1
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Mulye M, Singh MI, Jain V. From Processivity to Genome Maintenance: The Many Roles of Sliding Clamps. Genes (Basel) 2022; 13:2058. [PMID: 36360296 PMCID: PMC9690074 DOI: 10.3390/genes13112058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/03/2022] [Accepted: 11/04/2022] [Indexed: 07/30/2023] Open
Abstract
Sliding clamps play a pivotal role in the process of replication by increasing the processivity of the replicative polymerase. They also serve as an interacting platform for a plethora of other proteins, which have an important role in other DNA metabolic processes, including DNA repair. In other words, clamps have evolved, as has been correctly referred to, into a mobile "tool-belt" on the DNA, and provide a platform for several proteins that are involved in maintaining genome integrity. Because of the central role played by the sliding clamp in various processes, its study becomes essential and relevant in understanding these processes and exploring the protein as an important drug target. In this review, we provide an updated report on the functioning, interactions, and moonlighting roles of the sliding clamps in various organisms and its utilization as a drug target.
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Affiliation(s)
- Meenakshi Mulye
- Correspondence: (M.M.); (V.J.); Tel.: +91-755-269-1425 (V.J.); Fax: +91-755-269-2392 (V.J.)
| | | | - Vikas Jain
- Correspondence: (M.M.); (V.J.); Tel.: +91-755-269-1425 (V.J.); Fax: +91-755-269-2392 (V.J.)
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2
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Chu X, Suo Z, Wang J. Investigating the Conformational Dynamics of a Y-Family DNA Polymerase during Its Folding and Binding to DNA and a Nucleotide. JACS AU 2022; 2:341-356. [PMID: 35252985 PMCID: PMC8889613 DOI: 10.1021/jacsau.1c00368] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Indexed: 06/14/2023]
Abstract
During DNA polymerization, the Y-family DNA polymerases are capable of bypassing various DNA damage, which can stall the replication fork progression. It has been well acknowledged that the structures of the Y-family DNA polymerases have been naturally evolved to undertake this vital task. However, the mechanisms of how these proteins utilize their unique structural and conformational dynamical features to perform the translesion DNA synthesis are less understood. Here, we developed structure-based models to study the precatalytic DNA polymerization process, including DNA and nucleotide binding to DPO4, a paradigmatic Y-family polymerase from Sulfolobus solfataricus. We studied the interplay between the folding and the conformational dynamics of DPO4 and found that DPO4 undergoes first unraveling (unfolding) and then folding for accomplishing the functional "open-to-closed" conformational transition. DNA binding dynamically modulates the conformational equilibrium in DPO4 during the stepwise binding through different types of interactions, leading to different conformational distributions of DPO4 at different DNA binding stages. We observed that nucleotide binding induces modulation of a few contacts surrounding the active site of the DPO4-DNA complex associated with a high free energy barrier. Our simulation results resonate with the experimental evidence that the conformational change at the active site led by nucleotide is the rate-limiting step of nucleotide incorporation. In combination with localized frustration analyses, we underlined the importance of DPO4 conformational dynamics and fluctuations in facilitating DNA and nucleotide binding. Our findings offer mechanistic insights into the processes of DPO4 conformational dynamics associated with the substrate binding and contribute to the understanding of the "structure-dynamics-function" relationship in the Y-family DNA polymerases.
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Affiliation(s)
- Xiakun Chu
- Department
of Chemistry, State University of New York
at Stony Brook, Stony
Brook, New York 11794, United States
| | - Zucai Suo
- Department
of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, United States
| | - Jin Wang
- Department
of Chemistry, State University of New York
at Stony Brook, Stony
Brook, New York 11794, United States
- Department
of Physics and Astronomy, State University
of New York at Stony Brook, Stony Brook, New York 11794, United States
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3
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Wu Y, Jaremko WJ, Wilson RC, Pata JD. Heterotrimeric PCNA increases the activity and fidelity of Dbh, a Y-family translesion DNA polymerase prone to creating single-base deletion mutations. DNA Repair (Amst) 2020; 96:102967. [PMID: 32961405 DOI: 10.1016/j.dnarep.2020.102967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/18/2020] [Accepted: 08/31/2020] [Indexed: 11/15/2022]
Abstract
Dbh is a Y-family translesion DNA polymerase from Sulfolobus acidocaldarius, an archaeal species that grows in harsh environmental conditions. Biochemically, Dbh displays a distinctive mutational profile, creating single-base deletion mutations at extraordinarily high frequencies (up to 50 %) in specific repeat sequences. In cells, however, Dbh does not appear to contribute significantly to spontaneous frameshifts in these same sequence contexts. This suggests that either the error-prone DNA synthesis activity of Dbh is reduced in vivo and/or Dbh is restricted from replicating these sequences. Here, we test the hypothesis that the propensity for Dbh to make single base deletion mutations is reduced through interaction with the S. acidocaldarius heterotrimeric sliding clamp processivity factor, PCNA-123. We first confirm that Dbh physically interacts with PCNA-123, with the interaction requiring both the PCNA-1 subunit and the C-terminal 10 amino acids of Dbh, which contain a predicted PCNA-interaction peptide (PIP) motif. This interaction stimulates the polymerase activity of Dbh, even on short, linear primer-template DNA, by increasing the rate of nucleotide incorporation. This stimulation requires an intact PCNA-123 heterotrimer and a DNA duplex length of at least 18 basepairs, the minimal length predicted from structural data to bind to both the polymerase and the clamp. Finally, we find that PCNA-123 increases the fidelity of Dbh on a single-base deletion hotspot sequence 3-fold by promoting an increase in the rate of correct, but not incorrect, nucleotide addition and propose that PCNA-123 induces Dbh to adopt a more active conformation that is less prone to creating deletions during DNA synthesis.
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Affiliation(s)
- Yifeng Wu
- Wadsworth Center, New York State Department of Health, Albany, NY, United States; Department of Biomedical Sciences, University at Albany, Albany, NY, United States
| | - William J Jaremko
- Wadsworth Center, New York State Department of Health, Albany, NY, United States
| | - Ryan C Wilson
- Wadsworth Center, New York State Department of Health, Albany, NY, United States
| | - Janice D Pata
- Wadsworth Center, New York State Department of Health, Albany, NY, United States; Department of Biomedical Sciences, University at Albany, Albany, NY, United States.
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4
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van Bostelen I, van Schendel R, Romeijn R, Tijsterman M. Translesion synthesis polymerases are dispensable for C. elegans reproduction but suppress genome scarring by polymerase theta-mediated end joining. PLoS Genet 2020; 16:e1008759. [PMID: 32330130 PMCID: PMC7202663 DOI: 10.1371/journal.pgen.1008759] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/06/2020] [Accepted: 04/06/2020] [Indexed: 12/30/2022] Open
Abstract
Bases within DNA are frequently damaged, producing obstacles to efficient and accurate DNA replication by replicative polymerases. Translesion synthesis (TLS) polymerases, via their ability to catalyze nucleotide additions to growing DNA chains across DNA lesions, promote replication of damaged DNA, thus preventing checkpoint activation, genome instability and cell death. In this study, we used C. elegans to determine the contribution of TLS activity on long-term stability of an animal genome. We monitored and compared the types of mutations that accumulate in REV1, REV3, POLH1 and POLK deficient animals that were grown under unchallenged conditions. We also addressed redundancies in TLS activity by combining all deficiencies. Remarkably, animals that are deficient for all Y-family polymerases as well as animals that have lost all TLS activity are viable and produce progeny, demonstrating that TLS is not essential for animal life. Whole genome sequencing analyses, however, reveal that TLS is needed to prevent genomic scars from accumulating. These scars, which are the product of polymerase theta-mediated end joining (TMEJ), are found overrepresented at guanine bases, consistent with TLS suppressing DNA double-strand breaks (DSBs) from occurring at replication-blocking guanine adducts. We found that in C. elegans, TLS across spontaneous damage is predominantly error free and anti-clastogenic, and thus ensures preservation of genetic information.
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Affiliation(s)
- Ivo van Bostelen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ron Romeijn
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
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5
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Quinet A, Lerner LK, Martins DJ, Menck CFM. Filling gaps in translesion DNA synthesis in human cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 836:127-142. [PMID: 30442338 DOI: 10.1016/j.mrgentox.2018.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 02/21/2018] [Indexed: 01/06/2023]
Abstract
During DNA replication, forks may encounter unrepaired lesions that hamper DNA synthesis. Cells have universal strategies to promote damage bypass allowing cells to survive. DNA damage tolerance can be performed upon template switch or by specialized DNA polymerases, known as translesion (TLS) polymerases. Human cells count on more than eleven TLS polymerases and this work reviews the functions of some of these enzymes: Rev1, Pol η, Pol ι, Pol κ, Pol θ and Pol ζ. The mechanisms of damage bypass vary according to the lesion, as well as to the TLS polymerases available, and may occur directly at the fork during replication. Alternatively, the lesion may be skipped, leaving a single-stranded DNA gap that will be replicated later. Details of the participation of these enzymes are revised for the replication of damaged template. TLS polymerases also have functions in other cellular processes. These include involvement in somatic hypermutation in immunoglobulin genes, direct participation in recombination and repair processes, and contributing to replicating noncanonical DNA structures. The importance of DNA damage replication to cell survival is supported by recent discoveries that certain genes encoding TLS polymerases are induced in response to DNA damaging agents, protecting cells from a subsequent challenge to DNA replication. We retrace the findings on these genotoxic (adaptive) responses of human cells and show the common aspects with the SOS responses in bacteria. Paradoxically, although TLS of DNA damage is normally an error prone mechanism, in general it protects from carcinogenesis, as evidenced by increased tumorigenesis in xeroderma pigmentosum variant patients, who are deficient in Pol η. As these TLS polymerases also promote cell survival, they constitute an important mechanism by which cancer cells acquire resistance to genotoxic chemotherapy. Therefore, the TLS polymerases are new potential targets for improving therapy against tumors.
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Affiliation(s)
- Annabel Quinet
- Saint Louis University School of Medicine, St. Louis, MO, United States.
| | - Leticia K Lerner
- MRC Laboratory of Molecular Biology,Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Davi J Martins
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Carlos F M Menck
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
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6
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Raper AT, Reed AJ, Gadkari VV, Suo Z. Advances in Structural and Single-Molecule Methods for Investigating DNA Lesion Bypass and Repair Polymerases. Chem Res Toxicol 2016; 30:260-269. [PMID: 28092942 DOI: 10.1021/acs.chemrestox.6b00342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Innovative advances in X-ray crystallography and single-molecule biophysics have yielded unprecedented insight into the mechanisms of DNA lesion bypass and damage repair. Time-dependent X-ray crystallography has been successfully applied to view the bypass of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxoG), a major oxidative DNA lesion, and the incorporation of the triphosphate form, 8-oxo-dGTP, catalyzed by human DNA polymerase β. Significant findings of these studies are highlighted here, and their contributions to the current mechanistic understanding of mutagenic translesion DNA synthesis (TLS) and base excision repair are discussed. In addition, single-molecule Förster resonance energy transfer (smFRET) techniques have recently been adapted to investigate nucleotide binding and incorporation opposite undamaged dG and 8-oxoG by Sulfolobus solfataricus DNA polymerase IV (Dpo4), a model Y-family DNA polymerase. The mechanistic response of Dpo4 to a DNA lesion and the complex smFRET technique are described here. In this perspective, we also describe how time-dependent X-ray crystallography and smFRET can be used to achieve the spatial and temporal resolutions necessary to answer some of the mechanistic questions that remain in the fields of TLS and DNA damage repair.
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Affiliation(s)
- Austin T Raper
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Andrew J Reed
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Varun V Gadkari
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
| | - Zucai Suo
- Department of Chemistry and Biochemistry and The Ohio State Biochemistry Program, The Ohio State University , Columbus, Ohio 43210, United States
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7
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Quinet A, Martins DJ, Vessoni AT, Biard D, Sarasin A, Stary A, Menck CFM. Translesion synthesis mechanisms depend on the nature of DNA damage in UV-irradiated human cells. Nucleic Acids Res 2016; 44:5717-31. [PMID: 27095204 PMCID: PMC4937316 DOI: 10.1093/nar/gkw280] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 04/06/2016] [Indexed: 12/17/2022] Open
Abstract
Ultraviolet-induced 6-4 photoproducts (6-4PP) and cyclobutane pyrimidine dimers (CPD) can be tolerated by translesion DNA polymerases (TLS Pols) at stalled replication forks or by gap-filling. Here, we investigated the involvement of Polη, Rev1 and Rev3L (Polζ catalytic subunit) in the specific bypass of 6-4PP and CPD in repair-deficient XP-C human cells. We combined DNA fiber assay and novel methodologies for detection and quantification of single-stranded DNA (ssDNA) gaps on ongoing replication forks and postreplication repair (PRR) tracts in the human genome. We demonstrated that Rev3L, but not Rev1, is required for postreplicative gap-filling, while Polη and Rev1 are responsible for TLS at stalled replication forks. Moreover, specific photolyases were employed to show that in XP-C cells, CPD arrest replication forks, while 6-4PP are responsible for the generation of ssDNA gaps and PRR tracts. On the other hand, in the absence of Polη or Rev1, both types of lesion block replication forks progression. Altogether, the data directly show that, in the human genome, Polη and Rev1 bypass CPD and 6-4PP at replication forks, while only 6-4PP are also tolerated by a Polζ-dependent gap-filling mechanism, independent of S phase.
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Affiliation(s)
- Annabel Quinet
- Institute of Biomedical Sciences, University of São Paulo, SP, 05508-000, Brazil
| | - Davi Jardim Martins
- Institute of Biomedical Sciences, University of São Paulo, SP, 05508-000, Brazil
| | | | - Denis Biard
- CEA, IMETI, SEPIA, Team Cellular Engineering and Human Syndromes, F-92265 Fontenay-aux-Roses, France
| | - Alain Sarasin
- CNRS-UMR8200, Université Paris Sud, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France
| | - Anne Stary
- CNRS-UMR8200, Université Paris Sud, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France
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8
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Gao X, Dan S, Xie Y, Qin H, Tang D, Liu X, He QY, Liu L. 14-3-3ζ reduces DNA damage by interacting with and stabilizing proliferating cell nuclear antigen. J Cell Biochem 2016; 116:158-69. [PMID: 25169136 DOI: 10.1002/jcb.24955] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 08/22/2014] [Indexed: 01/16/2023]
Abstract
Proliferating cell nuclear antigen (PCNA) is a processivity factor of DNA replication which plays critical roles in the regulation of DNA replication and repair. In this study, we show that PCNA interacts directly in vitro and in cells with 14-3-3ζ, an adaptor protein that regulates cell growth and response to DNA damage in eukaryotes. The interaction is mediated by at least two PCNA-binding sites on 14-3-3ζ, one of which is a novel non-canonical PIP (PCNA interacting protein) box. We find that DNA damages induced by UVC irradiation and MMS (methyl methanesulfonate) can enhance both the interaction of these two proteins and their co-localization with chromatin. Functional analyses suggest that 14-3-3ζ stabilizes PCNA possibly by regulating its ubiquitination, which impacts on DNA damage repair and cell viability.
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Affiliation(s)
- Xuejuan Gao
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou, 510632, China
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9
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HUS1 regulates in vivo responses to genotoxic chemotherapies. Oncogene 2015; 35:662-9. [PMID: 25915840 DOI: 10.1038/onc.2015.118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 03/08/2015] [Accepted: 03/10/2015] [Indexed: 12/14/2022]
Abstract
Cells are under constant attack from genotoxins and rely on a multifaceted DNA damage response (DDR) network to maintain genomic integrity. Central to the DDR are the ATM and ATR kinases, which respond primarily to double-strand DNA breaks (DSBs) and replication stress, respectively. Optimal ATR signaling requires the RAD9A-RAD1-HUS1 (9-1-1) complex, a toroidal clamp that is loaded at damage sites and scaffolds signaling and repair factors. Whereas complete ATR pathway inactivation causes embryonic lethality, partial Hus1 impairment has been accomplished in adult mice using hypomorphic (Hus1(neo)) and null (Hus1(Δ1)) Hus1 alleles, and here we use this system to define the tissue- and cell type-specific actions of the HUS1-mediated DDR in vivo. Hus1(neo/Δ1) mice showed hypersensitivity to agents that cause replication stress, including the crosslinking agent mitomycin C (MMC) and the replication inhibitor hydroxyurea, but not the DSB inducer ionizing radiation. Analysis of tissue morphology, genomic instability, cell proliferation and apoptosis revealed that MMC treatment caused severe damage in highly replicating tissues of mice with partial Hus1 inactivation. The role of the 9-1-1 complex in responding to MMC was partially ATR-independent, as a HUS1 mutant that was proficient for ATR-induced checkpoint kinase 1 phosphorylation nevertheless conferred MMC hypersensitivity. To assess the interplay between the ATM and ATR pathways in responding to replication stress in vivo, we used Hus1/Atm double mutant mice. Whereas Hus1(neo/neo) and Atm(-/-) single mutant mice survived low-dose MMC similar to wild-type controls, Hus1(neo/neo)Atm(-/-) double mutants showed striking MMC hypersensitivity, consistent with a model in which MMC exposure in the context of Hus1 dysfunction results in DSBs to which the ATM pathway normally responds. This improved understanding of the inter-dependency between two major DDR mechanisms during the response to a conventional chemotherapeutic illustrates how inhibition of checkpoint factors such as HUS1 may be effective for the treatment of ATM-deficient and other cancers.
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10
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Wright CM, van der Merwe M, DeBrot AH, Bjornsti MA. DNA topoisomerase I domain interactions impact enzyme activity and sensitivity to camptothecin. J Biol Chem 2015; 290:12068-78. [PMID: 25795777 DOI: 10.1074/jbc.m114.635078] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Indexed: 11/06/2022] Open
Abstract
During processes such as DNA replication and transcription, DNA topoisomerase I (Top1) catalyzes the relaxation of DNA supercoils. The nuclear enzyme is also the cellular target of camptothecin (CPT) chemotherapeutics. Top1 contains four domains: the highly conserved core and C-terminal domains involved in catalysis, a coiled-coil linker domain of variable length, and a poorly conserved N-terminal domain. Yeast and human Top1 share a common reaction mechanism and domain structure. However, the human Top1 is ∼100-fold more sensitive to CPT. Moreover, substitutions of a conserved Gly(717) residue, which alter intrinsic enzyme sensitivity to CPT, induce distinct phenotypes in yeast. To address the structural basis for these differences, reciprocal swaps of yeast and human Top1 domains were engineered in chimeric enzymes. Here we report that intrinsic Top1 sensitivity to CPT is dictated by the composition of the conserved core and C-terminal domains. However, independent of CPT, biochemically similar chimeric enzymes produced strikingly distinct phenotypes in yeast. Expression of a human Top1 chimera containing the yeast linker domain proved toxic, even in the context of a catalytically inactive Y723F enzyme. Lethality was suppressed either by splicing the yeast N-terminal domain into the chimera, deleting the human N-terminal residues, or in enzymes reconstituted by polypeptide complementation. These data demonstrate a functional interaction between the N-terminal and linker domains, which, when mispaired between yeast and human enzymes, induces cell lethality. Because toxicity was independent of enzyme catalysis, the inappropriate coordination of N-terminal and linker domains may induce aberrant Top1-protein interactions to impair cell growth.
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Affiliation(s)
- Christine M Wright
- From the Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Marié van der Merwe
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Amanda H DeBrot
- From the Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Mary-Ann Bjornsti
- From the Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
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11
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Jansen JG, Tsaalbi-Shtylik A, de Wind N. Roles of mutagenic translesion synthesis in mammalian genome stability, health and disease. DNA Repair (Amst) 2015; 29:56-64. [PMID: 25655219 DOI: 10.1016/j.dnarep.2015.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/22/2014] [Accepted: 01/07/2015] [Indexed: 01/08/2023]
Abstract
Most spontaneous and DNA damage-induced nucleotide substitutions in eukaryotes depend on translesion synthesis polymerases Rev1 and Pol ζ, the latter consisting of the catalytic subunit Rev3 and the accessory protein Rev7. Here we review the regulation, and the biochemical and cellular functions, of Rev1/Pol ζ-dependent translesion synthesis. These are correlated with phenotypes of mouse models with defects in Rev1, Rev3 or Rev7. The data indicate that Rev1/Pol ζ-mediated translesion synthesis is important for adaptive immunity while playing paradoxical roles in oncogenesis. On the other hand, by enabling the replication of endogenously damaged templates, Rev1/Pol ζ -dependent translesion synthesis protects stem cells, thereby preventing features of ageing. In conclusion, Rev1/Pol ζ-dependent translesion synthesis at DNA helix-distorting nucleotide lesions orchestrates pleiotropic responses that determine organismal fitness and disease.
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Affiliation(s)
- Jacob G Jansen
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Anastasia Tsaalbi-Shtylik
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Niels de Wind
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands.
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12
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Wit N, Buoninfante OA, van den Berk PCM, Jansen JG, Hogenbirk MA, de Wind N, Jacobs H. Roles of PCNA ubiquitination and TLS polymerases κ and η in the bypass of methyl methanesulfonate-induced DNA damage. Nucleic Acids Res 2014; 43:282-94. [PMID: 25505145 PMCID: PMC4288191 DOI: 10.1093/nar/gku1301] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Translesion synthesis (TLS) provides a highly conserved mechanism that enables DNA synthesis on a damaged template. TLS is performed by specialized DNA polymerases of which polymerase (Pol) κ is important for the cellular response to DNA damage induced by benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), ultraviolet (UV) light and the alkylating agent methyl methanesulfonate (MMS). As TLS polymerases are intrinsically error-prone, tight regulation of their activity is required. One level of control is provided by ubiquitination of the homotrimeric DNA clamp PCNA at lysine residue 164 (PCNA-Ub). We here show that Polκ can function independently of PCNA modification and that Polη can function as a backup during TLS of MMS-induced lesions. Compared to cell lines deficient for PCNA modification (Pcna(K164R)) or Polκ, double mutant cell lines display hypersensitivity to MMS but not to BPDE or UV-C. Double mutant cells also displayed delayed post-replicative TLS, accumulate higher levels of replication stress and delayed S-phase progression. Furthermore, we show that Polη and Polκ are redundant in the DNA damage bypass of MMS-induced DNA damage. Taken together, we provide evidence for PCNA-Ub-independent activation of Polκ and establish Polη as an important backup polymerase in the absence of Polκ in response to MMS-induced DNA damage.
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Affiliation(s)
- Niek Wit
- Division of Biological Stress Responses, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | - Paul C M van den Berk
- Division of Biological Stress Responses, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Jacob G Jansen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marc A Hogenbirk
- Division of Biological Stress Responses, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Niels de Wind
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Heinz Jacobs
- Division of Biological Stress Responses, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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13
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Dynamic conformational change regulates the protein-DNA recognition: an investigation on binding of a Y-family polymerase to its target DNA. PLoS Comput Biol 2014; 10:e1003804. [PMID: 25188490 PMCID: PMC4154647 DOI: 10.1371/journal.pcbi.1003804] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/10/2014] [Indexed: 12/02/2022] Open
Abstract
Protein-DNA recognition is a central biological process that governs the life of cells. A protein will often undergo a conformational transition to form the functional complex with its target DNA. The protein conformational dynamics are expected to contribute to the stability and specificity of DNA recognition and therefore may control the functional activity of the protein-DNA complex. Understanding how the conformational dynamics influences the protein-DNA recognition is still challenging. Here, we developed a two-basin structure-based model to explore functional dynamics in Sulfolobus solfataricus DNA Y-family polymerase IV (DPO4) during its binding to DNA. With explicit consideration of non-specific and specific interactions between DPO4 and DNA, we found that DPO4-DNA recognition is comprised of first 3D diffusion, then a short-range adjustment sliding on DNA and finally specific binding. Interestingly, we found that DPO4 is under a conformational equilibrium between multiple states during the binding process and the distributions of the conformations vary at different binding stages. By modulating the strength of the electrostatic interactions, the flexibility of the linker, and the conformational dynamics in DPO4, we drew a clear picture on how DPO4 dynamically regulates the DNA recognition. We argue that the unique features of flexibility and conformational dynamics in DPO4-DNA recognition have direct implications for low-fidelity translesion DNA synthesis, most of which is found to be accomplished by the Y-family DNA polymerases. Our results help complete the description of the DNA synthesis process for the Y-family polymerases. Furthermore, the methods developed here can be widely applied for future investigations on how various proteins recognize and bind specific DNA substrates. Protein-DNA recognition is crucial for many key biological processes in cells. Protein often undergoes large-scale conformational change during DNA recognition. However, the physical and global understanding of flexible protein-DNA binding is still challenging. Here, we developed a theoretical approach to investigate binding of a Y-family DNA polymerase to its target DNA during the DNA synthesis process. The results of electrostatic-controlled multi-step DNA binding process accompanied with multi-state conformational transition of protein occurring throughout are in remarkable agreement with experiments. During the process of protein-DNA recognition, the flexibility is found to facilitate both the conformational transition of protein (intra-chain dynamics) and DNA binding (inter-chain dynamics) simultaneously. Therefore, we provided a quantitative description of protein-DNA binding mechanism that flexibility or conformational change regulates DNA recognition dynamically, leading to high efficiency and specificity of function for protein-DNA recognition.
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14
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Quinet A, Vessoni AT, Rocha CRR, Gottifredi V, Biard D, Sarasin A, Menck CFM, Stary A. Gap-filling and bypass at the replication fork are both active mechanisms for tolerance of low-dose ultraviolet-induced DNA damage in the human genome. DNA Repair (Amst) 2013; 14:27-38. [PMID: 24380689 DOI: 10.1016/j.dnarep.2013.12.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 11/26/2013] [Accepted: 12/10/2013] [Indexed: 10/25/2022]
Abstract
Ultraviolet (UV)-induced DNA damage are removed by nucleotide excision repair (NER) or can be tolerated by specialized translesion synthesis (TLS) polymerases, such as Polη. TLS may act at stalled replication forks or through an S-phase independent gap-filling mechanism. After UVC irradiation, Polη-deficient (XP-V) human cells were arrested in early S-phase and exhibited both single-strand DNA (ssDNA) and prolonged replication fork stalling, as detected by DNA fiber assay. In contrast, NER deficiency in XP-C cells caused no apparent defect in S-phase progression despite the accumulation of ssDNA and a G2-phase arrest. These data indicate that while Polη is essential for DNA synthesis at ongoing damaged replication forks, NER deficiency might unmask the involvement of tolerance pathway through a gap-filling mechanism. ATR knock down by siRNA or caffeine addition provoked increased cell death in both XP-V and XP-C cells exposed to low-dose of UVC, underscoring the involvement of ATR/Chk1 pathway in both DNA damage tolerance mechanisms. We generated a unique human cell line deficient in XPC and Polη proteins, which exhibited both S- and G2-phase arrest after UVC irradiation, consistent with both single deficiencies. In these XP-C/Polη(KD) cells, UVC-induced replicative intermediates may collapse into double-strand breaks, leading to cell death. In conclusion, both TLS at stalled replication forks and gap-filling are active mechanisms for the tolerance of UVC-induced DNA damage in human cells and the preference for one or another pathway depends on the cellular genotype.
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Affiliation(s)
- Annabel Quinet
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil; CNRS-UMR8200, Université Paris Sud, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France.
| | - Alexandre T Vessoni
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil.
| | - Clarissa R R Rocha
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil.
| | | | - Denis Biard
- CEA, DSV-iMETI-SEPIA, BP6, 92265 Fontenay-aux-Roses, France.
| | - Alain Sarasin
- CNRS-UMR8200, Université Paris Sud, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France.
| | - Carlos F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil.
| | - Anne Stary
- CNRS-UMR8200, Université Paris Sud, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France.
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15
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Abstract
The structural features that enable replicative DNA polymerases to synthesize DNA rapidly and accurately also limit their ability to copy damaged DNA. Direct replication of DNA damage is termed translesion synthesis (TLS), a mechanism conserved from bacteria to mammals and executed by an array of specialized DNA polymerases. This chapter examines how these translesion polymerases replicate damaged DNA and how they are regulated to balance their ability to replicate DNA lesions with the risk of undesirable mutagenesis. It also discusses how TLS is co-opted to increase the diversity of the immunoglobulin gene hypermutation and the contribution it makes to the mutations that sculpt the genome of cancer cells.
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Affiliation(s)
- Julian E Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom.
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16
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Abstract
Rad9 plays a crucial role in maintaining genomic stability by regulating cell cycle checkpoints, DNA repair, telomere stability, and apoptosis. Rad9 controls these processes mainly as part of the heterotrimeric 9-1-1 (Rad9-Hus1-Rad1) complex. However, in recent years it has been demonstrated that Rad9 can also act independently of the 9-1-1 complex as a transcriptional factor, participate in immunoglobulin class switch recombination, and show 3'-5' exonuclease activity. Aberrant Rad9 expression has been associated with prostate, breast, lung, skin, thyroid, and gastric cancers. High expression of Rad9 is causally related to, at least, human prostate cancer growth. On the other hand, deletion of Mrad9, the mouse homolog, is responsible for increased skin cancer incidence. These results reveal that Rad9 can act as an oncogene or tumor suppressor. Which of the many functions of Rad9 are causally related to initiation and progression of tumorigenesis and the mechanistic details by which Rad9 induces or suppresses tumorigenesis are presently not known, but are crucial for the development of targeted therapeutic interventions.
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Affiliation(s)
- Constantinos G Broustas
- Center for Radiological Research, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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17
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Wong RP, Aguissa-Touré AH, Wani AA, Khosravi S, Martinka M, Martinka M, Li G. Elevated expression of Rad18 regulates melanoma cell proliferation. Pigment Cell Melanoma Res 2012; 25:213-8. [DOI: 10.1111/j.1755-148x.2011.00948.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Collura A, Kemp PAVD, Boiteux S. Abasic sites linked to dUTP incorporation in DNA are a major cause of spontaneous mutations in absence of base excision repair and Rad17-Mec3-Ddc1 (9-1-1) DNA damage checkpoint clamp in Saccharomyces cerevisiae. DNA Repair (Amst) 2012; 11:294-303. [PMID: 22226374 DOI: 10.1016/j.dnarep.2011.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/21/2011] [Accepted: 12/09/2011] [Indexed: 12/28/2022]
Abstract
In Saccharomyces cerevisiae, inactivation of base excision repair (BER) AP endonucleases (Apn1p and Apn2p) results in constitutive phosphorylation of Rad53p and delay in cell cycle progression at the G2/M transition. These data led us to investigate genetic interactions between Apn1p, Apn2p and DNA damage checkpoint proteins. The results show that mec1 sml1, rad53 sml1 and rad9 is synthetic lethal with apn1 apn2. In contrast, apn1 apn2 rad17, apn1 apn2 ddc1 and apn1 apn2 rad24 triple mutants are viable, although they exhibit a strong Can(R) spontaneous mutator phenotype. In these strains, high Can(R) mutation rate is dependent upon functional uracil DNA N-glycosylase (Ung1p) and mutation spectra are dominated by AT to CG events. The results point to a role for Rad17-Mec3-Ddc1 (9-1-1) checkpoint clamp in the prevention of mutations caused by abasic (AP) sites linked to incorporation of dUTP into DNA followed by the excision of uracil by Ung1p. The antimutator role of the (9-1-1) clamp can either rely on its essential function in the induction of the DNA damage checkpoint or to another function that specifically impacts DNA repair and/or mutagenesis at AP sites. Here, we show that the abrogation of the DNA damage checkpoint is not sufficient to enhance spontaneous mutagenesis in the apn1 apn2 rad9 sml1 quadruple mutant. Spontaneous mutagenesis was also explored in strains deficient in the two major DNA N-glycosylases/AP-lyases (Ntg1p and Ntg2p). Indeed, apn1 apn2 ntg1 ntg2 exhibits a strong Ung1p-dependent Can(R) mutator phenotype with a spectrum enriched in AT to CG, like apn1 apn2 rad17. However, genetic analysis reveals that ntg1 ntg2 and rad17 are not epistatic for spontaneous mutagenesis in apn1 apn2. We conclude that under normal growth conditions, dUTP incorporation into DNA is a major source of AP sites that cause high genetic instability in the absence of BER factors (Apn1p, Apn2p, Ntg1p and Ntg2p) and Rad17-Mec3-Ddc1 (9-1-1) checkpoint clamp in yeast.
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Affiliation(s)
- Ada Collura
- CEA, iRCM, 18 route du Panorama, 92265 Fontenay aux Roses, France.
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19
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Curtis MJ, Hays JB. Cooperative responses of DNA-damage-activated protein kinases ATR and ATM and DNA translesion polymerases to replication-blocking DNA damage in a stem-cell niche. DNA Repair (Amst) 2011; 10:1272-81. [PMID: 22018494 DOI: 10.1016/j.dnarep.2011.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 09/28/2011] [Accepted: 10/02/2011] [Indexed: 01/27/2023]
Abstract
Conserved DNA-damage responses (DDRs) efficiently cope with replication blocks and double-strand breaks (DSBs) in cultured eukaryotic cells; DDRs in tissues remain poorly understood. DDR-inactivating mutations lethal in animals are tolerated in Arabidopsis, whose root meristem provides a powerful stem-cell-niche model. We imaged UVB-induced death of specific meristem cells in single and double Arabidopsis mutants to elucidate cooperation among DNA translesion synthesis (TLS) polymerases (Polη, Polζ) and DNA-damage-activated protein kinases (ATR, ATM). Death was 100-fold higher in stem and progenitor (StPr) cells than in transiently amplifying cells. Quantitative analyses of dose-response plots showed that Polη and Polζ act redundantly to tolerate replication blocks and that Polζ-mediated TLS requires ATR. Deficient TLS resulted in ATM-signaled death, which first appeared 10-14h post-UVB. Although ssDNA downstream of blocks was likely cleaved into DSBs throughout S phase, death pathways appeared to initiate late in S. In atm mutants death appeared much later, likely signaled by a slow ATR-dependent pathway. To bypass replication blocks, tissues may use TLS rather than error-free pathways that could generate genomic aberrations. Dynamic balances among ATR and ATM death-avoidance and death-signaling functions determine how many DSB-burdened StPr cells are killed. Their replacement by less-burdened quiescent-center cells then restores growth homeostasis.
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Affiliation(s)
- Marc J Curtis
- Department of Environmental and Molecular Toxicology, Oregon State University, 1007 ALS, Campus Way, Corvallis, OR 97331, United States
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20
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López de Saro FJ. Regulation of interactions with sliding clamps during DNA replication and repair. Curr Genomics 2011; 10:206-15. [PMID: 19881914 PMCID: PMC2705854 DOI: 10.2174/138920209788185234] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 03/09/2009] [Accepted: 03/16/2009] [Indexed: 01/12/2023] Open
Abstract
The molecular machines that replicate the genome consist of many interacting components. Essential to the organization of the replication machinery are ring-shaped proteins, like PCNA (Proliferating Cell Nuclear Antigen) or the β- clamp, collectively named sliding clamps. They encircle the DNA molecule and slide on it freely and bidirectionally. Sliding clamps are typically associated to DNA polymerases and provide these enzymes with the processivity required to synthesize large chromosomes. Additionally, they interact with a large array of proteins that perform enzymatic reactions on DNA, targeting and orchestrating their functions. In recent years there have been a large number of studies that have analyzed the structural details of how sliding clamps interact with their ligands. However, much remains to be learned in relation to how these interactions are regulated to occur coordinately and sequentially. Since sliding clamps participate in reactions in which many different enzymes bind and then release from the clamp in an orchestrated way, it is critical to analyze how these changes in affinity take place. In this review I focus the attention on the mechanisms by which various types of enzymes interact with sliding clamps and what is known about the regulation of this binding. Especially I describe emerging paradigms on how enzymes switch places on sliding clamps during DNA replication and repair of prokaryotic and eukaryotic genomes.
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Affiliation(s)
- Francisco J López de Saro
- Laboratorio de Ecología Molecular, Centro de Astrobiología (CSIC-INTA), 28850 Torrejón de Ardoz, Madrid, Spain
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21
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de Groote FH, Jansen JG, Masuda Y, Shah DM, Kamiya K, de Wind N, Siegal G. The Rev1 translesion synthesis polymerase has multiple distinct DNA binding modes. DNA Repair (Amst) 2011; 10:915-25. [PMID: 21752727 DOI: 10.1016/j.dnarep.2011.04.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 03/25/2011] [Accepted: 04/27/2011] [Indexed: 11/17/2022]
Abstract
Rev1 is a eukaryotic DNA polymerase of the Y family involved in translesion synthesis (TLS), a major damage tolerance pathway that allows DNA replication at damaged templates. Uniquely amongst the Y family polymerases, the N-terminal part of Rev1, dubbed the BRCA1 C-terminal homology (BRCT) region, includes a BRCT domain. While most BRCT domains mediate protein-protein interactions, Rev1 contains a predicted α-helix N-terminal to the BRCT domain and in human Replication Factor C (RFC) such a BRCT region endows the protein with DNA binding capacity. Here, we studied the DNA binding properties of yeast and mouse Rev1. Our results show that the BRCT region of Rev1 specifically binds to a 5' phosphorylated, recessed, primer-template junction. This DNA binding depends on the extra α-helix, N-terminal to the BRCT domain. Surprisingly, a stretch of 20 amino acids N-terminal to the predicted α-helix is also critical for high-affinity DNA binding. In addition to 5' primer-template junction binding, Rev1 efficiently binds to a recessed 3' primer-template junction. These dual DNA binding characteristics are discussed in view of the proposed recruitment of Rev1 by 5' primer-template junctions, downstream of stalled replication forks.
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Affiliation(s)
- Frederik H de Groote
- Department of Protein Chemistry, Leiden Institute of Chemistry, Gorlaeus Laboratory, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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22
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Ho TV, Guainazzi A, Derkunt SB, Enoiu M, Schärer OD. Structure-dependent bypass of DNA interstrand crosslinks by translesion synthesis polymerases. Nucleic Acids Res 2011; 39:7455-64. [PMID: 21666254 PMCID: PMC3177197 DOI: 10.1093/nar/gkr448] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
DNA interstrand crosslinks (ICLs), inhibit DNA metabolism by covalently linking two strands of DNA and are formed by antitumor agents such as cisplatin and nitrogen mustards. Multiple complex repair pathways of ICLs exist in humans that share translesion synthesis (TLS) past a partially processed ICL as a common step. We have generated site-specific major groove ICLs and studied the ability of Y-family polymerases and Pol ζ to bypass ICLs that induce different degrees of distortion in DNA. Two main factors influenced the efficiency of ICL bypass: the length of the dsDNA flanking the ICL and the length of the crosslink bridging two bases. Our study shows that ICLs can readily be bypassed by TLS polymerases if they are appropriately processed and that the structure of the ICL influences which polymerases are able to read through it.
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Affiliation(s)
- The Vinh Ho
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-3400, USA
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23
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Krijger PH, Lee KY, Wit N, van den Berka PC, Wu X, Roest HP, Maas A, Ding H, Hoeijmakers JH, Myung K, Jacobs H. HLTF and SHPRH are not essential for PCNA polyubiquitination, survival and somatic hypermutation: existence of an alternative E3 ligase. DNA Repair (Amst) 2011; 10:438-44. [PMID: 21269891 PMCID: PMC3381732 DOI: 10.1016/j.dnarep.2010.12.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 11/24/2010] [Accepted: 12/21/2010] [Indexed: 12/11/2022]
Abstract
DNA damage tolerance is regulated at least in part at the level of proliferating cell nuclear antigen (PCNA) ubiquitination. Monoubiquitination (PCNA-Ub) at lysine residue 164 (K164) stimulates error-prone translesion synthesis (TLS), Rad5-dependent polyubiquitination (PCNA-Ub(n)) stimulates error-free template switching (TS). To generate high affinity antibodies by somatic hypermutation (SHM), B cells profit from error-prone TLS polymerases. Consistent with the role of PCNA-Ub in stimulating TLS, hypermutated B cells of PCNA(K164R) mutant mice display a defect in generating selective point mutations. Two Rad5 orthologs, HLTF and SHPRH have been identified as alternative E3 ligases generating PCNA-Ub(n) in mammals. As PCNA-Ub and PCNA-Ub(n) both make use of K164, error-free PCNA-Ub(n)-dependent TS may suppress error-prone PCNA-Ub-dependent TLS. To determine a regulatory role of Shprh and Hltf in SHM, we generated Shprh/Hltf double mutant mice. Interestingly, while the formation of PCNA-Ub and PCNA-Ub(n) is prohibited in PCNA(K164R) MEFs, the formation of PCNA-Ub(n) is not abolished in Shprh/Hltf mutant MEFs. In line with these observations Shprh/Hltf double mutant B cells were not hypersensitive to DNA damage. Furthermore, SHM was normal in Shprh/Hltf mutant B cells. These data suggest the existence of an alternative E3 ligase in the generation of PCNA-Ub(n).
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Affiliation(s)
- Peter H.L. Krijger
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Kyoo-Young Lee
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Niek Wit
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | | | - Xiaoli Wu
- Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada R3E OW3
| | - Henk P. Roest
- CBG, Department of Cell Biology and Genetics, Cancer Genomics Center, Erasmus Medical Center, 3015 GE, Rotterdam, The Netherlands
| | - Alex Maas
- CBG, Department of Cell Biology and Genetics, Cancer Genomics Center, Erasmus Medical Center, 3015 GE, Rotterdam, The Netherlands
| | - Hao Ding
- Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada R3E OW3
| | - Jan H.J. Hoeijmakers
- CBG, Department of Cell Biology and Genetics, Cancer Genomics Center, Erasmus Medical Center, 3015 GE, Rotterdam, The Netherlands
| | - Kyungjae Myung
- Genome Instability Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Heinz Jacobs
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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24
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Wit N, Krijger PHL, van den Berk PCM, Jacobs H. Lysine residue 185 of Rad1 is a topological but not a functional counterpart of lysine residue 164 of PCNA. PLoS One 2011; 6:e16669. [PMID: 21304913 PMCID: PMC3031632 DOI: 10.1371/journal.pone.0016669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 01/10/2011] [Indexed: 12/11/2022] Open
Abstract
Monoubiquitylation of the homotrimeric DNA sliding clamp PCNA at lysine residue 164 (PCNAK164) is a highly conserved, DNA damage-inducible process that is mediated by the E2/E3 complex Rad6/Rad18. This ubiquitylation event recruits translesion synthesis (TLS) polymerases capable of replicating across damaged DNA templates. Besides PCNA, the Rad6/Rad18 complex was recently shown in yeast to ubiquitylate also 9-1-1, a heterotrimeric DNA sliding clamp composed of Rad9, Rad1, and Hus1 in a DNA damage-inducible manner. Based on the highly similar crystal structures of PCNA and 9-1-1, K185 of Rad1 (Rad1K185) was identified as the only topological equivalent of PCNAK164. To investigate a potential role of posttranslational modifications of Rad1K185 in DNA damage management, we here generated a mouse model with a conditional deletable Rad1K185R allele. The Rad1K185 residue was found to be dispensable for Chk1 activation, DNA damage survival, and class switch recombination of immunoglobulin genes as well as recruitment of TLS polymerases during somatic hypermutation of immunoglobulin genes. Our data indicate that Rad1K185 is not a functional counterpart of PCNAK164.
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Affiliation(s)
- Niek Wit
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Peter H. L. Krijger
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | - Heinz Jacobs
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
- * E-mail:
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25
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Krijger PHL, Wit N, van den Berk PCM, Jacobs H. The Fanconi anemia core complex is dispensable during somatic hypermutation and class switch recombination. PLoS One 2010; 5:e15236. [PMID: 21209924 PMCID: PMC3012132 DOI: 10.1371/journal.pone.0015236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 10/31/2010] [Indexed: 01/25/2023] Open
Abstract
To generate high affinity antibodies during an immune response, B cells undergo somatic hypermutation (SHM) of their immunoglobulin genes. Error-prone translesion synthesis (TLS) DNA polymerases have been reported to be responsible for all mutations at template A/T and at least a fraction of G/C transversions. In contrast to A/T mutations which depend on PCNA ubiquitination, it remains unclear how G/C transversions are regulated during SHM. Several lines of evidence indicate a mechanistic link between the Fanconi Anemia (FA) pathway and TLS. To investigate the contribution of the FA pathway in SHM we analyzed FancG-deficient B cells. B cells deficient for FancG, an essential member of the FA core complex, were hypersensitive to treatment with cross-linking agents. However, the frequencies and nucleotide exchange spectra of SHM remained comparable between wild-type and FancG-deficient B cells. These data indicate that the FA pathway is not involved in regulating the outcome of SHM in mammals. In addition, the FA pathway appears dispensable for class switch recombination.
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Affiliation(s)
- Peter H. L. Krijger
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Niek Wit
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | - Heinz Jacobs
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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26
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Bobola MS, Kolstoe DD, Blank A, Silber JR. Minimally cytotoxic doses of temozolomide produce radiosensitization in human glioblastoma cells regardless of MGMT expression. Mol Cancer Ther 2010; 9:1208-18. [PMID: 20457618 DOI: 10.1158/1535-7163.mct-10-0010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Concurrent treatment with the methylating agent temozolomide during radiotherapy has yielded the first significant improvement in the survival of adult glioblastomas (GBM) in the last three decades. However, improved survival is observed in a minority of patients, most frequently those whose tumors display CpG methylation of the O(6)-methylguanine (O(6)-meG)-DNA methyltransferase (MGMT) promoter, and adult GBMs remain invariably fatal. Some, although not all, preclinical studies have shown that temozolomide can increase radiosensitivity in GBM cells that lack MGMT, the sole activity in human cells that removes O(6)-meG from DNA. Here, we systematically examined the temozolomide dose dependence of radiation killing in established GBM cell lines that differ in ability to remove O(6)-meG or tolerate its lethality. Our results show that minimally cytotoxic doses of temozolomide can produce dose-dependent radiosensitization in MGMT-deficient cells, MGMT-proficient cells, and MGMT-deficient cells that lack mismatch repair, a process that renders cells tolerant of the lethality of O(6)-meG. In cells that either possess or lack MGMT activity, radiosensitization requires exposure to temozolomide before but not after radiation and is accompanied by formation of double-strand breaks within 45 minutes of radiation. Moreover, suppressing alkyladenine-DNA glycosylase, the only activity in human cells that excises 3-methyladenine from DNA, reduces the temozolomide dose dependence of radiosensitization, indicating that radiosensitization is mediated by 3-methyladenine as well as by O(6)-meG. These results provide novel information on which to base further mechanistic study of radiosensitization by temozolomide in human GBM cells and to develop strategies to improve the outcome of concurrent temozolomide radiotherapy.
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Affiliation(s)
- Michael S Bobola
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195-6470, USA
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27
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Abstract
The Rad9-Hus1-Rad1 checkpoint clamp (9-1-1) is a central player in the cellular response to DNA damage; three groups have determined the crystal structure of 9-1-1, providing new insight into its loading mechanism and association with DNA damage checkpoint and repair enzymes.
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Affiliation(s)
- Michael Kemp
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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28
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A DinB variant reveals diverse physiological consequences of incomplete TLS extension by a Y-family DNA polymerase. Proc Natl Acad Sci U S A 2009; 106:21137-42. [PMID: 19948952 DOI: 10.1073/pnas.0907257106] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The only Y-family DNA polymerase conserved among all domains of life, DinB and its mammalian ortholog pol kappa, catalyzes proficient bypass of damaged DNA in translesion synthesis (TLS). Y-family DNA polymerases, including DinB, have been implicated in diverse biological phenomena ranging from adaptive mutagenesis in bacteria to several human cancers. Complete TLS requires dNTP insertion opposite a replication blocking lesion and subsequent extension with several dNTP additions. Here we report remarkably proficient TLS extension by DinB from Escherichia coli. We also describe a TLS DNA polymerase variant generated by mutation of an evolutionarily conserved tyrosine (Y79). This mutant DinB protein is capable of catalyzing dNTP insertion opposite a replication-blocking lesion, but cannot complete TLS, stalling three nucleotides after an N(2)-dG adduct. Strikingly, expression of this variant transforms a bacteriostatic DNA damaging agent into a bactericidal drug, resulting in profound toxicity even in a dinB(+) background. We find that this phenomenon is not exclusively due to a futile cycle of abortive TLS followed by exonucleolytic reversal. Rather, gene products with roles in cell death and metal homeostasis modulate the toxicity of DinB(Y79L) expression. Together, these results indicate that DinB is specialized to perform remarkably proficient insertion and extension on damaged DNA, and also expose unexpected connections between TLS and cell fate.
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Separate roles of structured and unstructured regions of Y-family DNA polymerases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2009; 78:99-146. [PMID: 20663485 DOI: 10.1016/s1876-1623(08)78004-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
All organisms have multiple DNA polymerases specialized for translesion DNA synthesis (TLS) on damaged DNA templates. Mammalian TLS DNA polymerases include Pol eta, Pol iota, Pol kappa, and Rev1 (all classified as "Y-family" members) and Pol zeta (a "B-family" member). Y-family DNA polymerases have highly structured catalytic domains; however, some of these proteins adopt different structures when bound to DNA (such as archaeal Dpo4 and human Pol kappa), while others maintain similar structures independently of DNA binding (such as archaeal Dbh and Saccharomyces cerevisiae Pol eta). DNA binding-induced structural conversions of TLS polymerases depend on flexible regions present within the catalytic domains. In contrast, noncatalytic regions of Y-family proteins, which contain multiple domains and motifs for interactions with other proteins, are predicted to be mostly unstructured, except for short regions corresponding to ubiquitin-binding domains. In this review we discuss how the organization of structured and unstructured regions in TLS polymerases is relevant to their regulation and function during lesion bypass.
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Kunkel TA. Evolving views of DNA replication (in)fidelity. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2009; 74:91-101. [PMID: 19903750 PMCID: PMC3628614 DOI: 10.1101/sqb.2009.74.027] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
"It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material" (Watson and Crick 1953). In the years since this remarkable understatement, we have come to realize the enormous complexity of the cellular machinery devoted to replicating DNA with the accuracy needed to maintain genetic information over many generations, balanced by the emergence of mutations on which selection can act. This complexity is partly based on the need to remove or tolerate cytotoxic and mutagenic lesions in DNA generated by environmental stress. Considered here is the fidelity with which undamaged and damaged DNA is replicated by the many DNA polymerases now known to exist. Some of these seriously violate Watson-Crick base-pairing rules such that, depending on the polymerase, the composition and location of the error, and the ability to correct errors (or not), DNA synthesis error rates can vary by more than a millionfold. This offers the potential to modulate rates of point mutations over a wide range, with consequences that can be either deleterious or beneficial.
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Affiliation(s)
- T A Kunkel
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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31
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Krijger PHL, Langerak P, van den Berk PCM, Jacobs H. Dependence of nucleotide substitutions on Ung2, Msh2, and PCNA-Ub during somatic hypermutation. ACTA ACUST UNITED AC 2009; 206:2603-11. [PMID: 19901081 PMCID: PMC2806606 DOI: 10.1084/jem.20091707] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
During somatic hypermutation (SHM), B cells introduce mutations into their immunoglobulin genes to generate high affinity antibodies. Current models suggest a separation in the generation of G/C transversions by the Ung2-dependent pathway and the generation of A/T mutations by the Msh2/ubiquitinated proliferating cell nuclear antigen (PCNA-Ub)–dependent pathway. It is currently unknown whether these pathways compete to initiate mutagenesis and whether PCNA-Ub functions downstream of Ung2. Furthermore, these models do not explain why mice lacking Msh2 have a more than twofold reduction in the total mutation frequency. Our data indicate that PCNA-Ub is required for A/T mutagenesis downstream of both Msh2 and Ung2. Furthermore, we provide evidence that both pathways are noncompetitive to initiate mutagenesis and even collaborate to generate half of all G/C transversions. These findings significantly add to our understanding of SHM and necessitate an update of present SHM models.
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Affiliation(s)
- Peter H L Krijger
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
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32
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Wagner J, Etienne H, Fuchs RP, Cordonnier A, Burnouf D. Distinct beta-clamp interactions govern the activities of the Y family PolIV DNA polymerase. Mol Microbiol 2009; 74:1143-51. [PMID: 19843218 DOI: 10.1111/j.1365-2958.2009.06920.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The prototypic Y family DNA polymerase IV (PolIV) of Escherichia coli is involved in multiple replication-associated processes including spontaneous mutagenesis, translesion synthesis (TLS), cell fitness, survival under stressful conditions and checkpoint like functions. It interacts physically and functionally with the replisome's beta processivity clamp through the canonical PolIV C-terminal peptide (CTP). A second interaction that involves a portion of the little finger (LF) domain of PolIV has been structurally described. Here we show that the LF-beta interaction stabilizes the clamp-polymerase complex in vitro and is necessary for the access of PolIV to ongoing replication forks in vivo. However, in contrast to the CTP-beta, the LF-beta interaction is dispensable for the role of the polymerase in TLS. This discloses two independent modes of action for PolIV and, in turn, uncovers a novel way by which the cell may regulate the potentially deleterious effect of such low fidelity polymerases during replication.
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Affiliation(s)
- Jérôme Wagner
- CNRS FRE3211, ESBS, Université de Strasbourg, BP 10413, 67412 Strasbourg Cedex, France.
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33
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Jansen JG, Tsaalbi-Shtylik A, Hendriks G, Verspuy J, Gali H, Haracska L, de Wind N. Mammalian polymerase zeta is essential for post-replication repair of UV-induced DNA lesions. DNA Repair (Amst) 2009; 8:1444-51. [PMID: 19783229 DOI: 10.1016/j.dnarep.2009.09.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 08/17/2009] [Accepted: 09/10/2009] [Indexed: 01/11/2023]
Abstract
DNA polymerase zeta is believed to be an essential constituent of DNA damage tolerance, comprising several pathways that allow the replication of DNA templates containing unrepaired damage. We wanted to better define the role of polymerase zeta in DNA damage tolerance in mammalian cells. To this aim we have investigated replication of ultraviolet light-damaged DNA templates in mouse embryonic fibroblasts deficient for Rev3, the catalytic subunit of polymerase zeta. We found that Rev3 is important for a post-replication repair pathway of helix-distorting [6-4]pyrimidine-pyrimidone photoproducts and, to a lesser extent, of cyclobutane pyrimidine dimers. Unlike its partner Rev1, Rev3 appears not to be involved in an immediate translesion synthesis pathway at a stalled replication fork. The deficiency of Rev3(-/-) MEFs in post-replication repair of different photoproducts contributes to the extreme sensitivity of these cells to UV light.
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Affiliation(s)
- Jacob G Jansen
- Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, PO Box 9600, 2300 RC Leiden, The Netherlands
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Kohn KW, Aladjem MI, Weinstein JN, Pommier Y. Network architecture of signaling from uncoupled helicase-polymerase to cell cycle checkpoints and trans-lesion DNA synthesis. Cell Cycle 2009; 8:2281-99. [PMID: 19556879 DOI: 10.4161/cc.8.14.9102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
When replication is blocked by a template lesion or polymerase inhibitor while helicase continues unwinding the DNA, single stranded DNA (ssDNA) accumulates and becomes coated with RPA, which then initiates signals via PCNA mono-ubiquitination to activate trans-lesion polymerases and via ATR and Chk1 to inhibit Cdk2-dependent cell cycle progression. The signals are conveyed by way of a complex network of molecular interactions. To clarify those complexities, we have constructed a molecular interaction map (MIM) using a novel hierarchical assembly procedure. Molecules were arranged on the map in hierarchical levels according to interaction step distance from the DNA region of stalled replication. The hierarchical MIM allows us to disentangle the network's interlocking pathways and loops and to suggest functionally significant features of network architecture. The MIM shows how parallel pathways and multiple feedback loops can provide failsafe and robust switch-like responses to replication stress. Within the central level of hierarchy ATR and Claspin together appear to function as a nexus that conveys signals from many sources to many destinations. We noted a division of labor between those two molecules, separating enzymatic and structural roles. In addition, the network architecture disclosed by the hierarchical map, suggested a speculative model for how molecular crowding and the granular localization of network components in the cell nucleus can facilitate function.
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Affiliation(s)
- Kurt W Kohn
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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Separate domains of Rev1 mediate two modes of DNA damage bypass in mammalian cells. Mol Cell Biol 2009; 29:3113-23. [PMID: 19332561 DOI: 10.1128/mcb.00071-09] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The Y family DNA polymerase Rev1 has been proposed to play a regulatory role in the replication of damaged templates. To elucidate the mechanism by which Rev1 promotes DNA damage bypass, we have analyzed the progression of replication on UV light-damaged DNA in mouse embryonic fibroblasts that contain a defined deletion in the N-terminal BRCT domain of Rev1 or that are deficient for Rev1. We provide evidence that Rev1 plays a coordinating role in two modes of DNA damage bypass, i.e., an early and a late pathway. The cells carrying the deletion in the BRCT domain are deficient for the early pathway, reflecting a role of the BRCT domain of Rev1 in mutagenic translesion synthesis. Rev1-deficient cells display a defect in both modes of DNA damage bypass. Despite the persistent defect in the late replicational bypass of fork-blocking (6-4)pyrimidine-pyrimidone photoproducts, overall replication is not strongly affected by Rev1 deficiency. This results in almost completely replicated templates that contain gaps encompassing the photoproducts. These gaps are inducers of DNA damage signaling leading to an irreversible G(2) arrest. Our results corroborate a model in which Rev1-mediated DNA damage bypass at postreplicative gaps quenches irreversible DNA damage responses.
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Xing G, Kirouac K, Shin YJ, Bell SD, Ling H. Structural insight into recruitment of translesion DNA polymerase Dpo4 to sliding clamp PCNA. Mol Microbiol 2009; 71:678-91. [DOI: 10.1111/j.1365-2958.2008.06553.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Dumstorf CA, Mukhopadhyay S, Krishnan E, Haribabu B, McGregor WG. REV1 is implicated in the development of carcinogen-induced lung cancer. Mol Cancer Res 2009; 7:247-54. [PMID: 19176310 DOI: 10.1158/1541-7786.mcr-08-0399] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The somatic mutation hypothesis of cancer predicts that reducing the frequency of mutations induced by carcinogens will reduce the incidence of cancer. To examine this, we developed an antimutator strategy based on the manipulation of the level of a protein required for mutagenic bypass of DNA damage induced by the ubiquitous carcinogen benzo[a]pyrene. The expression of this protein, REV1, was reduced in mouse cells using a vector encoding a gene-specific targeting ribozyme. In the latter cells, mutagenesis induced by the activated form of benzo[a]pyrene was reduced by >90%. To examine if REV1 transcripts could be lowered in vivo, the plasmid was complexed with polyethyleneimine, a nonviral cationic polymer, and delivered to the lung via aerosol. The endogenous REV1 transcript in the bronchial epithelium as determined by quantitative real-time PCR in laser capture microdissected cells was reduced by 60%. There was a significant decrease in the multiplicity of carcinogen-induced lung tumors from 6.4 to 3.7 tumors per mouse. Additionally, REV1 inhibition completely abolished tumor formation in 27% of the carcinogen-exposed mice. These data support the central role of the translesion synthesis pathway in the development of lung cancer. Further, the selective modulation of members of this pathway presents novel potential targets for cancer prevention. The somatic mutation hypothesis of cancer predicts that the frequency of cancers will also be reduced.
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Affiliation(s)
- Chad A Dumstorf
- Department of Pharmacology, University of Louisville, Louisville, KY 40202, USA
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38
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Takata M, Ishiai M, Kitao H. The Fanconi anemia pathway: insights from somatic cell genetics using DT40 cell line. Mutat Res 2009; 668:92-102. [PMID: 19622405 DOI: 10.1016/j.mrfmmm.2008.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/15/2008] [Accepted: 12/24/2008] [Indexed: 10/21/2022]
Abstract
The Fanconi anemia (FA) pathway is a complex phosphorylation-ubiquitination network in the DNA damage signaling, which is still poorly understood. Defects in the "FA pathway" or in the related DNA repair proteins cause FA, a hereditary disorder that accompanies compromised DNA crosslink repair, poor hematopoetic stem cell survival, genomic instability, and cancer. For molecular dissection of the FA pathway, we have been using chicken B cell line DT40 as a model system. In this review, we will summarize our current understanding of the pathway, and discuss how studies using DT40 have contributed to this rapidly evolving field.
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Affiliation(s)
- Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effect Studies, Radiation Biology Center, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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39
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Abstract
DNA replication is a complex mechanism that functions due to the co-ordinated interplay of several dozen protein factors. In the last few years, numerous studies suggested a tight implication of DNA replication factors in several DNA transaction events that maintain the integrity of the genome. Therefore, DNA replication fork proteins have also to be considered as part of a general process aiming at replicating and protecting the genome in order to allow the correct function of a cell and of its eventual daughter cells. This is illustrated by several DNA repair pathways such as base excision repair, nucleotide excision repair, double-strand break repair, and mismatch repair. Furthermore, several of the replication proteins have also been shown to be essential in sensing and transducing DNA damages through the checkpoint cascade pathways. This review will summarize the properties of DNA replication proteins that function exclusively at the replication fork.
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40
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Palle K, Pattarello L, van der Merwe M, Losasso C, Benedetti P, Bjornsti MA. Disulfide cross-links reveal conserved features of DNA topoisomerase I architecture and a role for the N terminus in clamp closure. J Biol Chem 2008; 283:27767-27775. [PMID: 18693244 DOI: 10.1074/jbc.m804826200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In eukaryotes, DNA topoisomerase I (Top1) catalyzes the relaxation of supercoiled DNA by a conserved mechanism of transient DNA strand breakage, rotation, and religation. The unusual architecture of the monomeric human enzyme comprises a conserved protein clamp, which is tightly wrapped about duplex DNA, and an extended coiled-coil linker domain that appropriately positions the C-terminal active site tyrosine domain against the Top1 core to form the catalytic pocket. A structurally undefined N-terminal domain, dispensable for enzyme activity, mediates protein-protein interactions. Previously, reversible disulfide bonds were designed to assess whether locking the Top1 clamp around duplex DNA would restrict DNA strand rotation within the covalent Top1-DNA intermediate. The active site proximal disulfide bond in full-length Top1-clamp(534) restricted DNA rotation (Woo, M. H., Losasso, C., Guo, H., Pattarello, L., Benedetti, P., and Bjornsti, M. A. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 13767-13772), whereas the more distal disulfide bond of the N-terminally truncated Topo70-clamp(499) did not (Carey, J. F., Schultz, S. J., Sisson, L., Fazzio, T. G., and Champoux, J. J. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 5640-5645). To assess the contribution of the N-terminal domain to the dynamics of Top1 clamping of DNA, the same disulfide bonds were engineered into full-length Top1 and truncated Topo70, and the activities of these proteins were assessed in vitro and in yeast. Here we report that the N terminus impacts the opening and closing of the Top1 protein clamp. We also show that the architecture of yeast and human Top1 is conserved in so far as cysteine substitutions of the corresponding residues suffice to lock the Top1-clamp. However, the composition of the divergent N-terminal/linker domains impacts Top1-clamp activity and stability in vivo.
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Affiliation(s)
- Komaraiah Palle
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38015
| | - Luca Pattarello
- Department of Biology, University of Padua, Via U. Bassi 58/B, Padova, PD 35131, Italy
| | - Marié van der Merwe
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38015
| | - Carmen Losasso
- Department of Biology, University of Padua, Via U. Bassi 58/B, Padova, PD 35131, Italy
| | - Piero Benedetti
- Department of Biology, University of Padua, Via U. Bassi 58/B, Padova, PD 35131, Italy.
| | - Mary-Ann Bjornsti
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38015.
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Role of Dot1 in the response to alkylating DNA damage in Saccharomyces cerevisiae: regulation of DNA damage tolerance by the error-prone polymerases Polzeta/Rev1. Genetics 2008; 179:1197-210. [PMID: 18562671 DOI: 10.1534/genetics.108.089003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Maintenance of genomic integrity relies on a proper response to DNA injuries integrated by the DNA damage checkpoint; histone modifications play an important role in this response. Dot1 methylates lysine 79 of histone H3. In Saccharomyces cerevisiae, Dot1 is required for the meiotic recombination checkpoint as well as for chromatin silencing and the G(1)/S and intra-S DNA damage checkpoints in vegetative cells. Here, we report the analysis of the function of Dot1 in the response to alkylating damage. Unexpectedly, deletion of DOT1 results in increased resistance to the alkylating agent methyl methanesulfonate (MMS). This phenotype is independent of the dot1 silencing defect and does not result from reduced levels of DNA damage. Deletion of DOT1 partially or totally suppresses the MMS sensitivity of various DNA repair mutants (rad52, rad54, yku80, rad1, rad14, apn1, rad5, rad30). However, the rev1 dot1 and rev3 dot1 mutants show enhanced MMS sensitivity and dot1 does not attenuate the MMS sensitivity of rad52 rev3 or rad52 rev1. In addition, Rev3-dependent MMS-induced mutagenesis is increased in dot1 cells. We propose that Dot1 inhibits translesion synthesis (TLS) by Polzeta/Rev1 and that the MMS resistance observed in the dot1 mutant results from the enhanced TLS activity.
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Schroering AG, Williams KJ. Rapid induction of chromatin-associated DNA mismatch repair proteins after MNNG treatment. DNA Repair (Amst) 2008; 7:951-69. [PMID: 18468964 DOI: 10.1016/j.dnarep.2008.03.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 03/07/2008] [Accepted: 03/23/2008] [Indexed: 12/18/2022]
Abstract
Treatment with low concentrations of monofunctional alkylating agents induces a G2 arrest only after the second round of DNA synthesis in mammalian cells and requires a proficient mismatch repair (MMR) pathway. Here, we have investigated rapid alkylation-induced recruitment of DNA repair proteins to chromosomal DNA within synchronized populations of MMR proficient cells (HeLa MR) after N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment. Within the first hour, the concentrations of MutS alpha and PCNA increase well beyond their constitutive chromosomally bound levels and MutL alpha is newly recruited to the chromatin-bound MutS alpha. Remarkably, immunoprecipitation experiments demonstrate rapid association of these proteins on the alkylation-damaged chromatin, even when DNA replication is completely blocked. The extent of association of PCNA and MMR proteins on the chromatin is dependent upon the concentration of MNNG and on the specific type of replication block. A subpopulation of the MutS alpha-associated PCNA also becomes monoubiquitinated, a known requirement for PCNA to interact with translesion synthesis (TLS) polymerases. In addition, chromatin-bound SMC1 and NBS1 proteins, associated with DNA double-strand-breaks (DSBs), become phosphorylated within 1-2h of exposure to MNNG. However, these activated proteins are not co-localized on the chromatin with MutS alpha in response to MNNG exposure. PCNA, MutS alpha/MutL alpha and activated SMC1/NBS1 remain chromatin-bound for at least 6-8h after alkylation damage. Thus, cells that are exposed to low levels of alkylation treatment undergo rapid recruitment to and/or activation of key proteins already on the chromatin without the requirement for DNA replication, apparently via different DNA-damage signaling pathways.
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Affiliation(s)
- Allen G Schroering
- University of Toledo College of Medicine, Health Science Campus, Department of Biochemistry & Cancer Biology, Toledo, OH 43614, USA
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