA to form predominantly N-(deoxyguanosin-8-yl)-1-aminopyrene (dGAP). This bulky adduct has been shown to induce genetic mutations, which may implicate Y-family DNA polymerases in its bypass in vivo. To establish a kinetic mechanism for the bypass of such a prototype single-base lesion, we employed pre-steady-state kinetic methods to investigate individual nucleotide incorporations upstream, opposite, and downstream from a site-specifically placed dGAP lesion catalyzed by Sulfolobus solfataricus DNA polymerase IV (Dpo4), a model Y-family DNA polymerase. Dpo4 was able to bypass dGAP but paused strongly at two sites: opposite the lesion and immediately downstream from the lesion. Both nucleotide incorporation efficiency and fidelity decreased significantly at the pause sites, especially during extension of the bypass product. Interestingly, a 4-fold tighter binding affinity of damaged DNA to Dpo4 promoted catalysis through putative interactions between the active site residues of Dpo4 and 1-aminopyrene moiety at the first pause site. In the presence of a DNA trap, the kinetics of nucleotide incorporation at these sites was biphasic in which a small, fast phase preceded a larger, slow phase. In contrast, only a large, fast phase was observed during nucleotide incorporation at non-pause sites. Our kinetic studies support a general kinetic mechanism for lesion bypass catalyzed by numerous DNA polymerases.
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Affiliation(s)
- Shanen M Sherrer
- Department of Biochemistrythe Ohio State Biochemistry Program, Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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20
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Fasullo M, Sun M, Egner P. Stimulation of sister chromatid exchanges and mutation by aflatoxin B1-DNA adducts in Saccharomyces cerevisiae requires MEC1 (ATR), RAD53, and DUN1. Mol Carcinog 2008; 47:608-15. [PMID: 18228255 DOI: 10.1002/mc.20417] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The hepatocarcinogen aflatoxin B(1) (AFB(1)) is a potent recombinagen but weak mutagen in the yeast Saccharomyces cerevisiae. AFB(1) exposure induces DNA damage-inducible genes, such as RAD51 and those encoding ribonucleotide reductase (RNR), through a MEC1 (ATR homolog)-dependent pathway. Previous studies have indicated that MEC1 is required for both AFB(1)-associated recombination and mutation, and suggested that AFB(1)-DNA adducts are common substrates for recombination and mutagenesis. However, little is known about the downstream effectors of MEC1 required for genotoxic events associated with AFB(1) exposure. Here we show that AFB(1) exposure increases frequencies of RAD51-dependent unequal sister chromatid exchange (SCE) and activates Rad53 (CHK2). We found that MEC1, RAD53, and DUN1 are required for both AFB(1)-associated mutation and SCE. Deletion of SML1, which encodes an inhibitor of RNR, did not suppress the DUN1-dependent requirement for AFB(1)-associated genetic events, indicating that higher dNTP levels could not suppress the dun1 phenotype. We identified AFB(1)-DNA adducts and show that approximately the same number of adducts are obtained in both wild type and rad53 mutants. Since DUN1 is not required for UV-associated mutation and recombination, these studies define a distinct role for DUN1 in AFB(1)-associated mutagenesis and recombination. We speculate that AFB(1)-associated DNA adducts stall DNA replication, a consequence of which can either be mutation or recombination.
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Affiliation(s)
- Michael Fasullo
- Ordway Research Institute, Center for Medical Sciences, Department of Biomedical Sciences, State University of New York at Albany, 150 New Scotland Avenue, Albany, New York 12209, USA
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21
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Colis LC, Raychaudhury P, Basu AK. Mutational specificity of gamma-radiation-induced guanine-thymine and thymine-guanine intrastrand cross-links in mammalian cells and translesion synthesis past the guanine-thymine lesion by human DNA polymerase eta. Biochemistry 2008; 47:8070-9. [PMID: 18616294 PMCID: PMC2646719 DOI: 10.1021/bi800529f] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Comparative mutagenesis of γ- or X-ray-induced tandem DNA lesions G[8,5-Me]T and T[5-Me,8]G intrastrand cross-links was investigated in simian (COS-7) and human embryonic (293T) kidney cells. For G[8,5-Me]T in 293T cells, 5.8% of progeny contained targeted base substitutions, whereas 10.0% showed semitargeted single-base substitutions. Of the targeted mutations, the G → T mutation occurred with the highest frequency. The semitargeted mutations were detected up to two bases 5′ and three bases 3′ to the cross-link. The most prevalent semitargeted mutation was a C → T transition immediately 5′ to the G[8,5-Me]T cross-link. Frameshifts (4.6%) (mostly small deletions) and multiple-base substitutions (2.7%) also were detected. For the T[5-Me,8]G cross-link, a similar pattern of mutations was noted, but the mutational frequency was significantly higher than that of G[8,5-Me]T. Both targeted and semitargeted mutations occurred with a frequency of ∼16%, and both included a dominant G → T transversion. As in 293T cells, more than twice as many targeted mutations in COS cells occurred in T[5-Me,8]G (11.4%) as in G[8,5-Me]T (4.7%). Also, the level of semitargeted single-base substitutions 5′ to the lesion was increased and 3′ to the lesion decreased in T[5-Me,8]G relative to G[8,5-Me]T in COS cells. It appeared that the majority of the base substitutions at or near the cross-links resulted from incorporation of dAMP opposite the template base, in agreement with the so-called “A-rule”. To determine if human polymerase η (hpol η) might be involved in the mutagenic bypass, an in vitro bypass study of G[8,5-Me]T in the same sequence was carried out, which showed that hpol η can bypass the cross-link incorporating the correct dNMP opposite each cross-linked base. For G[8,5-Me]T, nucleotide incorporation by hpol η was significantly different from that by yeast pol η in that the latter was more error-prone opposite the cross-linked Gua. The incorporation of the correct nucleotide, dAMP, by hpol η opposite cross-linked T was 3−5-fold more efficient than that of a wrong nucleotide, whereas incorporation of dCMP opposite the cross-linked G was 10-fold more efficient than that with dTMP. Therefore, the nucleotide incorporation pattern by hpol η was not consistent with the observed cellular mutations. Nevertheless, at and near the lesion, hpol η was more error-prone compared to a control template. The in vitro data suggest that translesion synthesis by another Y-family DNA polymerase and/or flawed participation of an accessory protein is a more likely scenario in the mutagenesis of these lesions in mammalian cells. However, hpol η may play a role in correct bypass of the cross-links.
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Affiliation(s)
- Laureen C Colis
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA
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22
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Carlson KD, Johnson RE, Prakash L, Prakash S, Washington MT. Human DNA polymerase kappa forms nonproductive complexes with matched primer termini but not with mismatched primer termini. Proc Natl Acad Sci U S A 2006; 103:15776-81. [PMID: 17043239 PMCID: PMC1635079 DOI: 10.1073/pnas.0605785103] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Indexed: 11/18/2022] Open
Abstract
Human DNA polymerase kappa (pol kappa) is a member of the Y family of DNA polymerases that function in translesion synthesis. It synthesizes DNA with moderate fidelity and does not efficiently incorporate nucleotides opposite DNA lesions. Pol kappa has the unusual ability to efficiently extend from mismatched primer termini, and it extends readily from nucleotides inserted by other DNA polymerases opposite a variety of DNA lesions. All of this has suggested that pol kappa functions during the extension step of translesion synthesis. Here, we have carried out pre-steady-state kinetic studies of pol kappa using DNA with matched and mismatched primer termini. Interestingly, we find that mismatches present only a modest kinetic barrier to nucleotide incorporation by pol kappa. Moreover, and quite surprisingly, active-site titrations revealed that the concentration of active pol kappa is very low with matched DNA, and from DNA trapping experiments we determined that this was due to the formation of nonproductive protein.DNA complexes. In marked contrast, we found that the concentration of active pol kappa was six-fold greater with mismatched DNA than with matched DNA. Thus, pol kappa forms nonproductive complexes with matched but not with mismatched DNA. From these observations, we conclude that pol kappa has evolved to specifically function on DNA substrates with aberrant primer-terminal base pairs, such as the ones it would encounter during the extension step of translesion synthesis.
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Affiliation(s)
- Karissa D. Carlson
- *Department of Biochemistry, University of Iowa College of Medicine, 51 Newton Road, Iowa City, IA 52242-1109; and
| | - Robert E. Johnson
- Sealy Center for Molecular Science, University of Texas Medical Branch, 6.104 Blocker Medical Research Building, 11th and Mechanic Streets, Galveston, TX 77555-1061
| | - Louise Prakash
- Sealy Center for Molecular Science, University of Texas Medical Branch, 6.104 Blocker Medical Research Building, 11th and Mechanic Streets, Galveston, TX 77555-1061
| | - Satya Prakash
- Sealy Center for Molecular Science, University of Texas Medical Branch, 6.104 Blocker Medical Research Building, 11th and Mechanic Streets, Galveston, TX 77555-1061
| | - M. Todd Washington
- *Department of Biochemistry, University of Iowa College of Medicine, 51 Newton Road, Iowa City, IA 52242-1109; and
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Ghosal G, Muniyappa K. Hoogsteen base-pairing revisited: resolving a role in normal biological processes and human diseases. Biochem Biophys Res Commun 2006; 343:1-7. [PMID: 16540083 DOI: 10.1016/j.bbrc.2006.02.148] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 02/24/2006] [Indexed: 01/21/2023]
Abstract
For a long time since the discovery of an alternative type of hydrogen bonding between adenine and thymidine, termed Hoogsteen base-pairing, its biological role remained elusive. Recent experiments provide compelling evidence that Hoogsteen base pairs manifest in a gamut of nuclear processes encompassing gene expression, replication, recombination, and telomere length maintenance. An increasing number of proteins that have been shown to bind, unwind or cleave G-quadruplexes or triplexes with high specificity underscore their biological significance. In humans, the absence of these cellular factors or their dysfunction leads to a wide spectrum of genetic diseases including cancer, neurodegenerative syndromes, and a myriad of other disorders. Thus, development of clinically useful compounds that target G-quadruplexes or triplexes, and interfere with specific cellular processes, provides considerable promise for successful and improved treatment of human diseases.
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Affiliation(s)
- Gargi Ghosal
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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24
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Johnson RE, Prakash L, Prakash S. Yeast and human translesion DNA synthesis polymerases: expression, purification, and biochemical characterization. Methods Enzymol 2006; 408:390-407. [PMID: 16793382 DOI: 10.1016/s0076-6879(06)08024-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The emergence of translesion DNA synthesis (TLS) as a primary mechanism by which eukaryotic cells tolerate DNA damage has led to a large effort to characterize the biochemical properties of the individual DNA polymerases and their roles in promoting replication past DNA lesions. The low-fidelity Y family DNA polymerases constitute a large proportion of TLS polymerases, and four of the five subfamilies of this class of polymerases are represented in eukaryotes. The eukaryotic B family DNA polymerase Polzeta also functions in TLS. We have had success in expressing and purifying these TLS polymerases from yeast cells, sometimes in milligram quantities. The purified proteins have been used to determine their ability to synthesize DNA on various modified templates and to analyze the kinetic efficiencies with which bypass occurs. Purified proteins have also been used to determine the X-ray crystal structures of several Y-family DNA polymerases. This chapter describes a general outline of methods used in our laboratory for the expression and purification of these TLS DNA polymerases from yeast cells and for assaying some of their biochemical properties.
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Affiliation(s)
- Robert E Johnson
- Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston, USA
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25
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Zang H, Irimia A, Choi JY, Angel KC, Loukachevitch LV, Egli M, Guengerich FP. Efficient and high fidelity incorporation of dCTP opposite 7,8-dihydro-8-oxodeoxyguanosine by Sulfolobus solfataricus DNA polymerase Dpo4. J Biol Chem 2005; 281:2358-72. [PMID: 16306039 DOI: 10.1074/jbc.m510889200] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA polymerases insert dATP opposite the oxidative damage product 7,8-dihydro-8-oxodeoxyguanosine (8-oxoG) instead of dCTP, to the extent of >90% with some polymerases. Steady-state kinetics with the Y-family Sulfolobus solfataricus DNA polymerase IV (Dpo4) showed 90-fold higher incorporation efficiency of dCTP > dATP opposite 8-oxoG and 4-fold higher efficiency of extension beyond an 8-oxoG:C pair than an 8-oxoG:A pair. The catalytic efficiency for these events (with dCTP or C) was similar for G and 8-oxoG templates. Mass spectral analysis of extended DNA primers showed >/=95% incorporation of dCTP > dATP opposite 8-oxoG. Pre-steady-state kinetics showed faster rates of dCTP incorporation opposite 8-oxoG than G. The measured K(d)(,dCTP) was 15-fold lower for an oligonucleotide containing 8-oxoG than with G. Extension beyond an 8-oxoG:C pair was similar to G:C and faster than for an 8-oxoG:A pair, in contrast to other polymerases. The E(a) for dCTP insertion opposite 8-oxoG was lower than for opposite G. Crystal structures of Dpo4 complexes with oligonucleotides were solved with C, A, and G nucleoside triphosphates placed opposite 8-oxoG. With ddCTP, dCTP, and dATP the phosphodiester bonds were formed even in the presence of Ca(2+). The 8-oxoG:C pair showed classic Watson-Crick geometry; the 8-oxoG:A pair was in the syn:anti configuration, with the A hybridized in a Hoogsteen pair with 8-oxoG. With dGTP placed opposite 8-oxoG, pairing was not to the 8-oxoG but to the 5' C (and in classic Watson-Crick geometry), consistent with the low frequency of this frameshift event observed in the catalytic assays.
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Affiliation(s)
- Hong Zang
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, 638 Robinson Research Building, 23rd and Pierce Avenues, Nashville, TN 37232-0146, USA
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