1
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Schreuder A, Wendel TJ, Dorresteijn CGV, Noordermeer SM. (Single-stranded DNA) gaps in understanding BRCAness. Trends Genet 2024:S0168-9525(24)00100-8. [PMID: 38789375 DOI: 10.1016/j.tig.2024.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024]
Abstract
The tumour-suppressive roles of BRCA1 and 2 have been attributed to three seemingly distinct functions - homologous recombination, replication fork protection, and single-stranded (ss)DNA gap suppression - and their relative importance is under debate. In this review, we examine the origin and resolution of ssDNA gaps and discuss the recent advances in understanding the role of BRCA1/2 in gap suppression. There are ample data showing that gap accumulation in BRCA1/2-deficient cells is linked to genomic instability and chemosensitivity. However, it remains unclear whether there is a causative role and the function of BRCA1/2 in gap suppression cannot unambiguously be dissected from their other functions. We therefore conclude that the three functions of BRCA1 and 2 are closely intertwined and not mutually exclusive.
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Affiliation(s)
- Anne Schreuder
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Tiemen J Wendel
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Carlo G V Dorresteijn
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands
| | - Sylvie M Noordermeer
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands.
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2
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Yakoub G, Choi YS, Wong RP, Strauch T, Ann KJ, Cohen RE, Ulrich HD. Avidity-based biosensors for ubiquitylated PCNA reveal choreography of DNA damage bypass. SCIENCE ADVANCES 2023; 9:eadf3041. [PMID: 37672592 PMCID: PMC10482348 DOI: 10.1126/sciadv.adf3041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 08/03/2023] [Indexed: 09/08/2023]
Abstract
In eukaryotes, the posttranslational modifier ubiquitin is used to regulate the amounts, interactions, or activities of proteins in diverse pathways and signaling networks. Its effects are mediated by monoubiquitin or polyubiquitin chains of varying geometries. We describe the design, validation, and application of a series of avidity-based probes against the ubiquitylated forms of the DNA replication clamp, proliferating cell nuclear antigen (PCNA), in budding yeast. Directed against total ubiquitylated PCNA or specifically K63-polyubiquitylated PCNA, the probes are tunable in their activities and can be used either as biosensors or as inhibitors of the PCNA-dependent DNA damage bypass pathway. Used in live cells, the probes revealed the timing of PCNA ubiquitylation during damage bypass and a particular susceptibility of the ribosomal DNA locus to the activation of the pathway. Our approach is applicable to a wide range of ubiquitin-conjugated proteins, thus representing a generalizable strategy for the design of biosensors for specific (poly)ubiquitylated forms of individual substrates.
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Affiliation(s)
- George Yakoub
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Yun-Seok Choi
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Ronald P. Wong
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Tina Strauch
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Kezia J. Ann
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Robert E. Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Helle D. Ulrich
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
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3
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Sun H, Ma L, Tsai YF, Abeywardana T, Shen B, Zheng L. Okazaki fragment maturation: DNA flap dynamics for cell proliferation and survival. Trends Cell Biol 2023; 33:221-234. [PMID: 35879148 PMCID: PMC9867784 DOI: 10.1016/j.tcb.2022.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 01/24/2023]
Abstract
Unsuccessful processing of Okazaki fragments leads to the accumulation of DNA breaks which are associated with many human diseases including cancer and neurodegenerative disorders. Recently, Okazaki fragment maturation (OFM) has received renewed attention regarding how unprocessed Okazaki fragments are sensed and repaired, and how inappropriate OFM impacts on genome stability and cell viability, especially in cancer cells. We provide an overview of the highly efficient and faithful canonical OFM pathways and their regulation of genomic integrity and cell survival. We also discuss how cells induce alternative error-prone OFM processes to promote cell survival in response to environmental stresses. Such stress-induced OFM processes may be important mechanisms driving mutagenesis, cellular evolution, and resistance to radio/chemotherapy and targeted therapeutics in human cancers.
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Affiliation(s)
- Haitao Sun
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Lingzi Ma
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Ya-Fang Tsai
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Tharindu Abeywardana
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.
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4
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Allred DR. Integration of DNA Repair, Antigenic Variation, Cytoadhesion, and Chance in Babesia Survival: A Perspective. Front Cell Infect Microbiol 2022; 12:869696. [PMID: 35493746 PMCID: PMC9047050 DOI: 10.3389/fcimb.2022.869696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites live in hostile environments in which they are challenged chemically and their hosts attempt in many ways to kill them. In response, the parasites have evolved multiple mechanisms that take advantage of these challenges to enhance their survival. Perhaps the most impressive example is the evolutionary co-option of DNA repair mechanisms by the parasites as a means to rapidly manipulate the structure, antigenicity, and expression of the products of specific multigene families. The purpose of variant proteins that mediate cytoadhesion has long been thought to be primarily the avoidance of splenic clearance. Based upon known biology, I present an alternative perspective in which it is survival of the oxidative environment within which Babesia spp. parasites live that has driven integration of DNA repair, antigenic variation, and cytoadhesion, and speculate on how genome organization affects that integration. This perspective has ramifications for the development of parasite control strategies.
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Affiliation(s)
- David R. Allred
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, United States
- Genetics Institute, University of Florida, Gainesville, FL, United States
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
- *Correspondence: David R. Allred,
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5
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Zhang B, Zhang Q, Zhu X, Li D, Duan X, Jin J, Wang K, Xie Y, Liu Y. Mechanistic Insight Into Cadmium- and Zinc-Induced Inactivation of the Candida albicans Pif1 Helicase. Front Mol Biosci 2022; 8:778647. [PMID: 35127815 PMCID: PMC8815974 DOI: 10.3389/fmolb.2021.778647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/03/2021] [Indexed: 11/13/2022] Open
Abstract
Zinc and cadmium are environmental contaminants that can cause disease by affecting the activity of DNA-repair proteins. In this study, we investigated the effect of Zn2+ and Cd2+ on the Candida albicans Pif1, a DNA-repair helicase that plays a critical role in ensuring genomic stability. We show that Zn2+ and Cd2+ strongly inhibit both the ATPase and the unwinding activities of CaPif1, but have no effect on its DNA binding activity. High concentrations of Cd2+ may bind to the cysteine residues of CaPif1, and its inhibition appears to be difficult to be restored by ethylene diamine tetraacetic acid, while inhibition due to Zn2+ can. When the two ions are at low concentrations, increasing the concentration of ATP in the reaction can appropriately weaken the inhibitory effect of Zn2+, while cysteine can reduce the inhibitory effect of Cd2+. In addition, we found that for both Cd2+ and Zn2+ the inhibition effects were nearly 100 times greater in reduced environments than in non-reducing environments. When heavy metals stimulate the body’s response, the environment of the body becomes less reducing, and thus the tolerance of CaPif1 to heavy metals will be stronger. We propose that CaPif1 may resist the toxicity of heavy metals through this mechanism. Altogether, our results provide new insights into the mechanisms by which heavy metals are toxic to DNA-repair proteins.
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Affiliation(s)
- Bo Zhang
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
- *Correspondence: Yang Liu, ; Yan Xie, ; Bo Zhang,
| | - Qintao Zhang
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Xinting Zhu
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Dayu Li
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Xiaolei Duan
- Medical Laboratory, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jiao Jin
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Kejia Wang
- College of Life Sciences, Guizhou University, Guiyang, China
| | - Yan Xie
- School of Public Health, Zunyi Medical University, Zunyi, China
- *Correspondence: Yang Liu, ; Yan Xie, ; Bo Zhang,
| | - Yang Liu
- School of Public Health, Zunyi Medical University, Zunyi, China
- *Correspondence: Yang Liu, ; Yan Xie, ; Bo Zhang,
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6
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Che J, Hong X, Rao H. PCNA Ubiquitylation: Instructive or Permissive to DNA Damage Tolerance Pathways? Biomolecules 2021; 11:biom11101543. [PMID: 34680175 PMCID: PMC8533919 DOI: 10.3390/biom11101543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/12/2021] [Accepted: 10/15/2021] [Indexed: 11/16/2022] Open
Abstract
DNA lesions escaping from repair often block the DNA replicative polymerases required for DNA replication and are handled during the S/G2 phases by the DNA damage tolerance (DDT) mechanisms, which include the error-prone translesion synthesis (TLS) and the error-free template switching (TS) pathways. Where the mono-ubiquitylation of PCNA K164 is critical for TLS, the poly-ubiquitylation of the same residue is obligatory for TS. However, it is not known how cells divide the labor between TLS and TS. Due to the fact that the type of DNA lesion significantly influences the TLS and TS choice, we propose that, instead of altering the ratio between the mono- and poly-Ub forms of PCNA, the competition between TLS and TS would automatically determine the selection between the two pathways. Future studies, especially the single integrated lesion “i-Damage” system, would elucidate detailed mechanisms governing the choices of specific DDT pathways.
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Affiliation(s)
- Jun Che
- Correspondence: (J.C.); (H.R.)
| | | | - Hai Rao
- Correspondence: (J.C.); (H.R.)
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7
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Identifying PIF1 as a Potential Target of Wenxia Changfu Formula in Promoting Lung Cancer Cell Apoptosis: Bioinformatics Analysis and Biological Evidence. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:9942462. [PMID: 34608398 PMCID: PMC8487367 DOI: 10.1155/2021/9942462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 09/08/2021] [Indexed: 12/25/2022]
Abstract
Lung cancer remains the leading cause of cancer-related deaths worldwide. Traditional Chinese medicine (TCM) is a valuable resource of active natural products and plays an important role in cancer treatment with the advantages of high efficiency and safety. Wenxia Changfu formula (WCF) is modified from Dahuang Fuzi decoction from Han Dynasty and has been used for treating lung cancer in China. Our previous research showed that WCF had an antitumor effect in vivo and in vitro, while the mechanism has not been well illustrated. In this study, the effect of WCF on the proliferative ability in three lung cancer cells and one noncancerous human cell line was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. WCF suppressed A549, H460, and PC-9 cell viability in a dose-dependent manner, with no inhibition of noncancerous MRC-5 cells after 48 h treatment with WCF (0–50 mg/mL). Furthermore, we screened for genes in A549 cells using four WCF-treated samples and four control samples on a gene expression profile microarray. 21 genes were significantly downregulated by WCF, which may potentially play an important role in the proliferation of A549 cells. High-content screening evaluated whether silencing the 21 genes affected A549 cell growth. The results showed that PIF1 knockdown exhibited the most potent inhibition of cell proliferation compared with the other genes. Downregulation of PIF1 increased A549 cell apoptosis and the activity of caspase 3/7. Besides, RT-PCR showed that the expression levels of PIF1 mRNA decreased significantly in A549, H460, and PC-9 cells after WCF treatment. In conclusion, the present observations indicate that WCF may inhibit lung cancer cell proliferation by promoting apoptosis via regulating the expression of PIF1.
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8
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Prado F. Non-Recombinogenic Functions of Rad51, BRCA2, and Rad52 in DNA Damage Tolerance. Genes (Basel) 2021; 12:genes12101550. [PMID: 34680945 PMCID: PMC8535942 DOI: 10.3390/genes12101550] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/28/2022] Open
Abstract
The DNA damage tolerance (DDT) response is aimed to timely and safely complete DNA replication by facilitating the advance of replication forks through blocking lesions. This process is associated with an accumulation of single-strand DNA (ssDNA), both at the fork and behind the fork. Lesion bypass and ssDNA filling can be performed by translation synthesis (TLS) and template switching mechanisms. TLS uses low-fidelity polymerases to incorporate a dNTP opposite the blocking lesion, whereas template switching uses a Rad51/ssDNA nucleofilament and the sister chromatid to bypass the lesion. Rad51 is loaded at this nucleofilament by two mediator proteins, BRCA2 and Rad52, and these three factors are critical for homologous recombination (HR). Here, we review recent advances showing that Rad51, BRCA2, and Rad52 perform some of these functions through mechanisms that do not require the strand exchange activity of Rad51: the formation and protection of reversed fork structures aimed to bypass blocking lesions, and the promotion of TLS. These findings point to the central HR proteins as potential molecular switches in the choice of the mechanism of DDT.
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Affiliation(s)
- Félix Prado
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, 41092 Seville, Spain
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9
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Arbel M, Liefshitz B, Kupiec M. DNA damage bypass pathways and their effect on mutagenesis in yeast. FEMS Microbiol Rev 2021; 45:5896953. [PMID: 32840566 DOI: 10.1093/femsre/fuaa038] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/23/2020] [Indexed: 12/11/2022] Open
Abstract
What is the origin of mutations? In contrast to the naïve notion that mutations are unfortunate accidents, genetic research in microorganisms has demonstrated that most mutations are created by genetically encoded error-prone repair mechanisms. However, error-free repair pathways also exist, and it is still unclear how cells decide when to use one repair method or the other. Here, we summarize what is known about the DNA damage tolerance mechanisms (also known as post-replication repair) for perhaps the best-studied organism, the yeast Saccharomyces cerevisiae. We describe the latest research, which has established the existence of at least two error-free and two error-prone inter-related mechanisms of damage tolerance that compete for the handling of spontaneous DNA damage. We explore what is known about the induction of mutations by DNA damage. We point to potential paradoxes and to open questions that still remain unanswered.
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Affiliation(s)
- Matan Arbel
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Batia Liefshitz
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Ramat Aviv 69978, Israel
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10
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Simoneau A, Xiong R, Zou L. The trans cell cycle effects of PARP inhibitors underlie their selectivity toward BRCA1/2-deficient cells. Genes Dev 2021; 35:1271-1289. [PMID: 34385259 PMCID: PMC8415318 DOI: 10.1101/gad.348479.121] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 06/30/2021] [Indexed: 11/25/2022]
Abstract
In this study, Simoneau et al. investigated why PARPi is more effective than other DNA-damaging drugs when used to treat BRCA1/2-deficient tumors. They show that PARPi induces DSBs progressively through trans-cell-cycle ssDNA gaps, and BRCA1/2-deficient cells fail to slow down and repair DSBs over multiple cell cycles, explaining the unique efficacy of PARPi in BRCA1/2-deficient cells. PARP inhibitor (PARPi) is widely used to treat BRCA1/2-deficient tumors, but why PARPi is more effective than other DNA-damaging drugs is unclear. Here, we show that PARPi generates DNA double-strand breaks (DSBs) predominantly in a trans cell cycle manner. During the first S phase after PARPi exposure, PARPi induces single-stranded DNA (ssDNA) gaps behind DNA replication forks. By trapping PARP on DNA, PARPi prevents the completion of gap repair until the next S phase, leading to collisions of replication forks with ssDNA gaps and a surge of DSBs. In the second S phase, BRCA1/2-deficient cells are unable to suppress origin firing through ATR, resulting in continuous DNA synthesis and more DSBs. Furthermore, BRCA1/2-deficient cells cannot recruit RAD51 to repair collapsed forks. Thus, PARPi induces DSBs progressively through trans cell cycle ssDNA gaps, and BRCA1/2-deficient cells fail to slow down and repair DSBs over multiple cell cycles, explaining the unique efficacy of PARPi in BRCA1/2-deficient cells.
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Affiliation(s)
- Antoine Simoneau
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Rosalinda Xiong
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA.,Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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11
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Branzei D, Szakal B. DNA helicases in homologous recombination repair. Curr Opin Genet Dev 2021; 71:27-33. [PMID: 34271541 DOI: 10.1016/j.gde.2021.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 12/22/2022]
Abstract
Helicases are in the spotlight of DNA metabolism and are critical for DNA repair in all domains of life. At their biochemical core, they bind and hydrolyze ATP, converting this energy to translocate unidirectionally, with different strand polarities and substrate binding specificities, along one strand of a nucleic acid. In doing so, DNA and RNA helicases separate duplex strands or remove nucleoprotein complexes, affecting DNA repair and the architecture of replication forks. In this review, we focus on recent advances on the roles and regulations of DNA helicases in homologous recombination repair, a critical pathway for mending damaged chromosomes and for ensuring genome integrity.
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Affiliation(s)
- Dana Branzei
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, 20139, Milan, Italy; Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100, Pavia, Italy.
| | - Barnabas Szakal
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, 20139, Milan, Italy
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12
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Wong RP, Petriukov K, Ulrich HD. Daughter-strand gaps in DNA replication - substrates of lesion processing and initiators of distress signalling. DNA Repair (Amst) 2021; 105:103163. [PMID: 34186497 DOI: 10.1016/j.dnarep.2021.103163] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 10/21/2022]
Abstract
Dealing with DNA lesions during genome replication is particularly challenging because damaged replication templates interfere with the progression of the replicative DNA polymerases and thereby endanger the stability of the replisome. A variety of mechanisms for the recovery of replication forks exist, but both bacteria and eukaryotic cells also have the option of continuing replication downstream of the lesion, leaving behind a daughter-strand gap in the newly synthesized DNA. In this review, we address the significance of these single-stranded DNA structures as sites of DNA damage sensing and processing at a distance from ongoing genome replication. We describe the factors controlling the emergence of daughter-strand gaps from stalled replication intermediates, the benefits and risks of their expansion and repair via translesion synthesis or recombination-mediated template switching, and the mechanisms by which they activate local as well as global replication stress signals. Our growing understanding of daughter-strand gaps not only identifies them as targets of fundamental genome maintenance mechanisms, but also suggests that proper control over their activities has important practical implications for treatment strategies and resistance mechanisms in cancer therapy.
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Affiliation(s)
- Ronald P Wong
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, D - 55128 Mainz, Germany
| | - Kirill Petriukov
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, D - 55128 Mainz, Germany
| | - Helle D Ulrich
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, D - 55128 Mainz, Germany.
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13
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Alekseeva EA, Korolev VG. DNA Damage Tolerance in the Yeast Saccharomyces cerevisiae. RUSS J GENET+ 2021. [DOI: 10.1134/s1022795421040025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Piberger AL, Bowry A, Kelly RDW, Walker AK, González-Acosta D, Bailey LJ, Doherty AJ, Méndez J, Morris JR, Bryant HE, Petermann E. PrimPol-dependent single-stranded gap formation mediates homologous recombination at bulky DNA adducts. Nat Commun 2020; 11:5863. [PMID: 33203852 PMCID: PMC7673990 DOI: 10.1038/s41467-020-19570-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 10/15/2020] [Indexed: 11/09/2022] Open
Abstract
Stalled replication forks can be restarted and repaired by RAD51-mediated homologous recombination (HR), but HR can also perform post-replicative repair after bypass of the obstacle. Bulky DNA adducts are important replication-blocking lesions, but it is unknown whether they activate HR at stalled forks or behind ongoing forks. Using mainly BPDE-DNA adducts as model lesions, we show that HR induced by bulky adducts in mammalian cells predominantly occurs at post-replicative gaps formed by the DNA/RNA primase PrimPol. RAD51 recruitment under these conditions does not result from fork stalling, but rather occurs at gaps formed by PrimPol re-priming and resection by MRE11 and EXO1. In contrast, RAD51 loading at double-strand breaks does not require PrimPol. At bulky adducts, PrimPol promotes sister chromatid exchange and genetic recombination. Our data support that HR at bulky adducts in mammalian cells involves post-replicative gap repair and define a role for PrimPol in HR-mediated DNA damage tolerance.
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Affiliation(s)
- Ann Liza Piberger
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Akhil Bowry
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Richard D W Kelly
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Alexandra K Walker
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | | | - Laura J Bailey
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Juan Méndez
- Molecular Oncology Program, Spanish National Cancer Research Centre, Madrid, Spain
| | - Joanna R Morris
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Helen E Bryant
- Department of Oncology & Metabolism, The Medical School, University of Sheffield, Sheffield, S10 2RX, UK
| | - Eva Petermann
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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15
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Falquet B, Ölmezer G, Enkner F, Klein D, Challa K, Appanah R, Gasser SM, Rass U. Disease-associated DNA2 nuclease-helicase protects cells from lethal chromosome under-replication. Nucleic Acids Res 2020; 48:7265-7278. [PMID: 32544229 PMCID: PMC7367196 DOI: 10.1093/nar/gkaa524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 05/21/2020] [Accepted: 06/09/2020] [Indexed: 01/28/2023] Open
Abstract
DNA2 is an essential nuclease–helicase implicated in DNA repair, lagging-strand DNA synthesis, and the recovery of stalled DNA replication forks (RFs). In Saccharomyces cerevisiae, dna2Δ inviability is reversed by deletion of the conserved helicase PIF1 and/or DNA damage checkpoint-mediator RAD9. It has been suggested that Pif1 drives the formation of long 5′-flaps during Okazaki fragment maturation, and that the essential function of Dna2 is to remove these intermediates. In the absence of Dna2, 5′-flaps are thought to accumulate on the lagging strand, resulting in DNA damage-checkpoint arrest and cell death. In line with Dna2’s role in RF recovery, we find that the loss of Dna2 results in severe chromosome under-replication downstream of endogenous and exogenous RF-stalling. Importantly, unfaithful chromosome replication in Dna2-mutant cells is exacerbated by Pif1, which triggers the DNA damage checkpoint along a pathway involving Pif1’s ability to promote homologous recombination-coupled replication. We propose that Dna2 fulfils its essential function by promoting RF recovery, facilitating replication completion while suppressing excessive RF restart by recombination-dependent replication (RDR) and checkpoint activation. The critical nature of Dna2’s role in controlling the fate of stalled RFs provides a framework to rationalize the involvement of DNA2 in Seckel syndrome and cancer.
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Affiliation(s)
- Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Gizem Ölmezer
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Franz Enkner
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Dominique Klein
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Rowin Appanah
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Ulrich Rass
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
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16
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Zacheja T, Toth A, Harami GM, Yang Q, Schwindt E, Kovács M, Paeschke K, Burkovics P. Mgs1 protein supports genome stability via recognition of G-quadruplex DNA structures. FASEB J 2020; 34:12646-12662. [PMID: 32748509 DOI: 10.1096/fj.202000886r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/19/2020] [Accepted: 07/10/2020] [Indexed: 01/02/2023]
Abstract
The integrity of the genetic material is crucial for every organism. One intrinsic attack to genome stability is stalling of the replication fork which can result in DNA breakage. Several factors, such as DNA lesions or the formation of stable secondary structures (eg, G-quadruplexes) can lead to replication fork stalling. G-quadruplexes (G4s) are well-characterized stable secondary DNA structures that can form within specific single-stranded DNA sequence motifs and have been shown to block/pause the replication machinery. In most genomes several helicases have been described to regulate G4 unfolding to preserve genome integrity, however, different experiments raise the hypothesis that processing of G4s during DNA replication is more complex and requires additional, so far unknown, proteins. Here, we show that the Saccharomyces cerevisiae Mgs1 protein robustly binds to G4 structures in vitro and preferentially acts at regions with a strong potential to form G4 structures in vivo. Our results suggest that Mgs1 binds to G4-forming sites and has a role in the maintenance of genome integrity.
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Affiliation(s)
- Theresa Zacheja
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Agnes Toth
- Biological Research Centre, Institute of Genetics, Szeged, Hungary.,Doctoral School of Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Gabor M Harami
- ELTE-MTA Momentum Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Qianlu Yang
- Department of Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany.,Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Eike Schwindt
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Mihály Kovács
- ELTE-MTA Momentum Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary.,MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Katrin Paeschke
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany.,Department of Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Peter Burkovics
- Biological Research Centre, Institute of Genetics, Szeged, Hungary
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17
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Contractions of the C-Terminal Domain of Saccharomyces cerevisiae Rpb1p Are Mediated by Rad5p. G3-GENES GENOMES GENETICS 2020; 10:2543-2551. [PMID: 32467128 PMCID: PMC7341143 DOI: 10.1534/g3.120.401409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The C-terminal domain (CTD) is an essential domain of the largest subunit of RNA polymerase II, Rpb1p, and is composed of 26 tandem repeats of a seven-amino acid sequence, YSPTSPS. Despite being an essential domain within an essential gene, we have previously demonstrated that the CTD coding region is genetically unstable. Furthermore, yeast with a truncated or mutated CTD sequence are capable of promoting spontaneous genetic expansion or contraction of this coding region to improve fitness. We investigated the mechanism by which the CTD contracts using a tet-off reporter system for RPB1 to monitor genetic instability within the CTD coding region. We report that contractions require the post-replication repair factor Rad5p but, unlike expansions, not the homologous recombination factors Rad51p and Rad52p. Sequence analysis of contraction events reveals that deleted regions are flanked by microhomologies. We also find that G-quadruplex forming sequences predicted by the QGRS Mapper are enriched on the noncoding strand of the CTD compared to the body of RPB1. Formation of G-quadruplexes in the CTD coding region could block the replication fork, necessitating post-replication repair. We propose that contractions of the CTD result when microhomologies misalign during Rad5p-dependent template switching via fork reversal.
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18
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Access to PCNA by Srs2 and Elg1 Controls the Choice between Alternative Repair Pathways in Saccharomyces cerevisiae. mBio 2020; 11:mBio.00705-20. [PMID: 32371600 PMCID: PMC7403780 DOI: 10.1128/mbio.00705-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PCNA, the ring that encircles DNA maintaining the processivity of DNA polymerases, is modified by ubiquitin and SUMO. Whereas ubiquitin is required for bypassing lesions through the DNA damage tolerance (DDT) pathways, we show here that SUMOylation represses another pathway, salvage recombination. The Srs2 helicase is recruited to SUMOylated PCNA and prevents the salvage pathway from acting. The pathway can be induced by overexpressing the PCNA unloader Elg1, or the homologous recombination protein Rad52. Our results underscore the role of PCNA modifications in controlling the various bypass and DNA repair mechanisms. During DNA replication, stalling can occur when the replicative DNA polymerases encounter lesions or hard-to replicate regions. Under these circumstances, the processivity factor PCNA gets ubiquitylated at lysine 164, inducing the DNA damage tolerance (DDT) mechanisms that can bypass lesions encountered during DNA replication. PCNA can also be SUMOylated at the same residue or at lysine 127. Surprisingly, pol30-K164R mutants display a higher degree of sensitivity to DNA-damaging agents than pol30-KK127,164RR strains, unable to modify any of the lysines. Here, we show that in addition to translesion synthesis and strand-transfer DDT mechanisms, an alternative repair mechanism (“salvage recombination”) that copies information from the sister chromatid is repressed by the recruitment of Srs2 to SUMOylated PCNA. Overexpression of Elg1, the PCNA unloader, or of the recombination protein Rad52 allows its activation. We dissect the genetic requirements for this pathway, as well as the interactions between Srs2 and Elg1.
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19
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Langston RE, Palazzola D, Bonnell E, Wellinger RJ, Weinert T. Loss of Cdc13 causes genome instability by a deficiency in replication-dependent telomere capping. PLoS Genet 2020; 16:e1008733. [PMID: 32287268 PMCID: PMC7205313 DOI: 10.1371/journal.pgen.1008733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 05/07/2020] [Accepted: 03/23/2020] [Indexed: 01/02/2023] Open
Abstract
In budding yeast, Cdc13, Stn1, and Ten1 form the telomere-binding heterotrimer CST complex. Here we investigate the role of Cdc13/CST in maintaining genome stability by using a Chr VII disome system that can generate recombinants, chromosome loss, and enigmatic unstable chromosomes. In cells expressing a temperature sensitive CDC13 allele, cdc13F684S, unstable chromosomes frequently arise from problems in or near a telomere. We found that, when Cdc13 is defective, passage through S phase causes Exo1-dependent ssDNA and unstable chromosomes that are then the source for additional chromosome instability events (e.g. recombinants, chromosome truncations, dicentrics, and/or chromosome loss). We observed that genome instability arises from a defect in Cdc13’s function during DNA replication, not Cdc13’s putative post-replication telomere capping function. The molecular nature of the initial unstable chromosomes formed by a Cdc13-defect involves ssDNA and does not involve homologous recombination nor non-homologous end joining; we speculate the original unstable chromosome may be a one-ended double strand break. This system defines a link between Cdc13’s function during DNA replication and genome stability in the form of unstable chromosomes, that then progress to form other chromosome changes. Eukaryotic chromosomes are linear molecules with specialized end structures called telomeres. Telomeres contain both unique repetitive DNA sequences and specialized proteins that solve several biological problems by differentiating chromosomal ends from internal breaks, thus preventing chromosome instability. When telomeres are defective, the entire chromosome can become unstable and change, causing mutations and pathology (cancer, aging, etc.). Here we study how a defect in specific telomere proteins causes chromosomal rearrangements, using the model organism Saccharomyces cerevisiae (budding or brewer’s yeast). We find that when specific telomere proteins are defective, errors in DNA replication generate a type of damage that likely involves extensive single-stranded DNA that forms inherently unstable chromosomes, subject to many subsequent instances of instability (e.g. allelic recombinants, chromosome loss, truncations, dicentrics). The telomere protein Cdc13 is part of a protein complex called CST that is conserved in most organisms including mammalian cells. The technical capacity of studies in budding yeast allow a detailed, real-time examination of how telomere defects compromise chromosome stability in a single cell cycle, generating lessons likely relevant to how human telomeres keep human chromosomes stable.
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Affiliation(s)
- Rachel E. Langston
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
| | - Dominic Palazzola
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
| | - Erin Bonnell
- Department of Microbiology and Infectiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Raymund J. Wellinger
- Department of Microbiology and Infectiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ted Weinert
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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20
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Takahashi TS, Wollscheid HP, Lowther J, Ulrich HD. Effects of chain length and geometry on the activation of DNA damage bypass by polyubiquitylated PCNA. Nucleic Acids Res 2020; 48:3042-3052. [PMID: 32009145 PMCID: PMC7102961 DOI: 10.1093/nar/gkaa053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 01/15/2020] [Accepted: 01/30/2020] [Indexed: 01/06/2023] Open
Abstract
Ubiquitylation of the eukaryotic sliding clamp, PCNA, activates a pathway of DNA damage bypass that facilitates the replication of damaged DNA. In its monoubiquitylated form, PCNA recruits a set of damage-tolerant DNA polymerases for translesion synthesis. Alternatively, modification by K63-linked polyubiquitylation triggers a recombinogenic process involving template switching. Despite the identification of proteins interacting preferentially with polyubiquitylated PCNA, the molecular function of the chain and the relevance of its K63-linkage are poorly understood. Using genetically engineered mimics of polyubiquitylated PCNA, we have now examined the properties of the ubiquitin chain required for damage bypass in budding yeast. By varying key parameters such as the geometry of the junction, cleavability and capacity for branching, we demonstrate that either the structure of the ubiquitin-ubiquitin junction or its dynamic assembly or disassembly at the site of action exert a critical impact on damage bypass, even though known effectors of polyubiquitylated PCNA are not strictly linkage-selective. Moreover, we found that a single K63-junction supports substantial template switching activity, irrespective of its attachment site on PCNA. Our findings provide insight into the interrelationship between the two branches of damage bypass and suggest the existence of a yet unidentified, highly linkage-selective receptor of polyubiquitylated PCNA.
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Affiliation(s)
- Tomio S Takahashi
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | | | | | - Helle D Ulrich
- Institute of Molecular Biology gGmbH (IMB), Ackermannweg 4, D-55128 Mainz, Germany
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21
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Muellner J, Schmidt KH. Yeast Genome Maintenance by the Multifunctional PIF1 DNA Helicase Family. Genes (Basel) 2020; 11:genes11020224. [PMID: 32093266 PMCID: PMC7073672 DOI: 10.3390/genes11020224] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/11/2020] [Accepted: 02/13/2020] [Indexed: 12/04/2022] Open
Abstract
The two PIF1 family helicases in Saccharomyces cerevisiae, Rrm3, and ScPif1, associate with thousands of sites throughout the genome where they perform overlapping and distinct roles in telomere length maintenance, replication through non-histone proteins and G4 structures, lagging strand replication, replication fork convergence, the repair of DNA double-strand break ends, and transposable element mobility. ScPif1 and its fission yeast homolog Pfh1 also localize to mitochondria where they protect mitochondrial genome integrity. In addition to yeast serving as a model system for the rapid functional evaluation of human Pif1 variants, yeast cells lacking Rrm3 have proven useful for elucidating the cellular response to replication fork pausing at endogenous sites. Here, we review the increasingly important cellular functions of the yeast PIF1 helicases in maintaining genome integrity, and highlight recent advances in our understanding of their roles in facilitating fork progression through replisome barriers, their functional interactions with DNA repair, and replication stress response pathways.
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Affiliation(s)
- Julius Muellner
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA;
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
| | - Kristina H. Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA;
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
- Correspondence:
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22
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Pilzecker B, Buoninfante OA, Jacobs H. DNA damage tolerance in stem cells, ageing, mutagenesis, disease and cancer therapy. Nucleic Acids Res 2019; 47:7163-7181. [PMID: 31251805 PMCID: PMC6698745 DOI: 10.1093/nar/gkz531] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 05/22/2019] [Accepted: 06/26/2019] [Indexed: 12/12/2022] Open
Abstract
The DNA damage response network guards the stability of the genome from a plethora of exogenous and endogenous insults. An essential feature of the DNA damage response network is its capacity to tolerate DNA damage and structural impediments during DNA synthesis. This capacity, referred to as DNA damage tolerance (DDT), contributes to replication fork progression and stability in the presence of blocking structures or DNA lesions. Defective DDT can lead to a prolonged fork arrest and eventually cumulate in a fork collapse that involves the formation of DNA double strand breaks. Four principal modes of DDT have been distinguished: translesion synthesis, fork reversal, template switching and repriming. All DDT modes warrant continuation of replication through bypassing the fork stalling impediment or repriming downstream of the impediment in combination with filling of the single-stranded DNA gaps. In this way, DDT prevents secondary DNA damage and critically contributes to genome stability and cellular fitness. DDT plays a key role in mutagenesis, stem cell maintenance, ageing and the prevention of cancer. This review provides an overview of the role of DDT in these aspects.
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Affiliation(s)
- Bas Pilzecker
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Olimpia Alessandra Buoninfante
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Heinz Jacobs
- Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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23
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Wong RP, García-Rodríguez N, Zilio N, Hanulová M, Ulrich HD. Processing of DNA Polymerase-Blocking Lesions during Genome Replication Is Spatially and Temporally Segregated from Replication Forks. Mol Cell 2019; 77:3-16.e4. [PMID: 31607544 DOI: 10.1016/j.molcel.2019.09.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/23/2019] [Accepted: 09/10/2019] [Indexed: 11/25/2022]
Abstract
Tracing DNA repair factors by fluorescence microscopy provides valuable information about how DNA damage processing is orchestrated within cells. Most repair pathways involve single-stranded DNA (ssDNA), making replication protein A (RPA) a hallmark of DNA damage and replication stress. RPA foci emerging during S phase in response to tolerable loads of polymerase-blocking lesions are generally thought to indicate stalled replication intermediates. We now report that in budding yeast they predominantly form far away from sites of ongoing replication, and they do not overlap with any of the repair centers associated with collapsed replication forks or double-strand breaks. Instead, they represent sites of postreplicative DNA damage bypass involving translesion synthesis and homologous recombination. We propose that most RPA and recombination foci induced by polymerase-blocking lesions in the replication template are clusters of repair tracts arising from replication centers by polymerase re-priming and subsequent expansion of daughter-strand gaps over the course of S phase.
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Affiliation(s)
- Ronald P Wong
- Institute of Molecular Biology, 55128 Mainz, Germany
| | | | - Nicola Zilio
- Institute of Molecular Biology, 55128 Mainz, Germany
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24
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Bernal M, Yang X, Lisby M, Mazón G. The FANCM family Mph1 helicase localizes to the mitochondria and contributes to mtDNA stability. DNA Repair (Amst) 2019; 82:102684. [DOI: 10.1016/j.dnarep.2019.102684] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 11/24/2022]
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25
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Fang Y, Klosterman SJ, Tian C, Wang Y. Insights into VdCmr1-mediated protection against high temperature stress and UV irradiation in Verticillium dahliae. Environ Microbiol 2019; 21:2977-2996. [PMID: 31136051 DOI: 10.1111/1462-2920.14695] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/21/2019] [Accepted: 05/24/2019] [Indexed: 12/21/2022]
Abstract
The fungus Verticillium dahliae causes vascular wilt disease on more than 200 plant species worldwide. This fungus can survive for years in soil as melanized microsclerotia. We found that VdCmr1, a transcription factor, is required for the melanin production and increased survival following UV irradiation in V. dahliae but not for microsclerotia production or virulence. Here, we provided evidence how VdCmr1 protects against high temperature (HT) and UV irradiation in V. dahliae. The results indicate that VdCmr1 mediates entry to the diapause period in V. dahliae in response to HT and contributes to the expression of proteins to minimize protein misfolding and denaturation. VdCmr1 deletion results in the misregulation of DNA repair machinery, suggestive of reduced DNA repair capacity following UV irradiation and in correlation with the low survival rate of UV-treated VdCmr1 mutants. We discovered a putative VdCmr1-dependent gene cluster associated with secondary metabolism and stress responses. We also functionally characterized two VdCmr1-responsive genes participating in HT and UV response. These results shed further light on the roles of VdCmr1 in protection from HT or UV irradiation, and the additional insights into the mechanisms of this protection may be useful to exploit for more effective disease control.
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Affiliation(s)
- Yulin Fang
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Steven J Klosterman
- U.S. Department of Agriculture-Agricultural Research Service, Salinas, CA, 93905, USA
| | - Chengming Tian
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
| | - Yonglin Wang
- Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, China
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26
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DNA Replication Through Strand Displacement During Lagging Strand DNA Synthesis in Saccharomyces cerevisiae. Genes (Basel) 2019; 10:genes10020167. [PMID: 30795600 PMCID: PMC6409922 DOI: 10.3390/genes10020167] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/14/2019] [Accepted: 02/18/2019] [Indexed: 01/21/2023] Open
Abstract
This review discusses a set of experimental results that support the existence of extended strand displacement events during budding yeast lagging strand DNA synthesis. Starting from introducing the mechanisms and factors involved in leading and lagging strand DNA synthesis and some aspects of the architecture of the eukaryotic replisome, we discuss studies on bacterial, bacteriophage and viral DNA polymerases with potent strand displacement activities. We describe proposed pathways of Okazaki fragment processing via short and long flaps, with a focus on experimental results obtained in Saccharomyces cerevisiae that suggest the existence of frequent and extended strand displacement events during eukaryotic lagging strand DNA synthesis, and comment on their implications for genome integrity.
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27
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Prado F. Homologous Recombination: To Fork and Beyond. Genes (Basel) 2018; 9:genes9120603. [PMID: 30518053 PMCID: PMC6316604 DOI: 10.3390/genes9120603] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 11/29/2018] [Accepted: 11/29/2018] [Indexed: 12/15/2022] Open
Abstract
Accurate completion of genome duplication is threatened by multiple factors that hamper the advance and stability of the replication forks. Cells need to tolerate many of these blocking lesions to timely complete DNA replication, postponing their repair for later. This process of lesion bypass during DNA damage tolerance can lead to the accumulation of single-strand DNA (ssDNA) fragments behind the fork, which have to be filled in before chromosome segregation. Homologous recombination plays essential roles both at and behind the fork, through fork protection/lesion bypass and post-replicative ssDNA filling processes, respectively. I review here our current knowledge about the recombination mechanisms that operate at and behind the fork in eukaryotes, and how these mechanisms are controlled to prevent unscheduled and toxic recombination intermediates. A unifying model to integrate these mechanisms in a dynamic, replication fork-associated process is proposed from yeast results.
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Affiliation(s)
- Félix Prado
- Department of Genome Biology, Andalusian Molecular Biology and Regenerative Medicine Center (CABIMER), CSIC-University of Seville-University Pablo de Olavide, 41092 Seville, Spain.
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