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The rarA gene as part of an expanded RecFOR recombination pathway: Negative epistasis and synthetic lethality with ruvB, recG, and recQ. PLoS Genet 2021; 17:e1009972. [PMID: 34936656 PMCID: PMC8735627 DOI: 10.1371/journal.pgen.1009972] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 01/06/2022] [Accepted: 12/01/2021] [Indexed: 11/19/2022] Open
Abstract
The RarA protein, homologous to human WRNIP1 and yeast MgsA, is a AAA+ ATPase and one of the most highly conserved DNA repair proteins. With an apparent role in the repair of stalled or collapsed replication forks, the molecular function of this protein family remains obscure. Here, we demonstrate that RarA acts in late stages of recombinational DNA repair of post-replication gaps. A deletion of most of the rarA gene, when paired with a deletion of ruvB or ruvC, produces a growth defect, a strong synergistic increase in sensitivity to DNA damaging agents, cell elongation, and an increase in SOS induction. Except for SOS induction, these effects are all suppressed by inactivating recF, recO, or recJ, indicating that RarA, along with RuvB, acts downstream of RecA. SOS induction increases dramatically in a rarA ruvB recF/O triple mutant, suggesting the generation of large amounts of unrepaired ssDNA. The rarA ruvB defects are not suppressed (and in fact slightly increased) by recB inactivation, suggesting RarA acts primarily downstream of RecA in post-replication gaps rather than in double strand break repair. Inactivating rarA, ruvB and recG together is synthetically lethal, an outcome again suppressed by inactivation of recF, recO, or recJ. A rarA ruvB recQ triple deletion mutant is also inviable. Together, the results suggest the existence of multiple pathways, perhaps overlapping, for the resolution or reversal of recombination intermediates created by RecA protein in post-replication gaps within the broader RecF pathway. One of these paths involves RarA.
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2
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Thompson PS, Cortez D. New insights into abasic site repair and tolerance. DNA Repair (Amst) 2020; 90:102866. [PMID: 32417669 PMCID: PMC7299775 DOI: 10.1016/j.dnarep.2020.102866] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/21/2020] [Accepted: 04/21/2020] [Indexed: 12/13/2022]
Abstract
Thousands of apurinic/apyrimidinic (AP or abasic) sites form in each cell, each day. This simple DNA lesion can have profound consequences to cellular function, genome stability, and disease. As potent blocks to polymerases, they interfere with the reading and copying of the genome. Since they provide no coding information, they are potent sources of mutation. Due to their reactive chemistry, they are intermediates in the formation of lesions that are more challenging to repair including double-strand breaks, interstrand crosslinks, and DNA protein crosslinks. Given their prevalence and deleterious consequences, cells have multiple mechanisms of repairing and tolerating these lesions. While base excision repair of abasic sites in double-strand DNA has been studied for decades, new interest in abasic site processing has come from more recent insights into how they are processed in single-strand DNA. In this review, we discuss the source of abasic sites, their biological consequences, tolerance mechanisms, and how they are repaired in double and single-stranded DNA.
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Affiliation(s)
- Petria S Thompson
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN, 37232, USA
| | - David Cortez
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN, 37232, USA.
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3
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SUMOylation of PCNA by PIAS1 and PIAS4 promotes template switch in the chicken and human B cell lines. Proc Natl Acad Sci U S A 2018; 115:12793-12798. [PMID: 30487218 DOI: 10.1073/pnas.1716349115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA damage tolerance (DDT) releases replication blockage caused by damaged nucleotides on template strands employing two alternative pathways, error-prone translesion DNA synthesis (TLS) and error-free template switch (TS). Lys164 of proliferating cell nuclear antigen (PCNA) is SUMOylated during the physiological cell cycle. To explore the role for SUMOylation of PCNA in DDT, we characterized chicken DT40 and human TK6 B cells deficient in the PIAS1 and PIAS4 small ubiquitin-like modifier (SUMO) E3 ligases. DT40 cells have a unique advantage in the phenotypic analysis of DDT as they continuously diversify their immunoglobulin (Ig) variable genes by TLS and TS [Ig gene conversion (GC)], both relieving replication blocks at abasic sites without accompanying by DNA breakage. Remarkably, PIAS1 -/- /PIAS4 -/- cells displayed a multifold decrease in SUMOylation of PCNA at Lys164 and over a 90% decrease in the rate of TS. Likewise, PIAS1 -/- /PIAS4 -/- TK6 cells showed a shift of DDT from TS to TLS at a chemosynthetic UV lesion inserted into the genomic DNA. The PCNA K164R/K164R mutation caused a ∼90% decrease in the rate of Ig GC and no additional impact on PIAS1 -/- /PIAS4 -/- cells. This epistatic relationship between the PCNA K164R/K164R and the PIAS1 -/- /PIAS4 -/- mutations suggests that PIAS1 and PIAS4 promote TS mainly through SUMOylation of PCNA at Lys164. This idea is further supported by the data that overexpression of a PCNA-SUMO1 chimeric protein restores defects in TS in PIAS1 -/- /PIAS4 -/- cells. In conclusion, SUMOylation of PCNA at Lys164 promoted by PIAS1 and PIAS4 ensures the error-free release of replication blockage during physiological DNA replication in metazoan cells.
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Abstract
Replication forks frequently are challenged by lesions on the DNA template, replication-impeding DNA secondary structures, tightly bound proteins or nucleotide pool imbalance. Studies in bacteria have suggested that under these circumstances the fork may leave behind single-strand DNA gaps that are subsequently filled by homologous recombination, translesion DNA synthesis or template-switching repair synthesis. This review focuses on the template-switching pathways and how the mechanisms of these processes have been deduced from biochemical and genetic studies. I discuss how template-switching can contribute significantly to genetic instability, including mutational hotspots and frequent genetic rearrangements, and how template-switching may be elicited by replication fork damage.
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Affiliation(s)
- Susan T Lovett
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, 2454-9110, USA.
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McClung DJ, Calixto A, Mosera MN, Kumar R, Neidle EL, Elliott KT. Novel heterologous bacterial system reveals enhanced susceptibility to DNA damage mediated by yqgF, a nearly ubiquitous and often essential gene. MICROBIOLOGY-SGM 2016; 162:1808-1821. [PMID: 27527105 DOI: 10.1099/mic.0.000355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite its presence in most bacteria, yqgF remains one of only 13 essential genes of unknown function in Escherichia coli. Predictions of YqgF function often derive from sequence similarity to RuvC, the canonical Holliday junction resolvase. To clarify its role, we deleted yqgF from a bacterium where it is not essential, Acinetobacter baylyi ADP1. Loss of yqgF impaired growth and increased the frequency of transformation and allelic replacement (TAR). When E. coli yqgF was inserted in place of its A. baylyi chromosomal orthologue, wild-type growth and TAR were restored. Functional similarities of yqgF in both gamma-proteobacteria were further supported by defective 16S rRNA processing by the A. baylyi mutant, an effect previously shown in E. coli for a temperature-sensitive yqgF allele. However, our data question the validity of deducing YqgF function strictly by comparison to RuvC. A. baylyi studies indicated that YqgF and RuvC can function in opposition to one another. Relative to the wild type, the ΔyqgF mutant had increased TAR frequency and increased resistance to nalidixic acid, a DNA-damaging agent. In contrast, deletion of ruvC decreased TAR frequency and lowered resistance to nalidixic acid. YqgF, but not RuvC, appears to increase bacterial susceptibility to DNA damage, including UV radiation. Nevertheless, the effects of yqgF on growth and TAR frequency were found to depend on amino acids analogous to catalytically required residues of RuvC. This new heterologous system should facilitate future yqgF investigation by exploiting the viability of A. baylyi yqgF mutants. In addition, bioinformatic analysis showed that a non-essential gene immediately upstream of yqgF in A. baylyi and E. coli (yqgE) is similarly positioned in most gamma- and beta-proteobacteria. A small overlap in the coding sequences of these adjacent genes is typical. This conserved genetic arrangement raises the possibility of a functional partnership between yqgE and yqgF.
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Affiliation(s)
- Dylan J McClung
- Department of Biology, The College of New Jersey, Ewing, NJ, USA
| | - Abigail Calixto
- Department of Biology, The College of New Jersey, Ewing, NJ, USA
| | | | - Raagni Kumar
- Department of Biology, The College of New Jersey, Ewing, NJ, USA
| | - Ellen L Neidle
- Department of Microbiology, University of Georgia, Athens, GA, USA
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Livneh Z, Cohen IS, Paz-Elizur T, Davidovsky D, Carmi D, Swain U, Mirlas-Neisberg N. High-resolution genomic assays provide insight into the division of labor between TLS and HDR in mammalian replication of damaged DNA. DNA Repair (Amst) 2016; 44:59-67. [PMID: 27262613 DOI: 10.1016/j.dnarep.2016.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The multitude of DNA lesions that continuously form in DNA cannot all be detected and removed prior to replication. Thus, encounters of the replication fork with DNA damage become inevitable. Such encounters inhibit fork progression, leading to replication fork arrest or to replication re-priming downstream of the damage site. Either of these events will result in the formation of gap-lesion structures, in which a damaged base is located in a single stranded stretch of DNA, that is vulnerable to subsequent nicking. The double strand break that would ensue if ssDNA becomes nicked constitutes escalation of the damage from nucleotide(s)-specific to chromosomal scale. Cells employ two universal DNA damage tolerance (DDT) strategies to resolve these situations, by converting the gap-lesion structures into dsDNA without repairing the damage. The first is translesion DNA synthesis (TLS), in which a specialized low-fidelity DNA polymerase inserts a nucleotide opposite the damaged one. TLS is inherently mutagenic, due to the miscoding nature of most damaged nucleotides. The second strategy is homology-dependent repair (HDR), which relies on the presence of an identical intact sister chromatid. The molecular mechanisms that regulate the division of labor between these pathways are poorly understood. This review focuses on the balance between TLS and HDR in mammalian cells, discussing recent findings that were made possible thanks to newly developed high resolution genomic assays, and highlighting the role of the DNA lesion's properties in DDT pathway choice.
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Affiliation(s)
- Zvi Livneh
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Isadora S Cohen
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamar Paz-Elizur
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dana Davidovsky
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dalit Carmi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Umakanta Swain
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nataly Mirlas-Neisberg
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
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Kobayashi S, Keka IS, Guilbaud G, Sale J, Narita T, Abdel-Aziz HI, Wang X, Ogawa S, Sasanuma H, Chiu R, Oestergaard VH, Lisby M, Takeda S. The role of HERC2 and RNF8 ubiquitin E3 ligases in the promotion of translesion DNA synthesis in the chicken DT40 cell line. DNA Repair (Amst) 2016; 40:67-76. [PMID: 26994443 DOI: 10.1016/j.dnarep.2016.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/12/2016] [Accepted: 02/03/2016] [Indexed: 12/20/2022]
Abstract
The replicative DNA polymerases are generally blocked by template DNA damage. The resulting replication arrest can be released by one of two post-replication repair (PRR) pathways, translesion DNA synthesis (TLS) and template switching by homologous recombination (HR). The HERC2 ubiquitin ligase plays a role in homologous recombination by facilitating the assembly of the Ubc13 ubiquitin-conjugating enzyme with the RNF8 ubiquitin ligase. To explore the role of HERC2 and RNF8 in PRR, we examined immunoglobulin diversification in chicken DT40 cells deficient in HERC2 and RNF8. Unexpectedly, the HERC2(-/-) and RNF8(-/-) cells and HERC2(-/-)/RNF8(-/-) double mutant cells exhibit a significant reduction in the rate of immunoglobulin (Ig) hypermutation, compared to wild-type cells. Further, the HERC2(-/-) and RNF8(-/-) mutants exhibit defective maintenance of replication fork progression immediately after exposure to UV while retaining proficient post-replicative gap filling. These mutants are both proficient in mono-ubiquitination of PCNA. Taken together, these results suggest that HERC2 and RNF8 promote TLS past abasic sites and UV-lesions at or very close to stalled replication forks.
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Affiliation(s)
- Shunsuke Kobayashi
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Islam Shamima Keka
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Guillaume Guilbaud
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Julian Sale
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Takeo Narita
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan; Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - H Ismail Abdel-Aziz
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan; Faculty of Medicine, Seuz Canal University, circular road Ez-Eldeen, Ismailia 41522, Egypt
| | - Xin Wang
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Saki Ogawa
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Roland Chiu
- University College Groningen, University of Groningen, 9718 BG Groningen, Hoendiepskade 23-24, The Netherlands
| | - Vibe H Oestergaard
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Shunichi Takeda
- Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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Laureti L, Demol J, Fuchs RP, Pagès V. Bacterial Proliferation: Keep Dividing and Don't Mind the Gap. PLoS Genet 2015; 11:e1005757. [PMID: 26713761 PMCID: PMC4699847 DOI: 10.1371/journal.pgen.1005757] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/01/2015] [Indexed: 12/21/2022] Open
Abstract
DNA Damage Tolerance (DDT) mechanisms help dealing with unrepaired DNA lesions that block replication and challenge genome integrity. Previous in vitro studies showed that the bacterial replicase is able to re-prime downstream of a DNA lesion, leaving behind a single-stranded DNA gap. The question remains of what happens to this gap in vivo. Following the insertion of a single lesion in the chromosome of a living cell, we showed that this gap is mostly filled in by Homology Directed Gap Repair in a RecA dependent manner. When cells fail to repair this gap, or when homologous recombination is impaired, cells are still able to divide, leading to the loss of the damaged chromatid, suggesting that bacteria lack a stringent cell division checkpoint mechanism. Hence, at the expense of losing one chromatid, cell survival and proliferation are ensured. DNA Damage Tolerance (DDT) mechanisms help dealing with unrepaired DNA lesions that block replication, thus challenging genome integrity. Two DDT mechanisms have previously been described: error prone Translesion Synthesis operated by specialized DNA polymerases and error free bypass that uses the information of the sister chromatid to bypass the lesion. In this work, we set up a novel genetic system that allows to insert a single DNA blocking lesion in the chromosome of a living cell and to visualize the exchange of genetic information between the undamaged and the damaged strand. Using this system, we showed in vivo that the replication fork is able to re-prime downstream of the lesion, leaving a gap. This gap is mostly filled in by the error free pathway through the RecA homologous recombination mechanism. We show that when the gap is left unrepaired, cells are still able to divide by losing the damaged chromatid, which evidences the lack of a stringent cell division checkpoint system.
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Affiliation(s)
- Luisa Laureti
- Cancer Research Center of Marseille, Team DNA Damage Tolerance, CNRS, UMR7258; Inserm, U1068; Institut Paoli-Calmettes; Aix-Marseille University, Marseille, France
| | - Julien Demol
- Cancer Research Center of Marseille, Team DNA Damage Tolerance, CNRS, UMR7258; Inserm, U1068; Institut Paoli-Calmettes; Aix-Marseille University, Marseille, France
| | - Robert P. Fuchs
- Cancer Research Center of Marseille, Team DNA Damage Tolerance, CNRS, UMR7258; Inserm, U1068; Institut Paoli-Calmettes; Aix-Marseille University, Marseille, France
- * E-mail: (RPF); (VP)
| | - Vincent Pagès
- Cancer Research Center of Marseille, Team DNA Damage Tolerance, CNRS, UMR7258; Inserm, U1068; Institut Paoli-Calmettes; Aix-Marseille University, Marseille, France
- * E-mail: (RPF); (VP)
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Abstract
Gene conversion (conversion), the unidirectional transfer of DNA sequence information, occurs as a byproduct of recombinational repair of broken or damaged DNA molecules. Whereas excision repair processes replace damaged DNA by copying the complementary sequence from the undamaged strand of duplex DNA, recombinational mechanisms copy similar sequence, usually in another molecule, to replace the damaged sequence. In mitotic cells the other molecule is usually a sister chromatid, and the repair does not lead to genetic change. Less often a homologous chromosome or homologous sequence in an ectopic position is used. Conversion results from repair in two ways. First, if there was a double-strand gap at the site of a break, homologous sequence will be used as the template for synthesis to fill the gap, thus transferring sequence information in both strands. Second, recombinational repair uses complementary base pairing, and the heteroduplex molecule so formed is a source of conversion, both as heteroduplex and when donor (undamaged template) information is retained after correction of mismatched bases in heteroduplex. There are mechanisms that favour the use of sister molecules that must fail before ectopic homology can be used. Meiotic recombination events lead to the formation of crossovers required in meiosis for orderly segregation of pairs of homologous chromosomes. These events result from recombinational repair of programmed double-strand breaks, but in contrast with mitotic recombination, meiotic recombinational events occur predominantly between homologous chromosomes, so that transfer of sequence differences by conversion is very frequent. Transient recombination events that do not form crossovers form both between homologous chromosomes and between regions of ectopic homology, and leave their mark in the occurrence of frequent non-crossover conversion, including ectopic conversion.
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Genomic assay reveals tolerance of DNA damage by both translesion DNA synthesis and homology-dependent repair in mammalian cells. Proc Natl Acad Sci U S A 2013; 110:E1462-9. [PMID: 23530190 DOI: 10.1073/pnas.1216894110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA lesions can block replication forks and lead to the formation of single-stranded gaps. These replication complications are mitigated by DNA damage tolerance mechanisms, which prevent deleterious outcomes such as cell death, genomic instability, and carcinogenesis. The two main tolerance strategies are translesion DNA synthesis (TLS), in which low-fidelity DNA polymerases bypass the blocking lesion, and homology-dependent repair (HDR; postreplication repair), which is based on the homologous sister chromatid. Here we describe a unique high-resolution method for the simultaneous analysis of TLS and HDR across defined DNA lesions in mammalian genomes. The method is based on insertion of plasmids carrying defined site-specific DNA lesions into mammalian chromosomes, using phage integrase-mediated integration. Using this method we show that mammalian cells use HDR to tolerate DNA damage in their genome. Moreover, analysis of the tolerance of the UV light-induced 6-4 photoproduct, the tobacco smoke-induced benzo[a]pyrene-guanine adduct, and an artificial trimethylene insert shows that each of these three lesions is tolerated by both TLS and HDR. We also determined the specificity of nucleotide insertion opposite these lesions during TLS in human genomes. This unique method will be useful in elucidating the mechanism of DNA damage tolerance in mammalian chromosomes and their connection to pathological processes such as carcinogenesis.
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Diamant N, Hendel A, Vered I, Carell T, Reissner T, de Wind N, Geacinov N, Livneh Z. DNA damage bypass operates in the S and G2 phases of the cell cycle and exhibits differential mutagenicity. Nucleic Acids Res 2011; 40:170-80. [PMID: 21908406 PMCID: PMC3245908 DOI: 10.1093/nar/gkr596] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Translesion DNA synthesis (TLS) employs low-fidelity DNA polymerases to bypass replication-blocking lesions, and being associated with chromosomal replication was presumed to occur in the S phase of the cell cycle. Using immunostaining with anti-replication protein A antibodies, we show that in UV-irradiated mammalian cells, chromosomal single-stranded gaps formed in S phase during replication persist into the G2 phase of the cell cycle, where their repair is completed depending on DNA polymerase ζ and Rev1. Analysis of TLS using a high-resolution gapped-plasmid assay system in cell populations enriched by centrifugal elutriation for specific cell cycle phases showed that TLS operates both in S and G2. Moreover, the mutagenic specificity of TLS in G2 was different from S, and in some cases overall mutation frequency was higher. These results suggest that TLS repair of single-stranded gaps caused by DNA lesions can lag behind chromosomal replication, is separable from it, and occurs both in the S and G2 phases of the cell cycle. Such a mechanism may function to maintain efficient replication, which can progress despite the presence of DNA lesions, with TLS lagging behind and patching regions of discontinuity.
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Affiliation(s)
- Noam Diamant
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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Bichara M, Meier M, Wagner J, Cordonnier A, Lambert IB. Postreplication repair mechanisms in the presence of DNA adducts in Escherichia coli. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2011; 727:104-22. [DOI: 10.1016/j.mrrev.2011.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 04/25/2011] [Accepted: 04/26/2011] [Indexed: 02/02/2023]
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Adar S, Izhar L, Hendel A, Geacintov N, Livneh Z. Repair of gaps opposite lesions by homologous recombination in mammalian cells. Nucleic Acids Res 2009; 37:5737-48. [PMID: 19654238 PMCID: PMC2761288 DOI: 10.1093/nar/gkp632] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Damages in the DNA template inhibit the progression of replication, which may cause single-stranded gaps. Such situations can be tolerated by translesion DNA synthesis (TLS), or by homology-dependent repair (HDR), which is based on transfer or copying of the missing information from the replicated sister chromatid. Whereas it is well established that TLS plays an important role in DNA damage tolerance in mammalian cells, it is unknown whether HDR operates in this process. Using a newly developed plasmid-based assay that distinguishes between the three mechanisms of DNA damage tolerance, we found that mammalian cells can efficiently utilize HDR to repair DNA gaps opposite an abasic site or benzo[a]pyrene adduct. The majority of these events occurred by a physical strand transfer (homologous recombination repair; HRR), rather than a template switch mechanism. Furthermore, cells deficient in either the human RAD51 recombination protein or NBS1, but not Rad18, exhibited decreased gap repair through HDR, indicating a role for these proteins in DNA damage tolerance. To our knowledge, this is the first direct evidence of gap-lesion repair via HDR in mammalian cells, providing further molecular insight into the potential activity of HDR in overcoming replication obstacles and maintaining genome stability.
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Affiliation(s)
- Sheera Adar
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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